Accuracy of sequential sub-field synchronization of multiple digital camcorders through numerical optimization

The use of digital camcorders in biomechanical analyses can introduce errors due to inter-camera time offsets. The faster the motion being recorded the greater the error. A sequential synchronization method was developed in this study to achieve sub-field camera synchronization for multiple camcorders through numerical optimization. A recreational golfer performed ten drives while being recorded with four digital camcorders (60-Hz sampling rate). Video signals were sampled at 10,000 Hz to determine the actual inter-camera time offsets. The optimized inter-camera time offsets were computed based on three markers placed on the shaft, each separated by 200 mm. The inter-camera time offset error was computed as the difference between the optimized and actual inter-camera time offsets. The inter-camera time offset error reduced on average from 0.518 to 0.019 fields (1 field = 16.7 ms) or less due to sequential optimization. The optimized global reconstruction errors were less than 19% of the unadjusted values. It was concluded that the ability to synchronize multiple (two or more) cameras using a sequential sub-field optimization strategy promises to extend the use of relatively inexpensive digital camcorders to motions considered too fast for the low field rates of such cameras. The sequential approach presented provides a balance between computation time and reconstruction accuracy.     

Mapping physical education teachers’ professional learning and impacts on pupil learning in a community of practice in South Korea

Background: A new national physical education (PE) curriculum has been developed in South Korea and PE teachers have been challenged to deliver new transferable educational outcomes in character development through PE. In one geographical area, in order to support teachers to make required changes, a Communities of Practice (CoP) approach to continuing professional development (CPD) was adopted. Rather than being based in a single-school, this CoP brought PE teachers together from a number of schools with the aim of sharing learning and impacting on pedagogies, practices and pupils’ learning in character development through PE.

Aims: To map and analyse the ways in which teachers (i) learnt about character education in a CoP, (ii) used this learning to inform their pedagogies and practices, and (iii) impacted on pupil learning in and beyond PE.

Method: The participants were a university professor, 8 secondary school PE teachers from 8 different schools and 41 pupils. Data collection was undertaken in two phases in Autumn 2014 and Spring 2015. In-depth qualitative data were collected in the CoP and the teachers’ schools using individual interviews, focus groups with pupils, observations of lessons, open-ended questionnaires and document analysis. Data were analysed using a constructivist revision of grounded theory.

Findings: There was clear evidence of teacher learning in the CoP and changes to their pedagogies and indirect teaching behaviours (ITBs). Pupils were also able to identify the new intended learning about character development at both cognitive and behavioural levels, although there was little evidence of understanding about or intention to transfer this learning beyond PE (which was the original aim of the Government’s character education initiative). Barriers to teacher and pupil learning are also discussed.

Conclusion: Teachers’ professional learning in the CoP impacted on the development of both teachers’ pedagogies and ITBs which then influenced pupils’ learning, however, linking teachers’ professional learning to pupils’ learning remains challenging. This study has added further insights into the complexity of the processes linking policy, teachers’ learning and pupils’ learning outcomes. While it was possible to trace clear pathways from the CoP to teachers’ learning, and in some cases to pupils’ learning, it was also apparent that a wide range of factors intervened to influence the learning outcomes.     

Clothing as a source of fibres within museums

This paper examines the role of visitors’ clothing as a source of fibres and dust in museums. Some idealised experiments determined the mass of fibres and dust emitted from clothing and the range of particle sizes found. In chamber studies it was possible to examine the effect of different humidity and airflow on fibre release. Image analysis was used to determine particle size from sub-micron to giant particles including clothing fibre. Clothing was a significant contributor to fibre and dust generation and at low humidity winter garments composed largely of wool was especially large. High air velocity increased particle shedding from clothing. Clean clothing typically released a third to a tenth the weight of particulate material from dirty clothing. It is possible that the fibres and dust produced indoors from visitors could be reduced by an air-shower at the entrance, but less intrusive procedures such as keeping visitors at a distance from objects may be preferable.     

Early development among dual language learners: The roles of language use at home,maternal immigration,country of origin,and socio-demographic variables

Using nationally representative data from the ECLS-B, we examined children's outcomes and growth from 9 to 65 months as a function of language used in the home at 24 months (English only n = 7300; English and another language n = 1500; other language only n = 400). We also examined whether demographic variables moderated the effects of DLL status in predicting child outcomes. Results revealed substantial variation within the DLL population within and across language groups in immigration status, heritage country, child outcomes, and family socioeconomic risk. DLL status was associated with differential outcomes, gains over time, and processes in complex ways. Maternal birth outside of the U.S., child gender, and parental education moderated relations between home language and child outcomes. Use of the heritage language at home served as a protective factor for children of immigrant families for a few outcomes. Gender and parental education were more strongly associated with child outcomes among English-speaking households than among DLLs.     

