title: On the precipitability of binary Ti alloys bearing 4-period d-metal eutectoid stabilisers

authors: Bolzoni, Leandro

subjects: Titanium alloys

abstract: There is no specific, simple approach for predicting whether the addition of an eutectoid beta stabiliser to Ti leads to an ‘active’ eutectoid transformation upon primary processing (e.g., sintering). Here, we demonstrate that, among theoretical/empirical models, phase diagram features, and electronic structure parameters, the hypoeutectoid area is the best predictor, followed by the molybdenum equivalent parameter (MoE), of the precipitability for 4-period d-metals. As the area increases, which corresponds to the addition of progressively stronger β-eutectoid stabilisers, the less active the eutectoid phase transformation, changing from pearlitic to bainitic (i.e., need for an ageing heat treatment). This occurs if the MoE weighted coefficient is, respectively, lower than or higher than 1. This is because molybdenum is taken as reference, and the higher the coefficient, the larger the drop of the β transus temperature (i.e., higher stabilisation). Valid for 4-period d-metals, it remains to be proven for 5-period and 6-period d-metals.

text: On the precipitability of binary Ti alloys bearing 4-period d-metal eutectoid stabilisers There is no specific, simple approach for predicting whether the addition of an eutectoid beta stabiliser to Ti leads to an ‘active’ eutectoid transformation upon primary processing (e.g., sintering). Here, we demonstrate that, among theoretical/empirical models, phase diagram features, and electronic structure parameters, the hypoeutectoid area is the best predictor, followed by the molybdenum equivalent parameter (MoE), of the precipitability for 4-period d-metals. As the area increases, which corresponds to the addition of progressively stronger β-eutectoid stabilisers, the less active the eutectoid phase transformation, changing from pearlitic to bainitic (i.e., need for an ageing heat treatment). This occurs if the MoE weighted coefficient is, respectively, lower than or higher than 1. This is because molybdenum is taken as reference, and the higher the coefficient, the larger the drop of the β transus temperature (i.e., higher stabilisation). Valid for 4-period d-metals, it remains to be proven for 5-period and 6-period d-metals.

year: 2026-06

title: Genetic diversity and potential responses of New Zealand Rotifera and Antarctic Collembola to environmental changes

authors: Collins, Gemma Elyse

subjects: Mitochondrial DNA

abstract: Environmental changes can impact the diversity and abundance of biotic communities as well as their dispersal among geographic regions. The availability of sensitive molecular techniques has enabled assessments of diversity at levels previously unattainable and allowed investigation of how biota are influenced by their environment. This thesis examines the use of mitochondrial DNA sequence variation in New Zealand freshwater rotifers (Rotifera) and Antarctic springtails (Collembola) to assess diversity and determine responses to environmental changes.
 
Using mitochondrial cytochrome c oxidase subunit I (COI) DNA sequences, I examined the diversity of New Zealand rotifers. The rotifer phylum is comprised of a variety of species and individuals are often abundant in freshwater systems globally. Species are associated with specific trophic states and in New Zealand are routinely monitored as biological indicators of ecosystem health. At present, species’ identification relies on morphological characters which is time consuming and requires appropriate taxonomic expertise. Here, I assessed the use of COI sequences as an alternative for the routine identification of New Zealand rotifers. A total of 177 individuals were sequenced from 45 morphologically-recognised taxa. High intraspecific variation was found among 14 species (3.4 - 39.0% divergence) and based on comparisons with sequences available on GenBank, 18 species were genetically distinct from their global conspecifics (>6.6% divergence). I conclude that these distinct haplotypes are potentially endemic among putatively cosmopolitan species. A better understanding of rotifer diversity in New Zealand will allow the detection and potential control of future non-indigenous species’ incursions. 

In order to assess the effects of environmental temperature changes on the genetic structure of populations, I examined the diversity of COI sequences of Antarctic springtails relative to the environmental conditions during which they were active. The target species, Gomphiocephalus hodgsoni, is known to harbour high genetic (COI) diversity as well as having considerable variation in their ability to tolerate sub-zero temperature – specifically, there appear to be “warm” and “cold” adapted individuals. I sequenced 151 individuals collected in pitfall traps near Spaulding Pond, Taylor Valley and found 19 unique COI haplotypes that separated into two distinct groups (1.6% divergence), with one haplotype group comprising 80% of the sequenced population. During two-hourly sampling, air temperature was the strongest predictor of activity between the two haplotype groups (R2 = 0.56) and when combined with subsurface soil temperature, relative humidity and photosynthetically active radiation, explanatory power increased to R2 = 0.71. Air temperatures are predicted to continue increasing across most of Antarctica which is expected to impact springtails by a detectable amount. Monitoring programmes focussed on the temporal and spatial changes in COI haplotype diversity may provide a sensitive measure of population responses to climate change. 

