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Collisions in adolescent female rugby: incidence, magnitude, tackle technique, cognition and brain integrity across a season of participation : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
Get PDFRugby is a popular, fast-paced collision sport, but its high contact rate increases injury risks compared to those involved in non-contact sports. While rugby is well-known for its high concussion incidence, more recent concerns focus on former players who, despite never being diagnosed with a concussion, develop brain disorders such as chronic traumatic encephalopathy (CTE). It is suggested that repetitive head impact exposure in rugby places stress and strain on the brain, which, over time, may contribute to the development of neurodegenerative diseases. Youth and female players are particularly vulnerable to brain injury risk because developing brains are more susceptible to injury, and females face higher risks due to anatomical and physiological differences. Despite making up a significant proportion of rugby players in New Zealand, both youth and female players are underrepresented in research to date.
Forty-two participants, aged 12-17 yr, were recruited from two under-18 rugby teams in the Canterbury Metro Rugby Sub Union during the 2022 and 2023 seasons. Each participant wore an instrumented mouthguard (iMG) during all games and training sessions to quantify the incidence and magnitude of head acceleration events (HAEs), exceeding 8 g throughout the season, specifically measuring peak linear acceleration (PLA) and peak rotational acceleration (PRA). All sessions were video recorded to verify iMG-detected head impacts. iMG data were analysed to identify key characteristics, including the mechanism of impact (e.g. direct to the head or indirect), head location (e.g. forehead) and rugby event (e.g. ball carrier or breakdown). Tackle-related impacts were further examined to assess the techniques associated with HAEs for both the tackler and ball carrier. Finally, pre- and post-season magnetic resonance imaging (MRI) and neurocognitive testing were conducted to evaluate the effects of seasonal head impact exposure on brain health.
iMG data revealed female adolescent rugby players were exposed to similar magnitude of HAEs (PLA and PRA) as matched males and adult females, however, at a much lower incidence of HAEs per game, training, weekly and seasonally compared to adolescent males, adult males, adult females and previously reported adolescent female rugby players. The tackle was the most frequent event to record an iMG event, particularly for the tackler. Very few events followed RugbySmart recommended tackle guidelines for a safe tackle. The ball carrier was more likely to experience an indirect “whiplash” style HAE compared to a direct head impact event. Enhancing the ball carrier’s ability to anticipate a tackle and controlling their body posture while falling may reduce exposure to HAEs. Neurocognitive testing and MRI results revealed no significant change in brain function or structure following a rugby season. When analysing the influence of covariates on brain integrity, we found an association between reduced white matter brain integrity in the body of the corpus callosum, both with wearing headgear and an increased head impact burden. However, results should be interpreted with caution due to low participant numbers, only three participants regularly wearing headgear and the lack of a control group.
This thesis provides a comprehensive understanding of the head impacts that adolescent female rugby players are exposed to over a season. Improving tackle technique and training may reduce high-magnitude HAEs, lowering seasonal cumulative head burden and the risk of long-term brain diseases such as chronic traumatic encephalopathy (CTE)
The effects of black and red goji berry enrichment on physicochemical properties, glycaemic response and anti-diabetic abilities as functional food : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
No full textThe chronic diseases, such as type 2 diabetes and cardiovascular disease, are the main health issues worldwide and result in a large financial cost (Burton-Freeman, 2010; Sheehan & Ulchaker, 2010). Black goji berry fruits (Lycium ruthenicum) and red goji berry fruits (Lycium barbarum) are rich in dietary fibres and bioactive compounds, and they are widely consumed as super foods (Amagase & Farnsworth, 2011). While there is a lack of research on the physicochemical properties, glycaemic response and anti-diabetic abilities of goji berry enriched foods. Goji berry offers significant potential health benefit as a functional food ingredient.
In this study, wheat-based biscuits were enriched with 5%, 10%, and 15% black goji berry powder and red goji berry powder respectively and analysed raw goji berry powder and its enriched biscuits before and after in vitro digestion. Both goji berry powder was high in insoluble dietary fibre (IDF), soluble dietary fibre (SDF), and total dietary fibre (TDF), and low in protein content. These nutrients led higher moisture content and water holding capability (WHC) in goji berry enriched biscuits. With increasing enrichment, the hardness of biscuits deceased, and the spread ratio increased. Due to the large amount of phenolics in goji berry powder, the colour of enriched biscuits was significantly variable, and it was darker than control biscuits.
