Greater Average Loss Research Articles

Economics and Effectiveness of Alternative Weed Scouting Methods in Peanut

On-farm trials were conducted in 16 North Carolina peanut fields to obtain estimates of scouting times and quality of herbicide recommendations for different weed scouting methods. The fields were monitored for weed species and population density using four scouting methods: windshield (estimate made from the edge of the field), whole-field (estimate based on walk through the field), range (weed densities rated on 1–5 scale at six locations in the field), and counts (weeds estimated by counting at six locations in the field). The herbicide application decision support system (HADSS) was used to determine theoretical net return over herbicide investment and yield loss ($ and %) for each treatment in each field. Three scouts estimated average weed population densities using each scouting method. These values were entered into HADSS to obtain treatment recommendations. Independently collected count data from all three scouts were combined to determine the optimal treatment in each field and the relative ranking of each available treatment. When using the whole-field method, scouts observed a greater number of weed species than when using the other methods. The windshield, whole-field, and range scouting methods tended to overestimate density slightly at low densities and underestimate density substantially at high densities, compared to the count method. The windshield method required the least amount of time to complete (6 min per field), but also resulted in the greatest average loss. Even for this method, recommendations had theoretical net returns within 10% of the return for the optimal treatment 80% of the time. The count method appears to have less economic risk than the windshield, whole-field, and range scouting methods.

An overview of body weight of older persons, including the impact on mortality The national health and nutrition examination survey i-epidemiologic follow-up study

The authors studied distributions of body weight for height, change in body weight with age, and the relationship between body mass index and mortality among participants in the Epidemiologic Follow-up Study of the first National Health and Nutrition Examination Survey (NHEFS) (n = 14,407), a cohort study based on an representative sample of the U.S. population. Percentiles of body weight for height according to age and sex are presented. Crosssectional analyses of body weight suggest that mean body weight increases with age until late middle age, then plateaus and decreases for older aged persons. However, longitudinal analysis of change in weight with age shows that younger persons in the lower quintile at baseline tend to gain more than those in the higher quintile. Older persons in the higher quintile at baseline have the greatest average loss in weight. The relationship of body mass index to mortality is a U-shaped curve, with increased risks in the lowest and highest 15% of the distribution. Increased risk of mortality associated with the highest 15th percentile of the body mass index distribution, as well as the highest 15% of the joint distribution of body mass index and skinfold thickness, is statistically significant for white women. However, the risk diminishes when adjusted for the presence of disease and factors related to disease. More noteworthy is the fact that there is a statistically significant excess risk of mortality for both race and sex groups in the lowest 15% of the body mass index distribution after adjusting for smoking history, and presence of disease. Those in the lowest 15% of the joint body mass index and skinfold thickness distribution, were also at increased risk. Risk of mortality for both men and women who have lost 10% or more of their maximum lifetime weight within the last 10 years is statistically significant, even when controlling for current weight. This study has replicated previously reported relationships, while correcting for several methodological issues.