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Reinforced Timber Laminated Veneer Lumber (LVL) Connection Loaded Perpendicular to the Grain
No full textThe thesis reports the outcomes of a comprehensive study on how bolted timber connections with Laminated Veneer Lumber (LVL) respond to loading that is perpendicular to the grain. It investigates the topic in three main sections: understanding the stress-strain characteristic of LVL, checking how much splitting failure occurs in unreinforced bolted joints, and improving the splitting resistance by inserting self-tapping screws.
In the first phase, AS/NZS 4063.1-2010 tensile tests were conducted on LVL samples of two lengths using a three-point bending set-up. The load, deflection, stress, strain, and failures of the samples were measured and analyzed to evaluate their mechanical performance. Digital Image Correlation (DIC) identified key deformation stages-elastic, fracture, and softening. The bilinear model was used and proven to match the relationship between stress and strain under perpendicular tension.
The second phase focused on the splitting behavior of unreinforced bolted joints. Full-scale tests changed the distance between the loaded edge and the connection, the width of the connection and the placement of bolts. When the relative edge distance (he/h) surpassed 0.6, it was found that the main mode of resistance splitting involved ductile failure. With more connections added, the capacity grew less significantly. The findings were checked against DIN 1052, Van der Put, Ballerini, and the Australian standard. Even though the majority of models agreed with experiments for a single-bolt connection, the Australian model had a significant difference. Results from the models fell short when there were more than four bolts. Use of tensile strength parameters made the revised DIN 1052 model more precise.
In phase three, STS reinforcement was added to improve connection behavior. Various tests were performed that changed the screw diameter, the depth it was embedded, and where it was placed. STS reinforcement enhanced both strength and ductility by shifting failure modes from brittle to ductile. According to the withdrawal tests, the diameter and depth of the screw were critical. According to the DIC analysis, strain decreased, and the time for cracks to grow was delayed after using the STS. Based on the data and on SEM and regression statistics, resisting STS withdrawal was considered the main factor. After completing the study, it is recommended to incorporate STS rules into design codes to strengthen and secure timber connections
The relationship between gay community, other social networks, and HIV among gay, bisexual and other men who have sex with men
No full textThis thesis examines the relationship between social engagement with LGBTQ+ communities, broader social networks, and HIV prevention among gay, bisexual, and other men who have sex with men (GBMSM) in Australia.
Chapter 1 introduces what is known about social networks, community, and HIV prevention among GBMSM. Chapters 2 and 3 use data from the Gay Community Periodic Surveys from 1998-2020 in Chapter 2 and 2017-2021 in Chapter 3. Chapter 2 assesses long-term trends in gay social engagement among GBMSM and shows that social engagement with gay men is associated with HIV testing, PrEP uptake, and sexual behaviour. Chapter 3 is an analysis of self-reported HIV/STI testing frequency among GBMSM that shows gay social engagement is associated with more frequent STI testing. Chapter 4 uses survey data from the Asian GBMSM to investigate whether social engagement and experiences of discrimination among Asian GBMSM are associated with the use of effective HIV prevention strategies and the risk of HIV acquisition. This analysis found that discrimination based on sexual identity is associated with a higher likelihood of reporting sexual behaviours with a risk of HIV acquisition. Chapter 5 uses qualitative interviews with migrant GBMSM to understand their connections to health services and various communities. This study found GBMSM were influenced through informal sharing of sexual health information and norms aboutsexual health from friends and sexual partners. Chapter 6 uses a latent class analysis of national survey data from GBMSM to assess their sources of social support. This analysis found that connection to gay men specifically had positive associations with HIV/STI testing and use of HIV pre-exposure prophylaxis (PrEP), but that there was a substantial proportion of GBMSM who were not well connected to or supported by other LGBTQ+ people. Chapter 7 discusses the implications of this thesis and makes recommendations about HIV prevention research and implementation among GBMSM in Australia.
