Comparison of Approaches to Constructing Confidence Intervals for Mediating Effects Using Structural Equation Models     

Mike W.L. Cheung 《Structural equation modeling》2013,20(2):227-246

Regression mixture models, which have only recently begun to be used in applied research, are a new approach for finding differential effects. This approach comes at the cost of the assumption that error terms are normally distributed within classes. This study uses Monte Carlo simulations to explore the effects of relatively minor violations of this assumption. The use of an ordered polytomous outcome is then examined as an alternative that makes somewhat weaker assumptions, and finally both approaches are demonstrated with an applied example looking at differences in the effects of family management on the highly skewed outcome of drug use. Results show that violating the assumption of normal errors results in systematic bias in both latent class enumeration and parameter estimates. Additional classes that reflect violations of distributional assumptions are found. Under some conditions it is possible to come to conclusions that are consistent with the effects in the population, but when errors are skewed in both classes the results typically no longer reflect even the pattern of effects in the population. The polytomous regression model performs better under all scenarios examined and comes to reasonable results with the highly skewed outcome in the applied example. We recommend that careful evaluation of model sensitivity to distributional assumptions be the norm when conducting regression mixture models.  相似文献   

All-aqueous multiphase microfluidics     

Yang Song  Alban Sauret  Ho Cheung Shum 《Biomicrofluidics》2013,7(6)

Immiscible aqueous phases, formed by dissolving incompatible solutes in water, have been used in green chemical synthesis, molecular extraction and mimicking of cellular cytoplasm. Recently, a microfluidic approach has been introduced to generate all-aqueous emulsions and jets based on these immiscible aqueous phases; due to their biocompatibility, these all-aqueous structures have shown great promises as templates for fabricating biomaterials. The physico-chemical nature of interfaces between two immiscible aqueous phases leads to unique interfacial properties, such as an ultra-low interfacial tension. Strategies to manipulate components and direct their assembly at these interfaces needs to be explored. In this paper, we review progress on the topic over the past few years, with a focus on the fabrication and stabilization of all-aqueous structures in a multiphase microfluidic platform. We also discuss future efforts needed from the perspectives of fluidic physics, materials engineering, and biology for fulfilling potential applications ranging from materials fabrication to biomedical engineering.  相似文献   

Rethinking the mission of internationalization of higher education in the Asia-Pacific region     

Shun Wing Ng 《Compare》2012,42(3):439-459

This article adopts the critical theory approach to reflect and analyse the impacts of globalization on the internationalization process of higher education in the Asia-Pacific region. It argues that globalization forces many of the higher education institutions in the region to follow global practices and ideologies of the Anglo-American paradigm without developing their own unique systems and honouring the rich cultures of their own countries. While higher education institutions are indulging in internationalization in terms of marketization and economic pragmatism, they have to ask themselves, ‘What is missing in the process of internationalization?’ This article argues that internationalization of higher education contributes to building more than economically competitive and politically powerful states. It represents a commitment to the development of an internationalized curriculum where the pursuit of global citizenship, human harmony and a climate of global peace is of paramount importance.  相似文献   

Developing a Scale to Measure Students’ Attitudes toward Chemistry Lessons     

Derek Cheung 《International Journal of Science Education》2013,35(16):2185-2203

Students’ attitudes toward chemistry lessons in school are important dependent variables in curriculum evaluation. Although a variety of instruments have been developed by researchers to evaluate student attitudes, they are plagued with problems such as the lack of theoretical rationale and of empirical evidence to support the construct validity of data. This paper describes a study of students’ attitudes toward chemistry lessons in Hong Kong secondary schools. One of the scales in the Test of Science‐Related Attitudes developed by Fraser was modified to form an Attitude Toward Chemistry Lessons Scale (ATCLS). The construction of the ATCLS was based on a theoretical model with four dimensions: liking for chemistry theory lessons, liking for chemistry laboratory work, evaluative beliefs about school chemistry, and behavioural tendencies to learn chemistry. The arguments for inclusion of these four dimensions are presented. The final version of ATCLS was administered to 954 students. The results of confirmatory factor analysis indicated that there was a good fit between the hypothesised model and the observed data.  相似文献   

Integrating media education into liberal studies: a positive response to curriculum reform in Hong Kong     

C.K. Cheung 《Curriculum Journal》2013,24(4):437-446

Media education has been around for quite some time in the West (Bazalgette et al. 1990 Bazalgette, C., Bevort, E. and Savino, J. 1990. New directions: Media education worldwide, London: BFI.  [Google Scholar]), but it only started to gain acceptance in Asia (Cheung 2005 Cheung, C. K. 2005. Media education in Hong Kong: From civic education to curriculum reform. The Asia-Pacific Education Researcher, 14(1): 27–45.  [Google Scholar]), particularly in Hong Kong, in the last decade. Recently, it has been gaining more attention in Hong Kong thanks to the curriculum reform in which liberal studies will become one of the four core subjects to be taken by students in the New Senior Secondary Curriculum and media is one of the six themes to be studied in the subject of liberal studies. This article argues for the need for teaching media education in liberal studies and shows the many connections between the two subjects that facilitate this integration.  相似文献   

The Impact of Bombing Attacks on Civilians in Iraq     

Fuaad Mohammed Freh  Rudi Dallos  Man Cheung Chung 《International journal for the advancement of counseling》2013,35(4):273-285

  相似文献   

Students’ Attitudes Toward Chemistry Lessons: The Interaction Effect between Grade Level and Gender     

