This paper presents a numerical study of DC-biased AC-electrokinetic (DC-biased ACEK) flow over a pair of symmetrical electrodes. The flow mechanism is based on a transverse conductivity gradient created through incipient Faradaic reactions occurring at the electrodes when a DC-bias is applied. The DC biased AC electric field acting on this gradient generates a fluid flow in the form of vortexes. To understand more in depth the DC-biased ACEK flow mechanism, a phenomenological model is developed to study the effects of voltage, conductivity ratio, channel width, depth, and aspect ratio on the induced flow characteristics. It was found that flow velocity on the order of mm/s can be produced at higher voltage and conductivity ratio. Such rapid flow velocity is one of the highest reported in microsystems technology using electrokinetics. 相似文献
Anatomy is an important component in the vertical integration of basic science and clinical practice. Two common pedagogies are cadaveric dissection and examination of prosected specimens. Comparative studies mostly evaluate their immediate effectiveness. A randomized controlled trial design was employed to compare both the immediate and long-term effectiveness of dissection and prosection. Eighty third-year medical students undergoing their surgical rotation from the Yong Loo Lin School of Medicine were randomized into two groups: dissection and prosection. Each participated in a one-day hands-on course following a similar outline that demonstrated surgical anatomy in the context of its clinical relevance. A pre-course test was conducted to establish baseline knowledge. A post-course test was conducted immediately after and at a one-year interval to evaluate learner outcome and knowledge retention. A post-course survey was conducted to assess participant perception. Thirty-nine and thirty-eight participants for the dissection and prosection groups, respectively, were included for analysis. There was no significant difference between mean pre-course test scores between the dissection and prosection groups [12.6 (3.47) vs. 12.7 (3.16), P > 0.05]. Both the mean immediate [27.9 (4.30) vs. 24.9 (4.25), P < 0.05] and 1 year [23.9 (4.15) vs. 19.9 (4.05), P < 0.05] post-course test scores were significantly higher in the dissection group. However, when adjusted for course duration [dissection group took longer than prosection group (mean 411 vs. 265 min)], these findings were negated. There is no conclusive evidence of either pedagogy being superior in teaching surgical anatomy. Based on learner surveys, dissection provides a greater learner experience. 相似文献
In this study, we sought to identify how feedback about classroom observations affected novice university mathematics instructors’ (UMIs) teaching practices. Specifically, we examined how a Red–Yellow–Green feedback system (RYG feedback) affected graduate student instructor (GSI) scores on an observation protocol (GSIOP). The protocol was developed specifically for this population, and both the GSIOP and RYG feedback were used within a peer mentoring program for GSIs, wherein novice GSIs were mentored by more experienced GSIs. Mentors observed novices’ classrooms using the GSIOP and provided RYG feedback as part of observation–feedback cycles. We analyzed 100 sets of scores, each collected over the course of a semester containing on average three observation–feedback cycles. Analyzing the semester-long datasets longitudinally provided insight into what types of feedback informed and influenced observed teaching. After qualitatively coding the feedback provided to the GSIs by their mentors along multiple dimensions, we found certain forms of feedback were more influential for observable changes in GSIs’ teaching. For example, pedagogical feedback that included contextualization (context and focal events) demonstrated a more positive change in GSIOP score than feedback that lacked contextualization. Our results suggest that contextual formative feedback has a positive change to student-focused and teacher-focused observations.
This study investigates attributional beliefs of Singapore secondary students in their English study and how they can be predicted by self-construal, competence and achievement goals. A total of 1,496 students were administered surveys on seven attributions, independent and interdependent self-construals, previous achievement, self-efficacy, mastery approach and avoidance goals and performance approach and avoidance goals. We found that Singapore students attributed academic success mainly to internal regulation (effort, interest and study skills), followed by teachers’ help, ability, parents’ help and tuition classes. Hierarchical regression analyses showed that three predictors (self-construal, competence and achievement goals) explained 4.2–12.3% of the variances in students’ attributional beliefs. In particular, students with interdependent self-construal, high competence or mastery goals tended to attribute academic success to internal regulation (effort, interest and study skills) and support from teachers and parents. Students with low competence, high mastery avoidance goals or high performance goals were more likely to value tuition classes, and those with high performance avoidance goals also tended to ascribe academic success to ability and parent’s help. The findings are discussed in relation to the culture of Singapore. 相似文献
Learning Environments Research - The study examined the factor structure, reliability and validity of a Chinese version of the Constructivist Learning Environment Survey (C-CLES), an instrument for... 相似文献
