A microfluidic shear device that accommodates parallel high and low stress zones within the same culturing chamber

Fluid shear stress (FSS) plays a critical role in regulating endothelium function and maintaining vascular homeostasis. Current microfluidic devices for studying FSS effects on cells either separate high shear stress zone and low shear stress zone into different culturing chambers, or arranging the zones serially along the flow direction, which complicates subsequent data interpretation. In this paper, we report a diamond shaped microfluidic shear device where the high shear stress zone and the low shear stress zone are arranged in parallel within one culturing chamber. Since the zones with different shear stress magnitudes are aligned normal to the flow direction, the cells in one stress group are not substantially affected by the flow-induced cytokine/chemokine releases by cells in the other group. Cell loading experiments using human umbilical vein endothelial cells show that the device is able to reveal stress magnitude-dependent and loading duration-dependent cell responses. The co-existence of shear stress zones with varied magnitudes within the same culturing chamber not only ensures that all the cells are subject to the identical culturing conditions, but also allows the resemblance of the differential shear stress pattern in natural arterial conditions. The device is expected to provide a new solution for studying the effects of heterogeneous hemodynamic patterns in the onset and progression of various vascular diseases.     

Supporting prospective teachers' conceptions of modelling in science

This study investigated prospective secondary science teachers' understandings of and intentions to teach about scientific modelling in the context of a model‐based instructional module. Qualitative methods were used to explore the influence of instruction using dynamic computer modelling. Participants included 14 secondary science prospective teachers in the USA. Research questions included: (1) What do prospective teachers understand about models and modelling in science? (2) How do their understandings change, following building and testing dynamic computer models? and (3) What are prospective teachers' intentions to teach about scientific models? Scaffolds in the software, Model‐IT, enabled participants to easily build dynamic models. Findings related to the process, content, and epistemological aspects of modelling, including: (a) prospective teachers became more articulate with the language of modelling; and (b) the module enabled prospective teachers to think critically about aspects of modelling. Still, teachers did not appear to achieve full understanding of scientific modelling.     

When and why do initially high-achieving poor children fall behind?

In this paper, we examine the trajectories of initially higher- and lower-achieving children from lower and higher socio-economic status families from primary school through to university in England for the first time. We also explore what explains these trajectories. This enables us to provide new insights into when and why the performance of children with similar initial achievement diverges on the basis of their socio-economic background. Our results indicate that pupils from poor backgrounds who are higher achievers in primary school fall behind their better-off but lower-achieving peers during secondary school. This suggests that secondary school may be a critical period to intervene to prevent poor children from falling behind their richer peers. Our analysis suggests that there is less divergence in performance between pupils from different socio-economic backgrounds who attend the same schools. This result is particularly strong for children with low initial achievement. While we remain cautious about the implications of these findings, they provide suggestive evidence that schools (or the sorting of pupils into schools) play an important role in explaining why the test scores of richer and poorer children diverge over time.     

Academic Tenure and Conservative Philosophy*

The purpose of this essay is to investigate the meaning and justifiations of ‘tenure’ for university stanand to relate those justifiations to the mainstream of ideas in political philosophy, with particular emphasis on such ideas as can reasonably be described as ‘conservative’.     

Evaluating the impact of library services on the quality and cost of medical care

Recent federal regulations have minimized the role of the hospital library in contributing to the quality of medical care and in lowering hospital costs. We trace the events that have led to these assumptions and discuss the complex problem of evaluating the impact of library services. Current research on the value and effectiveness of information is outlined.     

The IQs of children with ADHD are normally distributed

The purpose of this investigation was to determine whether or not attention-deficit/hyperactivity disorder (ADHD)-when there was an absence of reading problems-was associated with having a high IQ. The vocabulary and block design short forms of the Wechsler Intelligence Scale for Children-Third Edition were administered to 63 children with ADHD, 69 children with reading difficulties (RD), and 68 children with comorbid ADHD + RD. Results indicated that the distributions of estimated Full Scale IQs (FSIQ) for each of the three groups of children did not differ significantly from a normal distribution, with the majority of children (more than 50%) in each group scoring in the average range. The percentage of children with ADHD who scored in the above-average range for FSIQ was not significantly higher than the percentages of children in the other two groups. No significant group differences emerged for estimated FSIQ, vocabulary, or block design. It was concluded that children with ADHD are no more likely to have an above-average IQ than are other children.     

What counts as knowing: Constructing a communicative repertoire for student demonstration of knowledge in science

The purpose of this study was twofold. One purpose was to identify the locally negotiated literate practices that defined ways of communicating information and knowledge across the curriculum in a fourth/fifth grade classroom. Through an ethnographic and sociolinguistic set of analyses, this investigation illustrated how the teacher worked to construct a learning environment that valued the use of multiple discourses as a way of communicating competence as a learner. Another purpose was specifically to address the ways that these practices contributed to student demonstration of knowledge in science. This was accomplished by an analysis of one student's presentation of science knowledge after a study of simple machines. A comparative analysis between his use of two discourses, written and oral, showed that the opportunity to choose between multiple discourses led to his success in demonstrating competence in ways that may have otherwise remained questionable. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 42: 139–165, 2005     

Teaching with student response systems in elementary and secondary education settings: A survey study

This study examined how 498 elementary and secondary educators use student response systems in their instruction. The teachers all completed an online questionnaire designed to learn about their goals for using response systems, the instructional strategies they employ when using the system, and the perceived effects of response systems. Participants in the study tended to use similar instructional strategies when using the technology as have been reported in higher education. These include posing questions to check for student understanding and diagnose student difficulties, sharing a display of student responses for all to see, asking students to discuss or rethink answers, and using feedback from responses to adjust instruction. A latent class analysis of the data yielded four profiles of teacher use based on frequency of use and breadth of instructional strategies employed. Teachers who used the technology most frequently and who employed broadest array of strategies were more likely to have received professional development in instructional strategies and to perceive the technology as more effective with students.     

Building Global Learning Experiences: A Case Study of a Hungarian,Ukrainian, and American Educational Partnership

Conceptions of education that fragment content and process and that compartmentalize learning may not produce globally conscious citizens. Thus, educational policies that attend to both content and process, as well as to the local and global, are more likely to foster citizens who are able to function successfully in a world characterized by complex global challenges. Multidimensional citizenship developed through an international partnership among Hungarian, Ukrainian, and American educators offers a case in point of how higher education can embrace a global dimension and expand professionalism in this new century.