The total phenolic content, individual phenolic substances, and antioxidant capacity of undigested extracts, gastric digesta and intestinal digesta from in vitro digestion of raw goji berry powder and goji berry enriched biscuits were investigated. The goji berry enriched biscuits had higher total phenolic content, total flavonoid content and total carotenoid content, and higher DPPH, FRAP and ABTS values than the control biscuits. During the digestion, more phenolic compounds from goji berry enriched biscuits were protected from degradation, which led to higher bio-accessibility of phenolics and stronger antioxidant activity. Both black goji berry fruits (Lycium ruthenicum) and red goji berry fruits (Lycium barbarum) were adopted and black goji berry had greater performance on antioxidant capacity.
When the effect of black and red goji berry and their enriched biscuits on inhibiting α-amylase and α-glucosidase, which are digestive enzymes playing crucial roles in postprandial blood glucose level and diabetes control were evaluated, the black and red goji berry enriched biscuits enhanced the inhibition by 19.16% (IC50 = 2.11 mg/mL) and 9.81% (IC50 = 3.31 mg/mL) on α-amylase and by 12.33% (IC50 = 56.24 mg/mL) and 21.15% (IC50 = 36.58 on α-glucosidase compared to biscuits without goji berry. The inhibition types of all goji berry powder and enriched biscuits were mixed inhibition with increasing maximum velocity (Vmax), decreasing Michaelis constant (Km), lower competitive inhibition constant (Kic), and higher uncompetitive constant (Kiu).
Anti-diabetic ability of black and red goji berry powder and their enriched biscuits were also investigated by both in vitro glycaemic response and glucose consumption in HepG2 cells. The results showed that goji berry effectively reduce release rate and content of reducing sugar during in vitro digestion compared to wheat flour and control biscuits, which obtained through glycaemic glucose equivalent (GGE) and area under curve (AUC). In addition, the glucose consumption was increased by treatments of goji berry powder and its enriched biscuits in insulin resistant HepG2.
These results and findings of this thesis suggest that the goji berry enriched biscuits are potentially functional food with acceptable physical properties and provide research basis for development and application of goji berry as a functional ingredient in health and food industry
SME’s export intensity: enhancers, inhibitors and firm characteristics
No full textThis study aims to investigate the factors explaining the variation in SMEs’ degree of internationalization, measured by export intensity (i.e. the share of export revenue in total revenue). Primary data were collected through survey administered using questionnaire in seven provinces in Indonesia, yielding 497 usable responses. Principal component analysis was used to solve dimensionality issues of perceptual variables while Generalized Linear Model (fractional logit regression) and the Ordinary Least Square regression were used in the estimation. The findings show that SMEs’ export expansion is positively affected by firm characteristics namely firm age and total employees, as well as some exhibiting factors namely owners’ international work experience, central government assistance, network relationships with non-government actors, location, export market of choices and years of exporting. By contrast, SMEs’ export continuation is adversely affected by perceived difficulties in overcoming informational and human resources barriers, distribution, logistics and promotional barriers, financial barriers, foreign government barriers, procedural barriers and price barriers. The findings suggest that post-export assistance is as important as creating new exporters. Further, the findings provide insights on specific types of assistances required by exporting SMEs to exploit their export-exhibiting factors while also overcoming the export-inhibiting factor
Organic phosphorus in the terrestrial environment: An update on current research and future directions
Get PDFIn 2016, a group of experts convened to set priorities for organic phosphorus (P) research, addressing global issues, methodological strengths and weaknesses, and the benefits of understanding the organic P cycle. Seven years later, scientists and students with an interest in organic P reconvened to discuss progress and new insights, and this review highlights recent major research updates. Interest in organic P research has increased since 2016, and new priorities have emerged, including the impact of climate change on organic P, the influence of geopolitical crises on P supplies, and the adoption of sustainable practices like regenerative agriculture. Climate change was a central theme in the 2023 discussions, with an increased emphasis on integrating P and especially organic P into climate change research, which has traditionally focused more on carbon (C) and nitrogen (N). The discussions highlighted disparities in