Hot filament technique for measuring the thermal conductivity of molten lithium fluoride

Molten salts, such as lithium fluoride, are attractive candidates for thermal energy storage in solar dynamic space power systems because of their high latent heat of fusion. However, these same salts have poor thermal conductivities which inhibit the transfer of heat into the solid phase and out of the liquid phase. One concept for improving the thermal conductivity of the thermal energy storage system is to add a conductive filler material to the molten salt. High thermal conductivity pitch-based graphite fibers are being considered for this application. Although there is some information available on the thermal conductivity of lithium fluoride solid, there is very little information on lithium fluoride liquid, and no information on molten salt graphite fiber composites. This paper describes a hot filament technique for determining the thermal conductivity of molten salts. The hot filament technique was used to find the thermal conductivity of molten lithium fluoride at 930 C, and the thermal conductivity values ranged from 1.2 to 1.6 W/mK. These values are comparable to the slightly larger value of 5.0 W/mK for lithium fluoride solid. In addition, two molten salt graphite fiber composites were characterized with the hot filament technique and these results are also presented

Insurance and the Utilization of Medical Services Among the Self-Employed

There has been substantial public policy concern over the relatively low rates of health insurance coverage among the self-employed in the United States. We use data from the Medical Expenditure Panel Survey conducted in 1996 to analyze how the self-employed and wage-earners differ both with respect to insurance coverage and utilization of a variety of health care services. Our results suggest that for the self-employed, the link between insurance and utilization of health care services is not as strong as assumed in the policy debate. For a number of medical care services, the self-employed have the same rates of utilization as wage-earners, despite the fact that they are substantially less likely to be insured. And when the self-employed are less likely than wage-earners to utilize a particular medical service, the differences generally do not seem very large. The self-employed thus appear to be able to finance access to health care from sources other than insurance. Further, analysis of out-of-pocket expenditures on health care suggests that doing so does not lead to substantial reductions in their ability to consume other goods and services. Finally, there is no evidence that children of the self-employed have less access to health care than the children of wage-earners. Hence, the public policy concerns that the relative lack of health insurance among the self-employed substantially reduces utilization of health care services or creates economic hardship appear to be misplaced.

Carmel River Lagoon Enhancement Project: Water Quality and Aquatic Wildlife Monitoring, 2006-7

This is a report to the California Department of Parks and Recreation. It describes water quality and aquatic invertebrate monitoring after the construction of the Carmel River Lagoon Enhancement Project. Included are data that have been collected for two years and preliminary assessment of the enhanced ecosystem. This report marks the completion of 3-years of monitoring water quality and aquatic habitat. The report adopts the same format and certain background text from previous years’ reporting by the same research group (e.g. Larson et al., 2005). (Document contains 100 pages