Science: Theses and Dissertations

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Open Access
Inhibition’s role in long-term attended repetition priming effects : evidence for logogens and “logogins”.
(2024) McLennan, Kristin S.
The number of competing sensory inputs are increasing at a rapid rate in today’s world. Researchers have long been interested in the underlying mechanisms that enable humans to selectively attend to relevant information while simultaneously disregarding irrelevant information. These mechanisms are critical to safeguard against sensory overload. Priming has been an avenue through which to study these mechanisms to help discover precisely how the brain is able to direct attention to information that is pertinent to the current task or situation. The size of the contribution of memory in this process has been a long-standing debate. This dissertation presents a series of experiments that explore the underlying cognitive mechanisms in long-term attended repetition positive priming effects and discusses these findings through an abstractionist perspective, an episodic perspective, and a predictive brain account. The paradigm used presents participants with a pair of items, one being an uppercase distractor word and the other being a lowercase target word, followed by another pair of such items with the lowercase item being either a word or a non-word. Participants were instructed to ignore the uppercase words and respond to the lowercase target items. The prime display required participants to read aloud the lowercase target word. In the following probe display, participants were asked to make a lexical decision (word/non-word judgment) to the lowercase target item. The relationship between the prime and probe targets was manipulated to produce two conditions. In the attended repetition (AR) condition the lowercase target word that was read aloud in the prime display was identical to the lowercase prime target word that appeared in the probe display. In the neutral control condition, the words presented in the prime display had no relationship to the words in the probe display. Six experiments are presented that were designed to explore AR effects at different lags involving a different number of intervening prime-probe couplets (trials). In all of the experiments, words appeared only once except to satisfy the AR conditions. Only in the AR conditions did words appear exactly twice, once as the prime target and subsequently as the probe target. For example, in a lag 10 AR condition the lowercase probe target word had appeared as the lowercase prime target word exactly 10 trials prior. Notably, one of the six experiments included a longer lag (80) combined with a lag 0 AR condition. The results demonstrated the importance of the inclusion of the lag 0 AR condition. That experiment did not produce long-term AR positive priming, consistent with findings reported by McLennan, Neumann, and Russell (2019, Experiment 2), which included a lag 144 condition combined with a lag 0 condition. However, the remaining experiments with long lags up to lag 144 did produce AR positive priming without a lag 0 condition. Apparently, the presence of a lag 0 AR condition abolishes long lag facilitatory priming effects. This finding cannot be easily accounted for by the two major theories of positive priming; the abstractionist account, and the episodic account. It is proposed that the absence of long-term positive priming in the presence of a lag 0 AR condition is the result of an unconscious inhibitory mechanism. This inhibitory processing mechanism is discussed in the context of a statistical learning process and is supported by past research involving a predictive brain hypothesis. Overall, the results suggest that facilitatory priming effects are mediated by both bottom-up input and top-down processing and, depending on the task context, the brain subliminally forms a perceptual hypothesis that can induce an inhibitory mechanism that modulates future responding.
Open Access
Deaf and hard of hearing people’s experiences and perspectives of speech and language therapy.
(2024) Lamb, Rosie
Deaf people have experienced oppression, particularly in relation to the use of signed languages. Due to the oral education movement, spoken language has a complex place in the field of educating and raising deaf children. This study aimed to review speech language therapy (SLT) practice from the perspective of deaf people and move towards providing deaf people the support they want. The current study was grounded in a transformative research paradigm and two frameworks were used to support research design: Kaupapa Māori Principles and the Deaf AcCESS checklist. Eleven deaf participants were recruited and chose to take part in either a focus group or one to one interview via Zoom; using spoken English or New Zealand Sign Language (NZSL). The sessions were recorded and written English transcripts were generated. The NZSL recordings were interpreted and then transcribed. Reflexive thematic analysis was used to analyse and create a narrative about the data. One main theme, Ensuring deaf kids are thriving and flourishing was created, outlining the participants’ views on the importance of seeing deaf children grow into confident, self-assured and well-rounded people. Examples were given regarding negative experiences which provide context for this theme. The main theme was further explored and described in three subthemes. Hearing differences provide a unique experience (subtheme one) explored participants’ experiences with communication. Participants expressed the need for access to language (signed and indigenous), culture (deaf and indigenous), that confidence is important, seeing themselves and sharing experiences is needed, they have a unique experience navigating towards successful communication and lipreading is important. The participants also discussed the challenges and considerations required for them to navigate towards successful communication. Look carefully; see the full picture (subtheme two) illustrated the importance of seeing deaf children within their environment and nurturing an environment that responded to them while understanding that each child and ecosystem will be different. The profession and professional responsibilities (subtheme three) considered aspects that require attention, by individual therapists and the SLT profession. The participants explained how important the relationship with the child was, that power dynamics must be considered, the child needs to be given autonomy, speech language therapists (SLTs) need to be honest and transparent, a diverse workforce needs to be developed and each individual therapist needs to be developing their culturally responsive practice. The findings of this study broadly aligned with findings of similar studies. However, this is the first New Zealand study to ask deaf people what their experiences and perceptions of speech language therapy are, and first internationally to include perspectives of those who use spoken language, and an indigenous voice. It adds to the evidence base for organisations, teams and individual SLTs to ensure that the service they are delivering is responsive to and based on the needs and aspirations of deaf people.
Open Access
The moderating effect of work-family spillover on occupational stress and burnout among experienced audiologists.
(2024) Singh, Hasnita Kiran
Research has underlined the importance of understanding the spillover between work and family as a means of decreasing occupational stress, burnout, and improving the well-being of employees and their clients. Though occupational stress, burnout, positive and negative spillover have been studied in healthcare, the focus has remained on nurses and doctors. The aim of this research was to expand this understanding on audiologists in a time of societal changes and increasing demand for hearing and balance care. As a part of the study, 66 experienced audiologists from Australia, Canada, United Kingdom and the United States of America completed a survey containing 87 items. The results of this study showed that work-family negative spillover acted bidirectionally and functioned as significant moderators in the relationship between occupational stress and occupational burnout. Similarly, work-to-family positive spillover had significant interactions with occupational stress and occupational. However, in this sample size of there was not enough evidence to suggest that family-to-work positive spillover played a significant moderating role in occupational stress leading to occupational burnout.
Open Access
Examining the anthropogenic influence on extreme weather over Aotearoa/New Zealand for varying synoptic states.
