UC Research Repository
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The UC Research Repository collects, stores and makes available original research from postgraduate students, researchers and academics based at the University of Canterbury.
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Recent Submissions
Thermophilic methane oxidation is widespread in Aotearoa-New Zealand geothermal fields
(Frontiers Media SA, 2023) Houghton , Karen M.; Carere, Carlo; Stott, Matthew; McDonald , Ian R.
Geothermal areas represent substantial point sources for greenhouse gas emissions such as methane. While it is known that methanotrophic microorganisms act as a biofilter, decreasing the efflux of methane in most soils to the atmosphere, the diversity and the extent to which methane is consumed by thermophilic microorganisms in geothermal ecosystems has not been widely explored. To determine the extent of biologically mediated methane oxidation at elevated temperatures, we set up 57 microcosms using soils from 14 Aotearoa-New Zealand geothermal fields and show that moderately thermophilic (>40°C) and thermophilic (>60°C) methane oxidation is common across the region. Methane oxidation was detected in 54% (n = 31) of the geothermal soil microcosms tested at temperatures up to 75°C (pH 1.5–8.1), with oxidation rates ranging from 0.5 to 17.4 μmol g−1 d−1 wet weight. The abundance of known aerobic methanotrophs (up to 60.7% Methylacidiphilum and 11.2% Methylothermus) and putative anaerobic methanotrophs (up to 76.7% Bathyarchaeota) provides some explanation for the rapid rates of methane oxidation observed in microcosms. However, not all methane oxidation was attributable to known taxa; in some methane-consuming microcosms we detected methanotroph taxa in conditions outside of their known temperature range for growth, and in other examples, we observed methane oxidation in the absence of known methanotrophs through 16S rRNA gene sequencing. Both of these observations suggest unidentified methane oxidizing microorganisms or undescribed methanotrophic syntrophic associations may also be present. Subsequent enrichment cultures from microcosms yielded communities not predicted by the original diversity studies and showed rates inconsistent with microcosms (≤24.5 μmol d−1), highlighting difficulties in culturing representative thermophilic methanotrophs. Finally, to determine the active methane oxidation processes, we attempted to elucidate metabolic pathways from two enrichment cultures actively oxidizing methane using metatranscriptomics. The most highly expressed genes in both enrichments (methane monooxygenases, methanol dehydrogenases and PqqA precursor peptides) were related to methanotrophs from Methylococcaceae, Methylocystaceae and Methylothermaceae. This is the first example of using metatranscriptomics to investigate methanotrophs from geothermal environments and gives insight into the metabolic pathways involved in thermophilic methanotrophy.
A systematic mapping study of bug reproduction and localization
(Elsevier BV, 2024) Wang , Di; Galster, Matthias; Morales-Trujillo , Miguel
Context: Identifying the root cause of a software bug and fixing it is challenging. One reason for this is that many bugs are not reproducible during bug fixing. Objective: We aim to provide an overview of existing works on bug reproduction and localization. We ask four research questions: RQ1: What types of problems have been studied in the area of bug reproduction and localization? RQ2: How are problems studied in previous research? RQ3: What are the main findings and outcomes of previous studies? RQ4: What are the gaps and challenges identified in previous studies? Method: We conducted a systematic mapping study analyzing research literature published between 2011 and 2021. The search for primary studies involved four major computer science digital libraries and resulted in 134 studies for analysis. Results: Regarding RQ1 we found that many studies focus on information retrieval-based approaches to support bug reproduction and localization. Regarding RQ2 we found that bug reports and source code are the typical data sources of bug reproduction and localization. Also, most studies include experiments with historical data but do not investigate ongoing projects. Regarding RQ3 we found that many studies adapt or combine existing approaches for bug reproduction and localization to improve their accuracy or applicability (e.g., combine requirements-related information and bug reports to increase information-retrieval-based techniques). Regarding RQ4 we found that existing solutions for bug reproduction and localization have rarely been integrated into the workflow of developers. Conclusion: Although bug reproduction and localization have been studied in quite some detail, new challenges and gaps emerge due to the evolution of software technologies and practices and the practical needs of software developers. For example, bug reproduction approaches for traditional web applications do not work well with modern “Single Page Web Applications” (SPA) and related technologies, e.g., Angular or React.
Lost voices: ethnic diversity in the New Zealand parliament will decline after the 2023 election
(2023) Tan, Alex; Vanvari N
Rolleston Glacier mass balance: trends and methods of observation
(2023) Purdie, Heather; Kerr T; Lorrey A; Vargo L; Porhemmat R; Rack W; Brasington J; Bealing P
Augmented Reality in Learning Settings: A Systematic Analysis of its Benefits and Avenues for Future Studies
(2024) Mohammadhossein N; Richter A; Lukosch, Stephan
Despite its increasing use in various settings, Augmented Reality (AR) technology is still often considered
experimental, partly due to a lack of clear understanding of the benefits of using AR. This study systematically reviews
research on the use of AR in learning settings. Our analysis of 93 relevant articles offers 21 benefits related to the
learning gains and outcomes of using AR. Our study shows that the positive effects of using AR on learners’
motivation and joy have been well-studied, whereas the effects on independent learning, concentration, spontaneous
learning, critical thinking, and practical skills have not yet been examined in detail. Beyond classifying and discussing
the benefits of using AR in learning settings, we elaborate avenues for future studies. We specifically point to the
importance of conducting long-term studies to determine the value of using AR in learning beyond the initial novelty
and exploring the integration of AR with other technologies.