Measuring leader perceptions of school readiness for reforms: use of an iterative model combining classical and Rasch methods

This study examines validity of data generated by the School Readiness for Reforms: Leader Questionnaire (SRR-LQ) using an iterative procedure that combines classical and Rasch rating scale analysis. Following content-validation and pilot-testing, principal axis factor extraction and promax rotation of factors yielded a five factor structure consistent with the content-validated subscales of the original instrument. Factors were identified based on inspection of pattern and structure coefficients. The rotated factor pattern, inter-factor correlations, convergent validity coefficients, and Cronbach's alpha reliability estimates supported the hypothesized construct properties. To further examine unidimensionality and efficacy of the rating scale structures, item-level data from each factor-defined subscale were subjected to analysis with the Rasch rating scale model. Data-to-model fit statistics and separation reliability for items and persons met acceptable criteria. Rating scale results suggested consistency of expected and observed step difficulties in rating categories, and correspondence of step calibrations with increases in the underlying variables. The combined approach yielded more comprehensive diagnostic information on the quality of the five SRR-LQ subscales; further research is continuing.     

Reading achievement gaps, correlates, and moderators of early reading achievement: Evidence from the Early Childhood Longitudinal Study (ECLS) kindergarten to first grade sample.

This study estimated reading achievement gaps in different ethnic, gender, and socioeconomic groups of 1st graders in the U.S. compared with specific reference groups and identified statistically significant correlates and moderators of early reading achievement. A subset of 2,296 students nested in 184 schools from the Early Childhood Longitudinal Study (ECLS) kindergarten to 1st-grade cohort were analyzed with hierarchical linear models. With child-level background differences controlled, significant 1st-grade reading differentials were found in African American children (-0.51 SD units below Whites), boys (-0.31 SD units below girls), and children from high-poverty households (-0.61 to -1.0 SD units below well-to-do children). In all 3 comparisons, the size of the reading gaps increased from kindergarten entry to 1st grade. Reading level at kindergarten entry was a significant child-level correlate, related to poverty status. At the school level, class size and elementary teacher certification rate were significant reading correlates in 1st grade. Cross-level interactions indicated reading achievement in African American children was moderated by the schools students attended, with attendance rates and reading time at home explaining the variance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Colloidal Stability & Conformational Changes in β-Lactoglobulin: Unfolding to Self-Assembly

A detailed understanding of the mechanism of unfolding, aggregation, and associated rheological changes is developed in this study for β-Lactoglobulin at different pH values through concomitant measurements utilizing dynamic light scattering (DLS), optical microrheology, Raman spectroscopy, and differential scanning calorimetry (DSC). The diffusion interaction parameter k_D emerges as an accurate predictor of colloidal stability for this protein consistent with observed aggregation trends and rheology. Drastic aggregation and gelation were observed at pH 5.5. Under this condition, the protein’s secondary and tertiary structures changed simultaneously. At higher pH (7.0 and 8.5), oligomerizaton with no gel formation occurred. For these solutions, tertiary structure and secondary structure transitions were sequential. The low frequency Raman data, which is a good indicator of hydrogen bonding and structuring in water, has been shown to exhibit a strong correlation with the rheological evolution with temperature. This study has, for the first time, demonstrated that this low frequency Raman data, in conjunction with the DSC endotherm, can be been utilized to deconvolve protein unfolding and aggregation/gelation. These findings can have important implications for the development of protein-based biotherapeutics, where the formulation viscosity, aggregation, and stability strongly affects efficacy or in foods where protein structuring is critical for functional and sensory performance.