Cascaded spiral microfluidic device for deterministic and high purity continuous separation of circulating tumor cells     

Tae Hyun Kim  Hyeun Joong Yoon  Philip Stella  Sunitha Nagrath 《Biomicrofluidics》2014,8(6)

Inertial microfluidics is an emerging class of technologies developed to separate circulating tumor cells (CTCs). However, defining design parameters and flow conditions for optimal operation remains nondeterministic due to incomplete understanding of the mechanics, which has led to challenges in designing efficient systems. Here, we perform a parametric study of the inertial focusing effects observed in low aspect ratio curvilinear microchannels and utilize the results to demonstrate the isolation of CTCs with high purity. First, we systematically vary parameters including the channel height, width, and radius of curvature over a wide range of flow velocities to analyze its effect on size dependent differential focusing and migration behaviors of binary (10 μm and 20 μm) particles. Second, we use these results to identify optimal flow regimes to achieve maximum separation in various channel configurations and establish design guidelines to readily provide information for developing spiral channels tailored to potentially arbitrary flow conditions that yield a desired equilibrium position for optimal size based CTC separation. Finally, we describe a fully integrated, sheath-less cascaded spiral microfluidic device to continuously isolate CTCs. Human breast cancer epithelial cells were successfully extracted from leukocytes, achieving 86.76% recovery, 97.91% depletion rate, and sustaining high viability upon collection to demonstrate the versatility of the device. Importantly, this device was designed without the cumbersome trail-and-error optimization process that has hindered the development of designing such inertial microfluidic systems.  相似文献   

This Issue: Theories of Bullying and Cyberbullying     

Sheri Bauman  Jina Yoon 《理论付诸实践》2014,53(4):253-256

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Early development among dual language learners: The roles of language use at home,maternal immigration,country of origin,and socio-demographic variables     

Adam Winsler  Margaret R. Burchinal  Hsiao-Chuan Tien  Ellen Peisner-Feinberg  Linda Espinosa  Dina C. Castro  Doré R. LaForett  Yoon Kyong Kim  Jessica De Feyter 《Early childhood research quarterly》2014

Using nationally representative data from the ECLS-B, we examined children's outcomes and growth from 9 to 65 months as a function of language used in the home at 24 months (English only n = 7300; English and another language n = 1500; other language only n = 400). We also examined whether demographic variables moderated the effects of DLL status in predicting child outcomes. Results revealed substantial variation within the DLL population within and across language groups in immigration status, heritage country, child outcomes, and family socioeconomic risk. DLL status was associated with differential outcomes, gains over time, and processes in complex ways. Maternal birth outside of the U.S., child gender, and parental education moderated relations between home language and child outcomes. Use of the heritage language at home served as a protective factor for children of immigrant families for a few outcomes. Gender and parental education were more strongly associated with child outcomes among English-speaking households than among DLLs.  相似文献   

The Relationship of Science Knowledge,Attitude and Decision Making on Socio-scientific Issues: The Case Study of Students’ Debates on a Nuclear Power Plant in Korea     

Hunkoog Jho  Hye-Gyoung Yoon  Mijung Kim 《Science & Education》2014,23(5):1131-1151

The purpose of this study was to investigate the relationship of students’ understanding of science knowledge, attitude and decision making on socio-scientific issues (SSI), especially on the issues of nuclear energy in Korea. SSI-focused instructions were developed to encourage students to understand and reflect on knowledge, attitude and decision making on nuclear energy in the current society. Eighty-nine students attended the instruction and participated in pre and post questionnaires to understand their understandings of nuclear energy. In this study, science knowledge was categorized into content and contextual knowledge, attitude consisted of images, safety, risk, potential, benefits and future roles, and decision making section included preference and alternative about lifetime extension of nuclear power plant. The results of questionnaires were analyzed by correlation, cross-tabulation and regression. As a result, while students’ understandings of science knowledge were significantly improved throughout the instruction, they maintained similar attitude and decision making on the issue. Regarding the relationship of the three domains, attitude showed some degree of connection to decision making whereas science knowledge did not show a significant relationship to decision making. This finding challenges SSI teaching in content-based science curriculum and classroom. Reflection and implications on the way of teaching SSI in the classroom were discussed further in this paper.  相似文献   

Private Nonprofit Organizations for Child Welfare Cases of South Korea and People’s Republic of China     

李伦知 《时代教育》2013,(18)

Private organizations and public sector regarding child welfare services have been two main actors in improving the quality of children ’s lives. In this paper, the author examines two cases of childre...  相似文献   

Cyber practicum: A future practicum classroom     

Yoon Jiyoon 《British journal of educational technology : journal of the Council for Educational Technology》2008,39(1):163-165

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Search strategies to identify information on adverse effects: a systematic review          下载免费PDF全文

Su Golder  Yoon Loke 《Medical Library and Historical Journal》2009,97(2):84-92

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Using memes and memetic processes to explain social and conceptual influences on student understanding about complex socio‐scientific issues     

Susan Yoon 《科学教学研究杂志》2008,45(8):900-921

This study investigated seventh grade learners' decision making about genetic engineering concepts and applications. A social network analyses supported by technology tracked changes in student understanding with a focus on social and conceptual influences. Results indicated that several social and conceptual mechanisms potentially affected how and why ideas were taken up in the learning system of the classroom. Mechanisms included copying or memetic processes such as “do as the smart students do” and friendship selection. Study outcomes are compared with the broader literature on memes and memetic processes to reveal general evolutionary ideas such as the development of prestige, identity versus problem‐solving strategies, extended phenotypes, and memeplexes. Educational implications for this research are also addressed. © 2008 Wiley Periodicals, Inc. J Res Sci Teach 45: 900–921, 2008  相似文献   

Relationships between cognitive diagnosis, CTT, and IRT indices: an empirical investigation     

Young-Sun Lee  Jimmy de la Torre  Yoon Soo Park 《Asia Pacific Education Review》2012,13(2):333-345

Cognitive diagnosis models (CDMs) continue to generate interest among researchers and practitioners because they can provide diagnostic information relevant to classroom instruction and student learning. However, its modeling component has outpaced its complementary component??test construction. Thus, most applications of cognitive diagnosis modeling involve retrofitting of CDMs to assessments constructed using classical test theory (CTT) or item response theory (IRT). This study explores the relationship between item statistics used in the CTT, IRT, and CDM frameworks using such an assessment, specifically a large-scale mathematics assessment. Furthermore, by highlighting differences between tests with varying levels of diagnosticity using a measure of item discrimination from a CDM approach, this study empirically uncovers some important CTT and IRT item characteristics. These results can be used to formulate practical guidelines in using IRT- or CTT-constructed assessments for cognitive diagnosis purposes.  相似文献   

Policy efforts to increase women faculty in Korea: reactions and changes at universities     

Namhee Kim  Hea Jun Yoon  Gary N. McLean 《Asia Pacific Education Review》2010,11(3):285-299

Since 2001, the issue of the low ratio of women faculty in universities has been prominent in Korea because of its negative impact on female students and gender equality at the university level that has affected human resource development and utilization at the national level. To address this issue, the Korean government developed and executed an education policy, the Policy on Women Faculty Increase (PWFI) from 2004 to 2006. This paper investigated reactions to the PWFI and changes made as a result of the policy in the conservative Korean higher education context. We found that although the PWFI has particularly contributed to increasing the representativeness of women faculty in areas in which women faculty used to be rare, overall the PWFI has not made significant improvements in most participating universities due to the lack of internal motives and drivers and effective systems to support the policy. Recommendations for improvements in the policy are offered.  相似文献