accessing analytical equipment globally, and its consequent impact on research quality and scope. To address these issues, coordinated efforts involving the research community, government policies, and international cooperation are needed, much the same as we see with the climate and biodiversity crises. Promoting sustainable agricultural practices, investing in soil health, and enhancing education and extension services are crucial. Future research should focus on standardizing analytical methods, integrating nutrient balance into models, and exploring soil-microbiome-plant interactions. Regular and intedisciplinary workshops, social media engagement, and the establishment of research networks are recommended to maintain momentum in organic P research. Raising public and stakeholder awareness about the importance of organic P is essential for advancing knowledge in this are
Rain-shelter cultivation promotes grapevine health by altering phyllosphere microecology in rainy areas
No full textGrapes are a globally significant fruit crop, but their cultivation is often challenged by leaf diseases, which limit industrial productivity. Rain-shelter cultivation has emerged as a sustainable agricultural strategy to mitigate these challenges. This study examines the effects of rain-shelter cultivation, compared to open-air cultivation, on the microclimate within the grape canopy and the microbial ecology of the grape phyllosphere. The research focused on two cultivation methods: rain-shelter and open-air cultivation. Key environmental factors such as temperature, relative humidity, and light intensity within the grape canopy were measured during the growing season. The study also explored how these conditions influence the biodiversity, stability, and functional roles of phyllosphere microbiota, particularly focusing on the community assembly processes of bacteria and oomycetes, and the efficacy of culturable microorganisms in combating grape leaf diseases. The results showed that rain-shelter cultivation signifcantly reduced leaf humidity, increased canopy temperature, and decreased light intensity, regardless of weather conditions. This approach led to a significant decrease in the incidence of grape downy mildew without affecting the overall Shannon diversity index of phyllosphere microbes. At the Class level, there was a reduction in Cystobasidiomycetes, Bacteroidia, Brocadiae, and Phycisphaerae, while Oligoflexia levels are significantly increased under rain-shelter conditions. Genus-level analysis revealed significant reductions in plant pathogens such as Erysiphe, Alternaria, and Cercospora. The study found that rain-shelter cultivation shifts fungal community assembly from stochastic to deterministic processes, while bacterial networks showed increased stability. Additionally, the beneficial microorganism Pseudomonas aeruginosa exhibited a preventive effect against grape leaf diseases, enhancing grape berry quality by increasing puncture resistance and leaf internode length. These findings provide understanding of the complex relationship between grape canopy microclimate, disease management, and microbial dynamics suggesting rainshelter cultivation as a viable strategy for sustainable grape production, it offers insights into the research and development of future biological control agents
Credit access and sustainable farm investments: A dual perspective on chemical and environmentally friendly inputs
No full textThis study investigates whether farmers with and without credit access and those with and without adequate credit access behave differently in farm investments. We distinguish between chemical input investments (i.e. chemical fertilizers and pesticides) and environmentally friendly ones (i.e. green pest management and organic fertilizers). We utilize the inverse probability-weighted regression adjustment estimator and multivalued treatment effects model to mitigate the selection bias and estimate first-hand data collected from 946 citrus farmers in China. The results show that access to credit significantly increases farmers’ expenditures on chemical pesticides and green pest management by 12.1% and 47.7%, respectively. However, farmers with and without access to adequate credit appear to differ in farm investments. Specifically, farmers accessing adequate credit spend 19.2% more on chemical pesticides and 42.1% more on green pest management than their counterparts without credit access, and they also spend 47.9% more on chemical pesticides than those accessing inadequate credit. Farmers receiving inadequate credit spend 62.6% more on green pest management but 19.4% less on chemical pesticides than those without credit access. Access to credit, regardless of adequate or inadequate credit, does not significantly affect chemical and organic fertilizer investments
Food production in the urban and peri-urban fabric: Food landscapes & peri-urban planning in New Zealand
No full textIsolate and plant host specificity of rhizosphere competence in Trichoderma species
