University of the Sunshine Coast
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Use of nanotechnology in concrete pavements
No full textConcrete pavements are commonly used infrastructural assets that require various types of materials. There are many technologies and materials to improve the engineering properties and sustainability of concrete pavements. One such technology that opens new horizons in civil engineering involves nanomaterials. Use of nanomaterials increases structural strength and durability against aggressive chemical compounds and elements that extend the effective service life of the concrete pavement. Furthermore, nanomaterials can enhance environmental stewardships of concrete pavements through the reduction of demand for raw materials for maintenance and rehabilitation. Therefore, nanomaterials play a pivotal role in the development of high-strength and low-energy concrete pavements, especially for heavy-duty applications. In this chapter, various types of nanomaterials and pertinent performance mechanisms on the structural response of concrete pavements are discussed. In addition, the results of laboratory and field studies on the environmental burdens of nano-concrete pavements are analyzed in detail. In conclusion, the challenges of nano-concrete pavements as resilient infrastructure are discussed
Does disease severity impact on plant foliar chemical and physical responses to two Corymbia citriodora subsp. variegata pathogens?
No full textEucalypt forests and industrial plantations are threatened by fungal pathogen outbreaks that compromise timber and non-timber products and tree survival. Understanding host-pathogen interactions may contribute to the development of disease management strategies and the selection of resistant genotypes. Resistant and susceptible plants respond differently to disease infection, presenting variations of phenotypic traits, such as leaf physical and chemical parameters that may influence host-pathogen interactions. This study evaluated physical and chemical responses of Corymbia citriodora subsp. variegata to two fungal pathogens, Quambalaria pitereka (a co-evolved pathogen) and Austropuccinia psidii (an established exotic pathogen), using severity of infection as an indicator of plant resistance/susceptibility. Our primary aim was to quantify differential plant responses between uninoculated (controls), susceptible (severely infected) and resistant plants for each pathogen. Plant growth rate, leaf toughness and foliar secondary metabolite profiles of control, resistant and susceptible plants were compared 14 days after pathogen inoculations. Leaf secondary metabolite profiles were analysed from uninfected regrowth of the same plants 90 days after inoculation. The results indicated that only susceptible plants elicited responses to pathogen damage. Susceptible plants infected by Q. pitereka had greater leaf toughness, and susceptible plants infected by A. psidii had reduced growth rates and altered expression of secondary metabolites in comparison to control and resistant plants. Austropuccinia psidii infection led to a reduction in the proportion of monoterpenes and monounsaturated hydrocarbons and an increase in long chain hydrocarbons. No differences in secondary metabolite profiles were found between the treatments 90 days after inoculation, suggesting that differences observed were in response to severe infection and that leaf chemistry is not a good predictive biomarker of susceptibility in C. citriodora subsp. variegata
Taxonomy of prokaryotic viruses: 2018-2019 update from the ICTV Bacterial and Archaeal Viruses Subcommittee
No full textThis article is a summary of the activities of the ICTV’s Bacterial and Archaeal Viruses Subcommittee for the years 2018 and 2019. Highlights include the creation of a new order, 10 families, 22 subfamilies, 424 genera and 964 species. Some of our concerns about the ICTV’s ability to adjust to and incorporate new DNA- and protein-based taxonomic tools are discussed
How are we progressing with academic numeracy at regional universities? Perspectives from first-year undergraduate studies
No full textThis study provides an overview of the support provided for academic numeracy for first-year students across six Australian regional universities. Survey analysis of university academics provided an overview of the approaches used in academic numeracy in diverse cohorts. Further investigations via semi-structured interviews and secondary data were performed, providing details of the level of academic numeracy required in the subjects offered, identification of at-risk students and strategies for student support, and
student responses to service provision. A case study at one university provided a more detailed view of the factors influencing attrition in first-year academic numeracy subjects. This case study highlighted issues related to a one-size-fits-all approach and findings argue for a more nuanced cohort-based approach that combines conventional statistical analysis with analysis that provides a more detailed view of complex scenarios. The study suggests that while support services are not responding well to the issue of attrition, better targeting individual student support may lead to improvements
Voluntary Activation and Reflex Responses following Hamstring Strain Injury
No full textIntroduction:
There is a lack of definitive evidence supporting deficits in voluntary activation in participants with prior hamstring injury, moreover it remains unknown if spinal mechanisms contribute to suspected deficits.