This thesis shows how social connection between GBMSM remains relevant for HIV prevention, but adaptation to existing approaches to HIV prevention is needed to reach GBMSM who are not socially engaged with LGBTQ+ people
“The emotional pain has been my struggle” An Investigation into Emotion-Regulation Focused Interventions for People with Chronic Pain
No full textChronic pain is a substantial global health issue, affecting 20-30% of the population. Defined as pain that persists beyond three months the aetiology of chronic pain is varied and complex, and frequently unrelated to injury. Regardless of how it manifests, chronic pain occurs with heightened negative emotional states, such as anger, worry, fear and low mood. Additionally, psychological comorbidities (e.g., anxiety and depression), are present in more than half the population, contributing to declining quality of life, increasing disability, heightened pain intensity and are a predictor for treatment failure. Recent evidence points to emotion dysregulation, as a contributing factor in the development and maintenance of chronic pain and psychological comorbidities. Emotion regulation is defined as the capability to influence the duration, intensity and frequency of emotions, and has been found to play a role in depression, anxiety, stress, wellbeing and pain intensity in people with chronic pain. While psychological therapy is a standard inclusion in holistic pain management programs for people with chronic pain, evidence suggests that emotion dysregulation may be undertreated in current standard psychological interventions. This finding has led to increasing development of emotion regulation focused interventions for people with chronic pain and growing investigation of their efficacy in clinical trials. This PhD will explore the extent that interventions focused on improving emotion regulation can alter psychological and pain related outcomes. Of particular interest are emotion regulation skills focused (ERSF) interventions, defined as those that target emotional awareness, expression, and identification of emotional triggers through key skills or strategies aimed at improving these elements as key stages in the emotional generative process. Chapter 1 is an overview of the literature and the background to the field, Chapter 2 is a systematic review and meta-analysis of ERSF interventions for chronic pain, Chapter 3 is a randomised controlled trial exploring the efficacy an internet-delivered ERSF intervention developed as part of this PhD, Chapter 4 is a qualitative study exploring the acceptability of the same intervention, and Chapter 5 is a general discussion of the findings of the studies included in the thesis
Does adjusting for legal factors make the racial gap in imprisonment risks disappear?
Get PDFAboriginal Australians are almost twice as likely as non-Aboriginal Australians to receive a prison sentence. Past research has shown that this difference usually disappears when controls are introduced for relevant legal factors, such as offence seriousness, number of concurrent offences and prior criminal record. It is possible, however, that courts place more weight on certain legal factors when sentencing Aboriginal defendants than when sentencing non-Aboriginal defendants. This study employs an Oaxaca-Blinder decomposition to explore this possibility in relation to assault and theft offences in New South Wales between 2019 and 2023. We find that about 17% of the gap for assault offences and 23% of the gap for property offences is not explicable in terms of sentence-relevant factors. If the weight assigned by courts to legal factors, such as prior criminal record and prior imprisonment, were the same for Aboriginal and non-Aboriginal defendants, around 150 fewer adult Aboriginal defendants would receive a prison sentence for the offences of assault and theft over the period of this study
A Pedagogical Evaluation of Online Adaptive Tutorials to Support Teaching and Learning
Get PDFIn the fast-paced technology world we live in, it is imperative that we pause, assess, and reflect on the efficacy of some of the online teaching and learning tools available to understand whether they offer benefits, and how best to implement them.
This real-world quasi-experimental research was conducted to investigate potential benefits of integrating Adaptive Tutorials as a supplementary tool in higher education. The research aims to explore student uptake of Adaptive Tutorials based on different subject domains and pedagogical environments. This was achieved by testing a variety of STEM (Science, Technology, Engineering Mathematics) subjects with the goal of being able to provide students support and guidance, leading to their improved subject knowledge confidence and learning outcomes. The role of instant, adaptive, formative feedback was also considered. Tutorials were designed within the framework of Cognitive Load Theory, with the Smart Sparrow™ Adaptive eLearning Platform as the testbed.
The five experiments carried out included a flipped-style Chemistry course as well as running an Adaptive Tutorial in parallel to a Pathology laboratory. To review and test knowledge, experiments were conducted in a Human Computer Interaction course and a Petroleum Engineering course. Likewise, an experiment was carried out in a Mathematics course post-lecture, as a means of reinforcing newly acquired concepts.
Quantitative data comprising marks was compared and analysed between students who did and did not utilise the tutorials. Similarly qualitative data was compared and analysed from questionnaires designed to gain insight into students’ user experiences and perceived benefits.
