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   

Adaptive controller design for spacecraft formation flying using sliding mode controller and neural networks     

Jonghee Bae  Youdan Kim 《Journal of The Franklin Institute》2012,349(2):578-603

A spacecraft formation flying controller is designed using a sliding mode control scheme with the adaptive gain and neural networks. Six-degree-of-freedom spacecraft nonlinear dynamic model is considered, and a leader–follower approach is adopted for efficient spacecraft formation flying. Uncertainties and external disturbances have effects on controlling the relative position and attitude of the spacecrafts in the formation. The main benefit of the sliding mode control is the robust stability of the closed-loop system. To improve the performance of the sliding mode control, an adaptive controller based on neural networks is used to compensate for the effects of the modeling error, external disturbance, and nonlinearities. The stability analysis of the closed-loop system is performed using the Lyapunov stability theorem. A spacecraft model with 12 thrusts as actuators is considered for controlling the relative position and attitude of the follower spacecraft. Numerical simulation results are presented to show the effectiveness of the proposed controller.  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   

Distributed framework for yard planning in container terminals     

Kap Hwan Kim  Xiao-hui Zhang 《浙江大学学报(A卷英文版)》2010,11(12):992-997

This study discusses a yard planning system,which considers various resources such as storage space,yard cranes,and traffic areas in container terminals.The system is based on the function for estimating resource requirements of yard plans.For a given yard plan,the proposed system allows planners to check the feasibility of the plan which requires a certain amount of workload of resources in related blocks during a planning horizon.The yard planning system in this study is aimed at balancing workloads among the blocks and providing the ability to modify current yard plans by detecting blocks and periods with overloaded workloads.The system implements its planning function in a distributed manner in which planners construct yard plans under their individual control and send and receive only limited necessary information for the negotiation.  相似文献   

Social information processing and coping strategies of shy/withdrawn and aggressive children: does friendship matter?     

Burgess KB  Wojslawowicz JC  Rubin KH  Rose-Krasnor L  Booth-LaForce C 《Child development》2006,77(2):371-383

The primary objectives of this investigation were to examine the attributions, emotional reactions, and coping strategies of shy/withdrawn and aggressive girls and boys and to examine whether such social cognitions differ within the relationship context of friendship. Drawn from a sample of fifth and sixth graders (M age = 10.79 years; SD = .77), 78 shy/withdrawn, 76 aggressive, and 85 control children were presented with hypothetical social situations that first involved unfamiliar peers, and then a mutual good friend. Results revealed group and gender differences and similarities, depending on the relationship context. From our findings emerges a central message: friends' involvement during interpersonal challenges or stressors mitigates children's attributions, emotions, and coping responses.  相似文献   

A System of Student Feedback: Considerations of Academic Staff Taken into Account     

Veerle Hulpiau  Evelien Masschelein  Luc Van Der Stockt  Piet Verhesschen  Kim Waeytens 《Tertiary Education and Management》2013,19(1):35-45

As a consequence of the suspension of a system of yearly evaluations of individual courses with student questionnaires, the University of Leuven organised a broad consultation of the academic community focussing on what they expect from a system based on student feedback. The study revealed that this community attaches great importance to a clear definition of the goals of student feedback, improvement and accountability, and a logical translation of these goals into a concrete approach. The study also confirmed the need of academic staff for a concrete response to the importance they give to quality improvement and enhancement besides accountability.  相似文献   

Academic socialization of doctoral students through feedback networks: a qualitative understanding of the graduate feedback landscape     

Kyung Min Kim 《Teaching in Higher Education》2013,18(8):963-980

ABSTRACT

Scholars focus on the social nature of academic writing to refine an understanding of feedback interactions in higher education. However, studies on the various sources of feedback – feedback networks – have been scarce, particularly during the initial years of doctoral education. Using a qualitative case study approach, multiple sources of feedback for four students in one doctoral program in the United States were identified in line with broader trends focusing on feedback as a social practice. Informed by the academic socialization framework [Duff, Patricia A. 2012. “Second Language Socialization.” In Handbook of Language Socialization, edited by Alessandro Duranti, Elinor Ochs, and Bambi B. Schieffelin, 564–586. Malden: Wiley-Blackwell], this study aims (1) to navigate the landscape of graduate feedback, including interactions beyond class as well as oral and written feedback, and (2) to elucidate the socialization process. Findings suggest that academic writing development is defined as how feedback is situated within disciplinary, academic communities of interaction. This article describes how the larger network of feedback creates the types of interaction that characterizes the community.  相似文献   

Mapping beliefs about teaching to patterns of instruction within science,technology, engineering,and mathematics     

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   

Assessing mentoring in organizations: an evaluation of commercial mentoring instruments     

Brad Gilbreath  Gail L. Rose  Kim E. Dietrich 《Mentoring & Tutoring: Partnership in Learning》2013,21(4):379-393

The purpose of this article is to inform readers about the types of instruments available for assessing and improving mentoring in organizations. Extensive review of the psychological, business and medical literature was conducted to identify commercially published, practitioner‐oriented instruments. All of the instruments that were identified – including the Alleman mentoring activities questionnaire, Mentoring in the moment, Mentoring skills assessment, and Principles of adult mentoring scale – are evaluated herein. Each instrument’s target audience, raters, subscales, response options, psychometric properties, and relative strengths and weaknesses are described. Although these instruments are reported to be used extensively, evidence of their validity is not always available. This review presents information that, in combination with first‐hand inspection of the instruments, should enable practitioners to differentiate between instruments that may be a fit for their needs from those that are not. Furthermore, it may introduce academic readers to instruments that are not covered in the scholarly literature in spite of their common use for non‐research purposes.  相似文献   

Enhancing Project-Based Learning Through Online Between-Group Collaboration     

Yiping Lou  S. Kim MacGregor 《Educational Research and Evaluation》2013,19(4-6):419-440

This research explored how between-group collaboration enhanced the co-construction of knowledge and performance on project-based learning tasks of collaborative learning groups. The findings of 2 case studies, one that focused on between-group mentoring and one that focused on between-group project review, revealed that both strategies were perceived favorably by the students and had a positive impact on the collaborative learning skills, the knowledge revealed through their online dialogue, and the project performance of all students, especially the less effective groups. The results provide some insights into the computer-supported collaborative learning process among students in a higher education context.  相似文献