The cementation of coarse dust to indoor surfaces

Dust accumulation is an important management and conservation problem in historic houses. Laboratory and field observations show that high relative humidity enhances the cementation of particles to underlying surfaces. The hygroscopic nature of particles or the fibres to which they adhere influences this cementation process. The cements, which can form in a matter of hours at high humidity, appear to be microcrystalline calcites. Reducing the impact of this process on heritage objects requires preventing dust deposits, especially in periods of high humidity.     

“Gangnam Style” in Dhaka and inter-Asian refraction

This essay explores the political implications of the flash mob dance in Dhaka, Bangladesh performed in response to the 2012 global viral sensation of South Korean rapper PSY’s “Gangnam Style” music video. The global fame of “Gangnam Style” has much to do with its success online and in the U.S. popular music industry. It, however, also solicited suspicion from popular culture critics that the images of comical PSY worked successfully thanks to unchecked consumption of the racial stereotypes of Asian men. While recognizing these problems as more than valid, this essay simultaneously calls for a more transnational and inter-Asian understanding of the material to argue for a productive quality of PSY’s performance. Using “refraction” as a mode of thinking about inter-Asian circulation of pop culture, this essay considers the flash mob performed in Dhaka, Bangladesh as an important yet underexplored case study that shows different performative practices associated with “Gangnam Style” deeply rooted in historicity of colonialism and nationalism. The case study shows that the circulation of “Gangnam Style” materialized through a performance in Dhaka enlarged contemporary discourse among young urban Bangladeshi spectators around Bangladeshiness and its cultural identity. This complicated an easy assumption about “Gangnam Style” and its success in the U.S. mainstream pop culture, while simultaneously displacing the Bangladeshi cultural subjects from the immobile position of “the Other.”     

A new perspective on in vitro assessment method for evaluating quantum dot toxicity by using microfluidics technology

In this study, we demonstrate a new perspective on in vitro assessment method for evaluating quantum dot (QD) toxicity by using microfluidics technology. A new biomimetic approach, based on the flow exposure condition, was applied in order to characterize the cytotoxic potential of QD. In addition, the outcomes obtained from the flow exposure condition were compared to those of the static exposure condition. An in vitro cell array system was established that used an integrated multicompartmented microfluidic device to develop a sensitive flow exposure condition. QDs modified with cetyltrimethyl ammonium bromide∕trioctylphosphine oxide were used for the cytotoxicity assessment. The results suggested noticeable differences in the number of detached and deformed cells and the viability percentages between two different exposure conditions. The intracellular production of reactive oxygen species and release of cadmium were found to be the possible causes of QD-induced cytotoxicity, irrespective of the types of exposure condition. In contrast to the static exposure, the flow exposure apparently avoided the gravitational settling of particles and probably assisted in the homogeneous distribution of nanoparticles in the culture medium during exposure time. Moreover, the flow exposure condition resembled in vivo physiological conditions very closely, and thus, the flow exposure condition can offer potential advantages for nanotoxicity research.     

The effects of captions on deaf students' content comprehension, cognitive load, and motivation in online learning

The authors examined the effects of captions on deaf students' content comprehension, cognitive load, and motivation in online learning. The participants in the study were 62 deaf adult students who had limited reading comprehension skills and used sign language as a first language. Participants were randomly assigned to either the control group or the experimental group. The independent variable was the presence of captions, and the dependent variables were content comprehension, cognitive load, and motivation. The study applied a posttest-only control group design. The results of the experiment indicated a significant difference (t = -2.16, p < .05) in content comprehension but no statistically significant difference in cognitive load and motivation between the two groups. These results led to suggestions for improvements in learning materials for deaf individuals.     

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.     

The incorporation of hands-on tasks in an online course: an analysis of a blended learning environment

This article describes the design and evaluation of a blended online/face-to-face course completed by more than 6000 learners throughout the United States of America and internationally. The educational impact was monitored using a variety of evaluation strategies. The results, in terms of achieved knowledge and overall satisfaction, indicate that a focus on online instruction combined with face-to-face, hands-on activities showed statistically significant improvement in the learners' understanding of the course material, while also validating the impact of the curriculum in their workplace. As illustrated through the blended course design, this study further showed that online learners with greater improvement in their pre- and posttest scores also exhibited significantly greater likelihood in demonstrating competency in several areas during the hands-on portion of the course. In particular, participants working in the information systems field exhibited the highest mean difference score (21.49) on the pre- and the posttests, while those working in the laboratory had the lowest (12.17). Likewise, the odds that participants who reviewed the course contents sought to further understand their job roles was 58.2 times greater for those in information systems, while it was only 19.0 times greater for laboratory staff, than those who did not review their job roles.     

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.     

Detecting Violations of Factorial Invariance Using Data-Based Specification Searches: A Monte Carlo Study

In testing factorial invariance, researchers have often used a reference variable strategy in which the factor loading for a variable (i.e., reference variable) is fixed to 1 for identification. This commonly used method can be misleading if the chosen reference variable is actually a noninvariant item. This simulation study suggests an alternative method for testing factorial invariance and evaluates the performance of the method in specification searches based on the modification index. The results of the study showed that the proposed specification searches performed well when the number of noninvariant variables was relatively small and this performance improved as sample size increased and the size of group differences increased. When the number of noninvariant variables was relatively large, however, the method rarely succeeded in detecting the noninvariant items in the specification searches. Implications of the findings are discussed along with the limitations of the study.