Overall results indicated most students found Adaptive Tutorials beneficial, particularly appreciating the use of instant, adaptive, formative feedback. Although they can be effectively integrated into a variety of STEM subjects and across a range of pedagogical scenarios, Adaptive Tutorials are less useful when used in parallel with face-to-face classes. Interestingly it would seem, students in ill-defined subjects may be less able to pinpoint a need to use them. Ultimately, with insight and adequate planning, Adaptive Tutorials can be an effective teaching and learning tool. Not only can they provide support and personalised guidance, but they also afford students an opportunity to consolidate and test their knowledge in a stress-free, low-risk environment. In so doing, they empower students to take ownership of their learning
Healthy lifestyle factors and combined macrovascular and microvascular events in diabetes patients with high cardiovascular risk: results from ADVANCE
Get PDFBackground: To explore whether healthy lifestyle factors (HLFs) predict a lower risk of major macrovascular and microvascular events and death in people with type 2 diabetes (T2D) with a high risk of vascular complications. Methods: Post hoc analyses of 11,133 participants with T2D in the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial who were assigned a score ranging from 0 to 4 based on the number of baseline HLFs: never smoked, moderate-to-vigorous physical activity, ideal waist/hip ratio, and low-to-moderate alcohol consumption. Multivariable Cox models were used to determine associations of 0, 1, 2, and ≥ 3 HLFs with vascular events and all-cause mortality. Results: Compared to participants with no HLFs, hazard ratios for participants with 3 or 4 HLFs were 0.68 (95% confidence interval [CI] 0.57–0.81) for the composite of major macrovascular or microvascular events, 0.58 (0.46–0.75) for major macrovascular events, 0.78 (0.61–0.99) for microvascular events, and 0.48 (0.37–0.63) for all-cause mortality during a median follow-up of 5 years. Each increment in HLF score was significantly associated with lower rates of these outcomes. There was no heterogeneity in the effect on any outcome by HLF across randomized intensive blood glucose control and blood pressure lowering treatments. Conclusions: HLFs are associated with lower risks of major macrovascular and microvascular events and lower rates of death in high-risk adults with T2D
Impression Management: Performing the Printed Self
Get PDFThis project explores the potential to understand mechanically reproduced art as a metaphor for performed selves in art practice and life. In my thesis, I focus particularly on a specific subset of the performed self, one known as Passing, and its shadow, the “sincere” and “authentic” selves. Passing is defined as ‘a cultural performance, whereby one member of a defined social group masquerades as another to enjoy the privileges afforded to the dominant group’. Through practice-based research, I position the mechanically-reproducible print as a medium for examining mutable identities and their agency and investigating how the material language of the print can be utilised to mask or reveal the print's identity. I argue that in essence, a print is an impression, and the act of making a print is entirely dependent on managing the transfer of the impression. As such, printmaking can be considered a form of impression management, a term used by sociologist Erving Goffman to describe the way in which we perform in social situations. Similarly, the making of prints constitutes impression management, both literally and metaphorically. The material language of the print is therefore well situated to act as a tool for examining the social phenomenon of the performed self. Here I suggest a new interpretation of the ontology of the print and the social and psychological experience of performing one’s self in everyday life, thus providing an original way of understanding the commonalities between art and lived experience
All or nothing? Facultative parthenogens, sexual conflict, and the paradox of sex
Get PDFEvolutionary biologists have been pondering the evolution of sex for over a century. Much progress has been made on this “queen of problems,” yet it remains essentially unresolved. We now know that sexual reproduction can have many benefits, as well as many costs, and obligate asexuality comes with its own set of limitations that may often result in extinction. Theory suggests that reproductive flexibility is optimal. Facultatively parthenogenic animals, which can flexibly switch between sexual and asexual reproduction, should be very common. However, they are not, and many form mosaics of populations where they seem to behave as either obligately sexual or obligately asexual. Recent theory suggests that sexual conflict is important in these systems. The sexual conflict hypothesis proposes that sexually antagonistic coevolution may result in the localised loss of parthenogenesis, or of males, potentially explaining the rarity of facultatively parthenogenic animals, as well as their reproductive mosaics. In this thesis, I seek to understand why facultatively parthenogenic animals often seem to forego the flexibility of which they are capable, and I evaluate the potential role of sexual conflict in this process.
In chapters two and three, I use a facultatively parthenogenic stick insect, Megacrania batesii, to try to understand how and why asexual populations are established and maintained. Using a series of laboratory crosses and an experiment employing semi-natural enclosures, I show that female resistance could play a central role. I found evidence of maternal effects and genetic effects promoting female resistance to sex, through both pre- and post-copulatory mechanisms. And by experimentally simulating male invasions of all-female populations in a semi-natural environment, I showed how these mechanisms can hinder such invasions. Together, my results uncover multiple mechanisms that can contribute to the formation of reproductive mosaics in facultative parthenogens, and that could ultimately result in facultative animals becoming obligately asexual.
