Welcome to Research Commons

Research Commons is the University of Waikato's open access research repository, housing research publications and theses produced by the University's staff and students.

Communities in Research Commons

Select a community to browse its collections.

Now showing 1 - 2 of 2

Recent Submissions

XGBoost: Scalable GPU accelerated learning
(2018) Mitchell, Rory; Adinets, Andrey; Rao, Thejaswi; Frank, Eibe
We describe the multi-GPU gradient boosting algorithm implemented in the XGBoost library (https://github.com/dmlc/xgboost). Our algorithm allows fast, scalable training on multi-GPU systems with all of the features of the XGBoost library. We employ data compression techniques to minimise the usage of scarce GPU memory while still allowing highly efficient implementation. Using our algorithm we show that it is possible to process 115 million training instances in under three minutes on a publicly available cloud computing instance. The algorithm is implemented using end-to-end GPU parallelism, with prediction, gradient calculation, feature quantisation, decision tree construction and evaluation phases all computed on device.
Relationship between microstructure, mechanical, and biological response in biomedical Ti–Nb–Cu alloys
(Elsevier, 2026) Peters, Linda M.; Manogar, Balakrishnan; Yang, Fei; Bolzoni, Leandro
Titanium alloys are highly used in biomedical applications, especially structural ones, due to their mechanical properties and biocompatibility. However, they are susceptible to pathogenic bacterial infections, a long-lasting challenge of biomaterials exacerbated by the rise of antibiotic resistant bacteria. To address this, novel Ti–Nb–Cu alloys with intrinsic antibacterial capability were developed and characterised in this study. It is found that changing the amount of Nb and Cu brings about manufacturability and microstructural modifications. Specifically, the amount of porosity increases, the microstructure changes from lamellar to β type, and precipitation of the eutectoid Ti₂Cu intermetallic phase occurs as the contents of Nb and Cu increase. Accordingly, the Ti–Nb–Cu alloys become stronger and less ductile, though they do not fail catastrophically. They always form a protective passivation layer against corrosion, though the corrosion rate is composition dependent. They are characterised by a very strong antibacterial efficacy against both gram negative and gram positive bacteria, and they are not cytotoxic. This combination makes the developed Ti–Nb–Cu alloys promising candidates for structural biomedical applications.
Struggle and solidarity in transforming urban futures: The fisher fight for Ennore wetlands in Tamil Nadu, India
(The University of Waikato, 2026) Jayaraman, Nityanand; Kurian, Priya A.; Barrett, Patrick
Mainstream academic research on sustainability transformation overwhelmingly sees it as an innovation-centred, top-down, governance-led process playing out within the capitalist system. This research addresses these biases and the neglect of subaltern agency by examining environmental justice struggles as forces of sustainability transformation. It focuses on the ongoing fisher struggle for the tidal wetlands of Ennore in Tamil Nadu, India. Stretching from the northern edge of Chennai, the Ennore wetlands have been a colonial frontier since the 18th century: first targeted by British empire-building, then by post-independence industrialisation, and later by neoliberal reforms that turned them into an industrial sacrifice zone. Fishers from oppressed castes have resisted this transformation and defended their lifeworlds against dispossession and degradation. Drawing on my research fieldwork as well as a decade of ethnographic engagement while working alongside the Ennore fishers in their struggle, I theorise how subaltern environmentalisms disrupt both the urban-industrial logics of development and the dominant sustainability paradigms that seek to manage their externalities, and how such disruptions enact material, epistemic, and ontological transformations. The thesis traces the struggle’s evolution over five decades from its hyper-local reactive form to a trans-scalar campaign involving legal interventions, coalition-building and cultural and gastro-activism as well as opportunistic campaigns involving more-than-human agents such as the Northeast monsoon and focusing events such as the 2015 Chennai floods. The study asks: 1. How do subaltern struggles emerge from the margins to challenge hegemonic processes that deny recognition to them and their ways of knowing? 