Surface tension induced convection in encapsulated liquid metals in microgravity: Apollo-Soyuz test project experiment no. MA-041

This experiment was designed to determine the extent of surface tension induced convection caused by a steplike compositional variation in a liquid metal. Preliminary results are presented

Pricing and Time on the Market for Residential Properties in a Major U.K. City

The pricing and length of time to sell single-family residential properties is a function of the interaction between buyer and seller behavior. This study estimates value effects in relation to the time on the market for residential properties within the Belfast (U.K).metropolitan area. Three distinctive characteristics of market are highlighted. First, the majority of sales are at a premium to the list price. Second, different factors influence time on the market for premium and discount sales. Third, the marketing period is examined for three events: listing to sales agreement, sales agreement to completion, and listing to completion.

Modeling thermal responses in human subjects following extended exposure to radiofrequency energy

BACKGROUND: This study examines the use of a simple thermoregulatory model for the human body exposed to extended (45 minute) exposures to radiofrequency/microwave (RF/MW) energy at different frequencies (100, 450, 2450 MHz) and under different environmental conditions. The exposure levels were comparable to or above present limits for human exposure to RF energy. METHODS: We adapted a compartmental model for the human thermoregulatory system developed by Hardy and Stolwijk, adding power to the torso skin, fat, and muscle compartments to simulate exposure to RF energy. The model uses values for parameters for "standard man" that were originally determined by Hardy and Stolwijk, with no additional adjustment. The model predicts changes in core and skin temperatures, sweat rate, and changes in skin blood flow as a result of RF energy exposure. RESULTS: The model yielded remarkably good quantitative agreement between predicted and measured changes in skin and core temperatures, and qualitative agreement between predicted and measured changes in skin blood flow. The model considerably underpredicted the measured sweat rates. CONCLUSIONS: The model, with previously determined parameter values, was successful in predicting major aspects of human thermoregulatory response to RF energy exposure over a wide frequency range, and at different environmental temperatures. The model was most successful in predicting changes in skin temperature, and it provides insights into the mechanisms by which the heat added to body by RF energy is dissipated to the environment. Several factors are discussed that may have contributed to the failure to account properly for sweat rate. Some features of the data, in particular heating of the legs and ankles during exposure at 100 MHz, would require a more complex model than that considered here

NASA scheduling technologies

This paper is a consolidated report on ten major planning and scheduling systems that have been developed by the National Aeronautics and Space Administration (NASA). A description of each system, its components, and how it could be potentially used in private industry is provided in this paper. The planning and scheduling technology represented by the systems ranges from activity based scheduling employing artificial intelligence (AI) techniques to constraint based, iterative repair scheduling. The space related application domains in which the systems have been deployed vary from Space Shuttle monitoring during launch countdown to long term Hubble Space Telescope (HST) scheduling. This paper also describes any correlation that may exist between the work done on different planning and scheduling systems. Finally, this paper documents the lessons learned from the work and research performed in planning and scheduling technology and describes the areas where future work will be conducted

Toward a physiological explanation of juvenile growth curves

Juvenile growth curves are generally sigmoid in shape: Growth is initially nearly exponential, but it slows to near zero as the animal approaches maturity. The drop‐off in growth rate is puzzling because, everything else being equal, selection favors growing as fast as possible. Existing theory posits sublinear scaling of resource acquisition with juvenile body mass and linear scaling of the requirement for maintenance, so the difference, fuel for growth, decreases as the juvenile increases in size. Experimental evidence, however, suggests that maintenance metabolism increases sublinearly not linearly with size. Here, we develop a new theory consistent with the experimental evidence. Our theory is based on the plausible assumption that there is a trade‐off in the capacity of capillaries to supply growing and developed cells. As the proportion of non‐growing cells increases, they take up more macromolecules from the capillaries, leaving fewer to support growing cells. The predicted growth curves are realistic and similar to those of previous models (Bertalanffy, Gompertz, and Logistic) but have the advantage of being derived from a plausible physiological model. We hope that our focus on resource delivery in capillaries will encourage new experimental work to identify the detailed physiological basis of the trade‐off underlying juvenile growth curves