Comparing universal kriging and land-use regression for predicting concentrations of gaseous oxides of nitrogen (NOx) for the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air)

BACKGROUND: Epidemiological studies that assess the health effects of long-term exposure to ambient air pollution are used to inform public policy. These studies rely on exposure models that use data collected from pollution monitoring sites to predict exposures at subject locations. Land use regression (LUR) and universal kriging (UK) have been suggested as potential prediction methods. We evaluate these approaches on a dataset including measurements from three seasons in Los Angeles, CA. METHODS: The measurements of gaseous oxides of nitrogen (NOx) used in this study are from a "snapshot" sampling campaign that is part of the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air). The measurements in Los Angeles were collected during three two-week periods in the summer, autumn, and winter, each with about 150 sites. The design included clusters of monitors on either side of busy roads to capture near-field gradients of traffic-related pollution. LUR and UK prediction models were created using geographic information system (GIS)-based covariates. Selection of covariates was based on 10-fold cross-validated (CV) R(2) and root mean square error (RMSE). Since UK requires specialized software, a computationally simpler two-step procedure was also employed to approximate fitting the UK model using readily available regression and GIS software. RESULTS: UK models consistently performed as well as or better than the analogous LUR models. The best CV R(2) values for season-specific UK models predicting log(NOx) were 0.75, 0.72, and 0.74 (CV RMSE 0.20, 0.17, and 0.15) for summer, autumn, and winter, respectively. The best CV R(2) values for season-specific LUR models predicting log(NOx) were 0.74, 0.60, and 0.67 (CV RMSE 0.20, 0.20, and 0.17). The two-stage approximation to UK also performed better than LUR and nearly as well as the full UK model with CV R(2) values 0.75, 0.70, and 0.70 (CV RMSE 0.20, 0.17, and 0.17) for summer, autumn, and winter, respectively. CONCLUSION: High quality LUR and UK prediction models for NOx in Los Angeles were developed for the three seasons based on data collected for MESA Air. In our study, UK consistently outperformed LUR. Similarly, the 2-step approach was more effective than the LUR models, with performance equal to or slightly worse than UK.     

REUSE OF DOMESTIC WASTEWATER FOR IRRIGATION IN ARID ZONES: A CASE STUDY1

ABSTRACT: The domestic sewage of the city of Beer-Sheva, Israel, which is located in an arid region, is treated in a series of facultative ponds. The treated effluent is stored temporarily in an open surface earthen reservoir (about 0.5 ± 10⁶ m³ in volume) and then used for irrigation. The effluent is applied via sprinkler and trickle irrigation systems. The main crops irrigated are cotton, wheat, alfalfa, and corn. Total cotton yield is over 5500 kg/ha, and the wheat grain yield is over 7500 kg/ha. The amount of effluent applied is about 6500 m³/ha for cotton (including preplant irrigation), and the wheat receives about 4500 m³/ha via irrigation and an additional 2000 m³/ha from precipitation. Due to the nutrient content in the effluent, the above yields are obtained without any additional fertilization.     

Uniparental disomy in fetuses diagnosed with balanced Robertsonian translocations: risk estimate

Forty-two fetuses with non-homologous Robertsonian translocations were analyzed for uniparental disomy (UPD). One fetus with a de novo translocation t(13q;14q) had maternal isodisomy of chromosome 14. In a summary of the published data (including the present study), 315 cases were analyzed for UPD after prenatal diagnosis of balanced Robertsonian translocations, of these two fetuses had UPD, giving a risk estimate of 0.65% (CI 0.2–2.3). This risk justifies the recommendation of UPD analysis in fetuses diagnosed prenatally with Robertsonian translocations, with the emphasis on the chromosomes known to contain imprinted genes, such as 14 and 15. We also discuss the possibility of UPD in offspring of Robertsonian translocation carriers with normal karyotype. Based on the risk for UPD in fetuses with Robertsonian translocation we suggest to test these fetuses for UPD and to do so on amniocytes rather than chorionic villi when the risk for unbalanced karyotype is ∼1%, comparable to the risk for UPD. Copyright © 2002 John Wiley & Sons, Ltd.     

TRICKLE IRRIGATION OF WHEAT APPLYING RENOVATED WASTEWATER1

ABSTRACT: A preliminary field experiment was conducted for trickle irrigation of winter wheat raised for grain production under arid conditions. Treated waste water was applied for trickle irrigation via a trickle system. Mean total amount of effluent applied was about 5700 m³/ha. In one of the experimental treatments, which was irrigated once a week, a grain yield of over 10,000 kg/ha was obtained, whereas in the other treatments the yields were about 8,500 kg/ha, which are above the mean yield obtained under sprinkler irrigation.     

Sex proportion and performance evaluation among high‐ranking military officers

This field study examined the relationships between sex proportion and performance evaluation among 3014 high‐ranking officers (Majors and Lieutenant Colonels) in the Israeli Defense Forces. Women's performance was rated lower than that of men when the women were token members of their units. However, the performance of women was rated higher than that of men when they constituted a higher proportion. Men's overall performance did not co‐vary with proportion. In addition, the interaction of sex with proportion had a significant effect on the dimensions of Operational and Analytic Competence. The pattern of findings supports Kanter's framework of skewed and tilted groups. Copyright © 2001 John Wiley & Sons, Ltd.     

SOLID SET IRRIGATION SYSTEM DESIGN USING LINEAR PROGRAMMING1

: Irrigation systems can be formulated to enable linear programming to be used to obtain optimal systems. Linear programming is a readily available technique in most scientific and technical centers which have computer facilities. The objective function towards a minimal cost is based on a suggested classification of the system components, and the constraints mainly refer to required pressures and discharges. A case study in which linear programming is used to determine optimal pipe diameters is given for the solution of a solid set under tree sprinkler system.