A systematic review of digital storytelling in language learning in adolescents and adults

Education and Information Technologies - Digital storytelling (DST) is a novel approach that uses modern computer technology to amplify language learning and teaching. The present study aims to...     

Chromatin modification mapping in nanochannels

We report the simultaneous mapping of multiple histone tail modifications on chromatin that has been confined to nanofluidic channels. In these channels, chromatin is elongated, and histone modification can be detected using fluorescently tagged monoclonal antibodies. Using reconstituted chromatin with three distinct histone sources and two histone tail modification probes (H3K4me3 and H3K9ac), we were able to distinguish chromatin from the different sources. Determined ratios of the two modifications were consistent with the bulk composition of histone mixtures. We determined that the major difficulty in transitioning the mapping method to site-specific profiling within single genomic molecules is the interference of naturally aggregating, off-the shelf antibodies with the internal structure of chromatin.     

The social practice of learning: a craft for the 21st century

This article argues that the social practice of learning (SPL), involving life-long learning, meta-learning, deep reflection, and dialogue in a community, should be the distinguishing knowledge base of schools in the twenty-first century. This article also analyses the strategies and challenges of the recent education reforms in Singapore through the lens of an SPL education paradigm. Although the Singapore government has done much to train teachers, trim syllabi and introduce new ways of teaching and learning, such as project work, the real challenge is to go beyond the provision of structural changes to the substance of the epistemological reform.     

Emerging requirements of computer related competencies for librarians

Computers and productivity tools help library patrons to access information, generate insights, structure results into a useful format, and produce knowledge. The use of these productivity tools by patrons requires librarians to alter their traditional professional role, which was primarily to provide information access for patrons, so that they can also provide expanded services and support to these patrons. This study focuses on understanding the computer and productivity tool skills that librarians desire for their new role in assisting patrons with information integration. Many aspiring and working librarians perceive their computer and productivity tool competencies as ranging from novice to proficient, and hope to increase their competencies to very skilled.     

Characterization and separation of Cryptosporidium and Giardia cells using on-chip dielectrophoresis

Dielectrophoresis (DEP) has been shown to have significant potential for the characterization of cells and could become an efficient tool for rapid identification and assessment of microorganisms. The present work is focused on the trapping, characterization, and separation of two species of Cryptosporidium (C. parvum and C. muris) and Giardia lambia (G. lambia) using a microfluidic experimental setup. Cryptosporidium oocysts, which are 2-4 μm in size and nearly spherical in shape, are used for the preliminary stage of prototype development and testing. G. lambia cysts are 8–12 μm in size. In order to facilitate effective trapping, simulations were performed to study the effects of buffer conductivity and applied voltage on the flow and cell transport inside the DEP chip. Microscopic experiments were performed using the fabricated device and the real part of Clausius—Mossotti factor of the cells was estimated from critical voltages for particle trapping at the electrodes under steady fluid flow. The dielectric properties of the cell compartments (cytoplasm and membrane) were calculated based on a single shell model of the cells. The separation of C. muris and G. lambia is achieved successfully at a frequency of 10 MHz and a voltage of 3 Vpp (peak to peak voltage).     

Density-dependent separation of encapsulated cells in a microfluidic channel by using a standing surface acoustic wave

This study presents a method for density-based separation of monodisperse encapsulated cells using a standing surface acoustic wave (SSAW) in a microchannel. Even though monodisperse polymer beads can be generated by the state-of-the-art technology in microfluidics, the quantity of encapsulated cells cannot be controlled precisely. In the present study, mono-disperse alginate beads in a laminar flow can be separated based on their density using acoustophoresis. A mixture of beads of equal sizes but dissimilar densities was hydrodynamically focused at the entrance and then actively driven toward the sidewalls by a SSAW. The lateral displacement of a bead is proportional to the density of the bead, i.e., the number of encapsulated cells in an alginate bead. Under optimized conditions, the recovery rate of a target bead group (large-cell-quantity alginate beads) reached up to 97% at a rate of 2300 beads per minute. A cell viability test also confirmed that the encapsulated cells were hardly damaged by the acoustic force. Moreover, cell-encapsulating beads that were cultured for 1 day were separated in a similar manner. In conclusion, this study demonstrated that a SSAW can successfully separate monodisperse particles by their density. With the present technique for separating cell-encapsulating beads, the current cell engineering technology can be significantly advanced.     

Dielectrophoretic capture voltage spectrum for measurement of dielectric properties and separation of cancer cells

In this paper, a new dielectrophoresis (DEP) method based on capture voltage spectrum is proposed for measuring dielectric properties of biological cells. The capture voltage spectrum can be obtained from the balance of dielectrophoretic force and Stokes drag force acting on the cell in a microfluidic device with fluid flow and strip electrodes. The method was demonstrated with the measurement of dielectric properties of human colon cancer cells (HT-29 cells). From the capture voltage spectrum, the real part of Clausius-Mossotti factor of HT-29 cells for different frequencies of applied electric field was obtained. The dielectric properties of cell interior and plasma membrane were then estimated by using single-shell dielectric model. The cell interior permittivity and conductivity were found to be insensitive to changes in the conductivity of the medium in which the cells are suspended, but the measured permittivity and conductivity of cell membrane were found to increase with the increase of medium conductivity. In addition, the measurement of capture voltage spectrum was found to be useful in providing the optimum operating conditions for separating HT-29 cells from other cells (such as red blood cells) using dielectrophoresis.     

Does concept‐mapping strategy work for everyone? The levels of generativity and learners' self‐regulated learning skills

The purpose of this study was to examine the effect of concept-mapping strategies with three different generativity levels (expert-generated concept map, partially learner-generated concept map, fully learner-generated concept map) on knowledge acquisition. Interaction between learners' self-regulated learning (SRL) skills and different levels of generativity was also tested. One hundred twenty-four undergraduate students, randomly assigned to three different concept-mapping groups, were differentiated by high and low levels of SRL skills. The findings suggest that the participants in the fully learner-generated map group significantly outperformed the participants in the expert-generated map group, and participants with high SRL skills significantly outperformed those with low SRL skills across all treatment levels.     

Chaotification of a class of linear switching systems based on a Shilnikov criterion

This paper proposes an approach for constructing and generating chaos from a class of three-dimensional linear switching systems via a heteroclinic loop based on the Shilnikov criterion. First, the existence of a switching rule for the system is derived by utilizing the Shilnikov heteroclinic criterion. Then a general design philosophy and its procedure of switching rule are provided to ensure that the proposed approach is applicable to engineering. Two numerical examples are presented to validate the main principle and the implementability of the scheme. Theoretical analysis and numerical simulation are used to demonstrate the feasibility and effectiveness of developed techniques.     

Functional observer based controller for stabilizing Takagi–Sugeno fuzzy systems with time-delays

This paper investigates the construction of a fuzzy functional observer for nonlinear systems with time-delays, and the application of the observer to estimate the state functions of the parallel distributed compensation controller for stabilizing the system. Two types of time-delays are considered: constant and time-varying delays with bounded time derivative. Stability conditions are obtained using Lyapunov–Krasovskii functional approach; and the conditions are transformed into linear matrix inequalities with equality constraints so that observer parameters can be calculated using the solution of these inequalities. Functional observer construction procedures are presented considering both constant and time-varying time-delays. Two examples, including one for obtaining a power system stabilizer for a single machine infinite bus system, are presented to illustrate effectiveness of the proposed design procedures.