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Powder metallurgy is a useful route to forming particulate composite materials; however, the densification of hard and soft powder mixtures is usually inhibited by the more refractory phase. The Bi-W powder compacts were uniaxially pressed at room temperature and the compaction behavior and mechanical properties were evaluated. Pressing was performed in incremental steps from ~1 to 540 MPa. After each step, the pressure was relieved and the thickness and sound-wave transit time were measured in situ (in the die), in order to determine the density and sound-wave velocity in the compact. The data show that the unreinforced Bi powder compacts to ~98 pct density at 540 MPa. The W reinforcement inhibits the densification process, resulting in increased levels of residual porosity. The compaction behavior was evaluated using a modified Heckel equation, while the porosity dependence of the ultrasonically determined elastic modulus was described by a site percolation approach. Postcompaction sound-wave velocity and Vicker’s hardness measurements show

A high percentage of school-age students with autism spectrum disorder (ASD) have reading comprehension difficulties leading to academic disadvantage. These difficulties may be related to differences in children's emergent literacy development in the preschool years. In this study, we examined the relationship between emergent literacy skills, broader cognitive and language ability, autism severity, and home literacy environment factors in 57 preschoolers with ASD. The children showed strengths in code-related emergent literacy skills such as alphabet knowledge, but significant difficulties with meaning-related emergent literacy skills. There was a significant relationship between meaning-related skills, autism severity, general oral language skills, and nonverbal cognition. Identification of these meaning-related precursors will guide the targets for early intervention to help ensure reading success for students with ASD.

The authors provide practical, evidence-based advice for teachers and educational leaders looking for helpful curricular and professional resources that support students' literacy development in the era of the Common Core State Standards.

State educational agency content coordinators commonly experience tensions in their professional roles related to distinct sets of beliefs, or logics, about who "should" control what students learn: the state bureaucracy, the local community, or the broader profession. Using an institutional logics frame and drawing on interviews with coordinators for English/language arts representing about a third of U.S. states, we illustrate how individuals navigate these competing traditions of decision-making. Multiple logics shaped coordinators' perceptions of their job responsibilities and goals, as well as the actions they felt were possible for them to take in creating and providing resources, communicating those resources to local stakeholders, and providing professional development. More consistent messaging to coordinators about the types of outreach the state views as acceptable would better support high-quality literacy instruction. [ABSTRACT FROM AUTHOR]

Despite decades of critiques and scores of innovations designed to abolish or weaken it, the school district remains a central institution of the American educational system. Yet, although the district remains the primary agent of local democratic control and serves as the main unit for educational decisions, relatively little attention has been given to the historical evolution of the school district as an institutional form. Reformers and researchers alike often hold misperceptions and inaccurate assumptions about the nature of the school district's development, precisely because the district has been understudied. The authors of this chapter offer a first step toward correcting that oversight by broadening our attention span, providing a solid historical overview of how the district has developed over the past two centuries, and exploring how scholars have analyzed districts at different points in our past. They focus on how the definition of what constitutes a school district has changed over time and on how perceptions of what it has meant to be a good or effective district has shifted throughout our history. They argue that the district has never been a static institution, that its changing forms and functions deserve greater recognition, and that conflicts regarding school districts often reflect deep and enduring frictions that are endemic to American social structures.

The deformation mechanism of body-centered cubic (bcc) nanocrystalline tantalum with grain sizes of 10–30 nm is investigated by nanoindentation, scanning electron microscopy and high-resolution transmission electron microscopy. In a deviation from molecular dynamics simulations and existing experimental observations on other bcc nanocrystalline metals, the plastic deformation of nanocrystalline Ta during nanoindentation is controlled by deformation twinning. The observation of multiple twin intersections suggests that the physical mechanism of deformation twinning in bcc nanocrystalline materials is different from that in face-centered cubic (fcc) nanocrystalline metals.