A microfluidic manifold with a single pump system to generate highly mono-disperse alginate beads for cell encapsulation

Cell encapsulation technology is a promising strategy applicable to tissue engineering and cell therapy. Many advanced microencapsulation chips that function via multiple syringe pumps have been developed to generate mono-disperse hydrogel beads encapsulating cells. However, their operation is difficult and only trained microfluidic engineers can use them with dexterity. Hence, we propose a microfluidic manifold system, driven by a single syringe pump, which can enable the setup of automated flow sequences and generate highly mono-disperse alginate beads by minimizing disturbances to the pump pressure. The encapsulation of P19 mouse embryonic carcinoma cells and embryonic body formation are demonstrated to prove the efficiency of the proposed system.     

Assessment and Learning of Qualitative Physics in Newton's Playground

ABSTRACT

Digital games are very popular in modern culture. The authors are examining ways to leverage these engaging environments to assess and support student competencies. The authors examine gameplay and learning using a physics game they developed called Newton's Playground. The sample consisted of 167 eighth- and ninth-grade students who played Newton's Playground for about 4 hr over the course of 1.5 weeks. Findings include significant pretest–posttest physics gains, and significant relations between in-game indicators and learning.     

Patterns of coparenting and young children's social–emotional adjustment in low-income families

This study identified coparenting patterns using data collected across 2007–2010 from low-income couples (N = 2915; 26.90% non-Hispanic White; 9.41% non-Hispanic Black; 34.24% Hispanic, 29.27% other or mixed race) with young children (M = 3.65 years; SD = 1.31 years; 48% girls) and examined relations with children's social–emotional adjustment. Latent profile analysis revealed four coparenting patterns: mutual high-quality (43.4%), moderate-quality, mothers less positive (31.8%), moderate-quality, fathers less positive (15.9%), and low-quality, mothers less positive (8.9%). When parents' perspectives on coparenting were positive and congruent, children fared best. Children also fared well when coparenting quality was moderate, and mothers were less positive than fathers. When coparenting quality was moderate and fathers were less positive than mothers, children showed the poorest adjustment.     

The Effect of Addition and Subtraction Practice within a Word-Problem Intervention on Addition and Subtraction Outcomes

This study examined the influence of addition and subtraction practice embedded within a word-problem intervention for Grade 3 students experiencing word-problem difficulty. Students (N = 448) were randomly assigned to one of two variants of a word-problem intervention or a business-as-usual comparison condition. Within the word-problem interventions, students participated in targeted addition and subtraction fact and computation practice for approximately 3 minutes of each 30-minute session across 47 intervention sessions, but also continually practiced addition and subtraction through word-problem solving. At posttest, students who participated in the intervention demonstrated improved single-digit addition and subtraction performance as well as improved double-digit addition and subtraction performance. At follow-up in Grade 4, persistence of effects was only identified for double-digit addition. Considering addition and subtraction are foundational to many other mathematics skills, addition and subtraction practice serves as an important component of mathematics intervention.     

Multiple linear regression: Identify potential health care stocks for investments using out-of-sample predictions

College-level statistics courses emphasize the use of the coefficient of determination, R-squared, in evaluating a linear regression model: higher R-squared is better. This often gives students an impression that higher R-squared implies better predictability since textbooks tend to use sample data to support the theory and students rarely have an opportunity to work on real data. In this paper, health care stocks are used as predictors and the result demonstrates that high R-squared does not necessarily mean high predictability and that multiple linear regression can be used in the study of data behavior. In particular, by learning the pattern of the near and far out-of-sample-prediction errors for different time periods throughout a dataset, the near out-of-sample prediction errors can be used to control the prediction errors and identify a subset of predictors that can well reflect the trend of S&P 500.     

