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Determining nitrate tolerances of Canterbury stygofauna
(2024) Close, Matthew Gregory
Nitrate is a contaminant of concern for New Zealand groundwater. Not only does nitrate have negative impacts on human health, but the effect it has on our groundwater communities is unknown.
In this project I investigate the sensitivity of New Zealand stygofauna to nitrate using stygofauna sourced from an alluvial aquifer in the Canterbury Plains. Various methods were tested to optimise future experimentation in this field, including trialling of an artificially made up zero nitrate groundwater solution and determining preference toward different types of in-lab habitats. LC50 and EC10 estimates were produced for the most common taxa for acute (7 days) and chronic (28 days) time periods. Eight separate nitrate experiments were conducted with durations ranging between 5 weeks and 29 weeks, specimen counts for each experiment ranged from 8 to 31, and a variety of taxa were tested. Amphipods were the most common, followed by copepods, with a few specimens of flatworms, isopods and ostracods.
In order to gain more insight into the lifestyles of these creatures, their life histories were also
investigated. Amphipods and copepods were successfully bred in the lab, and tests were conducted on the juveniles of amphipods, copepods, and ostracods. Different food types were trialled, with the most successful being small quantities of oat. Moulting behaviour was also investigated throughout the project, as well as a pathogen that targeted some of the crustaceans.
Nitrate was found to consistently have a negative effect on survival, with all significant estimates predicting LC50 values between 370 and 550mg/L nitrate at an acute timescale, and LC50 values
between 190 and 360mg/L nitrate at a chronic timescale. EC10 values were more difficult to estimate as they required more specimens to provide the necessary statistical power, but were predicted to be below 160mg/L nitrate at an acute timescale, and below 30mg/L nitrate at a chronic timescale.
The type and impact of sleep problems in children with chronic health conditions and parental beliefs and help-seeking behaviour
(2024) Morgan, Kylie
Children with chronic health conditions (CHC) experience a wide range of co-occurring challenges beyond the condition itself. One of the most common of these is sleep problems. Sleep is essential for children's healthy development. However, research suggests that children with CHC experience high rates of sleep problems and are at risk of further adverse impacts owing to the complex interaction between sleep, their CHC and wider well-being. Without effective treatment, these sleep problems are likely to persist, leading to further ongoing adverse impacts on children and their families. In spite of the adverse consequences of sleep problems, we know little about sleep problems in CHC both in New Zealand and globally, including the impact of sleep problems on families and parental attributions, causal beliefs, and help-seeking behaviour concerning their child's sleep problems. This thesis aimed to gain an understanding of parents' perceptions of the common types and topography of children's sleep problems; the impacts of children's sleep problems on the child and their family; parents' attributions and causal beliefs about their child's sleep problems; and parents' help-seeking behaviour for sleep problems in children with CHC in New Zealand.
This study included 91 primary caregivers of children (aged 0-18yr) with a diagnosed CHC and a parent-reported sleep problem who live in New Zealand. Respondents were recruited using snowball sampling. Information was gathered through an online survey consisting of 60 questions and delivered using Qualtrics over a 10-month period. Data were analyzed using descriptive statistics. Based on the data, 86% of parents reported their child experienced insomnia, with sleep onset latency and frequent night wakening’s the most common. Parents reported several secondary impacts of their child's sleep problem on the child and the family. The most common were sleep, mental health and well-being. Out of the 91 respondents, 70% of parents believed their child's CHC caused their sleep problems, and 66% of parents believed the sleep problem would not be resolved without treatment. Only 47% of parents indicated that they had tried a sleep intervention. Medical professionals were the most common source of information for parents who tried a sleep intervention, with two-thirds of parents reporting they were advised by medical professionals that the sleep problem was treatable. The most commonly tried sleep interventions were non-behavioural/non-medical sleep interventions, such as nutritional supplements and homeopathic/alternative remedies. However, prescribed medication, dietary changes and co-sleeping were reported to be the most effective in treating the sleep problem.
The findings of this study have several clinical implications. Firstly, it supports the need for parents to receive education on sleep and sleep problems for children with CHC, which may address any incorrect beliefs parents may have. Secondly, it supports the need for health professionals to integrate regular screening for sleep problems. Thirdly, health professionals may benefit from education on sleep problems for children with CHC and the current research on sleep interventions in addressing sleep problems (e.g., CBT-I, sleep hygiene education) for this population group. Further research is needed to understand if parent’s attributions and help-seeking behavior changes over the course of children's CHC. Further research is also needed to understand health professionals' knowledge of sleep problems in this population group and their causal beliefs about sleep problems. Lastly, there is a great need for urgent research to identify sleep interventions that are safe, feasible, and effective to reduce the adverse impacts of insufficient sleep on the child, their CHC, and their family.