In chapter four, I look more broadly across animals to review empirical evidence relevant to the sexual conflict hypothesis, investigating how parthenogenic females interact with males, and asking whether these interactions could constrain the evolution of parthenogenesis. I found that many facultative parthenogens have traits suggestive of sexual conflict. However, relevant work is scarce, and the evidence so far suggests that the costs and benefits of sex and parthenogenesis can be highly context-dependent. My thesis suggests interesting gaps in knowledge that could help us understand the role of sexual conflict in the paradox of sex
Mould-Free Manufacturing of Advanced Composite Structures using Eccentric Prestressing
Get PDFMould-free composite manufacturing eliminates the requirement for fixed tooling, reducing component costs and improving production flexibility. Researchers have successfully produced curved surfaces from flat tooling by controlling thermal strains in unsymmetric laminates using a technique to produce 4D printed composites (4DPC). However, 4DPC couples ply orientations and material properties to curvature, limiting the achievable geometries. This thesis presents eccentric fibre prestress (EFP) as an alternate method to 4DPC. EFP replicates the strain gradients of 4DPC but offers more flexibility in curvature selection through independent prestress control.
While EFP’s potential is promising, its application to mould-free manufacturing remains underexplored, particularly for complex, multi-curvature surfaces and practical structures with competing geometric and mechanical requirements. This thesis bridges these gaps via experimental demonstration ranging from the foundational coupon scale to practical applications. Models are validated by a parametric investigation on thin laminates with embedded optical sensors and a custom prestress fixture. Methods are developed to manufacture complex geometries using spatial stiffness tailoring and angle-ply layups. A NACA 4412 aerofoil is designed and manufactured using a genetic algorithm-inverse design tool while an optimisation model is developed to produce lightweight, 1/3 scale EFP automotive leaf springs for static and dynamic testing.
Results show that EFP effectively controls curvature, with a 3.9% and 2.0% average discrepancy between the predicted and observed curvatures and strains. Two novel parameters—thickness and modulus ratio—are manipulated to yield a 51.4% curvature increase within a same stiffness laminate. Stiffness tailoring accurately shapes complex geometries while doubly curved angle-ply laminates require extensive material characterisation to achieve similar results. An example EFP spring was 25% lighter than 4DPC meanwhile flax-carbon laminates are found to optimally balance spring mass and pretension requirement. Mechanical testing reveals good performance in EFP springs and prestress is found to positively influence the viscoelastic response of flax fibre. The study concludes that EFP is a viable mould-free method for structural composites, particularly in low-volume and prototype applications whereby flexibility is prioritised over throughput
Fast dehalogenation of halogenated compounds by cobalt complexes
Get PDFHalogenated substances, particularly per- and polyfluoroalkyl substances (PFASs) and chlorinated volatile organic compounds (Cl-VOCs), pose severe environmental and health risks due to their persistence and toxicity. This thesis develops simple, effective remediation technologies to overcome the inefficiency, high cost, and harsh conditions of existing methods. This project explores, for the first time, the reductive dehalogenation of these materials using macrocyclic organic compounds with highly conjugated structures with a chelated metal ion at their center. For the reductive defluorination, vitamin B12 (VB12) has been reported to defluorinate perfluorooctane sulfonic acid (PFOS) in the presence of TiIII citrate at 70 °C. In Chapter 2, the defluorination of branched PFOS using cobaltII phthalocyanine (CoPc) combined with TiIII citrate was investigated. This approach achieved 10.9% defluorination of technical PFOS and 54.5% defluorination of br-PFOS isomers within 8 hours, a significant improvement compared to the commonly reported catalyst, VB12, which achieved only 2.4% under the same conditions.
In Chapter 3, the project was extended to investigate the catalytic dehalogenation of Cl-VOCs such as trichloroethylene (TCE), perchloroethylene (PCE), and dichloromethane (DCM) using metal phthalocyanine derivatives. Within 5 minutes, soluble cobalt tetratrimethylammonium phthalocyanine (CoTTMeAPc) achieved high degradation efficiencies (94.6% for PCE, 91.7% for TCE, and 57.8% for DCM), outperforming soluble VB12 (21.6%, 15.4%, and 6.7%, respectively) within the same period. This was also superior to insoluble CoPc, which degraded only 27.4% of PCE, 41.6% of TCE, and 21.9% of DCM within 20 minutes. These results represent a significant improvement compared to insoluble metal phthalocyanines and VB12.
In Chapter 4, metal single-atom catalysts (M-SACs) supported on carbon black for the complete defluorination of branched PFOS was investigated. Various M-SACs, including Cu-SAC, Fe-SAC, Mn-SAC, Ni-SAC, and Co-SAC, were synthesized, with Co-SAC demonstrating superior defluorination of technical PFOS—achieving 19.44% defluorination (and complete defluorination of branched isomers) within 5 hours using nano zero-valent zinc (nZnº) as a cost-effective reducing agent. This approaches present a promising outlook for utilizing these catalysts in large-scale branched PFAS reduction processes with the use of electron donors