2. How do subaltern struggles for environmental justice contribute to transformative change for sustainability? Phrased differently, what does isustainability transformation look like when seen from the perspective of subaltern struggles? From my positionality as activist and researcher, I developed a novel methodological approach—solidarity ethnography—that extends activist ethnography by centring subaltern voices and foregrounding reflexivity. The qualitative study draws on analysis of field notes and interviews, archival work, and collaborative outputs of the Save Ennore Creek Campaign, which was set up by Chennai-based activists, including myself, to mobilise solidarity for the fisher struggle. Two analytical frameworks guide the study: Medina’s (2011) Foucaultian Epistemology of Resistance, which approaches domination and resistance using concepts drawn from Ignorance studies, and a Political Ecology framework of Transformative Resistance that I developed for this research. Together, they reframe domination and resistance as a dynamic of ignorance politics, allowing the analysis to trace how specific forms of ignorance are produced, mobilized, and contested, and how resistance under certain conditions becomes a force for sustainability transformations. The research reveals the role of ignorance, rather than knowledge, in policy-making and exposes the often uncivil and illiberal nature of civil society and liberal law to present a tentative theory of ‘civil’ dispossession that targets non-property spaces and their users. By tracing how Ennore’s fishers resist, persist, and transform, the thesis demonstrates that subaltern struggles are not merely reactive but generative; they reimagine both sustainability and transformation from the margins. In doing so, the research challenges dominant paradigms of sustainability and insists on a justice-first, present-centred approach to ecological and social futures.
Investigating impacts of sleep on recovery and performance in elite rugby union
(The University of Waikato, 2026-05-21) Teece, Angus R.; Beaven, Christopher Martyn; Driller, Matthew W.; Argus, Christos K.; Gill, Nicholas D.
Sleep plays a vital role in daily functioning of biological, cognitive, and physical performance for humans. Additionally, sleep has been widely regarded by athletes to play an important role in recovery from training and competition. Despite the increasing amount of sleep research in athlete populations, elite team sport athletes are still underrepresented in the literature, specifically in collision-based sports, despite the unique challenges facing this population. Therefore, this PhD thesis aims to enhance the understanding of sleep habits of professional, male Rugby Union athletes in both training and competition environments. Finally, the thesis evaluates interventions that could improve sleep in the same population. Study One subjectively assessed the sleep habits of 224 Rugby Union athletes across multiple levels of competition in Rugby Union athletes (academy, semi-professional, and professional) who completed the Athlete Sleep Behaviour Questionnaire and the Pittsburgh Sleep Quality Index. The results highlighted that differences exist between different levels of competition for specific sleep behaviours; however, sleep behaviours could be improved for all levels of competition in Rugby Union athletes. Study Two assessed the differences in sleep quality, quantity, and behaviours between 38 elite male and 27 elite female Rugby Union athletes via the Athlete Sleep Behaviour Questionnaire and the Pittsburgh Sleep Quality Index. Male athletes reported significantly longer sleep duration and higher sleep efficiency. The study highlighted that differences existed between elite male and female Rugby Union athletes and that elite male and female athletes face specific sleep challenges. Study Three investigated nightly sleep duration during a three-week preseason training period in 29 professional Rugby Union athletes using wrist actigraphy. Aerobic capacity and body composition were assessed at Baseline, at Week 3, and at Week 5. Participants were split into two groups for analysis as less than 7 h 30 min per night or greater than 7 h 30 min per night. The results highlighted that longer sleep duration during a preseason phase may assist in enhancing physical qualities including aerobic capacity and body composition. Study Four assessed the sleep and wake variability of 23 professional Rugby Union athletes during a preseason period of training. Sleep was monitored via wrist actigraphy for three weeks and the athletes completed a daily wellness questionnaire. Athletes were split into two groups based on their calculated sleep regularity index (regular and irregular). The regular group displayed significantly longer sleep duration and greater sleep efficiency and less wake episodes. The results highlighted that minimising variability in sleep onset and offset is beneficial for increasing sleep duration. Study Five