Collectively, these two studies contribute baseline data of the current genetic diversity and population structure among New Zealand rotifers and Antarctic springtails and provide a platform by which to monitor future environmental changes.

text: Genetic diversity and potential responses of New Zealand Rotifera and Antarctic Collembola to environmental changes Environmental changes can impact the diversity and abundance of biotic communities as well as their dispersal among geographic regions. The availability of sensitive molecular techniques has enabled assessments of diversity at levels previously unattainable and allowed investigation of how biota are influenced by their environment. This thesis examines the use of mitochondrial DNA sequence variation in New Zealand freshwater rotifers (Rotifera) and Antarctic springtails (Collembola) to assess diversity and determine responses to environmental changes.
 
Using mitochondrial cytochrome c oxidase subunit I (COI) DNA sequences, I examined the diversity of New Zealand rotifers. The rotifer phylum is comprised of a variety of species and individuals are often abundant in freshwater systems globally. Species are associated with specific trophic states and in New Zealand are routinely monitored as biological indicators of ecosystem health. At present, species’ identification relies on morphological characters which is time consuming and requires appropriate taxonomic expertise. Here, I assessed the use of COI sequences as an alternative for the routine identification of New Zealand rotifers. A total of 177 individuals were sequenced from 45 morphologically-recognised taxa. High intraspecific variation was found among 14 species (3.4 - 39.0% divergence) and based on comparisons with sequences available on GenBank, 18 species were genetically distinct from their global conspecifics (>6.6% divergence). I conclude that these distinct haplotypes are potentially endemic among putatively cosmopolitan species. A better understanding of rotifer diversity in New Zealand will allow the detection and potential control of future non-indigenous species’ incursions. 

In order to assess the effects of environmental temperature changes on the genetic structure of populations, I examined the diversity of COI sequences of Antarctic springtails relative to the environmental conditions during which they were active. The target species, Gomphiocephalus hodgsoni, is known to harbour high genetic (COI) diversity as well as having considerable variation in their ability to tolerate sub-zero temperature – specifically, there appear to be “warm” and “cold” adapted individuals. I sequenced 151 individuals collected in pitfall traps near Spaulding Pond, Taylor Valley and found 19 unique COI haplotypes that separated into two distinct groups (1.6% divergence), with one haplotype group comprising 80% of the sequenced population. During two-hourly sampling, air temperature was the strongest predictor of activity between the two haplotype groups (R2 = 0.56) and when combined with subsurface soil temperature, relative humidity and photosynthetically active radiation, explanatory power increased to R2 = 0.71. Air temperatures are predicted to continue increasing across most of Antarctica which is expected to impact springtails by a detectable amount. Monitoring programmes focussed on the temporal and spatial changes in COI haplotype diversity may provide a sensitive measure of population responses to climate change. 

Collectively, these two studies contribute baseline data of the current genetic diversity and population structure among New Zealand rotifers and Antarctic springtails and provide a platform by which to monitor future environmental changes.

year: 2015

title: “Whānau Vibes”: Reclamation of self, space and community within group fitness gyms.

authors: Metekingi, Cydney

abstract: Group fitness gyms are becoming more popular in Aotearoa, New Zealand. This thesis is an investigation of the lived experiences of Māori members within a commercialised fitness space called BFT Hamilton East, located in Kirikiriroa, Hamilton. Drawing on Indigenous anthropology and autoethnography, and grounded in Kaupapa Māori theory, this thesis firstly explores how the gym becomes a site in which Māori members seek to reclaim the narrative around their own bodies. I explore the colonial depictions, the politics of the Indigenous body and how Māori-owned clothing brands contribute to this reclamation. I then examine how Māori gym members use the gym space with a sense of purpose, balancing the values of culture and commercialisation. And finally, I investigate the importance of relational well-being and the use of whanaungatanga and manaakitanga to create a sense of belonging among participants in their search for connection. In foregrounding Indigenous ways of knowing, being and moving in a commercial group fitness gym, this thesis aims to contribute to the anthropological conversations that advocate for the inclusion of Indigenous methodologies into Anthropology, centring Indigenous agency and advocating for the decolonisation of fitness spaces.

text: “Whānau Vibes”: Reclamation of self, space and community within group fitness gyms. Group fitness gyms are becoming more popular in Aotearoa, New Zealand. This thesis is an investigation of the lived experiences of Māori members within a commercialised fitness space called BFT Hamilton East, located in Kirikiriroa, Hamilton. Drawing on Indigenous anthropology and autoethnography, and grounded in Kaupapa Māori theory, this thesis firstly explores how the gym becomes a site in which Māori members seek to reclaim the narrative around their own bodies. I explore the colonial depictions, the politics of the Indigenous body and how Māori-owned clothing brands contribute to this reclamation. I then examine how Māori gym members use the gym space with a sense of purpose, balancing the values of culture and commercialisation. And finally, I investigate the importance of relational well-being and the use of whanaungatanga and manaakitanga to create a sense of belonging among participants in their search for connection. In foregrounding Indigenous ways of knowing, being and moving in a commercial group fitness gym, this thesis aims to contribute to the anthropological conversations that advocate for the inclusion of Indigenous methodologies into Anthropology, centring Indigenous agency and advocating for the decolonisation of fitness spaces.

year: 2025