Purpose :
To determine the effect of prior hamstring strain injury on knee flexor concentric and eccentric strength, voluntary activation, surface electromyographic activity (sEMG), stretch and tendon reflex amplitudes.
Methods :
Twenty-five participants were recruited, twelve with a history of unilateral hamstring strain injury of at least moderate severity. Voluntary activation, strength and sEMG activity were recorded during maximal eccentric and concentric knee flexor contractions at 60°/s. Stretch and tendon reflexes were also recorded at rest.
Results :
Previously injured limbs exhibited lower levels of voluntary activation (mean difference= -24.1% [95% CI = -34.1 to -14.0%], p&0.001) strength (mean difference vs. control group = -0.37 Nm/kg [95%CI = -0.71 to -0.03 Nm/kg], p = 0.03) and normalised sEMG (mean difference = -17% [95% CI = -32 to -2%], p = 0.02) during maximal eccentric knee flexor contractions compared to control group. No such differences were seen in concentric contractions. Stretch reflexes (mean difference = -3.8% [95% CI = -6.8 to -0.8], p = 0.02) and tendon reflexes (mean difference = -13% [95%CI = -26 to 0%], p = 0.04) were also lower in previously injured compared to control biceps femoris muscles.
Conclusion :
Moderate to severe hamstring strain injury is associated with long-term deficits in voluntary activation during maximal eccentric contraction. Hamstring injury history is also associated with deficits in stretch reflex and tendon reflex amplitude
Asynchronous carbon sink saturation in African and Amazonian tropical forests
No full textStructurally intact tropical forests sequestered about half of the global terrestrial carbon uptake over the 1990s and early 2000s, removing about 15 per cent of anthropogenic carbon dioxide emissions1,2,3. Climate-driven vegetation models typically predict that this tropical forest ‘carbon sink’ will continue for decades4,5. Here we assess trends in the carbon sink using 244 structurally intact African tropical forests spanning 11 countries, compare them with 321 published plots from Amazonia and investigate the underlying drivers of the trends. The carbon sink in live aboveground biomass in intact African tropical forests has been stable for the three decades to 2015, at 0.66 tonnes of carbon per hectare per year (95 per cent confidence interval 0.53–0.79), in contrast to the long-term decline in Amazonian forests6. Therefore the carbon sink responses of Earth’s two largest expanses of tropical forest have diverged. The difference is largely driven by carbon losses from tree mortality, with no detectable multi-decadal trend in Africa and a long-term increase in Amazonia. Both continents show increasing tree growth, consistent with the expected net effect of rising atmospheric carbon dioxide and air temperature7,8,9. Despite the past stability of the African carbon sink, our most intensively monitored plots suggest a post-2010 increase in carbon losses, delayed compared to Amazonia, indicating asynchronous carbon sink saturation on the two continents. A statistical model including carbon dioxide, temperature, drought and forest dynamics accounts for the observed trends and indicates a long-term future decline in the African sink, whereas the Amazonian sink continues to weaken rapidly. Overall, the uptake of carbon into Earth’s intact tropical forests peaked in the 1990s. Given that the global terrestrial carbon sink is increasing in size, independent observations indicating greater recent carbon uptake into the Northern Hemisphere landmass10 reinforce our conclusion that the intact tropical forest carbon sink has already peaked. This saturation and ongoing decline of the tropical forest carbon sink has consequences for policies intended to stabilize Earth’s climate
Can education transform?: Contradictions between the emerging future and the walled past
No full textWhile many imagine education as far more flexible and student‐centered, creating a different system has been far more challenging. Why is this the case? What are the tensions between the imagined future and the weight of the past. This essay seeks to answer this question through insights gained from anticipatory action learning interventions in Australia, Malaysia, Norway, and the Philippines
Comparisons between individual and combined assays for quality control of wood treatments
No full textIndividual and batch analyses were examined for creosote-treated Pinus sylvestris poles. Retentions were slightly higher in combined analyses, but within natural population variations. Batch analysis provided a good guide to retention, but no data on within-batch variability