Stimulated Brillouin scattering in layered media: Nanoscale enhancement of silicon

© 2019 Optical Society of America. We report a theoretical study of stimulated Brillouin scattering (SBS) in general anisotropic media, incorporating the effects of both acoustic strain and local rotation. We apply our general theoretical framework to compute the SBS gain for layered media with periodic length scales smaller than all optical and acoustic wavelengths, where such composites behave like homogeneous anisotropic media. We predict that a layered medium composing nanometer-thin layers of silicon and As 2 S 3 glass has a bulk SBS gain of 1.28 × 10− 9 W −1 m. This is more than 500 times larger than that of silicon and almost double the gain of As 2 S 3 . The enhancement is due to a combination of roto-optic, photoelastic, and artificial photoelastic contributions in the composite structure

Persuasive Technology for Learning and Teaching – The EuroPLOT Project

The concept of persuasive design has demonstrated its benefits by changing human behavior in certain situations, but in the area of education and learning, this approach has rarely been used. To change this and to study the feasibility of persuasive technology in teaching and learning, the EuroPLOT project (PLOT = Persuasive Learning Objects and Technologies) has been funded 2010-2013 by the Education, Audiovisual and Culture Executive Agency (EACEA) in the Life-long Learning (LLL) programme. In this program two tools have been developed (PLOTMaker and PLOTLearner) which allow to create learning objects with inherently persuasive concepts embedded. These tools and the learning objects have been evaluated in four case studies: language learning (Ancient Hebrew), museum learning (Kaj Munk Museum, Denmark), chemical handling, and academic Business Computing. These case studies cover a wide range of different learning styles and learning groups, and the results obtained through the evaluation of these case studies show the wide range of success of persuasive learning. They also indicate the limitations and areas where improvements are required

Demonstration of PLOTs from the EuroPLOT project

The EuroPLOT project (2010-2013) has been funded to explore the concept of persuasive design for learning and teaching. It has developed Persuasive Learn-ing Objects and Technologies (PLOTs), manifested in two tools and a set of learning objects that have been tested and evaluated in four different case studies. These PLOTs will be shown in this demonstration, and the participants can try them out and experience for themselves the impact of persuasive technology that is embedded in these PLOTs. This will be one authoring tool (PLOTMaker) and one delivery tool (PLOTLearner). Furthermore, there will be learning objects shown which have been developed for those four different case studies. All of these PLOTs have already been tested and evaluated during case studies with real learners

Enhanced acousto-optic properties in layered media

© 2017 American Physical Society. We present a rigorous procedure for evaluating the photoelastic coefficients of a layered medium in which the periodicity is smaller than the wavelengths of all optical and acoustic fields. Analytical expressions are given for the coefficients of a composite material comprising thin layers of optically isotropic materials. These photoelastic coefficients include artificial contributions that are unique to structured media and arise from the optical and mechanical contrast between the constituents. Using numerical examples, we demonstrate that the acousto-optic properties of layered structures can be enhanced beyond those of the constituent materials. Furthermore, we show that the acousto-optic response can be tuned as desired

Do children\u27s food preferences align with dietary recommendations?

Objectives: To examine how Australian children\u27s reported everyday food preferences reflect dietary recommendations, and the impact of sociodemographic factors on these associations.Design:&nbsp; Cross-sectional survey.Setting/subjects: Three hundred and seventy-one parents of children aged 2&ndash;5 years, recruited from three socio-economic groups in two Australian cities, completed a survey on their child\u27s liking for 176 foods and drinks on a 5-point Likert scale in addition to demographic descriptors. Preferences were compared with the recommendations of the Dietary Guidelines for Children and Adolescents in Australia and the Australian Guide to Healthy Eating.Results:&nbsp; Foods in the Extra Foods (non-nutritious foods) and Cereals groups of the Australian Guide to Healthy Eating were highly liked (mean: 4.02 and 4.01, respectively), whilst foods in the Vegetables group were liked least (mean: 3.01). A large percentage of foods in the Cereals and Extra Foods groups were liked (64% and 56%, respectively) in contrast to the other food groups, especially Vegetables (7%). Children liked foods that were higher in sugar (r = 0.29, P &lt; 0.0001) and more energy-dense (r = 0.34, P &lt; 0.0001) but not those higher in saturated fat (r = 0.16, P = 0.03), total fat (r = 0.12, P = 0.12) or sodium (r = 0.10, P = 0.18). Sociodemographic variables (e.g. socio-economic status, parental education, children\u27s age and sex) explained little of the variation in children\u27s food preferences.Conclusions:&nbsp; Australian pre-school children\u27s food preferences align with dietary guidelines in some respects, but not others. Interventions are needed to shift children\u27s preferences away from non-nutritious foods that are high in energy density and sugar, and towards vegetables and fruits.<br /

RINGO2: an EMCCD-based polarimeter for GRB followup

We describe the design and construction of a new novel optical polarimeter (RINGO2) for the Liverpool Telescope. The instrument is designed for rapid (< 3 minute) followup observations of Gamma Ray Bursts in order to measure the early time polarization and time evolution on timescales of ~ 1 - 10000 seconds. By using a fast rotating Polaroid whose rotation is synchronized to control the readout of an electron multiplying CCD eight times per revolution, we can rebin our data in the time domain after acquisition with little noise penalty, thereby allowing us to explore the polarization evolution of these rapidly variable objects for the first time. © (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only