Much attention has recently been focused on the chemical ethylene dibromide (EDB). This chemical has been widely used in leaded gasoline, and has also been used to treat grains, citrus and other crops. It has been found in foods and in groundwater. This paper examines the possible health effects of exposure to EDB, as well as its regulation. The possible health effects and regulation of various chemical and physical alternatives to EDB are also examined. This paper concludes with some policy considerations pertinent to EDB.

CONC/11 is a computer program designed for calculating the performance of dish-type solar thermal collectors and power systems. It is intended to aid the system or collector designer in evaluating the performance to be expected with possible design alternatives. From design or test data on the characteristics of the various subsystems, CONC/11 calculates the efficiencies of the collector and the overall power system as functions of the receiver temperature for a specified insolation. If desired, CONC/11 will also determine the receiver aperture and the receiver temperature that will provide the highest efficiencies at a given insolation. The program handles both simple and compound concentrators. CONC/11 is written in Athena Extended Fortran (similar to Fortran 77) to operate primarily in an interactive mode on a Sperry 1100/81 computer. It could also be used on many small computers.

Stress analysis at Harvard University has examined the implication of non-zero interface stresses on model predictions. Stress distributions at distances greater than about 1 mm from the interface are shown to be independent of the interface stress at high creep intensities, and the predictions based on zero initial stress can be used with confidence. Numerical models for growth dynamics developed at MIT are compared with experimental data on t-V relationships and on interface shape obtained from impurity redistribution in aluminum-doped 10 cm wide ribbon. Comparison of primary creep responses in FZ (floating zone) and CZ (Czochralski) silicon above 1200/sup 0/C using four-point bending indicates that oxygen has a significant influence on the creep rate. Both the strain rate and resulting dislocation densities generated in FZ silicon are an order of magnitude higher than for the CZ material at comparable applied stress levels. A fiber optics probe suitable for temperature measurement during sheet growth has been constructed and tested. Study of the feasibility of using laser interferometric techniques for residual stress measurements has continued at the University of Illinois. The method has been successfully applied to CZ silicon, and is being evaluated for use with EFG ribbon.

Rotorua, New Zealand, lies inside a volcanic caldera. Natural steam is extensively used for space and water heating, and electric power generation. This report presents results of a preliminary reconnaissance survey of atmospheric H/sub 2/S levels in the area and attempts to relate these levels to health statistics in the region. 5 refs., 8 tabs. (ACR)