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Reliability, interrelationships, and minimal detectable changes of strength and power metrics among well-trained rugby sevens players
No full textDespite the importance of strength and power in rugby skills and match outcomes, there exists a noticeable gap in the measurement consistency and estimation of a true change of typical assessments designed to assess these qualities. To address this gap, we investigated the between-session reliability, interrelationships, and minimal detectable changes (MDC) of commonly used strength and power measures in team sports. Sixteen national-level rugby 7 s players were tested on two occasions, one week apart. Both the best and average (of 2–3 trials) peak force, peak power, height, distance, and/or strength indices during countermovement jump (CMJ), drop jump (DJ), isometric mid-thigh pull (IMTP), plyometric push-up (PPU), and standing long jump (SLJ) were obtained. Furthermore, one-repetition maximum (1RM) strength for bench press and back squat, reactive strength index, and dynamic strength index were also determined. Reliability was assessed using intraclass correlation coefficients (ICC) and coefficients of variation (CV), and used for MDC calculations, and interrelationships between variables were determined using correlation coefficients. Reliability was excellent for bench press, back squat, and SLJ (ICCs > 0.91); high to excellent for IMTP peak force, all CMJ, and DJ (except best DJ height and contact time), and PPU peak force parameters (ICCs > 0.78), with < 10% CVs (except PPU peak power). MDCs were generally smaller for average than best values. Large to very large relationships (r = 0.60 to 0.85) were observed between bench press, back squat, and IMTP with selected parameters of CMJ and PPU (p < 0.05), but not in DJ and SLJ. In conclusion, selected measures of strength and power displayed high to excellent reproducibility, with average values (rather than best) offering more stable assessments, and “smaller” MDCs. Based upon the relationships, it can be inferred that maximising strength would likely contribute to enhanced explosive performance
Debate on ultra-processed foods shouldn’t derail good dietary advice
No full textEvidence is mounting linking ultra-processed foods (UPF) to risk of chronic disease. Typically, UPF are foods that are energy-dense, high in fat, sugar and salt, low in fibre and with a long shelf life. Examples include biscuits, chips, candy, instant noodles, mass-produced bread, sweetened breakfast cereals, ready-to-eat meals and reconstituted meats.
Dietary recommendations encourage people to eat foods that are ‘whole’ or less processed. This can be a challenge when our food environments and food supply systems are dominated by UPF.
Categorising foods according to the type and extent of processing can help us understand the healthfulness of individual foods, diets and the food supply system. However, we must still consider the nutritional value, affordability, accessibility, sustainability and cultural acceptability of foods. And in some cases, foods classified as UFP may still be a component of a well-balanced dietary intake —for example, wholegrain bread.
While acknowledging this tension on the margins, there remains a strong case for promoting the consumption of fruits, vegetables, wholegrain and minimally processed foods
Eutrophication effects on stream macrophytes
No full textMacrophytes are large, autotrophic organisms residing in aquatic environments. In streams they play important roles as substrate, shelter, and food for higher trophic levels, alter water movements and perform biochemical transformations. Unfortunately, macrophyte diversity worldwide is under threat from multiple anthropogenic factors. Eutrophication, the process of nutrient enrichment following land use intensification, is a major driver of negative stream ecosystem change, often in combination with other anthropogenic pressures such as deforestation and introduction of non-native species. The current paradigm of macrophyte response to eutrophication notes the importance of the hydrological setting and substrate type, but always encompasses modification to competitive interactions between macrophyte growth forms as nutrient concentrations become less limiting and competition for light increases. However, details of the responses of macrophytes to increased nutrient inputs under multiple stressor environments are complex and still warrant investigation if effective guidance on macrophyte management is to be developed.
In this thesis, I have addressed questions related to nutrient concentrations at which macrophytes start to accrue excessive biomass, how this relates to community shifts, what these community shifts look like and how they may be modulated by other variables. Specifically, I have used a mix of field observations and mesocosm experiments to:
i) investigate differences in community composition of macrophyte communities in streams along a eutrophication gradient.
ii) experimentally explore how external nutrient concentrations affect internal nutrient status, and consequently the growth, morphology, and photosynthesis of stream macrophytes across a range of irradiances.
iii) investigate if these responses lead to differences in competitive outcomes between species in mixed cultures.
