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Xinyu Lu Saurin Patel Meng Zhang Sang Woo Joo Shizhi Qian Amod Ogale Xiangchun Xuan 《Biomicrofluidics》2014,8(2)
Electrophoresis plays an important role in many applications, which, however, has so far been extensively studied in Newtonian fluids only. This work presents the first experimental investigation of particle electrophoresis in viscoelastic polyethylene oxide (PEO) solutions through a microchannel constriction under pure DC electric fields. An oscillatory particle motion is observed in the constriction region, which is distinctly different from the particle behavior in a polymer-free Newtonian fluid. This stream-wise particle oscillation continues until a sufficient number of particles form a chain to pass through the constriction completely. It is speculated that such an unexpected particle oscillating phenomenon is a consequence of the competition between electrokinetic force and viscoelastic force induced in the constriction. The electric field magnitude, particle size, and PEO concentration are all found to positively affect this viscoelasticity-related particle oscillation due to their respective influences on the two forces. 相似文献
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This study examines the debates and discussions surrounding the Korean government's Me2Day, the largest social networking and microblogging site in the country used by 26 government bureaus, including the Blue House. Me2Day users post messages composed of up to 150 characters and establish links with other users through multimedia-based information and knowledge obtained from their browsers, desktop computers, e-mail messages, and mobile phones. This study provides a better understanding of the characteristics and structures of cyberspace communication between the Korean government and citizens. The results indicate that although each bureau had different goals in terms of using Me2Day, users were more likely to use the service if their bureau actively posted messages or responded to user comments. Users tended to have critical attitudes toward the Korean government when they were allowed to freely post messages and share information. 相似文献
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Cheryl Allendoerfer Denise Wilson Mee Joo Kim Elizabeth Burpee 《Teaching in Higher Education》2013,18(7):758-771
In this paper, we identify beliefs about teaching and patterns of instruction valued and emphasized by science, technology, engineering, and mathematics faculty in higher education in the USA. Drawing on the notion that effective teaching is student-centered rather than teacher-centered and must include a balance of knowledge-, learner-, community-, and assessment-centered learning environments; we use qualitative interview data to explore how faculty's reported beliefs about teaching are associated with their consideration of these four types of environments. Findings indicated that although a range of beliefs about teaching emerged, most were firmly located in knowledge-centered learning environments, with little or no focus on the remaining three learning environments. Furthermore, even patterns of instruction that were heavily student-centered were situated within a knowledge-centered learning framework. We argue that for student-centered instruction to be truly successful, faculty must consider all four learning environments in crafting and facilitating the classroom environment. 相似文献
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The Kalman filtering algorithm is used to identify a class of signals imbedded in high amplitude measurement noise. The considered class of signals is first modeled empirically as a nonlinear equation. The equation is then linearized and formulated as a Kalman filtering state estimation problem. Computer simulations yield excellent results for a variety of examples, a couple of which are presented in this paper. 相似文献
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Duck‐Joo Kwak 《Educational theory》2010,60(4):405-417
In this essay Duck‐Joo Kwak explores a moral perfectionist approach to citizenship education, which is distinct from liberal and communitarian models. One of educational challenges to this approach is how to cultivate our students' sense of membership, which is shaped by a thick sense of the good life, while being not merely compatible with but open to the pluralist perspective. Kwak maintains that what is required for this form of membership to society or community is our future citizens' ability to engage in highly self‐reflexive philosophical reflection on the human condition; such reflection gives them the skills necessary to live up to the tension between different selves of diverse origins or within a divided self. Examining Stanley Cavell's view of political education as an exemplar of the moral perfectionist approach to citizenship education, Kwak shows how the practice of his ordinary language philosophy can be a good way to cultivate this ability by teaching us how to “speak for others” by way of “speaking for oneself.” 相似文献
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This paper critically considers the attempt by a research-intensive university in Asia to draw on and make public the practices of teaching award winners in different disciplines through the use of narrative vignettes. More specifically, this paper examines what the vignettes suggest about the connection between award-winning teachers’ conceptions of teaching (CT) on the one hand, and scholarly investigations of practice on the other, and to what extent the vignettes meet the aim of using the scholarship of teaching and learning as an instrument of effective academic development. Content analysis of the vignettes revealed that award-winning teachers’ CT tend to focus predominantly on enhancing learning, followed by encouraging collective knowledge creation and transmission of knowledge. A two-dimensional framework was also used to analyse the vignettes along a tacit-integrated continuum and within an intuitive-reflective frame of inquiry. The findings are discussed in relation to teachers’ perception of their impact on students’ learning and ways to enhance their own practice, with implications for teaching awards, documentation, and dissemination of high-level teaching achievement. 相似文献
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Peer feedback is an inherent feature of classroom collaborative learning. Students invariably turn to their peers for feedback when carrying out an investigative task, and this feedback is usually implicit, unstructured and may positively or negatively influence students’ learning when they work on a task. This study explored the characteristics of verbal peer feedback during a collaborative investigative chemistry task involving New Zealand Year 13 students. During the planning stage of the students’ investigation, the discussions of five pairs of students were recorded and then transcribed. Analysis of transcribed verbal data focused on interactions that involved peer feedback along two dimensions, interactive/non-interactive and dialogic/authoritative (Mortimer and Scott, 2003). The findings indicated that although students adopted a predominantly interactive/authoritative communicative approach, with peer feedback as confirmation or evaluation, they are also capable of a more interactive/dialogic exchange, characterised by elaborative peer feedback. We discuss how this dialogic perspective on peer feedback provides an alternative approach to the analysis and study of student–student interactions during science investigations. The findings should be interpreted in light of the limitations in terms of sample size, grouping and specificity of the coding scheme. Implications for teacher practice are discussed in relation to facilitating peer feedback discourse in the science classroom. 相似文献
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Cultural Issues of the Internet in Classrooms 总被引：1，自引：0，他引：1
Jae-Eun Joo 《British journal of educational technology : journal of the Council for Educational Technology》1999,30(3):245-250
Despite the rapid and broad diffusion of the Internet in schools, educators have paid relatively little attention to the cultural impact of this new technology in teaching and learning. This article investigates some cultural issues that the Internet has introduced into classrooms, with illustrations of good practice. It aims to stimulate critical discussions among educators on ethical and cultural aspects of Internet use, including equality of access and participation for all people, and mutual respect for, and promotion of, under-represented languages and cultures. This article finally demonstrates an urgent need to re-shape the Internet as a human, rather than merely computer, network. 相似文献
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