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Objective To determine the amount of lead ingested in food by means of duplicate diet collections, nutrient intakes, and anthropometric measurements of young children. Design Once a month for a year, data were collected from 24-hour duplicate diets, hand wipes, a dust index, and anthropometric measurements. Quarterly, venous blood samples were obtained. Thermal ionization spectrometry by means of a lead-205 tracer was used to determine lead present in food, blood, and the hand wipes. A dust index was determined on the basis of observation of dust on surfaces in the home. Anthropometric measurements obtained were height, weight, head circumference, and mid-upper arm circumference.Subjects/setting Subjects were 21 children, aged 18 to 36 months, who resided in homes located in an urban area with potentially high lead levels. Main outcomes measured Lead contamination in food and on hands, and blood lead values, were determined. Statistical analysis performed Pearson correlation coefficients were used to determine relationships between lead content in food, blood, and hand wipes and growth. Multiple regression analyses examined the effect of food types and dust lead on lead levels in food, and the effect of these variables on head circumference. Results Mean blood levels were 0.3089±0.1496 µmol/L; 12 samples contained more than 0.4826 µmol/L. Total intake of lead from food was 4.95 [µgram]/day and ranged from 1.10 to -22.10 [µgram]/day. More than a fourth of the diets collected exceeded 6.00 [µgram]/day. Foods considered home prepared were moderately related to blood lead level, and the dust index and hand wipe lead levels were related to total food lead. Home-handled foods, canned foods, and hand-wipe lead were significant predictors of the lead content in food. A negative relationship was found between head circumference and blood lead level. Applications Level of lead in food was directly related to hand-wipe lead. This finding underscores the need for dietitians and other health professionals to stress the importance of cleanliness in environments that are potentially lead contaminated. Appropriate hand washing and surface cleaning should be emphasized when preparing and consuming food. The inverse relationship between head circumference and blood lead levels points to the need for additional studies to validate this finding while controlling for other extraneous variables., Lead exposure is the most common environmental health problem for children in the United States (1,2). One of every 6 children younger than 6 years of age is exposed to [...]

Yield prediction across a target production zone with varying strategies of agronomic practices has been a challenging problem to plant breeders when testing new genotypes for release. This study focused on comparing the importance of a new bioclimatic index called biological windows and six other traditional environmental indices as predictor variables of maize yields across sites (farmers' fields) and years, using a simple linear regression model. The yield data were collected for six hybrids evaluated in strip tests at 57 to 186 sites throughout Iowa during 1987-1994. The biological windows index was based on the Newhall Simulation Model and estimated the number of days the soil was moist and above 5 ° C. The environmental indices were July precipitation, temperature, the product of July precipitation and temperature, and the equivalent values for August. Because the actual values for the indices were not recorded at each site, all the indices were estimated for each site as the weighted averages of the data from 112 Iowa weather stations. Across years and within the Iowa sites, the mean percentiles of R-square distributions showed that biological windows had less predictive value for maize yields than the more traditional indicators such as August precipitation and temperature. For all indices, across years and within sites had much greater mean R-squares than across sites and within years, which had very low predictive values. For predicting yield across years within sites, there appeared to be an advantage in using August precipitation or the product of August precipitation and temperature over the five other indices. The R-square values for these two indices were at least 0.60 in 80% of the test sites for five hybrids., GENOTYPE X ENVIRONMENT INTERACTION (GEI) is a common problem that plant breeders face when releasing advanced plant materials for use in any relatively large target zone. Lin et al. (1986) [...]

Techniques based on intercultivar chromosome substitution lines in wheat (Triticum aestivum L.) have been used to identify and locate the genes controlling quantitative traits on a specific chromosome. For a particular trait, the number of segregating loci affecting differences between two parental lines are generally determined by the frequency distribution of recombinant inbred chromosome lines (RICLs). Recombinant inbred chromosome lines are the inbred progeny of crosses between a chromosome substitution line and its parent cultivar. The determination of the presence and the number of segregating loci becomes difficult (i) when the distribution exhibits no clear discrete classes, (ii) when there is a considerable chance of misclassifying lines into parental and recombinant types, and (iii) when loci are linked. We describe an approach to estimate the number of segregating loci responsible for the difference between a chromosome substitution line and parental cultivar using the derived RICLs when classification errors are likely. We also discuss the effects of linked loci on the estimates. The method was used to estimate the number of genes on chromosome 3A controlling grain yield, kernels [spike.sup.-1], kernel weight, spikes [m.sup.-2], grain volume weight, plant height and anthesis date in wheat., FOR A BETTER UNDERSTANDING of the genetics of continuous variation, it is important that the genes controlling quantitative characters be identified so that their individual properties may be investigated. Techniques [...]

Corn bran at three moisture contents (6%, 13%, and 24% d.b.) and feed rates (11.89, 23.86, and 35.86 g s-1) was ground using a hammer mill operated at two different tip speeds (19.0 and 47.0 m s-1). Geometric mean diameter (GMD) and energy consumption were observed within a split-plot experimental design. Additionally, the statistical precision of the split-plot experimental design was compared to the statistical precision of the experiment if it had been conducted as a randomized complete block design (RCBD) with a factorial treatment structure. Moisture content (MC) had a significant effect on GMD (final particle size) but not on energy consumption. Tip speed (TPS) had significant effects on both GMD and energy consumption. Feed rate (FR) had a significant effect on energy consumption but no significant effect on GMD of corn bran. Energy consumption was observed to increase with increasing TPS and FR. Conducting the experiment as a split-plot design substantially increased the precision for energy consumption with regard to FR and TPS, whereas the precision for MC was decreased when compared to an RCBD. Particle size GMD precision was only slightly affected by using a split-plot design as compared to conducting the experiment as an RCBD. Finally, if hard-to-change (HTC) and easy-to-change (ETC) factors exist, it is important to consider different-sized experimental units. Neglecting to consider this issue can result in inefficient use of resources and possibly lead to inaccurate and biased results. [ABSTRACT FROM AUTHOR]