Lethal and sublethal effects of Cadmium on Daphnia (Crustacea: Cladocera)

Acute and chronic toxicity studies were performed to determine the effects of cadmium on Daphnia pulex, Leydig 1860 emend. Richard 1896, D. magna Straus 1820, and D. parvula, Fordyce 1901, three cladocerans commonly found in fresh water. Test specimens were exposed to several series of concentrations of cadmium sulfate for 96 hours in the acute toxicity studies. The 24-, 48-, 72- and 96-hour 50 percent lethal doses (LDSO\u27s) were calculated by probit analysis using a computer program. Mortality was defined as immobilization. The 96-hour LD50\u27s for D. pulex ranged from 0.213 to 0.064 mg/liter. The 96-hour LD50 could not be determined for D. parvula; however, the 72-hour LD50 was 0.183 mg/liter. The 96-hour LD50 for D. magna was 0.086 mg/liter. All LD50\u27s were reported in terms of the salt concentration. Daphnia pulex was selected for long-term (chronic) study and was exposed to two concentrations of cadmium sulfate (0.012 and 0.025 mg/liter) at two temperatures (15.5 and 19.5 C). Molting, hatching of young, number of young, and mortality were observed every six hours for four weeks. Molting appeared to be a critical time for Daphnia exposed to cadmium sulfate. Dosed animals showed significantly higher mortality rates and produced 50 percent fewer young than the controls. The experimental temperatures did not alter the toxicity of cadmium

Health system outcomes and determinants amenable to public health in industrialized countries: a pooled, cross-sectional time series analysis

BACKGROUND: Few studies have tried to assess the combined cross-sectional and temporal contributions of a more comprehensive set of amenable factors to population health outcomes for wealthy countries during the last 30 years of the 20(th )century. We assessed the overall ecological associations between mortality and factors amenable to public health. These amenable factors included addictive and nutritional lifestyle, air quality, public health spending, healthcare coverage, and immunizations. METHODS: We used a pooled cross-sectional, time series analysis with corrected fixed effects regression models in an ecological design involving eighteen member countries of the Organisation for Economic Cooperation and Development during the period 1970 to 1999. RESULTS: Alcohol, tobacco, and fat consumption, and sometimes, air pollution were significantly associated with higher all-cause mortality and premature death. Immunizations, health care coverage, fruit/vegetable and protein consumption, and collective health expenditure had negative effects on mortality and premature death, even after controlling for the elderly, density of practicing physicians, doctor visits and per capita GDP. However, tobacco, air pollution, and fruit/vegetable intake were sometimes sensitive to adjustments. CONCLUSION: Mortality and premature deaths could be improved by focusing on factors that are amenable to public health policies. Tackling these issues should be reflected in the ongoing assessments of health system performance

United States Bureau of Mines Bulletin 3856

Report issued by the U.S. Bureau of Mines on the exploration of zinc ore deposits surrounding the Powell River area in Tennessee. Drilling methods and ore concentrates are presented. This report includes tables, and maps

On the identification of sales forecasting models in the presence of promotions

Shorter product life cycles and aggressive marketing, among other factors, have increased the complexity of sales forecasting. Forecasts are often produced using a Forecasting Support System that integrates univariate statistical forecasting with managerial judgment. Forecasting sales under promotional activity is one of the main reasons to use expert judgment. Alternatively, one can replace expert adjustments by regression models whose exogenous inputs are promotion features (price, display, etc.). However, these regression models may have large dimensionality as well as multicollinearity issues. We propose a novel promotional model that overcomes these limitations. It combines Principal Component Analysis to reduce the dimensionality of the problem and automatically identifies the demand dynamics. For items with limited history, the proposed model is capable of providing promotional forecasts by selectively pooling information across established products. The performance of the model is compared against forecasts provided by experts and statistical benchmarks, on weekly data; outperforming both substantially

Emergence of Captive Finance Companies and Risk Segmentation in Loan Markets: Theory and Evidence

A seller with some degree of market power in its product market can earn rents. In this context, there is a gain to granting credit to purchase of the product and thus to the establishment of a captive finance company. This paper examines the optimal behavior of such a durable good seller and its captive finance company. The model predicts a critical difference between the captive finance company's credit standard and that of independent lenders ("banks"), namely, that the captive finance company will adopt a more lenient credit standard. Thus, we should expect the likelihood of repayment of a captive loan to be lower than that of a bank loan, other things equal. This prediction is tested using a unique data set drawn from a major credit bureau in the United States, and the evidence supports the theoretical prediction. Copyright 2008 The Ohio State University.