Derek Cheung 《Research in Science Education》2009,39(1):75-91

The purpose of this quantitative study was to examine the interaction effect between grade level and gender with respect to students' attitudes toward chemistry lessons taught in secondary schools. The sample consisted of 954 chemistry students in grades Secondary 4–7 (approximately 16–19 years of age) in Hong Kong. Students' attitudes were surveyed using an attitude toward chemistry lessons scale (ATCLS), and subscale scores were produced on four dimensions: liking for chemistry theory lessons; liking for chemistry laboratory work; evaluative beliefs about school chemistry; and behavioral tendencies to learn chemistry. When the ATCLS data were subjected to two-way MANOVA, the interaction effect between grade level and gender on students' attitudes toward chemistry lessons was statistically significant. The interaction effect was attributable to scores on the theory lessons subscale and laboratory work subscale. Male students in Secondary 4 and 5 liked chemistry theory lessons more than their female counterparts. However, male students' liking for chemistry laboratory work declined when they progressed from Secondary 4 to Secondary 7; no such a significant decline in attitude toward chemistry laboratory work was found in females. Overall, both males and females were just marginally positive about chemistry lessons during the years of secondary schooling. Implications of these findings for curriculum design are discussed.  相似文献   

Source localization using TDOA and FDOA measurements based on semidefinite programming and reformulation linearization     

Zhi Zheng  Hongwang Zhang  Wen-Qin Wang  Hing Cheung So 《Journal of The Franklin Institute》2019,356(18):11817-11838

The problem of source localization using time-difference-of-arrival (TDOA) and frequency-difference-of-arrival (FDOA) measurements has been widely studied. It is commonly formulated as a weighted least squares (WLS) problem with quadratic equality constraints. Due to the nonconvex nature of this formulation, it is difficult to produce a global solution. To tackle this issue, semidefinite programming (SDP) is utilized to convert the WLS problem to a convex optimization problem. However, the SDP-based methods will suffer obvious performance degradation when the noise level is high. In this paper, we devise a new localization solution using the SDP together with reformulation-linearization technique (RLT). Specifically, we firstly apply the RLT strategy to convert the WLS problem to a convex problem, and then add the SDP constraint to tighten the feasible region of the resultant formulation. Moreover, this solution is also extended for cases when there are sensor position and velocity errors. Numerical results show that our solution has significant accuracy advantages over the existing localization schemes at high noise levels.  相似文献   

Control of impact loading during distracted running before and after gait retraining in runners     

Roy T. H. Cheung  Winko W. An  Ivan P. H. Au  Janet H. Zhang  Zoe Y. S. Chan  Aislinn J. MacPhail 《Journal of sports sciences》2018,36(13):1497-1501

Gait retraining using visual biofeedback has been reported to reduce impact loading in runners. However, most of the previous studies did not adequately examine the level of motor learning after training, as the modified gait pattern was not tested in a dual-task condition. Hence, this study sought to compare the landing peak positive acceleration (PPA) and vertical loading rates during distracted running before and after gait retraining. Sixteen recreational runners underwent a two-week visual biofeedback gait retraining program for impact loading reduction, with feedback on the PPA measured at heel. In the evaluation of PPA and vertical loading rates before and after the retraining, the participants performed a cognitive and verbal counting task while running. Repeated measures ANOVA indicated a significant interaction between feedback and training on PPA (F = 4.642; P = 0.048) but not vertical loading rates (F > 1.953; P > 0.067). Pairwise comparisons indicated a significantly lower PPA and vertical loading rates after gait retraining (P < 0.007; Cohen’s d > 0.68). Visual feedback after gait retraining reduced PPA and vertical loading rates during distracted running (P < 0.033; Cohen’s d > 0.36). Gait retraining is effective in lowering impact loading even when the runners are distracted. In dual-task situation, visual biofeedback provided beneficial influence on kinetics control after gait retraining.  相似文献   

Teachers’ perceptions of Incorporated Management Committees as a form of school-based management in Hong Kong     

Shereen M. C. Cheung  Flora L. F. Kan 《Asia Pacific Education Review》2009,10(2):139-148

The policy of the registration of School Management Committees (SMCs) as Incorporated Management Committees (IMCs) has led to a dispute between the School Sponsoring Bodies (SSBs) and the Education and Manpower Bureau (EMB, renamed Education Bureau, EDB in July 2007) and has caused great tension between the two parties. However, in this heated debate, little has been heard about teachers’ opinions on this important issue. Therefore, this study aims at finding out teachers’ perceptions of the newly proposed school management system and whether they are willing to participate in IMCs. In this study, 585 questionnaires were collected from a total of 652 which had been distributed to 25 schools (19 secondary schools and 9 primary schools), and five teacher representatives from five schools were involved in post-survey interviews. Findings from this study show that while the teachers were generally in favour of working hand in hand with the public (e.g. parents, alumni and members of the local community) for the betterment of schools, they had reservations about the registration of SMCs as IMCs because there would be legal implications of the Committees. Second, the teachers saw the IMCs as an administrative tool to improve school management, rather than as a means of enhancing students’ learning outcomes. Third, teachers were hesitant about taking up the posts of teacher managers due to the unpredictable workload and legal liability involved. Finally, teachers from Christian schools were generally much less in favour of including representatives from the public and the registration of the SMCs as IMCs. The findings imply that the EMB has a responsibility to clarify the legal implications of IMCs and the ways in which school representatives’ interests can be safeguarded. At the same time, SSBs need to regulate their management pattern and allow more transparency and accountability in managing their schools.

Flora L. F. KanEmail:

  相似文献