Geometrical effects in microfluidic-based microarrays for rapid, efficient single-cell capture of mammalian stem cells and plant cells

In this paper, a detailed numerical and experimental investigation into the optimisation of hydrodynamic micro-trapping arrays for high-throughput capture of single polystyrene (PS) microparticles and three different types of live cells at trapping times of 30 min or less is described. Four different trap geometries (triangular, square, conical, and elliptical) were investigated within three different device generations, in which device architecture, channel geometry, inter-trap spacing, trap size, and trap density were varied. Numerical simulation confirmed that (1) the calculated device dimensions permitted partitioned flow between the main channel and the trap channel, and further, preferential flow through the trap channel in the absence of any obstruction; (2) different trap shapes, all having the same dimensional parameters in terms of depth, trapping channel lengths and widths, main channel lengths and widths, produce contrasting streamline plots and that the interaction of the fluid with the different geometries can produce areas of stagnated flow or distorted field lines; and (3) that once trapped, any motion of the trapped particle or cell or a shift in its configuration within the trap can result in significant increases in pressures on the cell surface and variations in the shear stress distribution across the cell’s surface. Numerical outcomes were then validated experimentally in terms of the impact of these variations in device design elements on the percent occupancy of the trapping array (with one or more particles or cells) within these targeted short timeframes. Limitations on obtaining high trap occupancies in the devices were shown to be primarily a result of particle aggregation, channel clogging and the trap aperture size. These limitations could be overcome somewhat by optimisation of these device design elements and other operational variables, such as the average carrier fluid velocity. For example, for the 20 μm polystyrene microparticles, the number of filled traps increased from 32% to 42% during 5–10 min experiments in devices with smaller apertures. Similarly, a 40%–60% reduction in trapping channel size resulted in an increase in the amount of filled traps, from 0% to almost 90% in 10 min, for the human bone marrow derived mesenchymal stem cells, and 15%–85% in 15 min for the human embryonic stem cells. Last, a reduction of the average carrier fluid velocity by 50% resulted in an increase from 80% to 92% occupancy of single algae cells in traps. Interestingly, changes in the physical properties of the species being trapped also had a substantial impact, as regardless of the trap shape, higher percent occupancies were observed with cells compared to single PS microparticles in the same device, even though they are of approximately the same size. This investigation showed that in microfluidic single cell capture arrays, the trap shape that maximizes cell viability is not necessarily the most efficient for high-speed single cell capture. However, high-speed trapping configurations for delicate mammalian cells are possible but must be optimised for each cell type and designed principally in accordance with the trap size to cell size ratio.     

Word co-occurrences on Webpages as a measure of the relatedness of organizations: A new Webometrics concept

Web hyperlink analysis has been a key topic of Webometric research. However, inlink data collection from commercial search engines has been limited to only one source in recent years, which is not a promising prospect for the future development of the field. We need to tap into other Web data sources and to develop new methods. Toward this end, we propose a new Webometrics concept that is based on words rather than inlinks on Webpages. We propose that word co-occurrences on Webpages can be a measure of the relatedness of organizations. Word co-occurrence data can be collected from both general search engines and blog search engines, which expands data sources greatly. The proposed concept is tested in a group of companies in the LTE and WiMax sectors of the telecommunications industry. Data on the co-occurrences of company names on Webpages were collected from Google and Google Blog. The co-occurrence matrices were analyzed using MDS. The resulting MDS maps were compared with industry reality and with the MDS maps from co-link analysis. Results show that Web co-word analysis could potentially be as useful as Web co-link analysis. Google Blog seems to be a better source than Google for co-word data collection.     

Pre-service educators’ dispositions toward inclusive practices for students with emotional and behavioural difficulties

ABSTRACT

In response to challenging behaviour from students with emotional and behavioural difficulties (EBD), teachers around the world often label students as challenging, defining them by their disability. Negative views of students with EBD are a barrier to their inclusion and a major challenge for policy in the United States and elsewhere associated with access to the education system for students with disabilities. Pre-service teacher education has been highlighted as an optimum time to instil in pre-service educators a more equitable disposition toward behaviour management and inclusive practices. Therefore, the purpose of the current mixed-methods study was to assess whether or not an undergraduate course focused on relationship-based approaches to positive behaviour support could impact pre-service educators’ dispositions toward inclusive classroom practices for students with EBD. Survey results from 41 pre-service educators indicated that participants made significant improvements in their knowledge and understanding of compassionate behaviour management, intentional relationship building, and establishment of a welcoming classroom environment. Analysis of participants’ written responses to open-ended questions revealed several themes regarding changes in dispositions toward students with EBD. Implications for pre-service educator preparation and inclusion of students with EBD are discussed.     

The Growth of Phonological Awareness by Children With Reading Disabilities: A Result of Semantic Knowledge or Knowledge of Grapheme-Phoneme Correspondences?