investigated the prevalence of naps on match day in 30 professional Rugby Union athletes and its subjective link to match performance across a 17-match season. Athletes were asked about their napping practices and their perceived performance during match play. Additionally, three team coaches evaluated match performance of each participant. The results highlighted that 86% of athletes used pre-match naps with a greater amount taken during away matches compared to home matches. Additionally, the odds of an athlete rating their performance as “good” was increased when they napped and won the match. Study Six investigated the effectiveness of daytime naps on afternoon physical performance in a randomized cross-over design with 15 professional Rugby Union athletes. Athletes performed a nap or no nap condition on two occasions, separated by one week. Baseline testing of reaction time, self-reported wellness, and a 6-second peak power test on a cycle ergometer was completed in the morning followed by 2 x 45-minute training sessions. Athletes completed nap or no nap condition at 1200 h. Baseline measures were retested in the afternoon in addition to a 30-mintue fixed intensity interval cycle and a 4-minute maximal effort cycling test. The study highlighted that utilising daytime naps between training sessions on the same day, improved afternoon peak power and lowered perception of fatigue, soreness and exertion during afternoon training. In summary the series of studies in this thesis provides a foundation for understanding sleep in elite Rugby Union athletes. Sleep challenges and disturbances are prevalent amongst Rugby Union athletes in both training and competition environments. Results show that methods such as consistency in sleep onset and offset, daytime naps, and extending sleep duration can have benefits for Rugby Union athletes. These studies provide valuable information on sleep habits of not only professional Rugby Union athletes but rugby athletes of all levels and codes, which can be used to inform sleep hygiene protocols to target aspects that are most relevant within a given population. Moreover, aspects such as allowance of daytime naps and consistency in schedule to allow for consistent sleep and wake times should be considered when designing recovery within training programs.
Te ipu mahara - The chanting memories of an indigenous people
(The University of Waikato, 2025) Kana, Ivan; Tuaupiki, Haki
Te Ipu Mahara – The Chanting Memories of an Indigenous People explores how Māori knowledge systems have been retained, transmitted, and adapted across generations. Guided by kaupapa Māori methodology and framed within Indigenous research paradigms, this thesis examines the resilience of Mātauranga Māori (Māori knowledge) as both a living inheritance and a dynamic practice. While Māori knowledge systems are well established within Indigenous scholarship, this thesis contributes to that body of work by centring Māori voices to articulate how knowledge is retained, transmitted, and renewed through embodied, spiritual, and relational practices. The study investigates three central pou (pillars): Retention, Transference, and Survival & Innovation. Drawing on a combination of literature review, participant interviews, and oral histories, it identifies whakapapa as the architecture of memory; chanting, waiata (song), and karakia (prayer) as vital mnemonic and spiritual technologies; and wānanga (discussion) as enduring pedagogical spaces. It highlights the role of knowledge holders as kaitiaki mahara, whose responsibilities extend beyond preservation to adaptation and creativity. Findings demonstrate that Māori knowledge has survived not by remaining static, but through continual renewal. Colonisation disrupted traditional pathways, yet communities have responded with resilience - composing new oriori (lullaby), embedding mātauranga in classrooms, revitalising te reo Māori, and harnessing digital tools to sustain intergenerational transmission. Knowledge retention is shown to be holistic and embodied, encompassing spiritual, relational, and physical dimensions of learning. Academically, this research contributes to Indigenous scholarship on memory, pedagogy, and decolonisation. Culturally, it is an offering of utu - returning kōrero and reflections to the communities who sustain them. The metaphor of the ipu (vessel) captures the essence of this work: memory as something carried, chanted, embodied, and continually replenished. Ultimately, the thesis affirms that the survival of Māori knowledge systems is inseparable from the survival of Māori futures. Each chant, whakapapa, and act of wānanga binds past, present, and future together, ensuring that the wisdom of tūpuna (ancestors) endures as a pathway for the generations to come.