Preparation and Properties of In-Situ Devices Using the SALD and SALDVI Techniques

One of the many advantages of Selective Area Laser Deposition (SALD) and Selective Area Laser Deposition Vapor Infiltration (SALDVI) is that they can be used to embed in-situ micro-sensors within macro-components. A single-point SiC/C thermocouple sensor embedded within a SiC macro-component and electrically insulated with silicon nitride layers has been demonstrated. In many applications, multi-point sensors within a single component are needed, e.g., in monitoring the temperature gradient and distribution at different positions. In this paper, multi-point thermocouple devices are demonstrated. The macro-component is a SiC bulk shape made by infiltrating vapor deposited silicon carbide into a silicon carbide powder bed using the SALDVI technique. Multiple SiC/C thermocouples are embedded in-situ in the SiC bulk shape using the SALD technique. The transient and steady state responses ofthe embedded thermocouples are compared to reference thermocouples probing the surfaces of the bulk shape.Mechanical Engineerin

Fostering Creative Ecologies in Australasian Secondary Schools

This study investigates and compares elements of creativity in secondary schools and classrooms in Australia and Singapore. Statistical analysis and qualitative investigation of teacher, student and leadership perceptions of the emergence, fostering and absence of creativity in school learning environments is explored. This large-scale international study (n=717) reveals the impact of teacher behaviours, teaching environments and school leadership approaches that promote and impede the enhancement of creative, critical, and innovative thinking, organisation, and curriculum structures. Implications for Australian schools and teaching urge for secondary education to challenge current, practices, pedagogies and environments, arguing for school-based strategies and considerations that enhance creativity and critical thinking and the fostering of creative ecologies within Australian schools

A socioeconomic related 'digital divide' exists in how, not if, young people use computers

Government initiatives have tried to ensure uniform computer access for young people; however a divide related to socioeconomic status (SES) may still exist in the nature of information technology (IT) use. This study aimed to investigate this relationship in 1,351 Western Australian children between 6 and 17 years of age. All participants had computer access at school and 98.9% at home. Neighbourhood SES was related to computer use, IT activities, playing musical instruments, and participating in vigorous physical activity. Participants from higher SES neighbourhoods were more exposed to school computers, reading, playing musical instruments, and vigorous physical activity. Participants from lower SES neighbourhoods were more exposed to TV, electronic games, mobile phones, and non-academic computer activities at home. These patterns may impact future economic, academic, and health outcomes. Better insight into neighbourhood SES influences will assist in understanding and managing the impact of computer use on young people's health and development

The influence of age, gender and other information technology use on young people's computer use at school and home

Young people are exposed to a range of information technologies (IT) in different environments, including home and school, however the factors influencing IT use at home and school are poorly understood. The aim of this study was to investigate young people's computer exposure patterns at home and school, and related factors such as age, gender and the types of IT used. 1351 children in Years 1, 6, 9 and 11 from 10 schools in metropolitan Western Australia were surveyed. Most children had access to computers at home and school, with computer exposures comparable to TV, reading and writing. Total computer exposure was greater at home than school, and increased with age. Computer activities varied with age and gender and became more social with increased age, at the same time parental involvement reduced. Bedroom computer use was found to result in higher exposure patterns. High use of home and school computers were associated with each other. Associations varied depending on the type of IT exposure measure (frequency, mean weekly hours, usual and longest duration). The frequency and duration of children's computer exposure were associated with a complex interplay of the environment of use, the participant's age and gender and other IT activities

Associations between meeting sleep, physical activity or screen time behaviour guidelines and academic performance in Australian school children

Background: Current guidelines suggest too little sleep, too little physical activity, and too much sedentary time are associated with poor health outcomes. These behaviours may also influence academic performance in school children. The primary purpose of this study was to examine the relationships between sleep, physical activity, or sedentary behaviours and academic performance in a school with a well-developed and integrated technology use and well-being program. Methods: This was a cross-sectional survey of students (n = 934, Grades 5-12) in an Australian school with a bring-your-own device (tablet or laptop computer) policy. Students reported sleep, physical activity, and sedentary (screen and non-screen) behaviours. Academic performance was obtained from school records. Linear regressions were used to test the association between behaviours and academic performance outcomes. Results: Seventy-four percent of students met sleep guidelines (9 to 11 h for children 5-13 years and 8 to 10 h for 14-17 year olds), 21% met physical activity guidelines (60 min of moderate-to-vigorous physical activity every day), and 15% met screen time guidelines (no more than 2 h recreational screen time per day); only 2% met all three. There were no associations between meeting sleep guidelines and academic performance; however later weekend bedtimes were associated with poorer academic performance (- 3.4 points on the Average Academic Index, 95%CI: - 5.0, - 1.7, p <.001). There were no associations between meeting physical activity guidelines and academic performance. Meeting screen guidelines was associated with higher Average Academic Index (5.8, 95%CI: 3.6, 8.0, p <.001), Maths 7.9, 95%CI: 4.1, 11.6, p <.001) and English scores (3.8, 95%CI: 1.8, 5.8, p <.001) and higher time in sedentary behaviours was associated with poorer academic performance, including total sedentary behaviours in hrs/day (5.8 points on Average Academic Index, 95%CI: 3.6, 8.0, p <.001. Meeting at least two of the three behaviour guidelines was associated with better academic performance. Conclusions: Sleep and sedentary behaviours were linked to academic performance. School communities should emphasize comprehensive wellness strategies to address multiple behaviours to maximize student health and academic success

