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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ItemOpen Access
Trace gas oxidation sustains energy needs of a thermophilic archaeon at suboptimal temperatures
(Springer Science and Business Media LLC, 2024) Leung PM; Grinter R; Tudor-Matthew E; Lingford JP; Jimenez L; Lee HC; Milton M; Hanchapola I; Tanuwidjaya E; Kropp A; Peach HA; Carere, Carlo; Stott, Matthew; Schittenhelm RB; Greening C
Diverse aerobic bacteria use atmospheric hydrogen (H2) and carbon monoxide (CO) as energy sources to support growth and survival. Such trace gas oxidation is recognised as a globally significant process that serves as the main sink in the biogeochemical H2 cycle and sustains microbial biodiversity in oligotrophic ecosystems. However, it is unclear whether archaea can also use atmospheric H2. Here we show that a thermoacidophilic archaeon, Acidianus brierleyi (Thermoproteota), constitutively consumes H2 and CO to sub-atmospheric levels. Oxidation occurs across a wide range of temperatures (10 to 70 °C) and enhances ATP production during starvation-induced persistence under temperate conditions. The genome of A. brierleyi encodes a canonical CO dehydrogenase and four distinct [NiFe]-hydrogenases, which are differentially produced in response to electron donor and acceptor availability. Another archaeon, Metallosphaera sedula, can also oxidize atmospheric H2. Our results suggest that trace gas oxidation is a common trait of Sulfolobales archaea and may play a role in their survival and niche expansion, including during dispersal through temperate environments.
ItemOpen Access
Unethical practices in response to poor student quality: An Australian perspective
(2016) Steenkamp, Natasja; Roberts R
The purpose is to ascertain accounting academics’ perceptions whether (a) the standard of accounting education at Australian universities has deteriorated, (b) the quality of undergraduate students has deteriorated in recent years, and if the latter (c) impacted them, their jobs, their teaching and ethical practices, and (d) is obstructing the attractiveness of accounting academia as a career. An on-line survey was sent to accounting academics at 39 Australian universities to investigate participants’ perceptions about the deterioration in the standard of accounting education and the quality of undergraduate students and the impact on respondents’ well-being, ethical practices and their job satisfaction. The majority of respondents believe the standard of accounting education and the quality of undergraduate students have deteriorated. Many academics have experienced increased frustration, disillusionment, and struggle with workload. Respondents experience institutional pressures to achieve higher pass rates, deal with sub-par core skills, treat students as clients and increase student retention. As a result, a significant number of academics, have inflated grades or deflated coursework in order to ameliorate these pressures. Nonetheless, despite these challenges, the majority is not actively seeking to change jobs or leave academia, but agree that it is not a good time for others to aspire an academic career in accounting.
ItemOpen Access
Effect of the stress-dependency and anisotropy of unbound granular base and subgrade materials on the TSD deflection slopes
(2024) Kazemi N; Saleh, Mofreh; Lee, Chin-Long
The Traffic Speed Deflectometer (TSD) is a mobile vehicle that utilizes Doppler laser sensors to capture pavement surface deflection velocities. These velocities are then divided by the travel speed to obtain deflection slopes, which are used in pavement management tasks. Previous studies on pavement layer moduli back calculation using TSD have often overlooked the nonlinear stress-dependency and anisotropy of pavement layers materials. This research, employing ABAQUS finite element software, explores the impact of stress-dependency and anisotropy of unbound granular materials and fine-grained soil layers on TSD deflection slopes. Simulations of a 2D-axisymmetric pavement system, considering specific material properties and layer thicknesses under uniform tire loading, reveal a substantial difference of about 40% variation in deflection slopes when nonlinear stress-dependency is considered. Comparatively, considering an anisotropy ratio of 0.5 or higher maintains deflection slope differences around 10%, while an anisotropy ratio below 0.5 leads to a 40% variation. This study emphasizes that overlooking stress-dependency and anisotropy of pavement layers materials in analyzing TSD data in pavement layers’ back calculation is inadequate.
ItemOpen Access
A genus in the bacterial phylum Aquificota appears to be endemic to Aotearoa-New Zealand
(Springer Science and Business Media LLC, 2024) Power JF; Carere, Carlo; Welford HE; Hudson DT; Lee KC; Moreau JW; Ettema TJG; Reysenbach AL; Lee CK; Colman DR; Boyd ES; Morgan XC; McDonald IR; Craig Cary S; Stott, Matthew
Allopatric speciation has been difficult to examine among microorganisms, with prior reports of endemism restricted to sub-genus level taxa. Previous microbial community analysis via 16S rRNA gene sequencing of 925 geothermal springs from the Taupō Volcanic Zone (TVZ), Aotearoa-New Zealand, revealed widespread distribution and abundance of a single bacterial genus across 686 of these ecosystems (pH 1.2-9.6 and 17.4-99.8 °C). Here, we present evidence to suggest that this genus, Venenivibrio (phylum Aquificota), is endemic to Aotearoa-New Zealand. A specific environmental niche that increases habitat isolation was identified, with maximal read abundance of Venenivibrio occurring at pH 4-6, 50-70 °C, and low oxidation-reduction potentials. This was further highlighted by genomic and culture-based analyses of the only characterised species for the genus, Venenivibrio stagnispumantis CP.B2T, which confirmed a chemolithoautotrophic metabolism dependent on hydrogen oxidation. While similarity between Venenivibrio populations illustrated that dispersal is not limited across the TVZ, extensive amplicon, metagenomic, and phylogenomic analyses of global microbial communities from DNA sequence databases indicates Venenivibrio is geographically restricted to the Aotearoa-New Zealand archipelago. We conclude that geographic isolation, complemented by physicochemical constraints, has resulted in the establishment of an endemic bacterial genus.
ItemOpen Access
Mother Tongue versus English as a Second Language in Mathematical Word Problems: Implications to Language Policy Development in the Philippines
(Tawasul International Centre for Publishing, Research and Dialogue, online-publication-date) Bautista, Judy; Samonte I; Improgo CM; Gutierrez MR
This study investigated the performance of 150 Tagalog and 131 Sinugbuanong Bisaya grade three pupils with regard to solving mathematical word problems written in their mother-tongue (L1) and in English as their second language (L2). The respondents were subjected to a validated teacher-made parallel tests based on the competencies stipulated in the first and second quarter mathematics curriculum guide of the Philippines. Results of which were compared and analyzed using two-tailed t-test. Findings show that the Tagalog pupils performed better in their mother-tongue over English as their second language. On the other hand, Sinugbuanong Bisaya pupils performed better in English as their second language over their mother-tongue. While results appear contradictory, contextual discussions offer valuable insights into the situation, allowing avenues for more exploration and investigations. As implication to language policy development, this study offers the use of translanguaging in content area instruction and assessment, specifically in the teaching and learning of mathematical problem solving.