This study examined developmental associations between growth in domain-general cognitive processes (working memory and attention control) and growth in domain-specific skills (emergent literacy and numeracy) across the pre-kindergarten year, and their relative contributions to kindergarten reading and math achievement. One hundred sixty-four Head Start children (44% African American or Latino; 57% female) were followed longitudinally. Path analyses revealed that working memory and attention control predicted growth in emergent literacy and numeracy skills during the pre-kindergarten year, and furthermore, that growth in these domain-general cognitive skills made unique contributions to the prediction of kindergarten math and reading achievement, controlling for growth in domain-specific skills. These findings extend research highlighting the importance of working memory and attention control for academic learning, demonstrating the effects in early childhood, prior to school entry. We discuss the implications of these findings for pre-kindergarten programs, particularly those designed to reduce the school readiness gaps associated with socio-economic disadvantage.

Forty-four Head Start classrooms were randomly assigned to enriched intervention (Head Start REDI- Research-based, Developmentally Informed) or “usual practice” conditions. The intervention involved brief lessons, “hands on” extension activities, and specific teaching strategies linked empirically with the promotion of: 1) social-emotional competencies, and 2) language development and emergent literacy skills. Take-home materials were provided to parents to enhance skill development at home. Multi-method assessments of 356 4-year-old children tracked their progress over the course of the one-year program. Results revealed significant differences favoring children in the enriched intervention classrooms on measures of vocabulary, emergent literacy, emotional understanding, social problem-solving, social behavior, and learning engagement. Implications are discussed for developmental models of school readiness and for early educational programs and policies.

Cosmological constraints from X-ray and microwave observations of galaxy clusters are subjected to systematic uncertainties. Non-thermal pressure support due to internal gas motions in galaxy clusters is one of the major sources of astrophysical uncertainties. Using a mass-limited sample of galaxy clusters from a highresolution hydrodynamical cosmological simulation, we characterize the non-thermal pressure fraction profile and study its dependence on redshift, mass, and mass accretion rate. We find that the non-thermal pressure fraction profile is universal across redshift when galaxy cluster radii are defined with respect to the mean matter density of the universe instead of the commonly used critical density. We also find that the non-thermal pressure is predominantly radial, and the gas velocity anisotropy profile exhibits strong universality when galaxy cluster radii are defined with respect to the mean matter density of the universe. However, we find that the nonthermal pressure fraction is strongly dependent on the mass accretion rate of the galaxy cluster. We provide fitting formulae for the universal non-thermal pressure fraction and velocity anisotropy profiles of gas in galaxy clusters, which should be useful in modeling astrophysical uncertainties pertinent to using galaxy clusters as cosmological probes.

The use of galaxy clusters as cosmological probes hinges on our ability to measure their masses accurately and with high precision. Hydrostatic mass is one of the most common methods for estimating the masses of individual galaxy clusters, which suffer from biases due to departures from hydrostatic equilibrium. Using a large, mass-limited sample of massive galaxy clusters from a high-resolution hydrodynamical cosmological simulation, in this work we show that in addition to turbulent and bulk gas velocities, acceleration of gas introduces biases in the hydrostatic mass estimate of galaxy clusters. In unrelaxed clusters, the acceleration bias is comparable to the bias due to non-thermal pressure associated with merger-induced turbulent and bulk gas motions. In relaxed clusters, the mean mass bias due to acceleration is small ( 3%), but the scatter in the mass bias can be reduced by accounting for gas acceleration. Additionally, this acceleration bias is greater in the outskirts of higher redshift clusters where mergers are more frequent and clusters are accreting more rapidly. Since gas acceleration cannot be observed directly, it introduces an irreducible bias for hydrostatic mass estimates. This acceleration bias places limits on how well we can recover cluster masses from future Xray and microwave observations. We discuss implications for cluster mass estimates based on X-ray, Sunyaev-Zeldovich effect, and gravitational lensing observations and their impact on cluster cosmology.

The recent literature on language intervention has become increasingly focused upon developing treatments that more closely parallel normal language acquisition. However, there have been relatively few reports that directly compare imitative procedures to conversationalinteractive interventions. The purpose of the present study was to compare the relative effectiveness of imitative intervention and conversational recast language intervention applied to a wide range of grammatical morpheme and complex sentence targets in 21 children with specific language impairment. The results indicated that although both kinds of treatments were effective in triggering acquisition of most targets, consistently fewer presentations to first spontaneous use were required in the conversational procedure. In addition, the transition from elicited production to generalized spontaneous production was more rapid under conversationinteractive treatment. Finally, although imitation treatment was more effective in generating elicited production, a significantly greater number of spontaneous productions occurred under the conversational training procedures. The theoretical and applied ramifications of these findings are discussed.