To investigate relationships between eutrophication and macrophytes in streams in Aotearoa New Zealand, I surveyed 30 lowland streams on the country’s North Island, focusing on the Waikato region. I targeted sites with as few confounding factors as possible by using existing stream classification data to select reaches in each stream that had low slope, were unshaded, and a discharge of around 1 m3 s-1. From those meeting these criteria I used a pre-existing, land-use based nutrient yield model to selected streams expected to provide a range of nutrient concentration. At each site I sampled nutrients (N and P) in water and sediment and analyzed the dominant macrophyte species for internal N and P content. I quantified community structure on five transects across each stream.
To explore links between environment and macrophytes I combined stream descriptors from national datasets in combination with the macrophyte community data and a list of trait scores of the encountered species in a RLQ multivariate analysis. The results showed a gradient in macrophyte community structure, a striking feature of which was the change in percentage of non-native species in the streams: eutrophic streams have almost no native species present. Additionally, many nutrient enriched streams were heavily clogged by macrophyte biomass, with species showing traits related to high performance and effective dispersal. A subsidiary gradient in the RLQ analysis, driven by nitrate and sediment phosphorous, saw a high presence of emergent species in eutrophic streams. This can be because the emergent species have a high nitrogen use efficiency compared to submerged species and can deal with a high turbidity by growing out of the water. A second subsidiary gradient, driven by water column phosphorous, correlated with eutrophic streams having a high degree of submerged non-native species; Ceratophyllum demersum, Egeria densa, Lagarosiphon major, and Elodea canadensis, all species that disperse primarily through fragmentation and can utilize bicarbonate as a carbon source. Phosphorous and carbon availability probably is a major driver for the presence of these species in these streams.
To test inferences made from observational field investigations, growth, morphological, and photosynthetic responses to different levels of nutrient concentration were investigated in a new experimental mesocosm setup. The system comprised four flumes fed by local groundwater stripped of ions by a reverse osmosis system, then dosed with major ions, macro- and micronutrient elements in controlled amounts to ensure finely controlled growth conditions.
The first experiment addressed hypotheses around the impact of nitrate concentration on growth of two pondweed species common to Aotearoa New Zealand, Potamogeton crispus and P. ochreatus, and possible interactions between nutrient and irradiance. Four nutrient concentrations (control ~0 µg NO3—N L-1, low ~20 µg NO3—N L-1, medium ~250 µg NO3—N L-1, and, high ~5000 µg NO3—N L-1) were combined with four light levels (67.7, 44.5, 30.9, and 7.8 mol photons m-2 d1) in a full factorial design. I measured internal nitrogen (N) and carbon (C) content, growth rates, and morphology and used pulse amplitude modulated fluorometry to make photosynthesis-irradiance curves. The four external nutrient concentrations gave rise to two distinct groupings of plants based on their final internal nutrient content: a high-N group (2-4 % N) from high and medium nitrate treatments and a low-N group (~1 % N) from the low and control nitrate treatments. High-N plants of both species had faster growth rates and grew wider and taller than the low-N plants, but P. crispus grew widest and branched more, especially at high light levels. Low light availability negated any significant difference between N groups and, notably, low-N individuals of P. ochreatus performed better in this treatment than those of P. crispus. In general, the native P. ochreatus performed better than the non-native P. crispus under low nutrient stress, and the latter was best at high light and high nutrients. The results suggest that P. crispus has a great proliferation potential in eutrophic areas, and that lowering resource levels can help manage not only macrophyte proliferation, but also invasive species. A potential competitive advantage can be inferred for P crispus in eutrophic, well-lit waters.
