Stretching of DNA confined in nanochannels with charged walls

There is currently a growing interest in control of stretching of DNA inside nanoconfined regions due to the possibility to analyze and manipulate single biomolecules for applications such as DNA mapping and barcoding, which are based on stretching the DNA in a linear fashion. In the present work, we couple Finite Element Methods and Monte Carlo simulations in order to study the conformation of DNA molecules confined in nanofluidic channels with neutral and charged walls. We find that the electrostatic forces become more and more important when lowering the ionic strength of the solution. The influence of the nanochannel cross section geometry is also studied by evaluating the DNA elongation in square, rectangular, and triangular channels. We demonstrate that coupling electrostatically interacting walls with a triangular geometry is an efficient way to stretch DNA molecules at the scale of hundreds of nanometers. The paper reports experimental observations of λ-DNA molecules in poly(dimethylsiloxane) nanochannels filled with solutions of different ionic strength. The results are in good agreement with the theoretical predictions, confirming the crucial role of the electrostatic repulsion of the constraining walls on the molecule stretching.     

Essential skills for creative writing: Integrating multiple domain-specific perspectives

The aim of this work was to gather different perspectives on the “key ingredients” involved in creative writing by children – from experts of diverse disciplines, including teachers, linguists, psychologists, writers and art educators. Ultimately, we sought in the experts’ convergence or divergence insights on the relative importance of the relevant factors that may aid writing instruction, particularly for young children. We present a study using an expert knowledge elicitation method in which representatives from five domains of expertise pertaining to writing rated 28 factors (i.e., individual skills and attributes) covering six areas (general knowledge and cognition, creative cognition, conation, executive functioning, linguistic and psychomotor skills), according to their importance for creative writing. A Many-Facets Rasch Measurement (MFRM) model permitted us to quantify the relative importance of these writing factors across domain-specific expertise, while controlling for expert severity and other systematic evaluation biases. The identified similarities and domain-specific differences in the expert views offer a new basis for understanding the conceptual gaps between the scientific literature on creative writing, the writer's self-reflection on the act of writing creatively, and educators’ practices in teaching creative writing. Bridging such diverse approaches–that are, yet, relatively homogeneous within areas of expertise – appears to be useful in view of formulating process-oriented writing pedagogy that may, above all, better target the skills needed to improve children's creative writing development.     

Transformation of teacher training in a rapidly evolving digital environment

Education and Information Technologies - Today the increasing level of technology in education requires corresponding skills from the teachers. However, they often do not have them. The purpose of...