A Systematic Analysis of Experimental Studies Targeting Fractions for Students with Mathematics Difficulties

Developing an understanding of fractions is critical and is an educational focus, as reflected in national standards and principles. This study conducted a quantitative synthesis of 22 experimental studies to investigate the overall efficacy of previously conducted fraction interventions compared to standard instruction. Instruction type and achievement level were used to examine variations of the effect sizes. The results indicated that intervention was more effective than standard instruction only in problem‐solving domains, and the effects were differentiated by instruction type and achievement level. This study provides a diagnostic view of the current state of U.S. mathematics education on fractions, along with insights for future directions in fraction instruction, particularly focusing on students with mathematics difficulties. Educational implications and limitations are discussed.     

Density-dependent separation of encapsulated cells in a microfluidic channel by using a standing surface acoustic wave

This study presents a method for density-based separation of monodisperse encapsulated cells using a standing surface acoustic wave (SSAW) in a microchannel. Even though monodisperse polymer beads can be generated by the state-of-the-art technology in microfluidics, the quantity of encapsulated cells cannot be controlled precisely. In the present study, mono-disperse alginate beads in a laminar flow can be separated based on their density using acoustophoresis. A mixture of beads of equal sizes but dissimilar densities was hydrodynamically focused at the entrance and then actively driven toward the sidewalls by a SSAW. The lateral displacement of a bead is proportional to the density of the bead, i.e., the number of encapsulated cells in an alginate bead. Under optimized conditions, the recovery rate of a target bead group (large-cell-quantity alginate beads) reached up to 97% at a rate of 2300 beads per minute. A cell viability test also confirmed that the encapsulated cells were hardly damaged by the acoustic force. Moreover, cell-encapsulating beads that were cultured for 1 day were separated in a similar manner. In conclusion, this study demonstrated that a SSAW can successfully separate monodisperse particles by their density. With the present technique for separating cell-encapsulating beads, the current cell engineering technology can be significantly advanced.     

The Contribution of HBCUS to the Preparation of African American Women for Stem Careers: A Case Study

This study uses case study analysis to explore the ways that Spelman College, a historically Black women’s college, promotes the attainment of African American women in STEM fields. Although limited to one institution, the findings shed light on the ways that institutional characteristics, policies, and practices may mitigate the barriers that limit attainment of African American women in STEM fields. Drawing on the findings, the paper concludes with recommendations for improving policy and practice as well as recommendations for additional fruitful research.     

When tensions between ideology and practice become personal: Unpacking mentorship in early childhood teacher education

University-based teacher education programs are criticized for being too theoretical, disconnected from the everyday realities of schools. To bridge this gap, teacher education programs give students year-long field experiences under the joint tutelage of mentor teachers and university faculty. However, this assumes that mentor teachers will not only be exemplary teachers, but skilled mentors as well. This article explores the tensions between the theoretical and practical work of teaching within mentoring relationships, specifically in spaces where teacher agency is limited by political, social, and cultural factors. The sociocultural, language approaches in many teacher education programs are seen as idealistic when pushed up against skills-based language approaches, advocated in classrooms. Using qualitative methods, this project follows three mentor/mentee pairs as they negotiate their relationships in an urban area in the Southwest United States. While all three pre-service teachers strongly believed that learning was a social practice, constructed through child inquiry and play, they struggled to maintain their ideologies and beliefs during their field experience. Pre-service teachers held firmly to their beliefs about teaching and learning, but holding onto these beliefs were wrought with personal and philosophical tensions. Pre-service teachers found limited agency in their practice and little support in implementing their own practices. Most importantly, unequal power dynamics and communication issues were obstacles towards mutually beneficial mentorship. Thus, preservice programs must address the importance of developing and cultivating the mentor/mentee relationship—a relationship that is pivotal in the construction of preservice teachers’ identities and practices.     

The effect of self‐directed work teams on work ethic

This study examined the work ethic of manufacturing machine operators between self‐directed work teams and traditional work groups using four work ethic subscales: dependable, considerate, ambitious, and cooperative (Dawson, 1999 ; Petty, 1991 ). Differences in measured work ethic scores were also compared across six demographic variables: age, gender, level of education, years of full‐time work experience, years of experience as a supervisor, and work shift preference. Findings showed that there were significant differences in the work ethic between those two team structures and age groups. Implications for future research were presented.