The second mesocosm experiment investigated competitive interactions between the non-native and native pondweed. Four nutrient treatments were again used (0, 40, 120, and 400 µg NO3—N L-1), combined with two light treatments (18 and 3 mol photons m-2 d-1) in a full factorial design. In each treatment I compared growth of each species when plated in monoculture and mixed culture pots. For each replicate, growth rate and morphological traits (main stem length, lateral spread, branching degree, and root length) were measured. Neither species performed differently in mixed- or mono-specific cultures, indicating no inter-specific interactions under the experimental conditions. Rather, in mixed culture plots the outcome, in terms of growth differentials between taxa, reflected the responses of each species to the treatment. Increasing irradiance tended to result in P. crispus outperforming P. ochreatus, while increasing nutrient levels shifted allowed P. ochreatus to outperform P. ochreatus, particularly at low irradiance. Based on the results of this study, there is no direct short term competitive suppression of either species by the other, but differences in trait expression at different resource levels/combinations might still lead to competitive exclusion in a more natural setting.
In this thesis I have shown that macrophytes respond to increases in external nutrient level by taking up more nutrients, increasing growth and expressing morphological plasticity. This is species dependent, however, and it is these differences in the ability to respond that appear to shape the macrophyte communities in streams. Streams with high light and nutrient supplies are susceptible to high accrual of biomass by a subset of responsive species that may ultimately end up being the only species present in these streams. I found that the eutrophication threshold for nitrogen is quite low, below 250 µg NO3-N L 1. Macrophyte growth was evident at nitrate concentrations only seen in quite pristine streams and several nutrient species seem to determine community compositions in streams. Thus, management actions for the protection of stream ecosystems would benefit from managing resource levels in general rather than focusing on a specific stressor
Scientific Investigation of the Calf Raise Test Using the Calf Raise Mobile Application to Inform Test Administration and Interpretation
Get PDFThe Calf Raise Test (CRT) is a widely used functional assessment of triceps surae muscle-tendon unit function. While it exhibits acceptable reliability, administration inconsistencies and test parameter variations likely contribute to observed normative value discrepancies in the literature. Additionally, devices employed in research for standardisation and quantification of outcomes beyond the number of repetitions are often inaccessible in clinics. This Thesis addresses these gaps by conducting an evidence-based assessment of the CRT and examining how changes in test parameters affect outcomes. The overarching aims of this Thesis were to: (1) develop a valid and reliable method to assess the CRT in clinical practice that provides research-grade outcomes, and (2) examine the influence of changing CRT parameters on outcomes and triceps surae muscle function. To achieve these overarching aims, two literature reviews and three experimental studies were conducted.
The first literature review, aligned with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, provides an overview of CRT devices used in research. Thirty-five studies were included, identifying seven CRT devices. The linear encoder emerged as the most used, quantifying all three main CRT outcomes (repetitions, peak height, and total work). However, its limited clinical use is attributed to hardware costs and need for programming skills.
Chapter 3 introduces the Calf Raise application (CRapp), a smartphone application designed to aid standardise CRT procedures and automate outcomes. Thirteen individuals underwent single-leg CRT on both legs across three occasions. CRapp outcomes (i.e., repetitions, total work, total height, peak height, fatigue index, and peak power) were validated against 3D motion capture and force plate data, demonstrating excellent concurrent validity and agreement levels. The CRapp proved valid, reliable, and suitable for both research and clinical practice.
Chapter 4 explores the impact of varying ankle starting positions on CRT outcomes in 49 healthy individuals, accounting for gender, age, body mass index (BMI), and physical activity levels. Participants performed single-leg CRT in three randomised conditions on three occasions: flat (0°), incline (10° dorsiflexion), and step (full dorsiflexion). Analysis of CRapp data indicate significant effects of ankle starting position on all CRT outcomes, emphasising the importance of ankle start position for CRT administration and interpreting test outcomes.
Chapter 5 investigates the effects of varying cadence on CRT outcomes in 36 healthy individuals, considering gender, age, BMI, and physical activity levels. Participants performed single-leg CRT in three randomised conditions on three occasions: 30, 60, and 120 beats per minute. Significant cadence effects were observed on CRapp outcomes, hence this study confirmed that cadence does matter when administering the CRT and interpreting its outcomes.
