Possible ways to write ourselves in curriculum - teacher education - science knowledge

We report on an international collaboration between three teacher educator writers and researchers. We present our ways of investigating and reflecting on our practice through writing and our writings as ways of investigating our researching on teaching and learning science. We borrow from Pasolini (1990) and Deleuze and Guattari (1977) to affirm the possibility of resisting with/in reflexivity as we try to rewrite experiences of teaching in a plane of deconstruction. In this communication, understanding teachig as communicative, dialogic, we present our questioning around the centrality of knowlegde in the discussion of curriculum and teacher education

Influence of substrate miscut angle on surface morphology and luminescence properties of AlGaN

The influence of substrate miscut on Al0.5Ga0.5 N layers was investigated using cathodoluminescence (CL) hyperspectral imaging and secondary electron imaging in an environmental scanning electron microscope. The samples were also characterized using atomic force microscopy and high resolution X-ray diffraction. It was found that small changes in substrate miscut have a strong influence on the morphology and luminescence properties of the AlGaN layers. Two different types are resolved. For low miscut angle, a crack-free morphology consisting of randomly sized domains is observed, between which there are notable shifts in the AlGaN near band edge emission energy. For high miscut angle, a morphology with step bunches and compositional inhomogeneities along the step bunches, evidenced by an additional CL peak along the step bunches, are observed

Mean-field analysis of a dynamical phase transition in a cellular automaton model for collective motion

A cellular automaton model is presented for random walkers with biologically motivated interactions favoring local alignment and leading to collective motion or swarming behavior. The degree of alignment is controlled by a sensitivity parameter, and a dynamical phase transition exhibiting spontaneous breaking of rotational symmetry occurs at a critical parameter value. The model is analyzed using nonequilibrium mean field theory: Dispersion relations for the critical modes are derived, and a phase diagram is constructed. Mean field predictions for the two critical exponents describing the phase transition as a function of sensitivity and density are obtained analytically.Comment: 4 pages, 4 figures, final version as publishe

Global Diffusion in a Realistic Three-Dimensional Time-Dependent Nonturbulent Fluid Flow

We introduce and study the first model of an experimentally realizable three-dimensional time-dependent nonturbulent fluid flow to display the phenomenon of global diffusion of passive-scalar particles at arbitrarily small values of the nonintegrable perturbation. This type of chaotic advection, termed {\it resonance-induced diffusion\/}, is generic for a large class of flows.Comment: 4 pages, uuencoded compressed postscript file, to appear in Phys. Rev. Lett. Also available on the WWW from http://formentor.uib.es/~julyan/, or on paper by reques

The genealogy of judgement: towards a deep history of academic freedom

The classical conception of academic freedom associated with Wilhelm von Humboldt and the rise of the modern university has a quite specific cultural foundation that centres on the controversial mental faculty of 'judgement'. This article traces the roots of 'judgement' back to the Protestant Reformation, through its heyday as the signature feature of German idealism, and to its gradual loss of salience as both a philosophical and a psychological concept. This trajectory has been accompanied by a general shrinking in the scope of academic freedom from the promulgation of world-views to the offering of expert opinion

Site controlled red-yellow-green light emitting InGaN quantum discs on nano-tipped GaN rods

We report a method of growing site controlled InGaN multiple quantum discs (QDs) at uniform wafer scale on coalescence free ultra-high density (>80%) nanorod templates by metal organic chemical vapour deposition (MOCVD). The dislocation and coalescence free nature of the GaN space filling nanorod arrays eliminates the well-known emission problems seen in InGaN based visible light sources that these types of crystallographic defects cause. Correlative scanning transmission electron microscopy (STEM), energy-dispersive X-ray (EDX) mapping and cathodoluminescence (CL) hyperspectral imaging illustrates the controlled site selection of the red, yellow and green (RYG) emission at these nano tips. This article reveals that the nanorod tips’ broad emission in the RYG visible range is in fact achieved by manipulating the InGaN QD’s confinement dimensions, rather than significantly increasing the In%. This article details the easily controlled method of manipulating the QDs dimensions producing high crystal quality InGaN without complicated growth conditions needed for strain relaxation and alloy compositional changes seen for bulk planar GaN templates

Correction: Site controlled red-yellow-green light emitting InGaN quantum discs on nano-tipped GaN rods

Correction for 'Site controlled red-yellow-green light emitting InGaN quantum discs on nano-tipped GaN rods' by M. Conroy et al., Nanoscale, 2016, 8 , 11019-11026

A systematic comparison of polar and semipolar Si-doped AlGaN alloys with high AlN content

Abstract With a view to supporting the development of ultra-violet light-emitting diodes and related devices, the compositional, emission and morphology properties of Si-doped n-type Al x Ga1-x N alloys are extensively compared. This study has been designed to determine how the different Al x Ga1-x N crystal orientations (polar (0001) and semipolar (11–22)) affect group-III composition and Si incorporation. Wavelength dispersive x-ray (WDX) spectroscopy was used to determine the AlN mole fraction (x ≈ 0.57–0.85) and dopant concentration (3 × 1018–1 × 1019 cm−3) in various series of Al x Ga1-x N layers grown on (0001) and (11–22) AlN/sapphire templates by metalorganic chemical vapor deposition. The polar samples exhibit hexagonal surface features with Ga-rich boundaries confirmed by WDX mapping. Surface morphology was examined by atomic force microscopy for samples grown with different disilane flow rates and the semipolar samples were shown to have smoother surfaces than their polar counterparts, with an approximate 15% reduction in roughness. Optical characterization using cathodoluminescence (CL) spectroscopy allowed analysis of near-band edge emission in the range 4.0–5.4 eV as well as various deep impurity transition peaks in the range 2.7–4.8 eV. The combination of spatially-resolved characterization techniques, including CL and WDX, has provided detailed information on how the crystal growth direction affects the alloy and dopant concentrations.</jats:p

Wittgenstein's Thought Experiments and Relativity Theory

In this paper, I discuss the similarity between Wittgenstein’s use of thought experiments and Relativity Theory. I begin with introducing Wittgenstein’s idea of “thought experiments” and a tentative classification of different kinds of thought experiments in Wittgenstein’s work. Then, after presenting a short recap of some remarks on the analogy between Wittgenstein’s point of view and Einstein’s, I suggest three analogies between the status of Wittgenstein’s mental experiments and Relativity theory: the topics of time dilation, the search for invariants, and the role of measuring tools in Special Relativity. This last point will help to better define Wittgenstein’s idea of description as the core of his philosophical enterprise