(2024) Thomas, Anjali
The rapid and unprecedentedwarming of the climate system has led to an increase in the frequency and severity of extreme weather events, presenting significant challenges to ecosystems, societies, and economies across the globe. In Aotearoa New Zealand (hereafter, ANZ), a country with an intricate topography and distinct ecology, the consequences of these severe extremes are evident. Hence it is critically important to understand how human-induced forcings are shaping and amplifying the frequencies and intensities of extremes within the country. We use a large ensemble generated over the ANZ domain using the weather@home (w@h) regional climate model under two forcing scenarios. The first scenario represents pre-industrial settings, without any human-induced alterations, while the second scenario represents present-day conditions, with anthropogenic influences. Synoptic circulation patterns play a key role in shaping the weather of ANZ, thereby influencing the frequency and intensity of extreme weather events, ranging from heavy rainfall to droughts. In this thesis, we aim to statistically quantify how extremes such as temperature and precipitation have evolved with human-induced forcings over ANZ in combination with various large-scale circulation patterns. Self-organising maps, a machine learning classification approach was employed to derive the 12 major synoptic circulation patterns around ANZ. These circulation types represent a range of pressure patterns and are the basis of all the analysis in this thesis. In ANZ, due to anthropogenic forcings, there is an average increase of two to three times in the frequency of temperature extremes, based on the analysis of the w@h data. An approximate 1◦C rise in the mean temperature is also observed in the ANT scenario compared to the NAT scenario. Although certain synoptic states like low-pressure systems over the east/northeast of ANZ are infrequent, the frequency of temperature extremes is increased by a factor of seven in the ANT scenario than NAT during the winter season. Low-pressure centres to the northwest of New Zealand are frequently associated with high temperatures in both the ANT and NAT scenarios, likely linked to the advection of warm air of tropical origins for these patterns. The frequency of extreme temperatures in these synoptic patterns has also doubled between theNAT and ANT ensembles. In both scenarios, regions of the North Island like Northland and the east coast of the ANZ such as Canterbury regions experience higher temperatures with these circulation types. However, the west coast along the Southern Alps in the South Island experiences the largest increase in extreme temperatures with anthropogenic forcings. With extreme temperatures rising in intensity and frequency across all regions of ANZ due to anthropogenic influences, changes in precipitation patterns are anticipated, following the Clausius-Clapeyron (C-C) relationship. Therefore, this analysis examines the effects of human-induced forcing on precipitation within various large-scale circulation types. We also quantify the thermodynamic and dynamic influences of different circulation types on precipitation over ANZ relative to C-C rates. In general, the increase in precipitation intensity due to human-induced warming is less than the anticipated C-C value at the lower percentiles, but aligns with the C-C rates at higher percentiles for extreme precipitation. This is particularly clear for low-pressure systems to the southwest of ANZ and associated with westerly winds onto the South Island. These nodes also exhibit higher precipitation change due to human-induced warming, particularly in the west coast regions. Whereas, northwesterly circulation type display a reduction in precipitation in the ANT scenarios especially over the North Island compared to the expected C-C value. In addition, the number of wet days decreases in the ANT scenario compared to the NAT scenario. The highest reductions are observed on the west coast of the South Island for westerly winds, while there are slight increases on the east coast. However, the frequency of days with extreme precipitation increases for most circulation patterns, except for Northland and northwesterly flows. This highlights the combined impact of dynamics and thermodynamics in defining changes in both the intensity and occurrence patterns of precipitation across ANZ. Finally, we examine the changes in extreme temperatures, when coupled with dry, wet, and humid conditions, attributed to human-induced forcing over ANZ. Furthermore,we explore the impact of large-scale synoptic features on these alterations. High-pressure circulation types display a higher frequency of dry days and dry hot extremes, although their increase under the ANT scenario is less pronounced compared to the rise observed for wet hot extremes and humid hot extremes. Extreme temperatures tend to intensify on dry days, whereas they decrease on wet and humid days. While high relative humidity is less frequent and is typically associated with lower temperatures, its combination with extreme temperatures can exacerbate their severity. In the eastern coast regions of the South Island, hot humid temperatures intensify by over 4◦C due to human-induced warming in the ANT simulations during westerly flow patterns. This underscores the significant impact of relative humidity on extreme temperatures despite frequent dry hot days caused by the westerlies and the associated foehn effect in these regions.
Open Access
Time Domain Studies of Infrared-to-Visible Upconversion in Yb³⁺, Er³⁺ Co-doped β-NaYF₄ and β-KYF₄ Nanoparticles
(2024) Haenraets, Benjamin James
Lanthanide-doped nanoparticles based on fluoride hosts have potential uses in nextgeneration biomedical imaging modalities. Isomorphic β-NaYF₄ : 18%Yb³⁺, 2%Er³⁺ and β-KYF₄ : 18%Yb³⁺, 2%Er³⁺ nanoparticles have been synthesised by hydrothermal methods and were characterised using X-ray diffraction, scanning electron microscopy, and infrared absorption spectroscopy. For each nanoparticle species, upconversion fluorescence spectra have been used to investigate how green and red upconversion fluorescence intensities can be tuned by optically stimulating the (Yb) ²F₇/₂ → ²F₅/₂ transition with various excitation pulse widths. The green-to-red upconversion fluorescence intensity ratio for both nanoparticle species decreased with increasing excitation pulse width, indicating that multiple initial pathways populate the red fluorescing (Er) ⁴F₉/₂ state. Upconversion fluorescence transients have been used to monitor the time-dependent population of the (Er) ⁴F₉/₂ state in each nanoparticle species, along with the green fluorescing (Er) ²H₁₁/₂ and (Er) ⁴S₃/₂ states. Such time-dependent populations have been used to understand the behaviour of the green-to-red upconversion fluorescence intensity ratio with increasing excitation pulse width. It was determined that the dominant populating pathways of the (Er) ⁴F₉/₂ state vary between the nanoparticle species. A system of rate equations has been used to simulate these upconversion fluorescence transients to quantitatively understand the dynamics of the upconversion mechanisms in each nanoparticle species. The rate equations were computationally solved using the finite element method, and the simulations were fit to data using the Nelder-Mead algorithm. It has been inferred by simulating the upconversion fluorescence transients that upconversion mechanisms may be present in both nanoparticle species, which have previously not been accounted for by the rate equations. Upconversion mechanism rate constants have been obtained for each nanoparticle species, indicating that the populating pathway to the (Er) ⁴F₉/₂ state through the (Er) ⁴I₁₃/₂ state may be dominant in β-KYF4: 18%Yb³⁺, 2%Er³⁺ nanoparticles but not in β- NaYF₄: 18%Yb³⁺, 2%Er³⁺ nanoparticles. These differences contribute to understanding the discrepancies in the fluorescence behaviour of each nanoparticle species.
Open Access
Biosolids to enhance the establishment of New Zealand-native vegetation.