Chapter 6, a systematic review following PRISMA guidelines, examines changes in standing CRT parameters on triceps surae surface electromyography (EMG) activity and fatigue measures. Seven studies were included, indicating increased activity in medial gastrocnemius increased with feet externally rotated, knees straight, and added load; lateral gastrocnemius with feet internally rotated, knees straight, and added load; and soleus with knees bent, whole-body vibration, and added load. These findings can inform evidence-based practices, though further training studies are recommended.
Overall, this Thesis introduces the CRapp, an innovative, valid, and reliable method of quantifying key CRT outcomes. Also, this Thesis provides a better understanding of the influence of varying CRT parameters on outcomes. The evidence-base generated from this Thesis may be used to inform best practice use and interpretation of the CRT and guide future research
Scale locality of the energy cascade in magnetohydrodynamics
Get PDFTurbulence behaves differently in electrically charged fluids, such as plasmas, due to the turbulent motions being accompanied by magnetic field influences. This thesis looks at how the magnetic field in these fluids impacts energy transferred from large scales to small scales—the energy cascade—by analyzing data from numerical simulations of turbulence. We will be following Doan et al's approach of decomposing the fluctuations into large-scale and small-scale contributions using bandpass filtering, then plotting the flux of the energy and enstrophy in 2D and 3D magnetohydrodynamics. This will help quantify various aspects of the energy cascade, including the degree of scale-locality. The results will be compared to those from Doan et al's analysis of non-electrically charged fluids
Visualising categorical data: Linguistic case studies from te Reo Māori and New Zealand English
No full textCategorical variables are prevalent in real-world datasets across numerous domains, yet few visualisation techniques accommodate them effectively. This is especially true of datasets comprising three or more categorical variables, termed multivariate categorical data. Visualising such data is challenging due to the lack of inherent ordering of nominal categories, the so-called ‘curse of dimensionality’, and the potential variability in the number of categories per variable. Corpus linguistics, which involves the study of large digital collections of naturally occurring language, serves as the primary application domain in this thesis. This domain was chosen because it is rich in multivariate categorical data and, at the same time, is often visualised using only basic techniques.
This thesis contributes to the area of categorical data visualisation in several ways. First, we propose a taxonomy of techniques for visualising categorical data, highlight limitations of existing solutions, and identify relevant analysis tasks. Building on this foundation, the thesis introduces novel techniques and enhancements for visualising datasets involving multiple categorical variables. We focus on adapting the layout and interactive capabilities of an existing technique that uses a matrix of heatmaps to represent pairwise category intersections. These modifications show that directly visualising statistical test results for categorical data can be beneficial for exploring bivariate patterns and associations. Furthermore, we contribute the design, implementation and evaluation of a novel technique called MultiCat, which is not restricted to pairwise intersections but rather facilitates analysis of relationships among multiple variables simultaneously. Both these techniques are interactive and offer greater scalability than existing alternatives, thereby affording new possibilities for analysing multivariate categorical data. However, since categorical variables can occur within more complex data structures, we also consider their presence in networks and hypergraphs, which require specialised methods.
To demonstrate the application of these techniques, we draw on two linguistic case studies that focus on languages of special significance in Aotearoa New Zealand. Addressing the low-resource status of Māori, the country’s Indigenous language, we first contribute two related Twitter datasets—a monolingual Māori corpus and a mixed–language Māori–English corpus—together with an architecture for differentiating Māori and English words. Our initial case study uses the monolingual Māori corpus and proposed visualisation techniques to investigate grammatical possession in Māori, offering fresh insights into the linguistic practices of contemporary speakers. The second case study uses networks and hypergraphs with categorical attributes to explore Māori loanword co-occurrence in New Zealand English newspaper articles. We find that loanwords tend not to occur in isolation and that New Zealanders are still importing new (unlisted) borrowings from Māori.
