Molecular diffusion analysis of dynamic blood flow and plasma separation driven by self-powered microfluidic devices     

Sung Oh Woo  Myungkeun Oh  Kyle Nietfeld  Bailey Boehler  Yongki Choi 《Biomicrofluidics》2021,15(3)

Integration of microfluidic devices with pressure-driven, self-powered fluid flow propulsion methods has provided a very effective solution for on-chip, droplet blood testing applications. However, precise understanding of the physical process governing fluid dynamics in polydimethylsiloxane (PDMS)-based microfluidic devices remains unclear. Here, we propose a pressure-driven diffusion model using Fick''s law and the ideal gas law, the results of which agree well with the experimental fluid dynamics observed in our vacuum pocket-assisted, self-powered microfluidic devices. Notably, this model enables us to precisely tune the flow rate by adjusting two geometrical parameters of the vacuum pocket. By linking the self-powered fluid flow propulsion method to the sedimentation, we also show that direct plasma separation from a drop of whole blood can be achieved using only a simple construction without the need for external power sources, connectors, or a complex operational procedure. Finally, the potential of the vacuum pocket, along with a removable vacuum battery to be integrated with non-PDMS microfluidic devices to drive and control the fluid flow, is demonstrated.  相似文献   

Data‐driven refinements of a genetics learning progression     

Moraima Castro‐Faix  Ravit Golan Duncan  Jinnie Choi 《科学教学研究杂志》2021,58(1):3-39

Learning progressions are theoretical models that describe learning of scientific ideas and practices over time. These hypothetical progressions need to be tested and refined in order to productively inform instruction and assessment. In this paper, we report our attempts to revise a learning progression in genetics. In particular, we focused on two constructs that embody core ideas in classical genetics and one molecular construct. The revisions are based on analysis of pre‐ and postinterview data obtained from sixty 11th grade students before and after they engaged in a 10‐week unit that addressed these concepts. We found that while many of the students held ideas that aligned with the progression, there were several distinct dimensions of student reasoning that were not captured and led to substantial revisions of the constructs including: (a) the splitting of the construct dealing with meiosis (E) into two subconstructs (E1‐physical passage of genetic information and E2 – the role of sex cells), (b) the addition of new levels to constructs dealing with the universal nature and organization of the genetic code (A) and construct (F). For Construct A, the lower levels were expanded to include ideas about the localization of DNA in cells and to include ideas about the composition of DNA that were not captured in the progression. Revisions to Construct F included the expansion of existing levels and the addition of modes of inheritance such as codominance and incomplete dominance. The research we present offers insights about a methodological approach that can be used to test and refine progressions, as well as insights about student learning in genetics as we further describe and expand the stepping‐stone ideas in the progression and discuss further the multidimensional nature of learning progressions.  相似文献   

Effect of sport education on students’ perceived physical literacy,motivation, and physical activity levels in university required physical education: a cluster-randomized trial     

Choi  Siu Ming  Sum  Kim Wai Raymond  Leung  Fung Lin Elean  Wallhead  Tristan  Morgan  Kevin  Milton  Daniel  Ha  Sau Ching Amy  Sit  Hui Ping Cindy 《Higher Education》2021,81(6):1137-1155

Higher Education - Originating from the field of physical education, physical literacy is an individual disposition that accentuates the importance of lifelong physical activity. Sport education is...  相似文献   

Noise Levels in Hong Kong Primary Schools: Implications for classroom listening     

Ching Yee Choi 《International Journal of Disability, Development & Education》2005,52(4):345-360

Many researchers have stressed that the acoustic environment is crucial to the speech perception, academic performance, attention, and participation of students in classrooms. Classrooms in highly urbanised locations are especially vulnerable to noise, a major influence on the acoustic environment. The purpose of this investigation was to determine noise levels in one such urban environment, Hong Kong. The ambient noise level, and its relationship to the speech intensity levels of both teachers and students was surveyed in 47 primary school classrooms. Moreover, the presence of acoustical treatments for noise reduction and the use of classroom amplification systems were documented for each classroom. The survey found that the mean occupied noise level was 60.74 dB (A); the mean unamplified and amplified speech‐to‐noise ratios of teachers were 13.53 dB and 18.45 dB, respectively; while the mean unamplified speech‐to‐noise ratio for students was 4.13 dB. Most of the classrooms exhibited insufficient acoustical treatments to provide significant noise reduction. The listening environment in many Hong Kong primary schools was not favourable for optimal classroom learning. Recommendations for improving the acoustical environment in classrooms in highly urbanised locations such as Hong Kong are discussed.  相似文献   

Identifying indicators of university autonomy according to stakeholders’ interests     

Choi  Seungchan 《Tertiary Education and Management》2019,25(1):17-29

Tertiary Education and Management - This paper is an attempt to reconcile two different perspectives and come up with a more comprehensive conceptualization of university autonomy by adopting a...  相似文献   

Integrating failure in case-based learning: a conceptual framework for failure classification and its instructional implications     

