Efficient manipulation of microparticles in bubble streaming flows

Oscillating microbubbles of radius 20–100 μm driven by ultrasound initiate a steady streaming flow around the bubbles. In such flows, microparticles of even smaller sizes (radius 1–5 μm) exhibit size-dependent behaviors: particles of different sizes follow different characteristic trajectories despite density-matching. Adjusting the relative strengths of the streaming flow and a superimposed Poiseuille flow allows for a simple tuning of particle behavior, separating the trajectories of particles with a size resolution on the order of 1 μm. Selective trapping, accumulation, and release of particles can be achieved. We show here how to design bubble microfluidic devices that use these concepts to filter, enrich, and preconcentrate particles of selected sizes, either by concentrating them in discrete clusters (localized both stream- and spanwise) or by forcing them into narrow, continuous trajectory bundles of strong spanwise localization.     

The Effect of Three-Dimensional Simulations on the Understanding of Chemical Structures and Their Properties

In a series of three experimental studies, the effectiveness of three-dimensional computer simulations to aid the understanding of chemical structures and their properties was investigated. Arguments for the usefulness of three-dimensional simulations were derived from Mayer’s generative theory of multimedia learning. Simulations might lead to a decrease in cognitive load and thus support active learning. In our studies, the learning effectiveness of three-dimensional simulations was compared to two-dimensional illustrations by use of different versions of a computer programme concerning the modifications of carbon. The first and third study with freshman students of chemistry and biochemistry show that no more knowledge was acquired when participants learnt with three-dimensional simulations than with two-dimensional figures. In the second study with 16-year old secondary school students, use of simulations facilitated the acquisition of conceptual knowledge. It was concluded that three-dimensional simulations are more effective for younger students who lack the experience of learning with different visual representation formats in chemistry. In all three studies, a significant relationship between spatial ability and conceptual knowledge about the modifications of carbon was detected.     

Properties of publications on anatomy in medical education literature

Publications on anatomy in medical education appear to be largely anecdotal. To explore this, we investigated the literature on anatomy in medical education, aiming first to evaluate the contribution of the literature on anatomy in medical education to "best evidence medical education" (BEME) and second to evaluate the development of this literature toward more "best evidence" between 1985 and 2009. Four databases were searched for publications on anatomy in medical education published between 1985 and 2009, resulting in 525 references. Hundred publications were characterized by five variables (journal category, paper subject, paper category, author perspective, and paper perspective). Statements from these publications were characterized by two variables (category and foundation). The publications contained 797 statements that involved the words "anatomy," "anatomical," or "anatomist." Forty-five percent of the publications contained no explicit research question. Forty percent of the statements made were about "teaching methods" and 17% about "teaching content," 8% referred to "practical value," and 10% to "side effects" of anatomy education. Ten percent of the statements were "positional," five percent "traditional," four percent "self-evident," and two percent referred to "quality of care." Fifty-six percent of the statements had no foundation, 17% were founded on empirical data, and 27% by references. These results substantiated the critical comments about the anecdotal nature of the literature. However, it is encouraging to see that between 1985 and 2009 the number of publications is rising that these publications increasingly focus on teaching methods and that an academic writing style is developing. This suggests a growing body of empirical literature about anatomy education.     

Family resources and mid‐life level of education: a longitudinal study of the mediating influence of childhood parental involvement

This paper draws on the concept of parental involvement, popular among educators and policy‐makers, in investigating differences in level of attained education by family background. The question is if parental involvement in children's schooling at age 14 acts as a mediator between family resources and mid‐life level of attained education. Using structural equation modeling we analyze longitudinal survey and register data of a Swedish metropolitan cohort born in 1953 (n = 3300). Several of the commonly used indicators of involvement are investigated, distinguishing between parents' involvement beliefs, such as educational aspirations and agreement with school curriculum, and involvement practices, such as reading children's schoolbooks and helping with homework. We find that parents' educational aspirations are an important mediator between family resources and attained level of education, while other involvement forms are related to academic performance only. We also find that parental involvement is greater in families with more resources, which leads us to warn against developments turning more responsibility for children's schooling over to parents. Unless sensitive to the diverse family contexts this might increase the importance of family resources for children's educational outcomes.     

How the design and complexity of concept maps influence cognitive learning processes

Educational technology research and development - Concept maps are assumed to enhance learning as their inherent structure makes relations between information more salient. Nevertheless, research...     

The Chain and Post-Stratification Methods for Observed-Score Equating: Their Relationship to Population Invariance

The Non-Equivalent-groups Anchor Test (NEAT) design has been in wide use since at least the early 1940s. It involves two populations of test takers, P and Q, and makes use of an anchor test to link them. Two linking methods used for NEAT designs are those (a) based on chain equating and (b) that use the anchor test to post-stratify the distributions of the two operational test scores to a common population (i.e., Tucker equating and frequency estimation). We show that, under different sets of assumptions, both methods are observed score equating methods and we give conditions under which the methods give identical results. In addition, we develop analogues of the Dorans and Holland (2000) RMSD measures of population invariance of equating methods for the NEAT design for both chain and post-stratification equating methods.     

Using Networks to Visualize and Analyze Process Data for Educational Assessment

New technology enables interactive and adaptive scenario‐based tasks (SBTs) to be adopted in educational measurement. At the same time, it is a challenging problem to build appropriate psychometric models to analyze data collected from these tasks, due to the complexity of the data. This study focuses on process data collected from SBTs. We explore the potential of using concepts and methods from social network analysis to represent and analyze process data. Empirical data were collected from the assessment of Technology and Engineering Literacy, conducted as part of the National Assessment of Educational Progress. For the activity sequences in the process data, we created a transition network using weighted directed networks, with nodes representing actions and directed links connecting two actions only if the first action is followed by the second action in the sequence. This study shows how visualization of the transition networks represents process data and provides insights for item design. This study also explores how network measures are related to existing scoring rubrics and how detailed network measures can be used to make intergroup comparisons.     

How to improve argumentation comprehension in university students: experimental test of a training approach

Instructional Science - The ability to comprehend informal arguments is essential for scientific literacy but students often lack structural knowledge about these arguments, especially when the...     

Introduction to the Special Issue: Using Inquiry-Based Learning in Mathematics for Liberal Arts Courses

Abstract

Mathematics for liberal arts courses are a staple of most mathematics departments and are often populated with students who have disengaged from mathematics. Inquiry-based learning is a student-centered pedagogical tool for re-engaging students in mathematics. In this paper, we introduce a Special Issue of PRIMUS on “Using Inquiry-Based Learning in Mathematics for Liberal Arts Courses.”