(2024) Garcés-Hernández, Claudia Daniela
Biosolids are treated sewage sludge, the solid fraction resulting from sewage treatment. In countries with Wastewater Treatment Plants (WWTPs), ca. 27 kg of dry biosolids person⁻¹ yr⁻¹ are produced. In New Zealand, 40% of the biosolids are disposed of into landfills, where they generate methane (CH₄) and nitrous oxide (N₂O). Beneficial reuse of these biosolids would mitigate the environmental and economic costs of landfilling. When added to soil, biosolids improve soil fertility but may introduce unacceptable loads of contaminants, especially trace elements (TEs), xenobiotics, microplastics, and pathogens, that may endanger food safety. Potentially, biosolids may be used to establish NZ-native vegetation, particularly in low-fertility or degraded environments. In this role, a single application of biosolids would be used, reducing the risk of accumulation of TEs in the soil. Given that most NZ-native species are not used for food, there is little risk of contaminants entering the human food chain. It is unclear, however, how much biosolids would increase the growth of NZ-native species, since most of the NZ flora is adapted to low fertility soils, and previous research has shown variable results depending on plant species. Their TE uptake profiles are largely unknown. NZ-native species growing in biosolids-amended soil may change plant chemistry, potentially changing ecosystem nutrition and resulting in facilitating the entry of contaminants into food webs. This thesis sought to determine how the establishment of NZ-native plants could be enhanced by using biosolids in low-fertility substrates. Moreover, it aimed to determine the effect of biosolids on the fluxes of nutrients and TE-contaminants from biosolids-amended substrates to plants. A seedling experiment aimed to determine the potential use of biosolids in plant nurseries. Three distinct biosolids and one pond sludge from separate WWTPs in NZ were combined with shredded Pinus radiata bark at five rates from 0% and 50%. Six native species Veronica salicifolia (Banks & Sol. ex Benth.) L.B.Moore, Poa cita Edgar, Corokia cheesemanii Turril, Phormium tenax J.R.Forst & G.Forst, Griselinia littoralis Raoul and Cordyline australis (G.Forst.) Endl was grown for four months. All species, except Griselinia littoralis, Corokia cheesemanii and Poa cita showed accelerated growth at rates up to 10% ‘fresh’ biosolids and 30% ‘aged’ addition; these rates were considered as optimal for the specific plant species. Higher rates gave inconsistent growth results; therefore, plants grown at optimal rates were analysed for element uptake. The type and rate of biosolids were important factors that affected overall plant health, growth, and plant chemistry. Biosolids addition increased the plant concentrations of N, P, K, S, Mg, Ca, and Zn at optimal rates. None of the TEs exceeded risk levels for elements in animal fodder, indicating they are unlikely to pose a risk to local ecosystems. Lastly, the pond sludge was unsuitable as a growing substrate, due to low pH, lack of nutrients and proportionally high TEs. A field trial was set up at Christchurch Wastewater Treatment Plant (CWTP), where biosolids from the CWTP were added to a recent sandy soil at two rates equivalent to 500 kg N ha⁻¹ and 1,500 kg N ha⁻¹. Biosolids were added either as a surface application (Surface), mixed into the top 200 mm (Mixed), in trenches (Band) or as a mass placed underneath (at Depth) the seedling. With four replicates per treatment, the experiment comprised 32 plots with 15 NZ plant species in each. Following one year of growth, the plant growth was assessed by plant volume. Soil samples were collected in each plot and chemical analysis was performed to determine fertility and TEs concentration. Pittosporum eugenioides A.Cunn, Sophora microphylla Aiton and Phormium tenax J.R.Forst & G.Forst had significantly different canopy volume on some of the biosolids treatments. The rest of the species had no significant growth response to biosolids addition. The prevalence of exotic weeds was dependent on the configuration of the biosolids addition: there was a higher coverage when biosolids were surface applied and Mixed at a High rate, requiring more weed control. There were no other significant variations for other soil parameters responsible for soil fertility such as TC or Total N, and there were no changes in soil TEs concentrations, except when these were compared to its nearest control. Given that soil C was positively correlated with P, Cu and Zn along the experimental plot, the high spatial variability of the soil characteristics was likely the result of previous applications of pond sludge from the nearby maturation ponds. Field sampling was conducted at an active coal mine (Stockton mine) where biosolids have been used for rehabilitation and revegetation since 2012. The chemical properties of biosolids-amended substrates with those from other restoration practices were compared and, determined the uptake of nutrients and contaminants by native and exotic species both in biosolids-amended substrate and other restoration methods to determine the risk of TEs transfer to food chains. The natural soil collected from an undisturbed forest contained high TC and total N (23% C, and 0.5% N) and low Olsen-P 10 mg kg⁻¹ compared with the substrates of the rehabilitated areas. Trace element concentrations in forest soil were similar to suggested soil ecological guideline values for NZ’s soils (ECO-SGVs). Concentrations of Olsen-P were tenfold higher in the biosolids-amended substrates than in forest or other rehabilitation substrates. Biosolids-amended substrates contained Cu and Zn at concentrations 7 to 9-fold higher than the unamended substrate. In plant species planted for rehabilitation across several sites, the concentrations of Mn and Zn in the foliar tissue broadly reflected the soil concentrations. There were significant interspecific variations in the uptake of both essential and non-essential elements. Members of the Asteraceae family accumulated significantly higher concentrations of P, K, Mn, and Zn. These species could be proscribed in areas where high rates of biosolids addition have increased the concentrations of these elements in the substrates. At the rates of biosolids used in this study, the plant TEs concentrations did not exceed animal tolerance levels for fodder, indicating they are unlikely to pose an undue risk to local ecosystems. Nevertheless, biosolids significantly change the nutrient concentrations in the NZ-native species and this may result in changes in trophic systems e.g. herbivore nutrition. This study showed that biosolids can be added to substrates at rates of ca. 1,500 kg N ha⁻¹ (or 10% – 30% w/w in potting substrate) to augment the growth of most, but not all, NZ-native species. Given that the field trial (at CWTP) and field sampling (at Stockton Mine) indicated the accelerated development of weeds while in contact with biosolids, it is likely that biosolids accelerate the growth of exotic weeds more than NZ-native species. This is likely due to the high rates of available N and P contained in the biosolids. While these could be reduced by applying lower rates, this would offset the benefits of replenishing organic matter in the low- fertility substrate. Future work should investigate the blending of biosolids with high-C, low-nutrient materials, such as wood-waste, to produce a mixture that favours the growth of NZ-native plants over exotic weeds. Such mixtures would also reduce NO₃⁻-N leaching losses that may otherwise occur with high rates of biosolids addition. Research should also determine the long-term effects of biosolids addition: this study tested seedlings and other native species <12 years old.
Open Access
Experimental investigation of the effects of topographic features on lava flow analogues.
