Efficient implementation of associative classifiers for document classification

In practical text classification tasks, the ability to interpret the classification result is as important as the ability to classify exactly. Associative classifiers have many favorable characteristics such as rapid training, good classification accuracy, and excellent interpretation. However, associative classifiers also have some obstacles to overcome when they are applied in the area of text classification. The target text collection generally has a very high dimension, thus the training process might take a very long time. We propose a feature selection based on the mutual information between the word and class variables to reduce the space dimension of the associative classifiers. In addition, the training process of the associative classifier produces a huge amount of classification rules, which makes the prediction with a new document ineffective. We resolve this by introducing a new efficient method for storing and pruning classification rules. This method can also be used when predicting a test document. Experimental results using the 20-newsgroups dataset show many benefits of the associative classification in both training and predicting when applied to a real world problem.     

Collagen-based brain microvasculature model in vitro using three-dimensional printed template

We present an engineered three-dimensional (3D) in vitro brain microvasculature system embedded within the bulk of a collagen matrix. To create a hydrogel template for the functional brain microvascular structure, we fabricated an array of microchannels made of collagen I using microneedles and a 3D printed frame. By culturing mouse brain endothelial cells (bEnd.3) on the luminal surface of cylindrical collagen microchannels, we reconstructed an array of brain microvasculature in vitro with circular cross-sections. We characterized the barrier function of our brain microvasculature by measuring transendothelial permeability of 40 kDa fluorescein isothiocyanate-dextran (Stoke''s radius of ∼4.5 nm), based on an analytical model. The transendothelial permeability decreased significantly over 3 weeks of culture. We also present the disruption of the barrier function with a hyperosmotic mannitol as well as a subsequent recovery over 4 days. Our brain microvasculature model in vitro, consisting of system-in-hydrogel combined with the widely emerging 3D printing technique, can serve as a useful tool not only for fundamental studies associated with blood-brain barrier in physiological and pathological settings but also for pharmaceutical applications.     

The Challenges of Science Inquiry Teaching for Pre-Service Teachers in Elementary Classrooms: Difficulties on and under the Scene

In the context of the emphasis on inquiry teaching in science education, this study looks into how pre-service elementary teachers understand and practise science inquiry teaching during field experience. By examining inquiry lesson preparation, practice, and reflections of pre-service elementary teachers, we attempt to understand the difficulties they encounter and what could result from those difficulties in their practice. A total of 16 seniors (fourth-year students) in an elementary teacher education program participated in this study. In our findings, we highlight three difficulties ‘on the lesson’ that are related to teaching practices that were missing in the classrooms: (1) developing children’s own ideas and curiosity, (2) guiding children in designing valid experiments for their hypotheses, (3) scaffolding children’s data interpretation and discussion and another three difficulties ‘under the lesson’ that are related to problems with the pre-service teachers’ conceptualization of the task: (4) tension between guided and open inquiry, (5) incomplete understanding of hypothesis, and (6) lack of confidence in science content knowledge. Based on these findings, we discuss how these difficulties are complexly related in the pre-service teachers’ understandings and action. Several suggestions for science teacher education for inquiry teaching, especially hypothesis-based inquiry teaching, are then explored.     

Grounded blends and mathematical gesture spaces: developing mathematical understandings via gestures

This paper examines how a person’s gesture space can become endowed with mathematical meaning associated with mathematical spaces and how the resulting mathematical gesture space can be used to communicate and interpret mathematical features of gestures. We use the theory of grounded blends to analyse a case study of two teachers who used gestures to construct a graphical anti-derivative while working on a professional development task in a calculus modelling activity. Results indicate that mathematical gesture spaces can encourage mathematical experimentation, lighten the cognitive load for students and can be limited by a person’s physical constraints.     

A journey from the classroom to the world of educational reform: a study of three Korean teachers’ practitioner inquiry

This article explores three Korean teachers’ experiences of carrying out practitioner inquiry as a means of providing meaningful teaching under the test-centred schooling regime in Korea. Practitioner inquiry is a concept that includes multiple genres of educational research such as action research, teacher research, and self-study that aim to change practitioners’ individual practice and, ultimately, the schooling in a society. Based on the analysis of qualitative data, the researcher found that teachers developed their knowledge and expertise in their specific areas of interest and developed strong motivations for transforming the education system. However, their inquiry was limited in practice due to the imposition of test preparation and a prescribed national curriculum. As a result, greater collaboration among practitioners, which not just involves teachers, but wider entities such as administrators, policy makers, and researchers, is required to challenge the current unjust system.     

Multimodal Genre of Science Classroom Discourse: Mutual Contextualization Between Genre and Representation Construction

Research in Science Education - This paper argues that meaning-making with multimodal representations in science learning is always contextualized within a genre and, conversely, what constitutes...