Associations between health-related physical fitness and obesity in Taiwanese youth

Abstract

This study examined associations between four health-related physical fitness measures and obesity in Taiwanese youth aged 10–18 years. Data from 13,500 school-aged youth were randomly selected from the “School Physical Fitness Database” of Taiwan by sex and age. Variables examined were height, body mass and performance on modified sit-and-reach (flexibility), bent-leg sit-up (abdominal muscular strength/endurance), standing long jump (lower body explosive strength) and distance run/walk (cardiorespiratory endurance). Adjusted logistic regression analyses were performed. Increased odds of being obese with decreased fitness levels were observed for lower body explosive strength and cardiorespiratory endurance in both sexes. The highest odds of being obese was found in the least fit quintile of cardiorespiratory endurance compared with the most fit quintile both in boys (Odds ratio, OR = 10.44; 95% confidence interval (CI), 7.94–13.73) and girls (OR = 5.40; 95% CI, 3.90–7.47). These findings suggest that in addition to cardiorespiratory fitness, lower body explosive strength is also associated with childhood and adolescent obesity.     

Characterization and separation of Cryptosporidium and Giardia cells using on-chip dielectrophoresis

Dielectrophoresis (DEP) has been shown to have significant potential for the characterization of cells and could become an efficient tool for rapid identification and assessment of microorganisms. The present work is focused on the trapping, characterization, and separation of two species of Cryptosporidium (C. parvum and C. muris) and Giardia lambia (G. lambia) using a microfluidic experimental setup. Cryptosporidium oocysts, which are 2-4 μm in size and nearly spherical in shape, are used for the preliminary stage of prototype development and testing. G. lambia cysts are 8–12 μm in size. In order to facilitate effective trapping, simulations were performed to study the effects of buffer conductivity and applied voltage on the flow and cell transport inside the DEP chip. Microscopic experiments were performed using the fabricated device and the real part of Clausius—Mossotti factor of the cells was estimated from critical voltages for particle trapping at the electrodes under steady fluid flow. The dielectric properties of the cell compartments (cytoplasm and membrane) were calculated based on a single shell model of the cells. The separation of C. muris and G. lambia is achieved successfully at a frequency of 10 MHz and a voltage of 3 Vpp (peak to peak voltage).     

Dielectrophoretic capture voltage spectrum for measurement of dielectric properties and separation of cancer cells

In this paper, a new dielectrophoresis (DEP) method based on capture voltage spectrum is proposed for measuring dielectric properties of biological cells. The capture voltage spectrum can be obtained from the balance of dielectrophoretic force and Stokes drag force acting on the cell in a microfluidic device with fluid flow and strip electrodes. The method was demonstrated with the measurement of dielectric properties of human colon cancer cells (HT-29 cells). From the capture voltage spectrum, the real part of Clausius-Mossotti factor of HT-29 cells for different frequencies of applied electric field was obtained. The dielectric properties of cell interior and plasma membrane were then estimated by using single-shell dielectric model. The cell interior permittivity and conductivity were found to be insensitive to changes in the conductivity of the medium in which the cells are suspended, but the measured permittivity and conductivity of cell membrane were found to increase with the increase of medium conductivity. In addition, the measurement of capture voltage spectrum was found to be useful in providing the optimum operating conditions for separating HT-29 cells from other cells (such as red blood cells) using dielectrophoresis.     

Teacher Evaluation and Effectiveness in Hong Kong: Issues and Challenges

This article first provides an overview of teacher effectiveness and evaluation in Hong Kong. Several studies related to classroom environment and teacher behavior in selected subjects are referenced, as are recent studies of teachers instructional leadership. Finally, the preliminary use of the Revised Classroom Observation Instrument (RCOI) from the Louisiana School Effectiveness Study in three secondary schools is reported. The results from using the RCOI in Hong Kong indicate that some items may be irrelevant in the Hong Kong context (e.g., physical characteristics), while more items may be needed to reflect good teaching in Hong Kong (e.g., questioning skills). In addition, the potential use of teacher profiles to drive staff development and school improvement is explored.     

A hybrid dielectrophoretic system for trapping of microorganisms from water

Assessment of the microbial safety of water resources is among the most critical issues in global water safety. As the current detection methods have limitations such as high cost and long process time, new detection techniques have transpired among which microfluidics is the most attractive alternative. Here, we show a novel hybrid dielectrophoretic (DEP) system to separate and detect two common waterborne pathogens, Escherichia coli (E. coli), a bacterium, and Cryptosporidium parvum (C. parvum), a protozoan parasite, from water. The hybrid DEP system integrates a chemical surface coating with a microfluidic device containing inter-digitated microelectrodes to impart positive dielectrophoresis for enhanced trapping of the cells. Trimethoxy(3,3,3-trifluoropropyl) silane, (3-aminopropyl)triethoxysilane, and polydiallyl dimethyl ammonium chloride (p-DADMAC) were used as surface coatings. Static cell adhesion tests showed that among these coatings, the p-DADMAC-coated glass surface provided the most effective cell adhesion for both the pathogens. This was attributed to the positively charged p-DADMAC-coated surface interacting electrostatically with the negatively charged cells suspended in water leading to increased cell trapping efficiency. The trapping efficiency of E. coli and C. parvum increased from 29.0% and 61.3% in an uncoated DEP system to 51.9% and 82.2% in the hybrid DEP system, respectively. The hybrid system improved the cell trapping by encouraging the formation of cell pearl-chaining. The increment in trapping efficiency in the hybrid DEP system was achieved at an optimal frequency of 1 MHz and voltage of 2.5 V_pp for C. parvum and 2 V_pp for E. coli, the latter is lower than 2.5 V_pp and 7 V_pp, respectively, utilized for obtaining similar efficiency in an uncoated DEP system.     

个案研究方法在教育游戏研究中的应用

个案研究是以一个人或一个团体为研究对象,广泛搜集各种资料,综合运用各种方法,对复杂情境中的现象进行深入探究的研究策略。在我们开展的VISOLE(Virtual Interactive Student-Oriented Learning Environment)研究项目中,就采用个案研究方法来深入研究同学的动机、行为和学习成效,并取得了良好的效果。文章仔细讲解了采用该方法的动机、本个案研究的特点以及具体的研究过程。     

Teachers’ and Students’ Conceptions of Good Science Teaching

Capitalizing on the comments made by teachers on videos of exemplary science teaching, a video-based survey instrument on the topic of ‘Density’ was developed and used to investigate the conceptions of good science teaching held by 110 teachers and 4,024 year 7 students in Hong Kong. Six dimensions of good science teaching are identified from the 55-item questionnaire, namely, ‘focussing on science learning’, ‘facilitating students’ understanding’, ‘encouraging students’ involvement’, ‘creating conducive environment’, ‘encouraging active experimentation’ and ‘preparing students for exam (PSE)’. Significant gaps between teachers’ and students’ conceptions on certain dimensions have been revealed. The inconsistency on the dimension ‘PSE’ is particularly evident and possible reasons for the phenomenon are suggested. This study raises the important questions of how the gap can be addressed, and who is to change in order to close the gaps. Answers to these questions have huge implications for teacher education and teacher professional development.