Ultimately, the techniques developed in this thesis have broad applications both within and beyond the corpus linguistics community. By enabling more effective visualisation and analysis of multivariate categorical data, this research has the potential to facilitate deeper insights into domains as diverse as education, healthcare, business and science
Kia tata mai te pae tāwhiti: Nurturing success in psychology for Māori and Pasifika
No full textEmbarking on the university education journey is commonly perceived as a pathway to success and enhanced career prospects. However, for Māori and Pasifika students in psychology, this trajectory is distinctly burdened with challenges beyond their control, particularly concerning low clinician representation and educational achievement. This thesis thus explores the experiences, barriers, and aspirations of Māori and Pasifika students engaged in psychology studies in Tauranga Moana. Guided by the principles of Kaupapa Māori, the overarching goal of this thesis is to empower and advocate for students, shedding light on their unique journeys and fostering a platform for meaningful change within the academic landscape. Two group interviews with undergraduate students and two individual interviews with postgraduate students were conducted to explore the research topic. These were then analysed using inductive thematic analysis, and a social constructionist epistemology within a Kaupapa Māori paradigm, to contextualise participant experiences. Three core themes are identified in this analysis. The first theme, the Western Educational Environment, underscores the challenges students face within a system shaped by Western norms. A monocultural, individualistic approach to curriculum, assessments, and teaching methods impacts the diverse cultural perspectives of students, shaping their overall study experiences. The second theme, Pathways, explores the nuanced journeys of tauira navigating various options related to papers, qualifications, and future career prospects. The third theme, Equity, critically examines the (lack of) equity in relation to facilities and services at the Tauranga campus compared to those in Hamilton. Recommendations for the School of Psychology focus on improving discipline relevance for Māori and Pasifika students through methods integrating Kaupapa Māori content and strategies as well as addressing historical issues aims to empower, retain, and support students to higher positions in psychology
Network analysis of mindfulness and mental health symptoms among firefighters: A transdiagnostic lens
No full textPrevious research has established the protective role of mindfulness against various psychological disorders and maladaptive behaviours. However, the associations between specific facets of mindfulness and diverse mental health and behavioural outcomes have not been thoroughly investigated in populations with risky occupations. The aim of this study was to examine the direct and indirect associations between the five facets of mindfulness and prevalent mental health and behavioural outcomes among firefighters, including depression, post-traumatic stress disorder (PTSD), anger, suicide risk, sleep quality, and alcohol use. The assessment scores of 685 career firefighters (Mage=38.40, SD=8.64; 93.6% males; 77.7% White) including 154 (22.5%) military veterans, who completed measures of mindfulness, depression, PTSD, anger, suicide risk, sleep quality, and alcohol use, were investigated using both directional and non-directional network analysis. Directional network analysis indicated the primary role of anger in triggering PTSD and impacting mindfulness, leading to alcohol use, suicidal ideation, impaired sleep quality, and depression as an outcome. Mindfulness facets of Non-reactivity, Non-judging, and Describing were negatively associated with depression, while the Acting with awareness facet was inversely linked to anger. This study emphasizes the clinical significance of targeting specific mindfulness facets in interventions for high-risk occupations, such as firefighters. Focusing on Non-reactivity, Non-judging, Describing, and Acting with awareness may help mitigate anger, depression, and other negative outcomes. Addressing anger management could be especially important in preventing or reducing PTSD, alcohol use, suicidal ideation, sleep disturbances, and depression, ultimately enhancing psychological well-being and quality of life
Development of video quality metrics based on psychovisual models of early vision
No full textStreaming video incurs many distortions during processing, compression, storage, and transmission, all of which can reduce the user's perceived video quality. Developing adaptive video transmission methods that increase the efficient use of existing bandwidth and reduce storage space while preserving visual quality requires quality metrics that accurately describe how people perceive distortion. A severe problem for developing new video quality metrics is limited data on how the human visual system processes spatial and temporal information simultaneously. The problem is exacerbated by the fact that the few data recognized by the scientific community, collected in the middle of the last century, used the ideas of obsolete display technology and were subject to medical intervention during collection, which does not guarantee a proper description of the conditions under which media content is currently consumed. As a result, modern video quality metrics do not provide stable and reliable data for predicting the subjective assessment of user quality. This research aims to investigate how the metrics being developed are made more efficient for assessing video quality by including new data from the psychophysical early vision model in the metrics.