(2024) Cusack, Dale
Lava flows are well-studied natural phenomena, yet their behaviour remains not fully understood. Given lava’s significant impact on people, infrastructure, and agriculture, it is important to explore further lava flow dynamics. Lava flows encounter a variety of topographic features as they move down the flanks of volcanoes. This thesis employs both numerical and experimental methods to model lava flow using analogues. We developed numerical simulations of lava flow behaviour based on the shallow water equations. In addition, we explored the flow of analogue fluids with varying rheological properties, over and around different topographies. We developed and implemented new methods and novel techniques to measure flow properties suitable to inform inversion models to infer underlying rheology. We compared a simple force balance model of the channelised flow of different rheologies around a bend to a shallow water equation model to analyse the effects of inertial displacement and the development of the wetted contact line between the channel wall and the fluid. This study extends our understanding of the force balance model by quantifying the effect of the sector angle of the bend’s influence on the flow behaviour and how the rheology and density of the flow, subtly affect the development of the wetted contact lines. Our analogue experiments show that in the case of wax with temperature-dependent Newtonian rheology flowing over channel-spanning weirs, we discovered that basal cooling influences the apparent thickness of the fluid as it approaches a weir. The expected thickness of the flow differed from the thickness predicted by the Nusselt equations, due to the wax freezing on the channel base. Our novel methodology showed that the internal temperature profile for a cooling wax flow was quadratic across the thickness of the flow. We completed analogue experiments that examined the flow of Herschel-Bulkley fluids as they navigated past surface-piercing occlusions, observing the impact of geometry on the flow. This study produced a dataset that can inform an inversion model to infer the flow’s rheology, a method tested and validated in Muchiri et al. (2024a). We finally show the implications of our results providing examples from recent eruptions that produce similar responses to flow in various topographic scenarios. In the future, these responses could be quantified and compared to inversion models similar to those developed in association with this work to provide real-time rheological measurement of flowing lava.
Open Access
Validation of s simulation of magnetic resonance temperature map.
(2024) Hawken, Elizabeth
Magnetic Resonance Thermometry (MRT) leverages temperature-dependent magnetic resonance (MR) parameters within MRI machines, finding applications in both research and clinical settings. Despite its wide range of applications, MRT has not been extensively simulated in MR simulators, limiting the ability to cheaply and easily determine the effects of various parameters on MRT. This thesis investigates the feasibility of implementing an MRT technique within an MR simulator to generate temperature measurements that align with physical observations. The study begins by selecting an appropriate MRT technique and MR simulator, followed by a brief characterisation focusing on the accuracy of temperature measurements of the chosen method. Subsequently, the simulator’s output is compared with experimental MRI data, specifically the temperature change data of a cooling cube. Proton Resonance Frequency (PRF) MRT was chosen, along with the MR simulator PhoenixMR. Results of the characterisation of the accuracy of the reconstructed temperature maps indicate that the type of sequence affects the accuracy of the temperature measurements from the MR simulator. Specifically, with a gradient echo sequence, the accuracy of static temperature change maps is greater than with a spin echo sequence; however, this is reversed for dynamic temperature change measurements over time. It was also found that using an exponential decay model within the MR simulator to model heat diffusion yields simulated outputs that agree with experimental temperature data within experimental uncertainty. Hence, it was determined that PRF MRT could be successfully simulated in PhoenixMR.
Open Access
An evaluation of a telehealth-delivered stepped care intervention for improving the sleep of autistic children.
(2024) Clarke, Monique
Autistic children experience high rates of sleep disturbance which can be chronic, severe, and have detrimental impacts on the physical health, wellbeing, and daytime functioning of children and their families. This, together with a rise in Autism prevalence, has resulted in increased demand for accessible, effective, and efficient models of delivering sleep support. While pharmacological interventions are common and effective, behavioural sleep interventions (BSI) present several advantages. These include well-established efficacy, evidence of maintained treatment effects, minimal harmful side effects, enhanced selfefficacy in caregivers, and the potential for generalisation to daytime behavioural difficulties. Therefore, BSI is recommended as the primary treatment for sleep problems in Autistic children. However, geographic isolation, cost, and travel constraints, coupled with a shortage of trained professionals, prevent access to support services for many families. To address this need, this doctoral research, comprised of four studies, investigated the use of stepped-care and telehealth for the delivery of BSI, where less resource-intensive interventions (e.g., online parent psychoeducation) are delivered first, and mid-to higher intensity supports (i.e., group or individualised parent coaching via videoconferencing) are reserved for those who require additional assistance. Integrating the stepped-care model with telehealth has the potential to increase the number of families who can be supported and overcome barriers such as travel costs, time off work, and the need for childcare, making it an accessible, cost-effective, and timely delivery model for improving the sleep of Autistic children. The primary objectives of the research were to: (a) determine whether parents of Autistic children could utilise online parent education to independently select intervention strategies with a high level of appropriateness and implement them with fidelity, and (b) generate positive changes in their child’s sleep. Secondary aims were to (c) ascertain the respective benefits of online group and individualised coaching as an adjunct to self-directed online parent education; (d) assess the maintenance of intervention effects; and (e) determine whether treating sleep problems via telehealth would produce collateral effects for children and their parents. The first study presents a systematic review of existing literature, identifying key components of telehealth-delivered behavioural interventions (TDBIs) for improving activities of daily living (e.g., eating, sleeping, personal hygiene practices) in Autistic children; finding that self-directed telehealth approaches can result in increased adaptive skills among Autistic children. However, in some cases, individualised coaching via videoconferencing may be necessary to achieve adequate child outcomes. Studies 2 and 3 were applied projects involving 21 Autistic children (4 girls and 17 boys, aged 3-17 years) and their parents. A single-case AB design was used to evaluate the utility of the Good Nights Programme, a stepped-care telehealth-delivered behavioural sleep intervention (TDBSI) delivered across three consecutive support levels: 1) self-directed online psychoeducation, 2) group coaching via videoconferencing, and 3) individualised coaching via videoconferencing. With the goal of enhancing intervention efficacy, Study 3 introduced changes to the first two intervention phases. As such, parents received additional individualised guidance in the self-directed phase through the provision of individualised tip sheets, and modifications were made to content and its delivery during group coaching sessions. Findings suggest that self-directed approaches comprising written material, instructional videos, and other downloadable assessment and intervention resources are minimally effective. However, augmenting online materials with individualised tip sheets may assist parents in identifying appropriate strategies; serving as a moderately effective, yet still efficient, first step of the stepped-care model. Group coaching and individualised parent coaching via videoconferencing show promise as higher-intensity support for parents who do not achieve satisfactory results initially, and treatment effects were generally maintained at follow-up. Finally, in an investigation of potential collateral effects, Study 4 demonstrated that improved sleep as a result of participation in the TDBSI may produce several additional collateral benefits for children and their parents, including reduced emotional and behavioural difficulties and increased health-related quality of life for children, and improved sleep quality and emotional wellbeing for parents. Overall, findings indicate TDBSI may provide an efficacious and acceptable alternative to face-to-face intervention, offering time-efficient and accessible support. Given the high prevalence of sleep disturbance in Autistic children, the convenience and accessibility of TDBSIs, and the potential for TDBSI to generate improved sleep and other collateral benefits for Autistic children and their parents, this research is clinically important. Future research should include group comparisons of the unique contributions and costbenefit analysis of each intervention phase, as well as identification of mediating and moderating factors impacting parent engagement, fidelity, and child treatment outcomes. The scalability of treatment should also be examined through open trials, using a telehealth stepped-care model to deliver BSI for Autistic children within real-world clinical settings.
