Conformational Control of Exciton-Polariton Physics in Metal - Poly(9,9-dioctylfluorene) - Metal Cavities

Control is exerted over the exciton-polariton physics in metal - Poly(9,9-dioctyl fluorene) - metal microcavities via conformational changes to the polymer backbone. Using thin-film samples containing increasing fractions of $\beta$-phase chain segments, a systematic study is reported for the mode characteristics and resulting light emission properties of cavities containing two distinct exciton sub-populations within the same semiconductor. Ultrastrong coupling for disordered glassy-phase excitons is observed from angle-resolved reflectivity measurements, with Rabi splitting energies in excess of 1.05 eV (more than 30% of the exciton transition energy) for both TE- and TM-polarized light. A splitting of the lower polariton branch is then induced via introduction of $\beta$-phase excitons and increases with their growing fraction. In all cases, the photoluminescence emanates from the lowermost polariton branch, allowing conformational control to be exerted over the emission energy and its angular variation. Dispersion-free cavities with highly saturated blue-violet emission are thus enabled. Experimental results are discussed in terms of the full Hopfield Hamiltonian generalized to the case of two exciton oscillators. The importance of taking account of the molecular characteristics of the semiconductor for an accurate description of its strong coupling behaviour is directly considered, in specific relation to the role of the vibronic structure

Breakdown patterns in Branly's coheror

We use thermal imaging of Joule heating to see for the first time electrical conducting paths created by the so-called Branly effect in a two-dimensional metallic granular medium (aluminium). Multiple breakdowns are shown to occur when the medium is submitted to high voltage increases (more than 500 V) with rise times close to one hundred of microseconds.Comment: 4 pages, 5 figures, related informations at http://chemphys.weizmann.ac.il/~damien/index.htm

Holistic curriculum development: tutoring as a support process

In many programmes, tutorials have proved to be an effective way of providing both academic and personal support. The tutor's role in these involves different aspects of teaching and learning. In this article I explore the value of tutoring as a means of supporting the holistic curriculum development process. I reflect on the reason for introducing a system of tutoring for students in curriculum studies and the results of its implementation on students' academic performance, in order to contribute to a better understanding of this kind of intervention. A summary of empirical data on the implementation of the tutor system and feedback on the system and tutors' reflections on the process are provided. Finally, the outcomes of the implementation of tutoring on the students\' performance at the end of the academic year are discussed. Keywords: academic performance; first-year students; holistic curriculum development; tutoring South African Journal of Education Vol. 29 (1) 2009: pp. 17-3

Strontium ranelate: short- and long-term benefits for post-menopausal women with osteoporosis

Strontium ranelate is a bone-seeking element that has been assessed in post-menopausal osteoporosis in two large double-blind, placebo-controlled studies. This treatment is able to decrease the risk of vertebral fractures, by 41% over 3 yrs, and by 49% within the first year of treatment. This risk of non-vertebral fractures is decreased by 16% and, in patients at high risk for such a fracture, the risk of hip fracture is decreased by 36% over 3 yrs. Recent 5-yr data from these double-blind, placebo-controlled studies show that the anti-fracture efficacy is maintained over time. Treatment efficacy with strontium ranelate has been documented across a wide range of patient profiles: age, number of prevalent vertebral fractures, BMI, as well as family history of osteoporosis and addiction to smoking are not determinants of anti-fracture efficacy. During these clinical trials, safety was good. Its large spectrum of efficacy allows the use of strontium ranelate in the different subgroups of patients with post-menopausal osteoporosis

On control: An analysis of control phenomena in Afrikaans and an argument for dispensing with the minimal distance principle

No abstract

Exploring Educators’ Expectations and Experiences of In-Service Education and Training [INSET] as Continuing Professional Development Opportunities

In-Service Education and Training (INSET) is widely used to support educators to cope with ongoing changes in education. This paper examines the results of two surveys of INSET recipients’ expectations and their experiences of INSET before and after having attended a series of INSET workshops that were held with the intention of strengthening participants’ capacity to teach environmental education. The educators who participated in the survey were from three rural districts in the Limpopo Province, a far northern province in South Africa which borders on Zimbabwe. The survey outcomes were appraised against the backdrop of what is identified in the literature as constituting meaningful INSET. The analysis was undertaken to determine the capacity of INSET programmes to realise the presumed goals of INSET. The outcomes of this survey point to a measure of continuity between theory and practice, but also to trends in participants’ experiences of INSET that are not predominant in the literature

Modular minds and input in second language acquisition

The aim of this paper is twofold: i. firstly, to show why second language learners (from perhaps as early as age six, but certainly after age twelve or thereabouts) are claimed to. require instruction in addition to communicative exposure to the language; and ii. secondly, to dispel the idea that, as long as theories of how second languages are acquired keep changing, no insight into the acquisition process can be gained from them. The focus will be on theories of L2 acquisition that have a strong linguistic base to the exclusion of, for example, psychological process-based theories. By narrowing the focus of the paper, I hope to keep the main thrust of the argument clear. The choice of focus should not be taken to imply that other approaches have not provided useful perspectives on aspects of L2 acquisition