Gravity-oriented microfluidic device for uniform and massive cell spheroid formation     

Lee K  Kim C  Young Yang J  Lee H  Ahn B  Xu L  Yoon Kang J  Oh KW 《Biomicrofluidics》2012,6(1):14114-141147

We propose a simple method for forming massive and uniform three-dimensional (3-D) cell spheroids in a multi-level structured microfluidic device by gravitational force. The concept of orienting the device vertically has allowed spheroid formation, long-term perfusion, and retrieval of the cultured spheroids by user-friendly standard pipetting. We have successfully formed, perfused, and retrieved uniform, size-controllable, well-conditioned spheroids of human embryonic kidney 293 cells (HEK 293) in the gravity-oriented microfluidic device. We expect the proposed method will be a useful tool to study in-vitro 3-D cell models for the proliferation, differentiation, and metabolism of embryoid bodies or tumours.  相似文献   

Successful recanalization of chronic total occlusion of the superior mesenteric artery by transradial approach     

Woo Taek Kim  Sung Gyun Ahn  Jun-Won Lee  Joong Kyung Sung  Seung Hwan Lee  Junghan Yoon 《Journal of Zhejiang University. Science. B》2010,11(8):627-630

It is a challenge to confirm chronic mesenteric ischemia (CMI) as a cause of gastrointestinal (Gl) symptoms such as postprandial epigastric bloating,anorexia,and debilitating weight loss.Endovascular intervention for CMI has been gaining popularity because of the high morbidity associated with surgical revascularization.However,in EVI for superior mesenteric artery (SMA) occlusion,the transfemoral approach is limited by difficulty in coaxial alignment of the guiding catheter,which leads to insufficient back-up support.Herein,we report on a 58-year-old male patient with chronic total occlusion of the SMA,which was successfully revascularized by endovascular intervention via the left radial artery.Transradial endovascutar therapy may be another treatment option for the treatment of CMI.  相似文献   

A Meta-Analysis on Gender Differences in Mental Rotation Ability Measured by the Purdue Spatial Visualization Tests: Visualization of Rotations (PSVT:R)     

Yukiko Maeda  So Yoon Yoon 《Educational Psychology Review》2013,25(1):69-94

This meta-analysis was conducted to estimate the magnitude of gender difference in three-dimensional (3-D) mental rotation ability and to investigate how factors related to test administration conditions play a role in varying gender difference effect sizes and threatening validity. Individuals’ 3-D mental rotation ability was measured by the Purdue Spatial Visualization Tests: Visualization of Rotations (PSVT:R). We integrated 70 effect sizes of gender differences in mental rotation ability measured by the PSVT:R which were obtained from 40 primary studies. The results indicated that male participants outperformed females on the test (Hedges’ g?=?0.57). The I ² statistic indicated 41.7 % of variation in effect sizes reflects real heterogeneity. The moderator analysis indicated that male superiority on spatial ability tasks measured by the PSVT:R is related to the implementation of time limits. The gender difference became larger when stringent time limits (equal or less than 30 s per item) were implemented.  相似文献   

Identifying organizational knowledge creation enablers through content analysis: The voice from the industry     

Ji Hoon Song  Seung Won Yoon  Hea Jun Yoon 《Performance Improvement Quarterly》2011,24(2):71-88

The primary purpose of the current research was to identify core contextual factors that facilitate or hinder the process of organizational knowledge creation practices. The grounded theory framework and negotiated coding approach were employed. Serving as the fundamental research framework was Nonaka and his colleagues' knowledge creation and conversion theory, along with their proposed knowledge creation enablers. A total of 314 codeable units from 153 individuals were used for data analysis. All answers were coded and categorized into three emerged domains—organization, team/subgroup, and individual—for both areas of facilitating and hindering factors. Limitations and implications for further research are presented in the discussion section.  相似文献   

Teaching Young Children Science: Three Key Points     

Jiyoon Yoon  Jacqueline Ariri Onchwari 《Early Childhood Education Journal》2006,33(6):419-423

Many early childhood teachers report lacking confidence to teach science. Today, science education is defined as “doing science”, as opposed to memorization of facts (Seefeldt & Galper, 2002). This paper discusses developmentally appropriate practices in the context of teaching science. Knowledge of child development, individual differences and the role of children’s socio-cultural context are explicitly discussed. The use of questioning and the 5 Es (engaging, exploring, explaining, elaborating, evaluating) instructional model are also discussed. A sample science lesson is provided to model the use of 5 Es and questioning strategies.  相似文献   

Stephanie Hinnershitz. Race,Religion, and Civil Rights: Asian Students on the West Coast, 1900–1968. New Brunswick,NJ: Rutgers University Press, 2015. 258 pp. Hardcover $90.00. Paper $28.95.     