According to the Lexical Restructuring Model (Metsala & Walley, 1998 Metsala, J. L. and Walley, A. C. 1998. “Spoken vocabulary growth and the segmental restructuring of lexical representation: Precursors to phonemic awareness and early reading ability”. In Word recognition in beginning literacy, Edited by: Metsala, J. L. and Ehri, L. C. 89–120. Mahwah, NJ: Lawrence Erlbaum Associates, Inc.  [Google Scholar]), children move from holistic representations of words, to syllabic representations, and finally to phonemic representations through a restructuring process driven by their developing lexical base. In contrast, the psycholinguistic grain size theory put forth by Ziegler and Goswami (2005) Ziegler, J. C. and Goswami, U. 2005. Reading acquisition, developmental dyslexia, and skilled reading across languages: A psycholinguistic grain size theory.. Psychological Bulletin, 131: 3–29. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] suggests that the awareness of individual phonemes is not possible without direct literacy instruction. The purpose of this study was to examine whether semantic knowledge and/or knowledge of grapheme/phoneme correspondences influenced the acquisition of word-blending skills by a sample of children with a reading disability. Participants were 211 second-grade and third-grade students from public elementary schools who were assigned to a reading intervention. Hierarchical Linear Modeling techniques were used to model individual growth curves of word-blending skills. Overall, findings support the psycholinguistic grain size theory of reading and suggest that instruction in the relationship between orthographic patterns and their corresponding sounds is necessary for the development of phonological awareness.     

Political Socialization of International Students: Public-Issue Discourse and Discussion on the College Campus

ABSTRACT

This study examined international students’ interests in public issues in the U.S. and motivational factors behind their discourse or avoidance of such issues. In-depth interviews with international students revealed that they discuss certain public issues in the U.S. to gain or exchange information and knowledge, because these issues are relevant to themselves and others, or due to the misconceptions that others have about their country. Moreover, international students tend to avoid certain public issues because of the level of their knowledge and lack of interest in such issues and in order to avoid dissonance caused by the public issues.     

Assessing General Education and Special Education Majors’ Self‐Efficacy for Teaching Reading

In an era of teacher quality reforms, one overlooked area for assessing readiness for teaching is education majors’ self‐efficacy for teaching reading. This gap is unfortunate, as teaching reading is a common responsibility among general and special education teachers. In the current push for RTI—one in which more general education teachers are increasingly called upon to provide reading support to students with learning disabilities, in addition to the support received from special educators—it is important to determine preservice teachers’ self‐efficacy for teaching reading. Self‐efficacy is an important construct to consider as it is related to eventual teacher attrition. The purpose of the current study was to develop a scale to measure elementary and special education majors’ self‐efficacy for teaching reading. With a sample of 110 education majors, a three‐factor scale was developed and demonstrated strong psychometric properties. Implications for the future of teacher education programs are discussed.     

IP Address Data and its Place in the Library Community Today and in the Future

Internet Protocol (IP) technology has played an important role in the management of access to scholarly work within institutions since the advent of electronic publishing in the late 1990s. Despite recent efforts to explore alternative modes of authentication, the ubiquitous use of IP address authentication within the systems of libraries, publishers, and third party vendors around the world suggests it will continue to play a significant role for the foreseeable future. However, recent studies show that a large amount of the IP address data held within publisher systems is incorrect, improperly assigned, or requires clarification. Poor source data carries significant risks—not the least of which translates into unreliable usage reporting for libraries and publishers. The IP Registry is designed to help mitigate these challenges by creating a Registry of cleaned data that libraries and publishers can interact with in a centralized fashion thereby helping to ensure accuracy and reducing the level of resources necessary to manage and communicate changes to existing data. The database of more than 60,000 academic, corporate, and government libraries was created through the amalgamation of raw source data from more than 170 scholarly publishers. In addition to cleaned IP address data, the Registry includes standardized English naming, aliases, local language naming (and characters), hierarchies, and organizational IDs for each record. The importance of accurately understanding current usage and how libraries utilize published content is clear. Regardless of what the future holds, the need for a clean and stable source of IP address data is real for libraries, publishers, and vendors alike.     

Emergence of the Link Between the Approximate Number System and Symbolic Math Ability

Experimentally manipulating Approximate Number System (ANS) precision has been found to influence children’s subsequent symbolic math performance. Here in three experiments (N = 160; 81 girls; 3–5 year old) we replicated this effect and examined its duration and developmental trajectory. We found that modulation of 5-year-olds’ ANS precision continued to affect their symbolic math performance after a 30-min delay. Furthermore, our cross-sectional investigation revealed that children 4.5 years and older experienced a significant transfer effect of ANS manipulation on math performance, whereas younger children showed no such transfer, despite experiencing significant changes in ANS precision. These findings support the existence of a causal link between nonverbal numerical approximation and symbolic math performance that first emerges during the preschool years.