Cascaded spiral microfluidic device for deterministic and high purity continuous separation of circulating tumor cells

Inertial microfluidics is an emerging class of technologies developed to separate circulating tumor cells (CTCs). However, defining design parameters and flow conditions for optimal operation remains nondeterministic due to incomplete understanding of the mechanics, which has led to challenges in designing efficient systems. Here, we perform a parametric study of the inertial focusing effects observed in low aspect ratio curvilinear microchannels and utilize the results to demonstrate the isolation of CTCs with high purity. First, we systematically vary parameters including the channel height, width, and radius of curvature over a wide range of flow velocities to analyze its effect on size dependent differential focusing and migration behaviors of binary (10 μm and 20 μm) particles. Second, we use these results to identify optimal flow regimes to achieve maximum separation in various channel configurations and establish design guidelines to readily provide information for developing spiral channels tailored to potentially arbitrary flow conditions that yield a desired equilibrium position for optimal size based CTC separation. Finally, we describe a fully integrated, sheath-less cascaded spiral microfluidic device to continuously isolate CTCs. Human breast cancer epithelial cells were successfully extracted from leukocytes, achieving 86.76% recovery, 97.91% depletion rate, and sustaining high viability upon collection to demonstrate the versatility of the device. Importantly, this device was designed without the cumbersome trail-and-error optimization process that has hindered the development of designing such inertial microfluidic systems.     

A Modified Comparative Fit Index for Factorial Invariance Studies

As a prerequisite for meaningful comparison of latent variables across multiple populations, measurement invariance or specifically factorial invariance has often been evaluated in social science research. Alongside with the changes in the model chi-square values, the comparative fit index (CFI; Bentler, 1990) is a widely used fit index for evaluating different stages of factorial invariance, including metric invariance (equal factor loadings), scalar invariance (equal intercepts), and strict invariance (equal unique factor variances). Although previous literature generally showed that the CFI performed well for single-group structural equation modeling analyses, its applicability to multiple group analyses such as factorial invariance studies has not been examined. In this study we argue that the commonly used default baseline model for the CFI might not be suitable for factorial invariance studies because (a) it is not nested within the scalar invariance model, and thus (b) the resulting CFI values might not be sensitive to the group differences in the measurement model. We therefore proposed a modified version of the CFI with an alternative (and less restrictive) baseline model that allows observed variables to be correlated. Monte Carlo simulation studies were conducted to evaluate the utility of this modified CFI across various conditions including varying degree of noninvariance and different factorial invariance models. Results showed that the modified CFI outperformed both the conventional CFI and the ΔCFI (Cheung & Rensvold, 2002) in terms of sensitivity to small and medium noninvariance.     

An integrated framework for RFID adoption and diffusion with a stage-scale-scope cubicle model: A case of Indonesia

This study presents a comprehensive framework to identify dynamic radio frequency identification (RFID) adoption and diffusion from three different perspectives: stages of adoption, levels of analysis, and domain of issues. The main concern of this study is stages of adoption, which covers three phases in respect of the maturity of the RFID project and the sophistication of business applications and RFID technology. The level of analysis involves different units of analysis beyond the organization level, including the industry- and country-level, which is lacking in the current literature. To understand dimensions of RFID issues, a strategy, technology, organization, people and environment (STOPE) based approach was applied. An extensive review of prior literature was conducted to find various RFID success factors and the Delphi method was applied to find positions of these factors within the framework. Based on the Delphi, some factors belong to early stage of adoption, and some others persist in the later stages of adoption. At the country level, factors such as RFID national policy, R&D policy and income per capita were accepted by most experts at the preliminary and intermediate stage; strategy and environment were accepted as important domains. To find practical implications of the framework, a case study of Indonesia was conducted at each level of analysis. Analytic hierarchy process (AHP) was applied to identify most important factors and important domains of issues with respect to the factors from the Delphi results. At country level, RFID policy, vision of leadership and RFID potential market are the most important factors; strategy and environment are the most important domains.     

Family disruption and academic functioning in urban,black youth

The purpose of this study was to examine from an ecological perspective the relationships between multiple levels of family disruption and children's academic functioning in a sample of 390 urban, Black adolescents at age 14. Subjects in this cohort have been followed longitudinally since before their birth. Data from previous assessments at birth and age 7 years allowed for control of important correlates in this analyses. Examination of this unique sample, using multisource data collection procedures, provides important information about the many family disruptions among urban, low‐income families and the effects of these disruptions on academic outcomes. Results revealed several consistent findings, the most notable of which is that, when parents were married, adolescents demonstrated significantly higher grades, mediated through paternal involvement. Of all variables studied, the role of fathers in the lives of these adolescents was the most influential on academic outcomes. In this unique sample, even variables such as involvement with child protective services were not significantly related to outcomes after important control variables were factored into analyses. Results of this study have important implications for future research and for prevention and intervention efforts in urban, at‐risk samples. Emphasis is made for work in the school context, particularly for school psychologists. © 2011 Wiley Periodicals, Inc.     

Teaching about complex systems is no simple matter: building effective professional development for computer-supported complex systems instruction

The recent next generation science standards in the United States have emphasized learning about complex systems as a core feature of science learning. Over the past 15 years, a number of educational tools and theories have been investigated to help students learn about complex systems; but surprisingly, little research has been devoted to identifying the supports that teachers need to teach about complex systems in the classroom. In this paper, we aim to address this gap in the literature. We describe a 2-year professional development study in which we gathered data on teachers’ abilities and perceptions regarding the delivery of computer-supported complex systems curricula. We present results across the 2 years of the project and demonstrate the need for particular instructional supports to improve implementation efforts, including providing differentiated opportunities to build expertise and addressing teacher beliefs about whether computational-model construction belongs in the science classroom. Results from students’ classroom experiences and learning over the 2 years are offered to further illustrate the impact of these instructional supports.