Open Access
Mechanism of Action of Cell Envelope Proteinases on Selected Plant Proteins
(2024) Harper, Aimee
Ethical, environmental and health concerns around dairy products are driving a fast-growing industry for plant-based dairy alternatives, however, undesirable flavours and textures in current products are limiting their uptake into the mainstream. The proteolysis of caseins into peptides and amino acids in dairy products is a well understood process and is fundamental to developing the flavour and texture of fermented dairy products like cheese and yoghurt, yet proteolysis in plant-based alternatives is poorly understood. With this knowledge, bespoke fermentative processes could be engineered for specific food qualities in plant-based foods. This research aimed to lay the foundational groundwork for understanding how proteolysis, specifically that of cell envelope proteinases, works in plant-based dairy alternatives. A cell envelope proteinase from Lactococcus lactis, PrtP, was shown to be able to be expressed and purified in small amounts using Bacillus subtilis as an expression system. In the other component of this work, Lactic acid bacteria cultures were grown using plant proteins as the protein source, demonstrating that plant proteins are a viable substrate for these bacteria. Together, these results set the basis for future work on the detailed mechanisms of action of these proteinases in vitro and in vivo.
Open Access
Examining the association between victim impact statement emotions and sentencing decisions among mock jurors
(2024) Kilmore, Niamh
Victim Impact Statements (VIS) and their inclusion in criminal proceedings are controversial, largely because VIS are thought to be too emotional and as such may impair juror or judge decision-making. Across the literature, it does appear that presentation of a VIS results in harsher sentencing outcomes compared to when no VIS is present. There are, however, still some inconsistencies in these effects across the literature, potentially due to the differential impact of emotion expressed within the VIS on decision-making. The aim of the present study was to therefore examine the relationship between different emotions expressed within written VIS (including anger, sadness, fear and disgust) and sentencing decisions, including type of sentence or sentence restriction (ranging from no sentence to fines, unpaid community work or a prison sentence) and prison sentence length. This was examined within a sample of 491 mock juror participants residing in the U.K., recruited through Prolific. Participants were randomly assigned to read one of 10 VIS, and following VIS presentation, were asked to determine an appropriate sentence for the defendant, including sentence restriction as well as sentence length. The 10 VIS differed based on gender of the defendant (male or female) as well as the emotion expressed within the VIS (anger, disgust, fear, sadness, and a control). No significant effect of VIS emotion on sentence restriction or length was found. Participants who read one of the emotional VIS were, however, found to rate the impact the crime had on the victim as higher compared to those who read the control VIS. Male defendants were also found to receive longer prison sentences compared to females. This gender difference was found to be partially mediated by perceptions of dangerousness. These findings contribute to the ongoing debate around VIS and their role in criminal proceedings, as it suggests VIS including VIS emotions do not impact sentencing decisions.
Open Access
The influence of symptom severity and trauma experienced in childhood on negative emotionality in individuals diagnosed with attention deficit hyperactivity disorder
(2024) Szukiel, Ola Maria
Attention-deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental psychiatric disorder with prevalence rates in school-aged children ranging from 5-10%. Although not part of the current diagnostic framework, literature has consistently demonstrated that individuals with ADHD often encounter difficulties in the experience and regulation of negative emotions, including experiences of anger and hostility. This relationship has been associated with ADHD symptom severity. Additionally, literature in the ADHD domain has established a clear relationship between ADHD and childhood trauma with individuals diagnosed with ADHD being at greater risk for experiencing childhood traumas. Further, childhood traumas have been associated with elevated rates of negative emotionality. This study aimed to investigate the relationship between adolescent ADHD severity and retrospective report of childhood trauma in relation to late adolescent negative emotionality. Eighty-nine individuals with a childhood diagnosis of ADHD (mean age = 9.05 years, SD = 1.28), were seen at follow-up on average 9.30 (SD = 1.65) years later. Eighty- five non-ADHD controls were recruited at follow-up from similar demographic backgrounds. Relative to the comparison group, individuals diagnosed with ADHD had higher levels of emotional or physical abuse, and late adolescent anger and hostility. Mediation analyses revealed that the relationship between ADHD diagnostic status and adolescent anger and hostility was best explained by adolescent ADHD severity. Moderation analyses revealed that both emotional and physical abuse were independently associated with late adolescent negative emotionality. An interaction was revealed such that physical abuse was most predictive of anger when ADHD symptoms were low. Findings indicate that both ADHD severity and childhood abuse are independent predictors of late adolescent anger and hostility.
Open Access
Recovery, enhancement, and recreational fishing effects of New Zealand blackfoot abalone populations affected by cataclysmic disturbance.
