title: Identifying diazotrophs by incorporation of nitrogen from ¹⁵N₂ into RNA

authors: Addison, Sarah Louise

subjects: nitrogen fixing

abstract: The diversity and abundance of active diazotrophs was investigated in a New Zealand pulp and paper wastewater by enrichment with ¹⁵N₂. Purified ¹⁵N-RNA was analysed by reverse transcription, molecular cloning and sequence analysis of 16S rRNA to reveal a diverse community of bacteria as indicated by a Shannon Weaver Index value of > 2.8. The major class represented in the enriched culture were the γ-Proteobacteria at 85% with a secondary group of the phylum Firmicutes present at 8.2%, the remaining sequences were affiliated with the α- and β-Proteobacterial classes (1.4% and 4.3%, respectively). Three dominant genera, Aeromonas, Pseudomonas and Bacillus, were identified by comparison with published sequences and phylogenetic analysis. To confirm that representatives of the taxonomic groups identified from the active enriched nitrogen-fixing community were capable of fixing nitrogen Aeromonas and Pseudomonas species were cultivated and shown to possess nifH genes. In wastewater, fluorescence in situ hybridisation probing revealed that the dominant nitrogen-fixing population identified in this study were present in the population, but at lower levels. The population is, therefore, reliant on a small sub-population of diazotrophs to supply the community's nitrogen needs above that already present in the wastewater.

text: Identifying diazotrophs by incorporation of nitrogen from ¹⁵N₂ into RNA The diversity and abundance of active diazotrophs was investigated in a New Zealand pulp and paper wastewater by enrichment with ¹⁵N₂. Purified ¹⁵N-RNA was analysed by reverse transcription, molecular cloning and sequence analysis of 16S rRNA to reveal a diverse community of bacteria as indicated by a Shannon Weaver Index value of > 2.8. The major class represented in the enriched culture were the γ-Proteobacteria at 85% with a secondary group of the phylum Firmicutes present at 8.2%, the remaining sequences were affiliated with the α- and β-Proteobacterial classes (1.4% and 4.3%, respectively). Three dominant genera, Aeromonas, Pseudomonas and Bacillus, were identified by comparison with published sequences and phylogenetic analysis. To confirm that representatives of the taxonomic groups identified from the active enriched nitrogen-fixing community were capable of fixing nitrogen Aeromonas and Pseudomonas species were cultivated and shown to possess nifH genes. In wastewater, fluorescence in situ hybridisation probing revealed that the dominant nitrogen-fixing population identified in this study were present in the population, but at lower levels. The population is, therefore, reliant on a small sub-population of diazotrophs to supply the community's nitrogen needs above that already present in the wastewater.

year: 2010

title: Accuracy bounds for ensembles under 0 - 1 loss.

authors: Bouckaert, Remco R.

abstract: This paper is an attempt to increase the understanding in the behavior of ensembles for discrete variables in a quantitative way.  A set of tight upper and lower bounds for the accuracy of an ensemble is presented for wide classes of ensemble algorithms, including bagging and boosting.  The ensemble accuracy is expressed in terms of the accuracies of the members of the ensemble. 
Since those bounds represent best and worst case behavior only, we study typical behavior as well, and discuss its properties.  A parameterised bound is presented which describes ensemble bahavior as a mixture of dependent base classifier and independent base classifier areas.  Some empirical results are presented to support our conclusions.

text: Accuracy bounds for ensembles under 0 - 1 loss. This paper is an attempt to increase the understanding in the behavior of ensembles for discrete variables in a quantitative way.  A set of tight upper and lower bounds for the accuracy of an ensemble is presented for wide classes of ensemble algorithms, including bagging and boosting.  The ensemble accuracy is expressed in terms of the accuracies of the members of the ensemble. 
Since those bounds represent best and worst case behavior only, we study typical behavior as well, and discuss its properties.  A parameterised bound is presented which describes ensemble bahavior as a mixture of dependent base classifier and independent base classifier areas.  Some empirical results are presented to support our conclusions.

year: 2002-06-01

title: Exploring the experiences of Māori Wāhine in a STEM project-based secondary classroom: A relational and intersectional perspective

authors: Cheryl, Mitchell

abstract: Using phenomenology, an intersectional lens, and the principles of Kaupapa Māori research, this study investigates how young Māori (Indigenous) wāhine (women) ākonga (students) experience interdisciplinary project-based STEM education. Historical educational policies in Aotearoa New Zealand required Māori to assimilate into a Pākehā (European) school system, contributing to persistent academic underperformance, particularly in science. Māori have been more likely to leave school early, and those who remain often opt out of science subjects, especially Māori wāhine. International literature suggests that transdisciplinary STEM education grounded in social justice and equity can improve engagement and outcomes for underrepresented learners. The study was guided by two questions: (1) how Māori wāhine experienced the STEM programme, and (2) what their challenges were to succeed in STEM.

In 2016, while teaching at a low-decile (socioeconomic disadvantaged), urban, co-educational English-medium high school, I trialled an integrated, interdisciplinary project-based STEM class that incorporated meaningful phenomena and culturally responsive pedagogy. The class’s success led to STEM becoming a core component of a broader school initiative. In 2018, the seven Māori wāhine ākonga enrolled in the Year 11 (age 15–16) STEM class were invited to become “Story Sharers” and reflect on their experiences. As a teacher-researcher (insider), I used reflexive practices and clear role delineation to leverage contextual knowledge while minimising bias. Narrative data were collected over two years (2018–2019) through six semi-structured discussion groups and one individual interview. Quantitative data included tracking attendance records, retention, and academic achievement.

