Starter Fertilizer, Row Width, and Planting Date Effects on Corn Yield in North Central Iowa

Delayed planting or replanting of corn can result in significant yield losses. Recently, planting date studies in Iowa have shown 3% yield loss comparing mid-May planting dates with late April planting dates and 20-30% yield loss comparing June planting dates with late April planting dates. These yield losses can be partially attributed to the hastened vegetative development from increased accumulation of thermal units at later planting dates, which contribute to lessened capture of light resources and thus less carbon fixation. In Iowa, it has been shown that starter fertilizer can increase the early growth of corn from stage V3 to V8. Narrow row spacing will also improve light interception during early vegetative development. During the 1999 and 2000 growing seasons, the effects of planting date, row spacing, and starter fertilizer on corn yield were evaluated. The objective of this study was to determine whether the use of starter fertilizer and row spacing at later planting dates would reduce the associated yield loss by improving early resource capture

Initial Effects of Prescribed Burning on Survival and Nesting Success of Northern Bobwhites in West-Central Texas

Fire is often prescribed for managing habitat for northern bobwhites (Colinus virginianus) in the southeastern United States, yet little is known about its use as a tool in more xeric portions of the species’ range. This study was conducted from 1994 to 1995 on 3 sites in the northern Edwards Plateau ecoregion of Texas to monitor immediate post-burn effects on bobwhite ecology. Each site included a burned pasture paired with an unburned control. We radiomarked \u3e= 50 bobwhites (25/pasture) at each study site with neck-loop transmitters just prior to burning and monitored their survival and nesting habits for 6 months post-burn. Survival was similar (P \u3e 0.05) between burned and unburned areas. Predation was the leading cause of mortality, with mammals and raptors accounting for 68% and 31% of the predation, respectively. Nest initiation and success were low for both treatments. Nest sites occurred mostly in association with prickly pear cactus (Opuntia spp.). Our results suggest that relatively ‘‘cool’’ prescribed burns had few short-term effects on bobwhite survival in west-central Texas. However, reductions in cacti density and cover that often occur post-burn, especially if followed by an application of herbicide (i.e., picloram), may reduce the number of potential nesting sites for bobwhites

A twin study into the genetic and environmental influences on academic performance in science in 9-year-old boys and girls

We investigated for the first time the genetic and environmental aetiology behind scientific achievement in primary school children, with a special focus on possible aetiological differences for boys and girls. For a representative community sample of 2602 twin pairs assessed at 9 years, scientific achievement in school was rated by teachers based on National Curriculum criteria in three domains: Scientific Enquiry, Life Processes and Physical Processes. Results indicate that genetic influences account for over 60% of the variance in scientific achievement, with environmental influences accounting for the remaining variance. Environmental influences were mainly of the non-shared variety, suggesting that children from the same family experience school environments differently. An analysis of sex differences considering differences in means, variances and aetiology of individual differences found only differences in variance between the sexes, with boys showing greater variance in performance than girls

Why do spatial abilities predict mathematical performance?

Spatial ability predicts performance in mathematics and eventual expertise in science, technology and engineering. Spatial skills have also been shown to rely on neuronal networks partially shared with mathematics. Understanding the nature of this association can inform educational practices and intervention for mathematical underperformance. Using data on two aspects of spatial ability and three domains of mathematical ability from 4174 pairs of 12-year-old twins, we examined the relative genetic and environmental contributions to variation in spatial ability and to its relationship with different aspects of mathematics. Environmental effects explained most of the variation in spatial ability (~70%) and in mathematical ability (~60%) at this age, and the effects were the same for boys and girls. Genetic factors explained about 60% of the observed relationship between spatial ability and mathematics, with a substantial portion of the relationship explained by common environmental influences (26% and 14% by shared and non-shared environments respectively). These findings call for further research aimed at identifying specific environmental mediators of the spatial–mathematics relationship

Coyote Diets on the Rolling Plains Quail Research Ranch, Texas

Predation is a major cause of mortality and nest failure for the northern bobwhite (Colinus virginianus) across its range. Coyotes (Canis latrans) are a potential predator of bobwhites and typically the most common mesocarnivore on bobwhite range in Texas. Few data exist regarding the importance of bobwhites in the coyote’s diet in the Rolling Plains of Texas. We describe the seasonal and annual diets of coyotes on the Rolling Plains Quail Research Ranch (RPQRR), Fisher County, Texas. The RPQRR encompasses 1,902 ha of rolling terrain consisting of ridges and mesquite (Prosopis glandulosa) dominated rangeland; other common shrubs include netleaf hackberry (Celtis laevigata), littleleaf sumac (Rhus microphylla), lotebush (Ziziphus obtusifolia), wolfberry (Lycium berlandieri), chittam (Bumrlia lanuginosa), catclaws (Acacia spp., Mimosa spp.), and agarito (Mahonia trifoliolata). Prickly pear (Opuntia spp.) is abundant on most sites. The study area received 58 and 64 cm of rainfall, respectively during 2009 and 2010, below the 30-year average of 76 cm for Fisher County, Texas. We collected, and examined 720 coyote scats from December 2008 to December 2010. Each scat was prepared for analysis by placing it inside a nylon mesh bag and washing it for 2 cycles in an automatic washing machine. We analyzed scat contents macroscopically and any guard hairs were analyzed microscopically to identify prey to genus. We also collected estimates of abundance for a range of potential food sources including bobwhites, small mammals, and insects. Preliminary analyses suggest coyotes were minor predators of quail and their diets mainly consisted of seasonally-available mast (e.g., tunas of prickly pear) and rodents. Variation in timing and amount of rainfall during our study allowed us to document how coyotes adjusted their diets to the resulting fluctuations in food availability (especially mast)

Environment and Obesity in the National Children\u27s Study

Objective: In this review we describe the approach taken by the National Children’s Study (NCS), a 21-year prospective study of 100,000 American children, to understanding the role of environmental factors in the development of obesity. Data sources and extraction: We review the literature with regard to the two core hypotheses in the NCS that relate to environmental origins of obesity and describe strategies that will be used to test each hypothesis. Data synthesis: Although it is clear that obesity in an individual results from an imbalance between energy intake and expenditure, control of the obesity epidemic will require understanding of factors in the modern built environment and chemical exposures that may have the capacity to disrupt the link between energy intake and expenditure. The NCS is the largest prospective birth cohort study ever undertaken in the United States that is explicitly designed to seek information on the environmental causes of pediatric disease. Conclusions: Through its embrace of the life-course approach to epidemiology, the NCS will be able to study the origins of obesity from preconception through late adolescence, including factors ranging from genetic inheritance to individual behaviors to the social, built, and natural environment and chemical exposures. It will have sufficient statistical power to examine interactions among these multiple influences, including gene–environment and gene–obesity interactions. A major secondary benefit will derive from the banking of specimens for future analysis