Tuning bubbly structures in microchannels

Foams have many useful applications that arise from the structure and size distribution of the bubbles within them. Microfluidics allows for the rapid formation of uniform bubbles, where bubble size and volume fraction are functions of the input gas pressure, liquid flow rate, and device geometry. After formation, the microchannel confines the bubbles and determines the resulting foam structure. Bubbly structures can vary from a single row ("dripping"), to multiple rows ("alternating"), to densely packed bubbles ("bamboo" and dry foams). We show that each configuration arises in a distinct region of the operating space defined by bubble volume and volume fraction. We describe the boundaries between these regions using geometric arguments and show that the boundaries are functions of the channel aspect ratio. We compare these geometric arguments with foam structures observed in experiments using flow-focusing, T-junction, and co-flow designs to generate stable nitrogen bubbles in aqueous surfactant solution and stable droplets in oil containing dissolved surfactant. The outcome of this work is a set of design parameters that can be used to achieve desired foam structures as a function of device geometry and experimental control parameters.     

How do pre-kindergarteners spend their time? Gender,ethnicity, and income as predictors of experiences in pre-kindergarten classrooms

The current paper considers how children spend their time in state-funded pre-kindergarten programs and how time use relates to ethnicity, gender, and family income, based on the assumption that how time is spent in pre-kindergarten is relevant for the programs’ success in narrowing achievement gaps. Classroom observations of 2061 children in 652 pre-k programs in 11 states were analyzed. Findings indicated that the pre-kindergarten day was roughly equally divided among free choice, teacher-assigned activities, and meals/routines. Children spent much of their time in language/literacy, social studies, and art, and less time in math and gross motor activities. Much of the pre-k day was spent in ‘no coded learning activity.’ Children in classes with lower proportions of Latino and African American children and higher average income-to-need ratios were generally engaged in richer and more stimulating experiences. The child-level variables of ethnicity and income were generally unrelated to how children spent their time, above and beyond the effects of classroom-level ethnicity and income. There were generally small, but significant gender differences – always in the gender-stereotyped direction – in how time was spent, especially during free choice time.     

The relative effects of group size on reading progress of older students with reading difficulties

This study reports findings on the relative effects from a yearlong secondary intervention contrasting large-group, small-group, and school-provided interventions emphasizing word study, vocabulary development, fluency, and comprehension with seventh- and eighth-graders with reading difficulties. Findings indicate that few statistically significant results or clinically significant gains were associated with group size or intervention. Findings also indicate that a significant acceleration of reading outcomes for seventh- and eighth-graders from high-poverty schools is unlikely to result from a 50 min daily class. Instead, the findings indicate, achieving this outcome will require more comprehensive models including more extensive intervention (e.g., more time, even smaller groups), interventions that are longer in duration (multiple years), and interventions that vary in emphasis based on specific students’ needs (e.g., increased focus on comprehension or word study).     

A culture of assessment: A bioecological systems approach for early and continuous assessment of deaf infants and children

Even today, with all of the hearing technology and bilingual programs available, many Deaf children arrive at school with severe language delays. With a renewed focus on having Deaf children kindergarten-ready, assessment of language milestones becomes critical as seen in the campaign Child First and the legislation referred to as Language Equality & Acquisition for Deaf Kids (LEAD-K). Here, a strategy is proposed to ensure that Deaf children are kindergarten-ready. The focus is on a re-evaluation of the epistemologies of the social and individualized medical models of health, as well as Bronfenbrenner's bioecological systems approach, to assess all components that impact a Deaf child's ecology to permit maximizing their developmental potentials.     

Improving the writing and knowledge of emergent writers: the effects of self-regulated strategy development

The purpose of this study was to investigate the effectiveness of implementing the Self-Regulated Strategy Development (SRSD) model of instruction (Graham & Harris, 2005; Harris & Graham, 1996) on the writing skills and knowledge of six first grade students. A multiple-baseline design across participants with multiple probes (Kazdin, 2010) was used to test the effectiveness of the SRSD intervention, which included story writing and self-regulation strategy instruction. All students wrote stories in response to picture prompts during the baseline, instruction, post-instruction, and maintenance phases and stories were assessed for essential story components, length, and overall quality. Participants also participated in brief interviews during the baseline and post-instruction phases. Results indicated that SRSD can be beneficial for first grade writers. Participants wrote stories that contained more essential components, were longer, and of better quality after SRSD instruction. Participants also showed improvement in writing knowledge from pre- to post-instruction.     

A Community-Driven Metadata Framework for Describing Cultural Resources: The Digital Library North Project

This article describes the Digital Library North (DLN) project, a collaboration among researchers at the University of Alberta, staff at the Inuvialuit Cultural Resource Centre, and communities within the Inuvialuit Settlement Region (ISR) to develop a culturally appropriate metadata framework for a digital library of cultural resources. It will discuss gathering of data to inform the first iteration of the metadata framework and digital library prototype, as well as revisions made to both the framework and the digital library based on feedback obtained through community interaction with the prototype.     

Mapping the Final Frontier: A Publisher’s Experience Launching an Open Access Journal in the Burgeoning Mixed Access Economy

This article describes a program session that focused on publishers’ experiences launching Open Access (OA) journals and lessons learned. The speakers discussed the current journal marketplace, current journal business models, and the possible shape of the OA landscape and marketplace in the future.