Findings indicate that the Story Sharers valued co-constructed topics and tasks, a supportive whānau (family/community) class format, and authentic project work undertaken over extended learning periods. They consistently identified strengthened relationships, particularly among peers as central to engagement, wellbeing, motivation to learn, and as the most salient indicator of success. Academic performance increased relative to prior Year-10 e-asTTle (Electronic Assessment Tool for Teaching and Learning in mathematics, reading, and writing) benchmarks, alongside improved STEM class attendance, retention in school, and intentions to continue in STEM.

Interpretive thematic analysis using an intersectional lens revealed that racism, stereotyping, and impacts on wellbeing were significant barriers to learning. These discriminatory experiences were pervasive across school, community, and online spaces and were compounded by gendered and intergenerational dynamics. The Story Sharers described complex, fluid, and intersecting identities shaped by lived experiences, including witnessing discrimination against Māori wāhine in their whānau and the legacy of colonial schooling practices such as the suppression of te reo Māori.

In this study, STEM project-based learning was shaped by two interwoven design elements: relational pedagogy and relational thinking. Relational pedagogy prioritised relationships and co-construction within a whānau-formatted classroom. Relational thinking described the interdisciplinary logic of the programme itself, connecting disciplinary knowledge to place, context, and community so that learning is organised around meaningful phenomena rather than siloed subjects. Together, these elements functioned as a counterspace that fostered inclusive engagement, affirmed identities, and supported belonging for Māori wāhine. Grounded in culturally responsive and whānau-based approaches, this model enabled learners to challenge deficit narratives and engage meaningfully in STEM. The outcomes offer assurance that integrated, project-based STEM education, underpinned by these relational frameworks, can improve outcomes for learners whose identities and experiences have been marginalised in traditional schooling. However, policymakers must remain attentive to historical policy barriers and intersectional factors that continue to perpetuate inequities within the education system.

text: Exploring the experiences of Māori Wāhine in a STEM project-based secondary classroom: A relational and intersectional perspective Using phenomenology, an intersectional lens, and the principles of Kaupapa Māori research, this study investigates how young Māori (Indigenous) wāhine (women) ākonga (students) experience interdisciplinary project-based STEM education. Historical educational policies in Aotearoa New Zealand required Māori to assimilate into a Pākehā (European) school system, contributing to persistent academic underperformance, particularly in science. Māori have been more likely to leave school early, and those who remain often opt out of science subjects, especially Māori wāhine. International literature suggests that transdisciplinary STEM education grounded in social justice and equity can improve engagement and outcomes for underrepresented learners. The study was guided by two questions: (1) how Māori wāhine experienced the STEM programme, and (2) what their challenges were to succeed in STEM.

In 2016, while teaching at a low-decile (socioeconomic disadvantaged), urban, co-educational English-medium high school, I trialled an integrated, interdisciplinary project-based STEM class that incorporated meaningful phenomena and culturally responsive pedagogy. The class’s success led to STEM becoming a core component of a broader school initiative. In 2018, the seven Māori wāhine ākonga enrolled in the Year 11 (age 15–16) STEM class were invited to become “Story Sharers” and reflect on their experiences. As a teacher-researcher (insider), I used reflexive practices and clear role delineation to leverage contextual knowledge while minimising bias. Narrative data were collected over two years (2018–2019) through six semi-structured discussion groups and one individual interview. Quantitative data included tracking attendance records, retention, and academic achievement.

Findings indicate that the Story Sharers valued co-constructed topics and tasks, a supportive whānau (family/community) class format, and authentic project work undertaken over extended learning periods. They consistently identified strengthened relationships, particularly among peers as central to engagement, wellbeing, motivation to learn, and as the most salient indicator of success. Academic performance increased relative to prior Year-10 e-asTTle (Electronic Assessment Tool for Teaching and Learning in mathematics, reading, and writing) benchmarks, alongside improved STEM class attendance, retention in school, and intentions to continue in STEM.

Interpretive thematic analysis using an intersectional lens revealed that racism, stereotyping, and impacts on wellbeing were significant barriers to learning. These discriminatory experiences were pervasive across school, community, and online spaces and were compounded by gendered and intergenerational dynamics. The Story Sharers described complex, fluid, and intersecting identities shaped by lived experiences, including witnessing discrimination against Māori wāhine in their whānau and the legacy of colonial schooling practices such as the suppression of te reo Māori.

In this study, STEM project-based learning was shaped by two interwoven design elements: relational pedagogy and relational thinking. Relational pedagogy prioritised relationships and co-construction within a whānau-formatted classroom. Relational thinking described the interdisciplinary logic of the programme itself, connecting disciplinary knowledge to place, context, and community so that learning is organised around meaningful phenomena rather than siloed subjects. Together, these elements functioned as a counterspace that fostered inclusive engagement, affirmed identities, and supported belonging for Māori wāhine. Grounded in culturally responsive and whānau-based approaches, this model enabled learners to challenge deficit narratives and engage meaningfully in STEM. The outcomes offer assurance that integrated, project-based STEM education, underpinned by these relational frameworks, can improve outcomes for learners whose identities and experiences have been marginalised in traditional schooling. However, policymakers must remain attentive to historical policy barriers and intersectional factors that continue to perpetuate inequities within the education system.

year: 2025-10-17