In this study, a steady, incompressible, and laminar-free convective flow of a two-dimensional electrically conducting viscoelastic fluid over a moving stretching surface through a porous medium is considered. The boundary-layer equations are derived by considering Boussinesq and boundary-layer approximations. The nonlinear ordinary differential equations for the momentum and energy equations a...

The present study investigates how working memory and fluid intelligence are related in young children and how these links develop over time. The major aim is to determine which aspect of the working memory system – short-term storage or cognitive control drives the relationship with fluid intelligence. A sample of 119 children was followed from kindergarten to second grade and completed multip...

Beliefs about factors that affect school performance (means-ends or causality beliefs) and about self-efficacy and control (agency and control beliefs) were assessed in 313 East Berlin children (grades 2-6) before unification and 516 West Berlin children shortly after unification. Multiple-group analyses of mean and covariance structures yielded 2 major differences: (a) East Berlin children sho...

Spatial skill is highly related to success in math and science (e.g., Casey, Nuttall, Pezaris, & Benbow, 1995). However, little work has investigated the cognitive pathways by which the relation between spatial skill and math achievement emerges. We hypothesized that spatial skill plays a crucial role in the development of numerical reasoning by helping children to create a spatially meaningful...