Biomedical subjects
J A Broadway
Publications and source records attributed to J A Broadway.
Significant digits: foundations, myths and utilization.
Scientific text books, journal articles, and all types of other sources of scientific information frequently give certain recommendations and/or make statements of presumed fact concerning the issue of significant digits in scientific computation. Most of these "well-known" facts concerning significance in computation are false. This article discusses the folklore of significant digits, debunks the common cliches, illustrates the actual behavior of computational significance in a typical scenario, and makes recommendations concerning these matters.
Estimates of radiation dose and health risks to the United States population following the Chernobyl nuclear plant accident.
Estimates of both individual and collective doses received by the United States population following the Chernobyl accident have been made by using the data obtained from the U.S. Environmental Protection Agency's Environmental Radiation Ambient Monitoring System. Radionuclides associated with the debris first were measured in precipitation and surface air particulates at Portland, OR and Olympia, WA on 5 May 1986. Iodine-131 was the most consistently measured nuclide in all media, although several Cs and Ru isotopes also were observed. Strontium and any actinides notably were absent from the samples at the lower level of detection. The highest calculated individual-organ dose due to intake during May and June 1986 was 0.52 mSv to the infant thyroid in the state of Washington. This was predominantly (98%) from the ingestion of milk. The maximum U.S. collective dose equivalent to any organ was calculated to be 3,300 person-Sv to the thyroid. Risk estimates project three excess lung cancer deaths and an additional four deaths due to cancers of thyroid, breast and leukemia in the U.S. population over the next 45 y from exposure during the May-June 1986 interval. The only long-lived radionuclide measured in milk samples following the accident was 137Cs. We estimate 20 excess fatalities from the ingestion of 137Cs in milk during all subsequent years, with six of these due to lung cancer and the majority of the remainder distributed approximately equally among cancers of the thyroid, breast, liver and leukemia. A total of 100 excess fatalities from all dietary components was estimated. Because of the uncertainty of risk estimates from data such as those available for this study, all calculated values carry a range of uncertainty from a minimum of one-half the calculated value to a maximum of two times the calculated value. The estimated excess fatalities given above may be compared with corresponding projected cancer mortality from all other causes: 41,000 fatalities from thyroid cancer and 3,800,000 fatalities from lung cancer are estimated to occur within the U.S. population during the next 45 y.
Fully automatic quantitative analysis of alpha-radiation spectral data using a minicomputer.
Fully automatic computer programs for the analysis of alpha-spectroscopy data have been developed and installed on a PDP-11/45 minicomputer at the Eastern Environmental Radiation Facility (EERF) of the U.S. Environmental Protection Agency (EPA) in Montgomery, AL. The programs presently in use evaluate the activities of the U, Pu and Am nuclides of interest to EERF. A mathematical enhancement of the spectra processed makes reliable determination of nuclide gross counts possible without the human interaction previously necessary at the laboratory. A number of safeguards that attempt to detect conditions (anomalous chemistry, etc.) which may cause invalid analyses are provided in the programs.
Calculation of 90Sr and 89Sr concentrations in environmental samples using a generalized linear system.
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Radionuclides in human bone samples.
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United States population dose estimates for iodine-131 in the thyroid after the Chinese atmospheric nuclear weapons tests.
Analysis of samples collected within the United States after the Chinese atmospheric nuclear weapons tests of 26 September and 17 November 1976 indicates that the radiation dose to the thyroid from iodine-131 in milk was predominant. A U.S. population dose to the thyroid of 68,000 man-rads was calculated for the iodine-131 fallout. The four excess thyroid cancers that are estimated to occur as a result of the September test during the next 45 years will be masked by the 380,000 cases of thyroid cancer which are expected to occur in the United States from all causes during the same interval.