(2024) Gerrity, Shawn Thomas
The 2016 Kaikōura earthquake was an unprecedented disturbance causing severe, long-lasting impacts to the coastal ecosystem along the northeast region of New Zealand’s South Island. The resulting coastal uplift ranged from 0.1 – 6.4 meters, with extensive die-off of intertidal and shallow subtidal communities and destruction of biogenic habitat across 140 km of productive coastline. Over subsequent years, earthquake-related stressors such as the erosion of uplifted reef platforms and inundation by mobile gravel and sediment caused further disturbances to recovering habitats and communities. The earthquake and ongoing stressors were particularly devastating to the endemic New Zealand blackfoot abalone (Haliotis iris), or pāua, a species of great cultural and commercial importance. Pāua are large marine gastropods that inhabit inshore rocky reefs throughout New Zealand, and comprise valued cultural, recreational and commercial fisheries. Adult pāua aggregate on wave-exposed subtidal rocky reefs while juveniles settle from plankton and recruit into cryptic habitat in the low intertidal and shallow subtidal zones. The shallow nature of juvenile pāua and their habitats made them vulnerable to coastal uplift, which caused widespread mortality of juveniles and adults, and habitat destruction. This prompted an emergency closure of the pāua fishery along the Kaikōura coastline, which had been a productive and lucrative part of New Zealand’s wild capture fishery. The closure created a need from managers, fishers and mana whenua for scientific information on the affected populations and their recovery dynamics through time. This research was initially designed to quantify earthquake effects on juvenile pāua populations and their habitats, but grew to include surveys of commercial enhancement efforts during the fishery closure, and effects of the re-opening of the fishery, particularly the shore-based recreational fishery, after 5 years of closure. Pāua abundances and sizes were assayed at 26 coastal sites over 7 years. This data set includes c. 5,000 quadrat samples and 26,500 pāua shell measurements, providing long-term demographic information from which population assessments are derived. The absence of fishing pressure post-earthquake led to a rapid increase in juvenile pāua abundance across all sites where appropriate rocky habitat was present. The mean density of juvenile pāua across all of the sampled shallow habitats increased from 1.61 to 6.34 pāua m-2 in the first three years, indicating there was good post-earthquake reproduction in the remaining adult stock. Significant shifts in population structure occurred over time and after 4 years 60% of the shallow pāua achieved the average size of maturity at c. 85 mm shell length. Over that time period, the abundance of legal-sized pāua (125 mm shell length) more than doubled; these were so abundant that nearshore populations resembled an historical unfished population. The surprisingly fast rebuilding of inshore populations was due not only to having no fishing pressure, but also having a productive spawning biomass, good recruitment over several years, and quick replacement of abundant juvenile habitat after the coastal upheaval. These results indicated good recovery and contributed to the ministerial decision to reopen the Kaikōura coastline to commercial and recreational fishing in 2021. One initiative in response to the earthquake disturbance was the 2018 release of 167,000 hatchery-reared juvenile “seed” pāua by commercial pāua divers into natural habitats to enhance recovery. Surveys of the abundance and growth of the seed pāua showed the average annual growth after 3 years was c. 28 mm yr-1, and that many seed had reached mature sizes, although growth was poorer at sites densely populated with natural recruits. Seed pāua comprised ca. 12% of sampled populations after three years, suggesting there was a reasonable return on seeding them out. Alternative pāua enhancement methods of outplanting larvae were also trialled. In 2019 the experimental release of 200,000 swimming larvae into natural settlement habitat in the field did not significantly increase the abundance of recruit pāua after 5 months, and survival was very poor at 0.02%. However, outplanting small rocks containing recently settled post-larvae resulted in a significant increase in pāua abundance compared to controls. Survival of outplants using this method was much better at 9% after 4 months. This is one of the few long-term assessments of commercial-scale enhancement and larval outplanting in New Zealand, and comprised a report to industry to guide future population enhancement efforts The final component in this research gauged recreational fishing effects from the 2021 re-opening of Kaikōura pāua fishery, during which the recreational catch allocation was 5 tonnes but actual harvest was an estimated 42 tonnes. Subtidal surveys of fished and unfished sites before and after the fishing season showed significant negative effects from shore-based fishing, with a 72% reduction of legal size pāua biomass at fished sites, and no significant changes at unfished controls. At one easily accessible reef next to the highway, an estimated 92% of the legally sized pāua (>125 mm) were harvested. Intertidal surveys at 26 sites before and after the fishing season showed a 66% reduction of the legal size pāua that accumulated over the five-year closure. A stage-based matrix model parameterised with data from this thesis estimated a population decline of 14% during the 3-month recreational fishing season. If the recreational harvest had been held to the 5 t allocation limit, the model estimated positive population growth of 4%, highlighting the importance of constraining the harvest to the set allocation. The results highlight the vulnerability of this abalone fishery to acute, short-term fishing pressure without adequate protective controls, and are relevant to global management of abalone fisheries, most of which are under intense fishing pressure. Altogether, this research depicts the recovery, restoration, and subsequent recreational overfishing of an iconic abalone population. The work will help improve management initiatives and future enhancement efforts of the fishery by providing long-term demographic data sets, informative analyses and models, and recommendations based on detailed, long-term field research. The findings are relevant internationally, with many countries experiencing collapses to their abalone fisheries and seeking sustainable solutions. Drawing from the insights gained from this research, I offer recommendations to improve the sustainability of New Zealand’s abalone populations. These include consideration of key aspects of their life history and habitat requirements, and modern approaches to abalone fishery management.
Open Access
Investigation of the Lactococcus cremoris (SK11) PIII-type PrtP cell-envelope proteinase as a template for substrate tailored CEP-based construct design.
(2024) Walker, Matt
Cell-envelope proteinases of lactic acid bacteria catalyse the first step in the proteolytic system. They break down proteins from the surrounding media into polypeptides, which are transported via the cells peptide transport system into the cell for further processing. To date, research suggests that changes in the physicochemical properties of residues within the active site region of cell-envelope proteinases are responsible for differences in experimentally determined proteolytic profiles. PrtP’s are a type of cell-envelope proteinase and are ideal templates for engineering tailored substrate specificity. I have focused on the PIII-type PrtP from Lactococcus cremoris, which has multiple domains, including an enzymatically active protease domain (PR domain). This research investigates whether there are non-conserved residues, particularly within the PR domain, that can be targeted to modify substrate specificity or catalytic activity. This is desirable because it will identify residues that can be targeted in protein engineering tailored to specific substrates. For example, to hydrolyse proteins that comprise plant-based milks. Using multiple sequence alignments and visualization of AlphaFold models, four residues within the PR domain that may be important for substrate specificity or catalytic activity are identified. Surprisingly, during this analysis an extended duplicate region within the PIII-type enzymes cell wall spanning domain was identified that may be a defining characteristic of PIII-type PrtPs. Given that the PIII-type PrtP from Lactococcus cremoris has recently been suggested as a promising template for site directed engineering of bespoke CEP-based constructs this work undertook bioinformatic analysis of this protein and attempted to express and purify constructs of this protein. Limitations including fragmentation of the construct and aggregation prior to size exclusion chromatography resulted in being unable to purify useful amounts of the constructs for use in characterization. In conclusion, potentially promising residues of PIII-type PrtP from Lactococcus cremoris that could be used for substrate tailored protein engineering were identified, as well as confirming the catalytic site residues. This information can be used by others to engineer PIII-type PrtP enzymes by substituting these residues to alter the catalytic activity and/or substrate specificity of the protein. This could have commercial utility by developing active constructs with specific substrate specificity that can be used, for example, in manufacturing of dairy alternatives, which had a market value of over US$2.4 Billion in 2023. Other important applications are as diverse as enrichment of foods via the generation of bioactive compounds and the development of enzymes that can break down waste for use in bioremediation efforts.
Open Access
Feeling safe to speak up : the role of leader behaviours and psychological safety in the formal hierarchical context of New Zealand legal practice.