Yoon K. Pak 《History of education quarterly》2016,56(3):521-524

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Exploring the Use of Cases and Case Methods in Influencing Elementary Preservice Science Teachers' Self-Efficacy Beliefs     

Susan Yoon  Erminia Pedretti  Larry Pedretti  Jim Hewitt  Kirk Perris  Roland Van Oostveen 《Journal of Science Teacher Education》2006,17(1):15-35

In this study, we hypothesize that cases demonstrating exemplary practice in the science classroom can be used as a source for learning content and pedagogical skills that will improve teachers' self-efficacy beliefs. Twelve preservice elementary science teachers are followed as they participate in a case and case method activity illustrating the Grade 7 topic of robotics and fluids. While there was little evidence to show improvements in content knowledge, results indicate that the case acted as a boundary object for brokering between individual experiences and those found in the science teaching community by scaffolding for multiple points of entry, bridging the theory practice gap and offering beginning teachers more immediate access to the community of already practicing teachers.

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Deconstructing the genealogy of family-centredness in early childhood intervention using a poststructuralist lens / Deconstrucción de la genealogía del enfoque centrado en la familia en las intervenciones de atención temprana,desde un punto de vista post-estructuralista     

Yoon H. Lee 《Cultura y Educación》2016,28(2):328-343

This paper aims to examine the genealogy of family-centredness in early childhood intervention. In particular, it deconstructs the procedural requirements, such as the completion of the Individualized Family Service Plan (IFSP), which has operated to serve the notion of family-centredness. Employing a poststructuralist lens, the paper contends that the current knowledge/belief is constructed and institutionalized by the dominant groups, such as policymakers and professionals, and their discourse. Families are normalized with discursive practices to believe that their participation perfects the rules set by powered social institutions with knowledge and power; hence, they are at the centre in the practice of services and provisions. Blinded by the normalized discipline, the historically absented position of families in the construction of social structures has perpetuated through the existing practices. Thus, this paper offers a critical reflection on the understanding of multiple discourses. In particular, both service providers and families should be able to question the process of service provisioning, when necessary. By critically viewing the current case, the development of quality early childhood intervention programmes and family-centred practices might be purported across countries.  相似文献   

School Choice Policies Shaping Neighborhoods,School Locations,and Destinies     

Charisse Gulosino  Ee-Seul Yoon 《Peabody Journal of Education》2020,95(3):203-210

ABSTRACT

In this article, we introduce a special collection of research articles that consider the processes and consequences of school choice across different social and spatial contexts in order to better understand the relationship between school choice and stratification in educational opportunity. This special issue presents a wide range of studies that examine geographical configurations, locations, scales, and relationships, all of which shape and are shaped by school choice. We summarize the diverse theoretical perspectives and themes. We also highlight the articles’ key results and new contributions related to issues such as inter-district school choice, open enrollment school choice programs, diversification of curricular-related activities among EMO-operated schools, and geographic variation in achievement of the charter school sector  相似文献   

Testing Factorial Invariance With Unbalanced Samples     

Myeongsun Yoon  Mark H. C. Lai 《Structural equation modeling》2018,25(2):201-213

In testing the factorial invariance of a measure across groups, the groups are often of different sizes. Large imbalances in group size might affect the results of factorial invariance studies and lead to incorrect conclusions of invariance because the fit function in multiple-group factor analysis includes a weighting by group sample size. The implication is that violations of invariance might not be detected if the sample sizes of the 2 groups are severely unbalanced. In this study, we examined the effects of group size differences on results of factorial invariance tests, proposed a subsampling method to address unbalanced sample size issue in factorial invariance studies, and evaluated the proposed approach in various simulation conditions. Our findings confirm that violations of invariance might be masked in the case of severely unbalanced group size conditions and support the use of the proposed subsampling method to obtain accurate results for invariance studies.  相似文献