Deviant Encodings
(2003) Copeland, B. Jack; Proudfoot, D
What is computation? We describe a number of related techniques that enable Turing
machines to solve the halting problem. In each case, the machine’s (supposedly
impossible) behaviour is made possible by a feature of the encoding scheme employed
either to represent the input or to represent the output. Some means of excluding these
deviant encodings is required when using the Turing-machine concept to define the
traditional set of computable functions. The exercise of quarantining deviant encodings
casts fresh light on Turing's historic definition of computability.
Sustainability-Oriented Optimization and Decision Making of Community Buildings under Seismic Hazard
(MDPI AG, 2023) Anwar, GA; Hussain, M; Akber, MZ; Khan, MA; Khan, Aatif Ali
Optimization and decision-making tools are often utilized to enhance the performance of community buildings under extreme events, but this may compromise the ability of future generations to enhance performance. Hence, a sustainability-oriented approach is required to enhance the performance of community buildings under extreme events. In this context, this paper proposes an optimization and decision-making framework considering multiple performance indicators, including socioeconomic and environmental consequences as well as retrofit costs. These performance indicators are assessed by utilizing performance-based assessment methodologies in terms of sustainability dimensions. The performance indicators are then exploited as multiple performance objectives in a genetic optimization to determine the Pareto optimal solutions. Finally, the Pareto optimal solutions are utilized for decision making to extract ideal solutions for the given retrofit costs. The ideal solutions provide trade-offs between the consequences of extreme events and the retrofit costs required to reduce the consequences of extreme events.
Passive injection: A strategy for mitigating reservoir pressurization, induced seismicity and brine migration in geologic CO2 storage
(Elsevier BV, 2014) Dempsey, David; Kelkar, S; Pawar, R
Many technical, regulatory and public perception challenges remain to be addressed before large-scale deployment of CO2 geologic storage becomes a reality. Two major risks associated with injection of CO2 into the subsurface are the possibility of induced earthquakes compromising long-term seal integrity, and the displacement of saline brines resulting in contamination of shallow groundwater. Both induced seismicity and brine migration are caused by elevated pressures in the storage formation owing to the relative incompressibility of water. Here, we describe a strategy, termed passive injection that can be used to inject large amounts of CO2 in a storage formation with no increase, temporary or long-term, in reservoir pressure. Passive injection relies on the strategic placement of brine production wells to create negative pressure gradients that result in CO2 entering the formation at ambient pressure. Injection occurs at the intersection of pressure-depth profiles for a surface-pressurized, low-density CO2 column and a hydrostatic column of formation fluid. A multi-stage, square-ring well configuration is envisaged, in which brine production wells are repurposed for CO2 injection upon CO2 breakthrough, and the next concentric ring of production wells installed at a greater distance.Numerical simulations of passive injection are presented using the coupled thermo-hydro-mechanical (THM), multi-fluid, multi-phase numerical simulator FEHM. We consider CO2 injection into a 3km-deep, closed reservoir over a period of 50 years, with up to four stages of injection and production depending on well-spacing and production pressures. Storage rates as high as 4Mtyr-1 at 70% utilization of the reservoir pore volume are achieved under optimum conditions. Long-term mass production of brine is approximately 1.7 times that of CO2 sequestered. Geomechanical effects due to reservoir drawdown, cooling near injection wells, and surface subsidence are modeled. The risk of induced seismicity is quantified in terms of the Coulomb Failure Stress (CFS) for an optimally oriented fault in an extensional tectonic regime. Injection and production-induced changes in pressure and CFS confirm that, both during and at the conclusion of injection, (i) reservoir pressure is everywhere less than or equal to its initial value; and (ii) the risk of induced seismicity is everywhere reduced or unchanged. Thus, the primary risks of brine migration outside the primary reservoir and induced seismicity compromising seal integrity are neutralized.Passive injection produces large quantities of brine, the treatment and disposal of which represents an additional economic burden to CO2 geologic storage operations. Unless additional revenue streams or economies of scale can be leveraged, these costs are likely to limit the viability of the proposed scheme to only the most economically favorable sites. © 2014 The Authors.