(2024) Clarke, Emma Jane
This PhD research investigates the role of psychological safety in the relationship between leadership and employee wellbeing, and aims to advance our understanding of how leaders can foster a psychologically safe climate and enhance wellbeing in formal hierarchical work contexts. This research explores how psychological safety improves employees’ desire to continue working in high-demand, high-stress workplaces and to provide deeper insight into employee turnover and retention in the context of New Zealand legal practice. Psychological safety is defined as a belief among team members who respect and trust each other that they are safe to take interpersonal risks, make mistakes, and address issues without fear of being rejected by their leader and fellow team members. Law firms often have a formal hierarchical structure, which is characterised by significant power differences and control mechanisms that can prevent employees from raising concerns with their leaders about issues in the workplace. The present research contributes to legal practice by highlighting the important role that leaders play in hierarchical workplaces where turnover is high, particularly among early career women, and where many lawyers suffer from poor wellbeing. Three empirical studies were conducted with two data collections. A quantitative survey approach was used for data collection in the first study and interviews were conducted for the second and third studies. Survey results show that psychological safety is a mechanism through which leadership influences employee wellbeing (Study 1). Leaders who develop high-quality relationships with employees by displaying vulnerability and through role modelling capabilities and emotional regulation skills; who address wellbeing issues fairly and promptly; and who provide regular and timely feedback, help to improve perceptions of psychological safety and employee wellbeing (Study 2). When leaders provide employees with access to resilience-enabling resources, while fostering a climate of psychological safety, this contributes to a greater desire to continue working in high-demand roles, particularly for women (Study 3). This study uncovered gendered differences connected to strategies for coping with high workload and stress, as well as differing views on the factors that influence lawyers to leave legal practice. The research presented in this thesis has multidisciplinary applications and demonstrates that when leaders behave in a way that counteracts the barriers brought on by formal hierarchical structures, perceptions of psychological safety will improve and positively influence employee wellbeing and retention. To reduce dysfunctional turnover, leaders should focus on supporting employee resilience, while developing a learning culture where employees feel comfortable voicing their concerns and ideas without the fear of retribution.
Open Access
Feasibility study of groundwater nitrate predictions benefitting from iron and manganese measurements.
(2024) Van Der Boom, Romy
Rising nitrate in groundwater is a global environmental and health concern. This is a growing issue for the Canterbury plains in New Zealand, as increasing groundwater nitrate levels have been linked to intensification of land use. It is important to capture information about the trends in groundwater from when they were pristine and unaffected in order to isolate the cause of the increasing trends. It is difficult to establish trends in nitrate concentrations without historic data, however other parameters (such as iron and manganese) that have a more extensive sampling history may be used with statistical approaches to fill these gaps. Here, a model was created to predict nitrate prior to it being included in water quality testing, when iron or manganese was sampled. This study uses a parsimonious modelling approach which includes the use of multiple linear regression (MLR), random forest (RF) and boosted regression tree (BRT) models. A number of features (year, well depth, coordinates, dissolved manganese, dissolved iron, land use, soil type, season and rainfall) are used in the model as they were expected to influence trends in nitrates. But the only significant factors were well depth, year, land use, and latitude (following the direction of groundwater flow). The model's predictive accuracies were measured through use of an R² value. The R² values are highest for the BRT meaning that it is the best model for predicting nitrate, followed by RF models which also have relatively high R² scores compared the MLR model. While this study agrees with correlations between nitrate, iron, and manganese observed in previous research, using these relationships for predictive purposes proved ineffective and thus this study was unable to fill the historic data gaps in nitrate trends. A limitation of this study is that the groundwater is mainly oxic in the study area and further work is needed in mixed or reduced groundwater environments. Oxic environments have high oxygen content, while reduced environments refers to environments where oxygen is absent or very low.
Open Access
Structural characterisation of C. jejuni glycosyltransferases and M. tuberculosis isoprenyldiphosphate synthases.
(2024) Titterington, James Alexander
This work investigates the isoprenyl diphosphate synthase Rv2173 of Mycobacterium tuberculosis through elucidation and analysis of three 2.0-2.2 Å resolution structures; APO and two substrate bound forms with isopentenyl diphosphate and dimethylallyl diphosphate. This is supported by examination of the oligomeric state of Rv2173 via native mass spectrometry, size exclusion chromatography, small angle x-ray scattering and other methods. Analysis reveals a canonical all alpha-helical trans-isoprenyl diphosphate synthase fold that is dimeric for each form and aligns with literature predictions as to the expected product determination pathway of similar Mycobacterium tuberculosis isoprenyl diphosphate synthases. Additionally, this work investigates the glycosyltransferases of the Campylobacter jejuni N-linked glycosylation pathway, PglC, PglA and PglJ respectively. This is achieved through optimisation of the expression constructs, bacterial systems and purification methodology for each protein, supported by mass spectrometry, detergent analysis and circular dichorism. Exhaustive crystallisation trials of these glycosyltransferases were attempted across a range of commercial and bespoke conditions which provides a primer for promising formulations that can be trialled further. Where experimentally-determined structures were unavailable for analysis, in silico prediction models have been used to estimate hypothetical tertiary structure organisations. Understanding the hypothetical nature of these reviews, a discussion on the validity and state-of-the-art in regards to in silico modelling is also considered.
Open Access
An investigation of perceived barriers and cultural factors in treatment for traumatic brain injury in Aotearoa New Zealand.
(2024) Tsvuura, Joy
Prior research has shown that the harm due to Traumatic Brain Injury (TBI) is greater among Māori and Pacific populations in Aotearoa New Zealand. One potential factor that contributes to this disparity is differential access to health care. The main goal of the present study was to determine if Māori and Pacific persons perceived greater barriers to seeking medical treatment after sustaining a TBI than other ethnic groups. To address this question, we conducted an online survey in which students from the University of Canterbury community (N = 116) responded to questions relating to knowledge and beliefs about TBI, the importance of cultural attitudes when seeking medical treatment after a TBI, barriers to treatment, and responses to a hypothetical scenario in which a child has sustained a head injury. Due to the relatively small sample size, results from Māori and Pacific participants (n = 44) were compared against New Zealand European/Other groups (n = 72). Responses to subsets of questions for cultural attitudes and barriers to treatment had adequate internal reliability (Cronbach’s alpha = .732 and .742, respectively), so these items were summed to yield separate scales. Results showed that the Māori/Pacific group perceived significantly greater barriers to treatment than the NZ European/Other group (Ms = 38.3 and 32.6, respectively, d = 1.029), whereas there was no significant difference in terms of the importance of cultural factors (Ms = 31.7 and 30.1, respectively). Responses to questions on knowledge and beliefs about TBI and reactions when a child has a head injury generally showed no significant difference between groups. Overall, these results suggest that Māori and Pacific persons perceive greater barriers to accessing treatment after a TBI, which may contribute to disparities in health outcomes. Healthcare practitioners need to understand and address these barriers of TBI within Māori and Pacific populations to mitigate the negative outcomes associated with the reluctance to seeking medical treatment. By acknowledging cultural differences, practitioners may engage more effectively those needing treatment and improve health outcomes.