Rong  Hui  Choi  Ikseon 《Educational technology research and development : ETR & D》2019,67(3):617-637

Employing authentic cases experienced by practitioners in educational contexts is critical to expanding students’ experience and engaging students in authentic problems to promote their real-world problem-solving skills. Although in real life, practitioners experience both success and failure and learn from both, little research has been done so far to conceptualize why and how failure should be employed in case-based learning (CBL) as a way to develop students’ abilities to solve ill-structured problems. The goal of this paper is to theoretically justify the need for integrating failure cases in CBL to help students become better problem solvers. To achieve this, this paper attempted to approach failure from the perspective of human error and proposed a classification of failure based on the degree of explicitness of human error involved in problem solving. Based on discussions of potential benefits and challenges of integrating different types of failure cases in education, this paper also proposed instructional design strategies that can help facilitate better use of failure cases.

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Do Stability of Care and Teacher–Child Interaction Quality Predict Child Outcomes in Early Head Start?     

Ji Young Choi  Diane Horm  Shinyoung Jeon  Dahyung Ryu 《Early education and development》2019,30(3):337-356

Research Findings: This study examined whether children’s outcomes at age 3 were predicted by their experiences in Early Head Start (EHS), focusing on 2 key features of infant and toddler care: (a) stability of care and (b) teacher–child interactions. This study further explored potential interaction effects between stability of care and teacher–child interactions in predicting child outcomes. Three main results were found from secondary analyses of the recently released EHS longitudinal data set the EHS Family and Child Experiences Study (Vogel & Boller, 2009–2012). First, children who had stability of care (no teacher change) were rated as having fewer behavior problems and higher social competence. Second, children were rated as demonstrating better orientation/engagement and emotional regulation when they were in EHS classrooms observed to have higher emotional and behavioral support. Third, teacher–child interactions that are emotionally and behaviorally supportive may mitigate the potential drawbacks of experiencing instability of care on early social-emotional development. Study implications are discussed. Practice or Policy: Both stability and quality teacher–child interactions are important in center-based infant and toddler care, and ensuring quality teacher–child interactions is particularly important for children who experience teacher changes during their infant and toddler years.  相似文献   

Practicing Social Skills Training for Young Children with Low Peer Acceptance: A Cognitive-Social Learning Model     

Dong Hwa Choi  Juhu Kim 《Early Childhood Education Journal》2003,31(1):41-46

Peer acceptance during early childhood is related to children's academic achievement, adjustment in school, and even psychological well-being in adulthood. Children who experience low peer acceptance exhibit socially inappropriate behavior patterns, which are associated with irrelevant patterns of information processing. Therefore, as a way of helping children with low peer acceptance, a cognitive-social learning model of social skills training has been used because the model focuses on cognitive changes as well as behavioral changes. Three parts of the social skills training—enhancing skill concepts, promoting skill performance, and fostering skill maintenance/generalization—are discussed. In order to be successful, a trainer should understand the training model as well as behavioral patterns of children with low peer acceptance to provide theory-based and individualized feedback to each participant.  相似文献   

Continuity of Care,Caregiver–Child Interactions,and Toddler Social Competence and Problem Behaviors     

Karen Ruprecht  James Elicker  Ji Young Choi 《Early education and development》2016,27(2):221-239

ABSTRACT

Research Findings: Continuity of care is a recommended practice in child care intended to promote secure and supportive relationships between infants and toddlers and their caregivers. Toddlers (N = 115) between 12 and 24 months were observed in 30 continuity and 29 noncontinuity classrooms. The average duration of care for toddlers with caregivers was 14 months in the continuity rooms and 5 months in noncontinuity rooms. Toddlers observed in continuity rooms experienced higher levels of interactive involvement with their caregivers and were rated by their caregivers as having fewer problem behaviors compared with the toddlers in noncontinuity rooms. Toddlers in rooms with higher staff–child ratios also experienced more involved caregiving. We did not find evidence that the level of involved caregiving mediated the association between continuity of care and toddlers’ social competence or problem behaviors. Practice or Policy: Continuity of care may be a promising practice for programs that strive to provide high-quality care for infants and toddlers.  相似文献   

Influence of Cultural Orientations on Electronic Word-of-Mouth (eWOM) in Social Media     

Youngtae Choi 《Journal of Intercultural Communication Research》2019,48(3):292-313

This study explores how horizontal/vertical individualism and collectivism (HVIC) orientations influence electronic word-of-mouth (eWOM) (i.e., opinion leadership and opinion seeking) in social media. Online survey panel data through Amazon MTurk were collected from American social media users to address the research purpose. The results, using the structural equation modeling, show that the paths from horizontal individualism to opinion leadership, vertical individualism to opinion leadership and opinion seeking, horizontal collectivism to opinion leadership, and vertical collectivism to opinion leadership and opinion seeking were significant. This study provides theoretical and managerial implications regarding the influence of HVIC orientations on eWOM in social media.  相似文献