No full textRhizosphere competence, the ability of a microorganism to colonise and proliferate in the rhizosphere of developing roots, is often studied when mechanisms of individual Trichoderma biocontrol agents are investigated. However, the extent of rhizosphere competence of Trichoderma species and isolates within species has not been widely studied. The rhizosphere competence of 22 Trichoderma isolates from a range of species was assessed using Trichoderma coated sweet corn (Zea mays) seeds grown in non-sterile soil. Results showed that 82 % of the Trichoderma isolates inoculated onto the seeds produced rhizosphere populations significantly greater than the control, indicating rhizosphere competence was widespread within the species that were tested. The least and most rhizosphere-competent isolates belonged to the same species indicating that rhizosphere competence was not species specific. The three least (T. crassum LU555, Trichoderma harzianum LU672, and T. virens LU556) and most (Trichoderma atroviride LU132, T. harzianum LU151, and LU673) rhizosphere-competent isolates were assessed on six plant species (sweet corn, ryegrass, cauliflower, carrot, onion, and white clover). Ryegrass and cauliflower were the most receptive plants to colonisation of the rhizosphere by Trichoderma species, and clover the least. Preferential rhizosphere colonisation was observed between some Trichoderma isolates and the plant species indicating that overall rhizosphere competence was dependent on specific interactions between the Trichoderma isolate and the plant species. However, some isolates were more broadly rhizosphere-competent than others and may have greater potential as plant protection agents. Since only one time point was sampled, future work is required to determine the temporal dynamics of rhizosphere colonisation as well as the spatial colonisation along the length of the root to determine whether different isolates preferentially colonise different regions of the root over different time periods
Leaf dry matter content is phylogenetically conserved and related to environmental conditions, especially wildfire activity
No full textLeaf dry matter content (LDMC) is an important determinant of plant flammability. Investigating global patterns of LDMC could provide insights into worldwide plant flammability patterns, informing wildfire management. We characterised global patterns of LDMC across 4074 species from 216 families, revealing that phylogenetic and environmental constraints influence LDMC. LDMC varied across growth forms and taxonomic groups, displaying phylogenetic niche conservatism. Temperature, precipitation, aridity index, soil total nitrogen content and wildfire activity affected LDMC, and the effect of wildfire activity was stronger than other environmental factors across species with postfire regeneration abilities. Such species had higher LDMC, and their LDMC was less phylogenetically conserved and more strongly associated with fire activity. Our results suggest that, although LDMC shows phylogenetic niche conservatism, LDMC is determined by environmental factors, especially wildfire activity. Wildfire has likely acted as a selective pressure towards high LDMC across species that persist through fire using postfire regeneration
Population development, damage assessment, and susceptibility of maize hybrids to root-lesion nematodes (Pratylenchus neglectus and P. crenatus) under glasshouse conditions
No full textRoot-lesion nematodes, particularly Pratylenchus neglectus and P. crenatus (PNC), are widely distributed in New Zealand and cause significant damage to maize roots, reducing crop productivity. Despite their economic importance, no comprehensive assessment of commercial maize hybrids’ resistance to PNC has been conducted in the country. Significant variation was observed in the nematode reproduction factor (Rf) and final population (Pf) among hybrids. In Experiment 1
(initial population (Pi)=1250 PNC kg⁻¹ soil), Rf ranged from 3.1 in hybrid P8500 to 7.1 in hybrid P9127, with Pf values ranging from 3863 to 8903 PNC kg⁻¹ soil+roots in 45 days. In Experiment 2 (Pi=750 PNC kg⁻¹ soil), Rf ranged from 18.4 in hybrid P1613 to 37.5 in hybrid P8805, with Pf values from 13,784 to 28,426 PNC kg⁻¹ soil+roots in 60 days. These results indicate active nematode reproduction and substantial hybrid-dependent variation in host response. Experiment 3
examined the impact of varying initial inoculum densities (500, 1000 and 1500 PNC kg⁻¹ soil), showing a dose-dependent increase in Pf and corresponding root damage. Susceptible hybrid (P9127) exhibited up to 42% root dry weight and 22% shoot dry weight reductions. This study is the first systematic evaluation of PNC resistance in New Zealand maize hybrids.
It identifies P9127 and P8805 as highly susceptible, and P0891, P8500, and P1613 as moderately resistant. These findings offer valuable benchmarks for future breeding and support nematode management in New Zealand