Open Access
Externalising behaviour of adolescents exposed prenatally to opioids : preliminary findings from a regional birth cohort.
(2024) McLeod, Hannah
In New Zealand, Methadone Maintenance Therapy is recommended for pregnant women with an opioid dependency. However adverse outcomes for infants born to these women have been consistently observed, with suggestion that with age, these children may be at an increased risk of adverse outcomes, including cognitive impairment, emotional and behavioural difficulties, and poorer educational outcomes. Despite these concerns, the longer-term impact of prenatal opioid and methadone exposure on older children and adolescents remains under studied. To address this gap, the current study aimed to characterise the extent of caregiver-reported externalising behaviour problems in children and adolescents exposed prenatally to opioids at ages 9 and 16-18 years, compared to a non-opioid exposed control group. Additionally, the study aimed to describe the neuropsychological functioning, including measures of inhibitory control, reward sensitivity and risk-taking propensity in the same cohort, and to examine the associations these outcomes had with externalising behaviour problems at age 18. Drawing on data from a subsample of a prospective longitudinal study, the study included data at two time points; 9 and 16-18 years (18years). The sample at 9 years included 85 children in the opioid-exposed group (OE) and 99 children in the non-opioid control group (NE). The sample at 18 years included 31 adolescents in the OE group and 45 adolescents in the NE group. Externalising behaviour problems were assessed at ages 9- and 18-years using caregiver reports from the Behaviour Assessment Schedule for Children (BASC). Laboratory-based tasks were utilized to assess inhibitory control (The Stop Signal Task), reward sensitivity (Delay Discounting Task), and risk-taking propensity (Balloon Analogue Risk Task) at age 18 years. Results showed that at both ages 9 and 18 years, children/adolescents in the OE group exhibited significantly higher levels of conduct problems (p <.001), attention problems (p <.001), hyperactivity problems (p <.001) and overall externalising problems (p <.001) compared to children/adolescents in the NE group. The age of onset and persistence of such problems was particularly concerning, with approximately one third of adolescents in the OE group from the 18-year sample exhibiting onset of externalising problems at age 9 that persisted into adolescence (p <.01). Additionally, at age 18, adolescents in the OE group exhibited diminished inhibitory control on the Stop Signal Task (p=.05), and a heightened sensitivity to rewards in the Delay Discounting Task (p=.04) compared to the NE group. However risk-taking propensity did not significantly differ between the groups on the BART. Finally, externalising behaviour problems were significantly associated with poorer inhibitory control and heightened reward sensitivity at age 18 in the OE group. These findings indicate that children and adolescents born to mothers with an opioid dependency during pregnancy may be at an increased risk of developing externalising behaviour problems, including, conduct, hyperactivity, and attention problems during middle childhood and adolescence. They may also experience deficits in cognitive processes such as inhibitory control and reward sensitivity that may pose additional risk of later impulsive and risk-taking behaviour, drug use, driving accidents, mental health challenges, and academic and occupational difficulties. These findings raise concerns about the behavioural development of this population of high-risk adolescents. Without targeted prevention, intervention and adequate support for these adolescents and families, these challenges may persist and lead to serious negative outcomes.
Open Access
An investigation into the effects of taking orally-absorbed broad-spectrum micronutrients for the treatment of stress and emotion dysregulation.
(2024) Katta, Nurina Maria
Background: Research has shown micronutrient capsules can improve mental wellbeing in clinical and nonclinical recipients, including stress and emotion dysregulation. As previous evidence has shown that individuals can struggle with taking capsules, investigation into alternative modalities of taking micronutrients is important. This thesis investigated the effects of orally absorbed broad-spectrum micronutrients on stress and emotion dysregulation. Method: To assess the effects of this new modality of taking micronutrients, two randomised trials were conducted. The first study (Study 1) was a double-blind, randomised placebo-controlled trial aiming to investigate the efficacy and safety of treating stress and wellbeing with a broad-spectrum micronutrient powder that is absorbed via the oral mucosa. Seventy-two mild to severely stressed students, assessed using the Depression Anxiety Stress Scale 21 (DASS-21), were randomised to placebo or micronutrients and took one dose per day for four weeks. Symptoms of stress, depression, anxiety, irritability, anger, diet, and side effects were measured with online questionnaires every two weeks. Study 2 researched the effect of the same broad-spectrum micronutrient product tested in Study 1 on emotion dysregulation in 5-to-10-year-old children using a three-phased randomised open-label waitlist-controlled study design. The primary outcome measures were the Revised Clinician-rated Temper and Irritability Scale (CL-ARI) and the Clinical Global Impressions-Improvement Scale (CGI-I). Forty-eight children with moderate to severe symptoms of irritability were randomised to an initial treatment group (ITG) or a waitlist control group (IWLG), who took the micronutrients with a four-week delayed start. The two groups alternated between taking the micronutrients for four weeks or having a four-week break. For the last three months of the trial, both groups took the micronutrients continuously. Results: In Study 1, there were no group differences on the primary outcome measures of stress (DASS-21) (d = 0.15, p = .525) and self-reported improvement (Modified Clinical Global Impressions Improvement Scale (M-CGI-I), with 17.1% of the micronutrient and 16.2% of the placebo group identifying themselves as ‘much’ to ‘very much’ improved. However, the micronutrient group experienced a statistically significant greater reduction in irritability (d = 0.54, p = .024) and anger (d = 0.62, p = .011) relative to placebo, measured with the Affective Reactivity Scale (ARI) and the Abbreviated Profile of Mood States (POMS), respectively. No group differences were found on the remaining measures, with both groups showing significant improvements, and there were significantly more headaches and drowsiness reported in the micronutrient group. Belief in treatment assignment was significantly correlated to self-reported improvement (r = -0.247, p = .049). Overall, seven (10%) dropped out with no group differences. In Study 2, at the end of the RCT phase, the micronutrient group showed largely reduced symptoms of irritability compared to the IWLG (CL-ARI; d = 1.25, p < .001), and 67% in the ITG compared to 8% in the IWLG ‘much’ or ‘very much’ improved (CGI-I). Additionally, the micronutrient group showed large improvements in emotional and behavioural difficulties (Strength and Difficulties Questionnaire (SDQ); d = 1.28, p < .001). The IWLG reported significantly more headaches (p = .040) and sweating (p = .037), and overall adherence rates were high (93%). Overall, seven participants (14.5%) dropped out with no group differences. Conclusion: This new modality of taking micronutrients was no better than the placebo in reducing stress; however, both studies indicated that orally absorbed micronutrients are safe to take, and Study 2 showed that they can effectively improve emotion dysregulation in children. Future double-blinded, randomised, placebo-controlled trials are needed to support these findings