Radial velocities of five globular clusters obtained with AAOmega

Using the recently commissioned multi-object spectrograph AAOmega on the 3.9m AAT we have obtained medium-resolution near-infrared spectra for 10,500 stars in and around five southern globular clusters. The targets were 47 Tuc, M12, M30, M55 and NGC 288. We have measured radial velocities to +/- 1 km/s with the cross correlation method and estimated metallicity, effective temperature, surface gra vity and rotational velocity for each star by fitting synthetic model spectra. An analysis of the velocity maps and velocity dispersion of member stars revealed systemic rotation in four of the target clusters.Comment: 4 pages, 6 figures, accepted for publication by Astronomische Nachrichte

Control of the Cross Section Geometry of Extruded Dental Porcelain Slurries for Rapid Prototyping Applications

This study investigates the dependence of the cross section geometry of extruded dental porcelain slurries on the rheological property of the slurry and the extrusion conditions. It is found that a pseudoplastic slurry is a basic requirement for obtaining extruded lines with rectangular cross sections. The cross section geometry of the extrudate is also strongly affected by extrusion parameters including the extrusion nozzle height, nozzle moving speed, and extrusion rate. Proper combinations of these extrusion parameters are necessary in order to obtain extrudates with near rectangular cross sections. The results obtained have been explained in terms of the interactions among the rheological properties of the slurry, the shear rate imposed on the slurry during extrusion, the wettability of the slurry on the substrate, and the forced flow of the slurry during extrusion.The authors gratefully acknowledge financial support provided by the National Science Foundation under Grant Nos: DMI-9908249 and DMI-0218169.Mechanical Engineerin

A novel tool to measure extracellular glutamate in the Zebrafish nervous system in vivo

Glutamate is the major excitatory neurotransmitter in the brain. Its release and eventual recycling are key to rapid sustained neural activity. We have paired the gfap promoter region with the glutamate reporter molecule, iGluSnFR, to drive expression in glial cells throughout the nervous system. Tg(gfap:iGluSnFR) is expressed on the glial membrane of Müller glia cells in the retina, which rapidly respond to stimulation and the release of extracellular glutamate. As glial cells are associated with most, if not all, synapses, Tg(gfap:iGluSnFR) is a novel and exciting tool to measure neuronal activity and extracellular glutamate dynamics in many regions of the nervous system. Glutamate is the major excitatory neurotransmitter in the brain. Its release and eventual recycling are key to rapid sustained neural activity.1 Glial cells play a key role in the uptake and recycling of glutamate from the synaptic cleft. iGluSnFR has been used to study synaptic activity by measuring glutamate dynamics in the zebrafish nervous system.2,3 Previous work has also used iGluSnFR in glial cells; however, this was done transiently in the mouse using viral vectors.2,4 As such, we designed a transgene to stably express iGluSnFR in the glial cells of the zebrafish nervous system. We report a novel transgenic zebrafish, Tg(gfap:iGluSnFR), that displays the glutamate-sensitive fluorescent reporter iGluSnFR specifically on the membrane of glial cells (Figure 1A–C). This molecule is expressed on the glial membrane in many brain regions and rapidly responds to stimulation and the release of extracellular glutamate (Figure 1D–F, Supplementary Data; Supplementary Data are available online at www.liebertpub.com/zeb). Thus, pairing the sensitivity of iGluSnFR and optical transparency of the zebrafish provides a powerful tool for understanding glutamate dynamics in neural tissues in vivo

SALDVI of SiC into Metal and Ceramic Powders

Selective Area Laser Deposition Vapor Infiltration (SALDVI) is the SFF technique using gas phase precursors to locally infiltrate a powder bed into a desired shape. Experiments were performed with a CO2 laser and the silicon carbide forming gas precursor Si(CH3)4. This paper will report on the microstructural aspects of SiC into a variety of metal and ceramic powders including Mo, SiC, ZrO2, and WC.The authors acknowledge the support for this research by the Office of Naval Research (grant #N00014-95-1-0978).Mechanical Engineerin

Microstructure Evaluation for Laser Densification of Dental Porcelains

The feasibility of dental restorations has been investigated using a multi-materials laser densification (MMLD) process, where dental alloy and porcelain powders are laser densified layer by layer to form solid bodies. The present study focuses on the densification behavior of dental porcelain powders in response to a moving laser source. Effects of the laser processing temperature and the green density of the powder bed on microstructure, distortion, macro-cracks, porosities and phase contents of the laser densified porcelain have been investigated. The condition to generate continuous porcelain bodies from powder compacts have also be studied. It is found that the geometry, composition and density of densified porcelain bodies are strongly affected by the laser processing temperature and the green density of the powder compact.Mechanical Engineerin