Dahui Lee

The development of communication technologies, resulting in the arrival of the Internet and the World-Wide-Web has been rapid, influencing almost all aspects of modern society including education. Concepts of epistemology, how we know what we know, have been forced to rapidly adjust to these new and emerging technologies. Online communities of learners have developed in virtual spaces where community members share knowledge and resources as well as offer support and feedback. This is particularly prominent in the field of learning to play the guitar. This paper presents findings of a systematic literature review to empirically examine the question: What does it mean epistemologically to use digital methods when learning the guitar? With a particular focus on self-directed learning through online communities, notions of epistemic inertia and resonance are discussed, and concepts of epistemic indulgence and discretion are presented. This paper also presents the conception of the evolving communication in online guitar communities, in the form of tablature developed in word processors and simple imaging software, to be a folksonomy, which is itself a product of epistemic resonance.

© The Author 2017.The observation of replica bands in single-unit-cell FeSe on SrTiO3 by angle-resolved photoemission spectroscopy has led to the conjecture that the coupling between FeSe electrons and the STO phonons are responsible for the enhancement of T c over other FeSe-based superconductors. However the recent observation of a similar superconducting gap in single-unit-cell FeSe/STO raised the question of whether a similar mechanism applies. Here we report the ARPES study of the electronic structure of FeSe/STO. Similar to the results in FeSe/STO, clear replica bands are observed. We also present a comparative study of STO and STO bare surfaces, and observe similar replica bands separated by approximately the same energy, indicating this coupling is a generic feature of the STO surfaces and interfaces. Our findings suggest that the large superconducting gaps observed in FeSe films grown on different STO surface terminations are likely enhanced by a common mechanism.

© 2016 Macmillan Publishers Limited.Layered transition metal dichalcogenides are ideal systems for exploring the effects of dimensionality on correlated electronic phases such as charge density wave order and superconductivity. In bulk NbSe 2 a CDW sets in at T CDW = 33 K and superconductivity sets in at T c = 7.2 K. Below T c these electronic states coexist but their microscopic formation mechanisms remain controversial. Here we present an electronic characterization study of a single two-dimensional layer of NbSe 2 by means of low-temperature scanning tunnelling microscopy/spectroscopy, angle-resolved photoemission spectroscopy, and electrical transport measurements. We demonstrate that 3 × 3 CDW order in NbSe 2 remains intact in two dimensions. Superconductivity also still remains in the 2D limit, but its onset temperature is depressed to 1.9 K. Our STS measurements at 5 K reveal a CDW gap of= 4 meV at the Fermi energy, which is accessible by means of STS owing to the removal of bands crossing the Fermi level for a single layer. Our observations are consistent with the simplified electronic structure of single-layer NbSe 2, thus providing insight into CDW formation and superconductivity in this model strongly correlated system.