Photonic quasi-crystal LEDs: design, modelling, and optimisation

In this paper we investigate improvement in performance attainable by etching Photonic Crystals and Photonic Quasi-Crystals into the top emitting surface of LEDs. We describe the physical mechanisms of extraction enhancement through ordered surface patterning and investigate benefits in terms of total extraction enhancement, beam directionality, and far field beam quality. Factors such as lattice geometry, etch depth, and epitaxy thickness are investigated. We show that a great variety of far field beam profiles of benefit in applications such as projection TV light engines and direct flat panel display illumination can be obtained simply by adjusting geometric design parameters. Our results show that PCs can provide significant improvement in extraction enhancement for applications requiring non Lambertian beam shapes when etched into standard "production line" epitaxy wafers in comparison to "state of the art" surface roughened thin-GaN LED devices. We investigate PC beam steering effects in these devices confirming that PCs do in fact re-direct light from trapped modes confined within the epi-structure to radiating modes. We also show that by tailoring the thickness of the epi-structure to complement the properties of the photonic crystal, extraction enhancement can be improved by a factor of 9 for some applications

Numerical analysis of suction embedded plate anchors in structured clay

As offshore energy developments move towards deeper water, moored floating production facilities are increasingly preferred to fixed structures. Anchoring systems are therefore of great interest to engineers working on deep water developments. Suction embedded plate anchors (SEPLAs) are rapidly becoming a popular solution, possessing a more accurate and predictable installation process compared to traditional alternatives. In this paper, finite element analysis has been conducted to evaluate the ultimate pullout capacity of SEPLAs in a range of post-keying configurations. Previous numerical studies of anchor pullout capacity have generally treated the soil as an elastic-perfectly plastic medium. However, the mechanical behaviour of natural clays is affected by inter-particle bonding, or structure, which cannot be accounted for using simple elasto-plastic models. Here, an advanced constitutive model formulated within the kinematic hardening framework is used to accurately predict the degradation of structure as an anchor embedded in a natural soft clay deposit is loaded to its pullout capacity. In comparison with an idealised, non-softening clay, the degradation of clay structure due to plastic strains in the soil mass results in a lower pullout capacity factor, a quantity commonly used in design, and a more complex load–displacement relationship. It can be concluded that clay structure has an important effect on the pullout behaviour of plate anchors.Peer ReviewedPostprint (author's final draft

No preference in female sika deer for conspecific over heterospecific male sexual calls in a mate choice context

Mating signals can be used both in contexts of species recognition and mate quality assessment. This study examines species recognition abilities in oestrous females presented with male mating calls from both conspecifics and closely related allopatric heterospecifics. Red deer and sika deer are naturally allopatric polygynous species capable of hybridization during sympatry. Male mating calls are sexually selected and differ greatly between species. Previous work indicated that most but not all oestrous red deer hinds prefer male mating calls from conspecifics over heterospecific sika deer. Using two-speaker playback experiments, we extend this examination by measuring the preference responses of oestrous sika deer hinds to these stimuli. We predicted that oestrous sika deer hinds will show little flexibility in behavioural responses and prefer conspecific calls over heterospecific calls, similar to those of red deer hinds. In contrast, sika deer hinds showed high levels of flexibility and no difference in overall preference behaviours, suggesting that vocal behaviour does not provide a solid barrier to hybridization in this species. The asymmetry in heterospecific preference responses between these species is discussed in relation to possible causation and hybridization patterns observed in free-ranging populations

Do red deer hinds prefer stags that produce harsh roars in mate choice contexts?

Red deer stags give two types of roars during the breeding season, termed ‘common’ and ‘harsh’ roars. This study tested the hypothesis that the characteristic spectro-temporal structure of male harsh roars functions to directly attract females towards male callers during the breeding season. The results show that oestrous hinds look for longer towards speakers broadcasting sequences containing harsh roars, but do not preferentially approach or spend more time in close proximity to speakers broadcasting harsh roars over those broadcasting only common roars. While these observations confirm that the specific acoustic structure of male harsh roars functions to draw the attention of hinds, they are not consistent with the notion that these calls have an immediate impact on mate choice decisions by stimulating oestrous hinds to move towards male callers. Consequently, we suggest that intersexual selection through female mate choice is unlikely to be a major factor driving the evolution of male red deer harsh roars

Effects of a Self-Management Procedure Using Student Feedback on Staff Members\u27 Use of Praise in an Out-of-School Time Program

Out-of-school time (OST) programs are under increasing pressure to improve student achievement. However, OST program administrators face a number of challenges to improving program effectiveness including inconsistent student participation, inexperienced staff members, and a lack of high-quality professional development. OST program administrators can address these challenges by implementing staff development practices that encourage the use of effective instructional strategies. Specific praise is a simple and effective instructional strategy that has been linked to improved student engagement, enhanced academic achievement, and stronger student-teacher relationships. Unfortunately, there have been very few studies examining the effects of interventions designed to increase OST staff members’ use of specific praise. One staff development strategy that could be both feasible and effective is the use of self-management. Although there are a variety of approaches to self-management designed for teachers, not all self-management strategies are effective. One strategy that might increase the feasibility and effectiveness of self-management programs is the use of student feedback. The process of comparing self-evaluations against a third-party standard such as student feedback is called matching in the self-management literature. Students can be a useful source of feedback because they observe their teachers frequently and can report the use of instructional strategies like specific praise. The purpose of this study was to examine the effects of a self-management procedure using student feedback on OST staff members’ use of specific praise. A multiple-baseline design across participants was used to examine the effects of the intervention on specific praise rates. All participants increased their use of specific praise after implementing the self-management procedures. General praise rates became more variable throughout the study. These findings provide evidence for a functional effect on specific praise but not for general praise. Teachers reported high levels of satisfaction with the feasibility and effectiveness of the intervention. A statistically significant correlation was found between specific praise rates and student reports of specific praise

Program Improvement and Practice: In-Service and Pre-Service Student Teaching Reflections

A qualitative study was conducted with graduates (in-service teachers) and pre-service teacher candidates from a traditional elementary education program to explore perceptions of the student teaching process and its impact on teaching philosophy and practices. The program graduates and pre-service teachers described their experience as valuable, but believed their knowledge of pedagogy and classroom management to be deficient. The value of the internship process and implications for program improvement are discussed. Theory without practice is dead, and practice without theory is blind. — Ano