The work proposed in this thesis comprises three main contributions: Firstly, the development of a novel method, software, and test equipment for research and measurement of the characteristics of the human visual system using modern display systems. Secondly, the refinement of the parameters of a multidimensional model of human contrast sensitivity appropriate to modern display technology of viewing conditions. The contrast sensitivity function works like a filter through which visual stimuli must pass to be perceived by the observer. Only video artefacts in the passband region can be humanly perceived. Thirdly, the creation of a new full-reference and the first non-reference video quality metrics which consider the psychophysical features of the user's video experience. That provides stability in predicting the user's subjective rating of a video.
Among the three contributions of this thesis, first, a method for researching and measuring the characteristics of human visual systems on modern displays. In the proposed thesis, 27,840 visibility thresholds of spatio-temporal sinusoidal variations were measured by a new method using different spatial sizes and temporal modulation rates. The obtained data is 96% more than any current contrast sensitivity function dataset and best describes a human's perception of video artefacts on a modern display. A multidimensional model of human contrast sensitivity in modern conditions of video content presentation is proposed for the first time based on new large-scale data and demonstrated that the presented visibility model has a distinct advantage for further development of media content transfer technologies. Since there is a limited number of video evaluation metrics based on fundamental knowledge about the work of the human visual system, a new full-reference metric is herein proposed. This proposed video quality metric extends the peak signal-to-noise ratio metric to include human visual system features. Finally, a new non-reference video quality metric that includes the psychophysical features of the user's video experience with stability in predicting the user's subjective rating of a video is proposed. The experimental results show that the proposed video quality metric achieves 81% more consistent performance in predicting user subjective quality among commonly used non-reference video quality metrics and comparable consistent performance to full-reference metrics on three independent video datasets.
The thesis also presents a large-scale database suitable for testing video streaming quality under video compression with artefacts, forming a learning base for future video quality metrics. The final dataset comprises 4.1 million video quality perceptual thresholds. The new database will contribute to the solution of a strong need for non-reference video quality metrics for user-generated video content to prevent loss of video quality caused by distortion during recording, compression and signal transmission
DNA repair in Antarctic bacteria - characterisation of two nuclease proteins from Antarctic dry valley metagenomes
No full textDNA repair processes are crucial for the growth and survival of all organisms. This is especially true for organisms, that inhabit extreme habitats, like the Antarctic Dry Valleys. The Dry Valleys are one of the coldest and driest desert environments on Earth. The conditions in the Dry Valleys, including high levels of UV radiation, low temperatures, multiple daily freeze-thaw cycles, desiccation, and low nutrient levels, are highly damaging to the genomic DNA of the organisms inhabiting them. The Dry Valleys are dominated by microorganisms, which have a range of adaptations to survive in this extreme environment. Previous studies focus largely on the metabolic adaptation of Dry Valley inhabitants. In this thesis, the DNA repair machinery of bacteria in the Dry Valleys was examined to determine how organisms survive the DNA-damaging conditions.
Our understanding of DNA repair and replication in bacteria pathways is largely based on studies of isolated organisms and pathogens, which have been extensively studied. Methods such as metagenomic sequencing allow us to find novel proteins from currently unculturable organisms. In a search for novel DNA repair proteins in bacterial metagenomes from the Dry Valleys, two unique nuclease proteins were chosen for structural and biochemical characterisation. One of these nuclease proteins belongs to the currently uncharacterised protein domain UPF0102. This protein is distantly related to the archaeal Holliday junction resolvases and is a Type II restriction endonuclease type protein. The activity of DV-Hjc and the UPF0102 domain was characterised in vitro using biochemical assays and in vivo in E. coli knockout cells. Biochemical characterisation of the protein showed that the protein has strong binding affinity with double-stranded DNA substrates and Holliday-junction mimicking substrates. The structure of the protein was determined via X-ray crystallography at a resolution of 0.9 Å and structural features were related to its activity, revealing an extensive DNA binding surface and an active site similar to that of archaeal Holliday junction resolvases. The second nuclease characterised in this thesis is part of a unique nuclease-ligase fusion protein and belongs to the nuclease group of MBL-β-CASP proteins. The biochemical characterisation of the protein showed its ability to bind and cleave DNA, specific activity was observed with abasic site substrates