Molecular mechanics of mineralized collagen fibrils in bone

Bone is a natural composite of collagen protein and the mineral hydroxyapatite. The structure of bone is known to be important to its load-bearing characteristics, but relatively little is known about this structure or the mechanism that govern deformation at the molecular scale. Here we perform full-atomistic calculations of the three-dimensional molecular structure of a mineralized collagen protein matrix to try to better understand its mechanical characteristics under tensile loading at various mineral densities. We find that as the mineral density increases, the tensile modulus of the network increases monotonically and well beyond that of pure collagen fibrils. Our results suggest that the mineral crystals within this network bears up to four times the stress of the collagen fibrils, whereas the collagen is predominantly responsible for the material’s deformation response. These findings reveal the mechanism by which bone is able to achieve superior energy dissipation and fracture resistance characteristics beyond its individual constituents.United States. Office of Naval Research (N000141010562)United States. Army Research Office (W991NF-09-1-0541)United States. Army Research Office (W911NF-10-1-0127)National Science Foundation (U.S.) (CMMI-0642545

Forecasting the number of teleworkers in Australia

This paper presents an exploratory analysis of teleworking in Australia. A number of changing patterns of teleworking in Australia are identified from perspectives of age group, educational level and gender, and the underlying causes for such changes are discussed. A strong correlation between the number of teleworkers and the number of households with computers and Internet access is identified. This facilitates the use of linear regression modeling for forecasting the number of teleworkers in Australia using both the number of households with computers and Internet access. The findings and the subsequent predictions are of practical significance to the individual organisations and government policy makers on how to effectively embrace the phenomenon of teleworking in Australia

Decoding near-concordant U-Pb zircon ages spanning several hundred million years: recrystallisation, metamictisation or diffusion?

In situ isotopic (U-Pb, Lu-Hf) and trace element analyses of zircon populations in six samples of the intrusive Mawson Charnockite, east Antarctica, emphasise complex zircon behaviour during very high-grade metamorphism. The combination of geochemical data sets is used to distinguish xenocrysts and identify a population of primary igneous zircon in situations where U-Pb data spread close to concordia over a few hundred Myr. The population is filtered to exclude grains with: (1) U-Pb ages >2% discordant, (2) anomalous trace element-content (Th, U, Y, REE) and (3) outlying Hf-isotopic values. Rare metamorphic-type grains were also excluded. Upon filtering the population, minimum emplacement ages for each sample were determined using the oldest grain(s). This approach improves upon age determinations in complex data sets that use weighted mean or isochron methods. Our results suggest that the Mawson Charnockite was emplaced episodically at c. 1145-1140 Ma, c. 1080-1050 Ma and c. 985-960 Ma. Core-outer core-rim and core-rim textures were identified but are not correlated with U-Pb ages. We establish that recrystallisation (mainly of zircon rims) must have occurred shortly following igneous crystallisation and that metamictisation/cracking is a Paleozoic to Recent event. Therefore, intra-zircon diffusion in a high-T, high-strain environment during Meso-Neoproterozoic orogenesis is inferred to have caused the extensive U-Pb isotopic disturbance. Charnockitic magmatism prior to c. 1,000 Ma has not previously been recorded in the Mawson region and indicates that orogenesis may have commenced c. 150 Myr earlier than previously thought. Correlations with similar aged rocks in adjacent regions have implications for supercontinent reconstructions

Testing for Hendra virus: difficulties experienced by veterinarians in Queensland prior to 2011

Objective: To identify the perceived barriers to Hendra virus (HeV) management by private equine veterinarians in Queensland.\ud \ud Design: An exploratory qualitative study of private equine veterinarians registered and working in coastal Queensland.\ud \ud Methods: A questionnaire that included eight open-ended questions about the management of HeV was used in face-to-face in-depth interviews with 21 veterinary personnel working in equine or mixed private practice between Far North and South-East Queensland in 2009–10. The qualitative data was entered and analysed thematically using QSR's International's Nvivo 9 qualitative data analysis software.\ud \ud Results: This study revealed key issues associated with HeV testing: (1) inadequate knowledge of testing procedures and laboratory diagnostic pathways; (2) difficulty in accessing laboratory services; (3) responsibility for cost of collection and transport of specimen; and (4) the role of government. Participants perceived these issues as reducing potential HeV case management efficiency.\ud \ud Conclusion: Although HeV management plans have been modified in part since 2009–10, this study highlights the importance of considering the perspectives of private veterinary practitioners in any biosecurity protocols

Inspiring writing: Bridging the gap between art and literacy in the classroom

Vanderburg, RM ORCiD: 0000-0003-0439-1806Writing is a cognitively draining activity filled with complex steps and procedures (Hayes and Flower, 1980). Students have to navigate the planning, text production, and revision components of writing (Flower and Hayes, 1981). Research has focused on using many different tasks (Vanderburg, 1996) and processes (Vanderburg and Swanson, 2007) which reduce the cognitive drain of the writing process. The goal of this paper is to present two different activities which teachers can use to reduce the cognitive drain during the writing process. One activity uses drawing as a mediation tool assisting in visualising text and implementing supportive quotes in student writing. The second activity uses drawing to reduce the cognitive drain while instructing how to write an expository text with a thesis and supporting evidence

Inspiring writing: Bridging the gap between art and literacy in the classroom

Writing is a cognitively draining activity filled with complex steps and procedures (Hayes and Flower, 1980). Students have to navigate the planning, text production, and revision components of writing (Flower and Hayes, 1981). Research has focused on using many different tasks (Vanderburg, 1996) and processes (Vanderburg and Swanson, 2007) which reduce the cognitive drain of the writing process. The goal of this paper is to present two different activities which teachers can use to reduce the cognitive drain during the writing process. One activity uses drawing as a mediation tool assisting in visualising text and implementing supportive quotes in student writing. The second activity uses drawing to reduce the cognitive drain while instructing how to write an expository text with a thesis and supporting evidence

Efficient Flow Computation on Massive Grid Terrain Datasets

The original publication is available at www.springerlink.comAs detailed terrain data becomes available, GIS terrain applications target larger geographic areas at ner resolutions. Processing the massive data involved in such applications presents signi cant challenges to GIS systems and demands algorithms that are optimized both for data movement and computation. In this paper we develop e cient algorithms for flow routing on massive terrains, extending our previous work on flow accumulation. We have implemented these algorithms in the Terraflow system, which is the rst comprehensive terrain flow software system designed and optimized for massive data. We compare the performance of Terraflow with that of state of the art commercial and open-source GIS systems. On large terrains, Terraflow outperforms existing systems by a factor of 2 to 1000, and is capable of solving problems no system was previously able to solve