Hybrid capillary-inserted microfluidic device for sheathless particle focusing and separation in viscoelastic flow

A novel microfluidic device which consists of two stages for particle focusing and separation using a viscoelastic fluid has been developed. A circular capillary tube was used for three-dimensional particle pre-alignment before the separation process, which was inserted in a polydimethylsiloxane microchannel. Particles with diameters of 5 and 10 μm were focused at the centerline in the capillary tube, and the location of particles was initialized at the first bifurcation. Then, 5 and 10 μm particles were successfully separated in the expansion region based on size-dependent lateral migration, with ∼99% separation efficiency. The proposed device was further applied to separation of MCF-7 cells from leukocytes. Based on the cell size distribution, an approximate size cutoff for separation was determined to be 16 μm. At 200 μl/min, 94% of MCF-7 cells were separated with the purity of ∼97%. According to the trypan blue exclusion assay, high viability (∼90%) could be achieved for the separated MCF-7 cells. The use of a commercially available capillary tube enables the device to be highly versatile in dealing with particles in a wide size range by using capillary tubes with different inner diameters.     

Perceptions of Retirement Affect Career Commitment: The Mediating Role of Retirement System Satisfaction for Two Teacher Age Groups

This study investigated a sample of California elementary, intermediate, and high school employed teachers (N = 247) to assess the effects of retirement perceptions on career commitment among teachers who are in different age groupings. Using path analysis, the influence of five retirement perceptions variables was examined: concerns about retirement benefits, understanding of the retirement system, perceived need for system change, control over the retirement plan, and satisfaction with current salary. The results indicated that the pattern of results differed for younger and older teachers. For the younger (age 21–45) group, concerns about retirement benefits (such as losing or reducing benefits through geographic mobility) and control over the retirement plan had significant, large, and direct effects on career commitment. For the older (age 46+) group, retirement variables had a significant effect on career commitment via the mediator of satisfaction with the retirement system. Given these findings, for younger teachers, strategies might focus on providing greater control over the retirement plan, such as in offering choice in how their retirement monies are invested. Older teachers need to feel safe about retirement in the sense of being satisfied with the system and its benefits to commit to their jobs.     

Big Math for Little Kids: The Effectiveness of a Preschool and Kindergarten Mathematics Curriculum

Research Findings: Big Math for Little Kids (BMLK) is a mathematics curriculum developed for use with 4- and 5-year-old children. To investigate the BMLK curriculum's effect on children's mathematics knowledge, this cluster-randomized controlled trial randomly assigned child care centers to provide mathematics instruction to children, using either the BMLK mathematics curriculum or the centers’ business-as-usual curriculum, over a 2-year period when children were in prekindergarten and kindergarten. Participants in the study were 762 children and their teachers at 16 publicly subsidized child care centers. The study assessed children's mathematics knowledge using the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B), Direct Mathematics Assessment, a measure of young children's mathematics knowledge that is not aligned with the curriculum. The ECLS-B scores of children in the BMLK group increased significantly more than did those of children in the comparison group. The study also included exploratory analyses to examine whether children in the BMLK group demonstrated evidence of improved mathematical language. Practice or Policy: These results indicate that the BMLK curriculum, which is designed to help teachers use play-based, developmentally appropriate mathematics instruction, has a positive impact on young children's mathematics knowledge as measured by a general mathematics assessment that is not aligned with the curriculum.     

Musculoskeletal stiffness during hopping and running does not change following downhill backwards walking

Eccentric contractions that provide spring energy can also cause muscle damage. The aim of this study was to explore leg and vertical stiffness following muscle damage induced by an eccentric exercise protocol. Twenty active males completed 60 minutes of backward-walking on a treadmill at 0.67 m/s and a gradient of ? 8.5° to induce muscle damage. Tests were performed immediately before; immediately post; and 24, 48, and 168 hours post eccentric exercise. Tests included running at 3.35 m/s and hopping at 2.2 Hz using single- and double-legged actions. Leg and vertical stiffness were measured from kinetic and kinematic data, and electromyography (EMG) of five muscles of the preferred limb were recorded during hopping. Increases in pain scores (over 37%) occurred post-exercise and 24 and 48 hours later (p < 0.001). A 7% decrease in maximal voluntary contraction occurred immediately post-exercise (p = 0.019). Changes in knee kinematics during single-legged hopping were observed 168 hours post (p < 0.05). No significant changes were observed in EMG, creatine kinase activity, leg, or vertical stiffness. Results indicate that knee mechanics may be altered to maintain consistent levels of leg and vertical stiffness when eccentric exercise-induced muscle damage is present in the lower legs.     

A Campus-Wide Investigation of Clicker Implementation: The Status of Peer Discussion in STEM Classes

At the University of Maine, middle and high school teachers observed more than 250 university science, technology, engineering, and mathematics classes and collected information on the nature of instruction, including how clickers were being used. Comparisons of classes taught with (n = 80) and without (n = 184) clickers show that, while instructional behaviors differ, the use of clickers alone does not significantly impact the time instructors spend lecturing. One possible explanation stems from the observation of three distinct modes of clicker use: peer discussion, in which students had the opportunity to talk with one another during clicker questions; individual thinking, in which no peer discussion was observed; and alternative collaboration, in which students had time for discussion, but it was not paired with clicker questions. Investigation of these modes revealed differences in the range of behaviors, the amount of time instructors lecture, and how challenging the clicker questions were to answer. Because instructors can vary their instructional style from one clicker question to the next, we also explored differences in how individual instructors incorporated peer discussion during clicker questions. These findings provide new insights into the range of clicker implementation at a campus-wide level and how such findings can be used to inform targeted professional development for faculty.     

Transforming engagement: a case study of building intrinsic motivation in a child with autism

This longitudinal case study of a 10‐year‐old girl with autism and severe communication impairment measures the impact of the MORE (Means, Opportunities, Reasons and Expectations) approach to enhancing engagement and communication. Through detailed observation of video data over a period of 28 months, engagement behaviours including interaction with adults and following adult directions increased, while resistant behaviours such as kicking, hitting and pushing adults away decreased. Fluctuation between different ‘states’ demonstrated that the frequency and duration of engagement was influenced by the MORE approach and an emphasis on developing intrinsic motivation. In order to enable further efficacy research, core features of the intervention and the changes in engagement over time are described.     

EDUCATION FOR SUSTAINABLE DEVELOPMENT: A SINO-ENGLISH COMPARATIVE STUDY IN ENVIRONMENTAL EDUCATION

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Relations Among the Home Language and Literacy Environment and Children’s Language Abilities: A Study of Head Start Dual Language Learners and Their Mothers

Research Findings: This study explored the relations between Spanish–English dual language learner (DLL) children’s home language and literacy experiences and their expressive vocabulary and oral comprehension abilities in Spanish and in English. Data from Spanish–English mothers of 93 preschool-age Head Start children who resided in central Pennsylvania were analyzed. Children completed the Picture Vocabulary and Oral Comprehension subtests of the Batería III Woodcock–Muñoz and the Woodcock–Johnson III Tests of Achievement. Results revealed that the language spoken by mothers and children and the frequency of mother–child reading at home influenced children’s Spanish language abilities. In addition, the frequency with which children told a story was positively related to children’s performance on English oral language measures. Practice or Policy: The findings suggest that language and literacy experiences at home have a differential impact on DLLs’ language abilities in their 2 languages. Specific components of the home environment that benefit and support DLL children’s language abilities are discussed.