Otago University Research Archive
Not a member yet
10699 research outputs found
Sort by
Approximating Solutions to Convection-Diffusion Equations by Tensor Train Decompositions
No full textA finite volume method for solving general time-homogeneous convection-diffusion equations with zero source term is presented. Computational efficiency of the method is improved by performing linear algebra in the tensor train format. To our knowledge this is the first time that the tensor train format and the finite volume method have been combined for this purpose.
Finite volume methods, tensors and tensor decompositions are reviewed by summarising prominent texts on each respective topic. We extend a finite volume method for convection equations to include diffusion terms and show that the method preserves integrals and positivity. The time discretisation uses an explicit Euler step that leads to a sequence of linear systems of equations defining a discrete approximation of the solution at some final time. The recurrence is stepped forwards in time by performing algebraic operations in the tensor train format. In some cases, this leads to a significant increase in computational efficiency.
We use our tensor train implementation of the finite volume method to approximate the allele frequency spectrum in three populations by solving the Wright-Fisher diffusion equation. Our method did not appear to outperform current methods for approximating the allele frequency spectrum. However, we develop some interesting and efficient tools for approximating the allele frequency spectrum if the solution to the Wright-Fisher diffusion equation is known in tensor train format
Computer Vision for Measuring Boxes: a comparison of Model-based Bayesian Inference and Convolutional Neural Networks
No full textThis thesis compares two approaches for measuring the dimensions of boxes using computer vision (CV). The first approach is model-based Bayesian Inference (MBI), which uses a geometric cuboid model as well a camera-conveyor system model. The second approach is using Convolutional Neural Networks (CNNs). The methods were compared on: statistical scoring rules that were applied to posterior probability density function estimates, training and testing times, robustness to noise addition, and cuboid edge roundedness. Convolutional Neural Network (CNN) training data was generated by photo-realistic rendering of computer generated 3D CAD models, consisting of: 6,000 training images, 2,000 validation images, 2,000 testing images spread across five textures. Training was performed using Keras. MCMC was implemented in Python 3 using the same test data as used with CNN models. Methods of the CNN and MBI approaches were also briefly compared on images of real boxes. It was found that Corner Detection (CD) performance was the strong limiting factor for MBI performance, which was able to form tight posterior estimates when complete CD occurred. Due to low mixing, sometimes MCMC sampling runs became stuck in local minima, causing overly tight estimates and leading to poor scores. With full CD and good mixing, MCMC scores would tend to outperform CNN scores. MCMC suffered from an approximately 1000 times longer testing time than CNN (70 s vs 70 ms). However, CNN required significant time (strongly reduced by GPU) and data to pre-train the model before use. The robustness of the techniques were measured by systematically adding gaussian noise to images, as well as rounding the edges of the boxes. It was found that above a threshold noise variance of 100 (images used a 255 RGB colour scale) the CD failed to detect corners, breaking the MBI and causing poor performance compared to CNN, which broke more gracefully. Likewise, when box edges were rounded it was found that above an edge rounding threshold of 0.15 (0=cuboid and 1=sphere) CD failed, breaking the MBI and causing poor performance compared to CNN, which broke more gracefully. A single-image-input (SII) CNN model demonstrated greater robustness with respect to noise addition than a two-image-input (TII) CNN model. There was negligible difference between SII and TII with respect to box edge rounding
Health and wellbeing of under-25 year olds in the Midland region 2019
No full textIn this report the New Zealand Child and Youth Epidemiology Service (NZCYES) presents information to assist in the planning and funding of services that can collectively improve, promote and protect the health and wellbeing of children and young people aged under-25 years. This is the final of three age-based reports: indicators presented in 2017 had a focus on the first five years of life, and the 2018 report had a focus on the health and wellbeing of under-15 year olds.
Data for the indicators presented in this report were extracted in 2019 from a range of routinely collected national datasets. The report provides an analysis of the most recent data available for each indicator at the time of writing. Unadjusted rates should be interpreted in light of the differing patterns in age structure, ethnic composition, social and material deprivation in each DHB and in Aotearoa overall. Evidence for good practice is presented for each section, compiled from published scholarly literature and from publicly available guidelines, policies, and reports. Where possible, the evidence for good practice includes discussion of equity issues relevant to each indicator, to inform service planning and delivery.
The two review topics included in this report were selected by DHB representatives: Alcohol use in young people by Lee Smith and Promoting mental wellbeing in schools by Judith Adams and Georgia Richardson. These two sections of the report can inform strategies to promote health and wellbeing for all young people. Intervention and treatment services, supportive environments, and healthy cultural norms around drinking are some key components to addressing hazardous alcohol consumption in Aotearoa’s youngest generations. Through school-based initiatives, services can support the mental wellbeing of children and adolescents and thus invest in their long-term flourishing.
Navigating sexual and reproductive health is important to the lives of many young people. Information on reproductive planning and pregnancy rates can provide an indication about the accessibility of services and provide an indication about the future social and economic participation of this generation of young people and the sustainability of the overall population and economy.1 These indicators are presented in the section on Reproductive health.
The section on Mental Health presents information on the prevalence of selected mental health diagnoses in young people, the mental health services utilised by young people and the hospitalisations of young people that are associated with mental health issues.
Selected indicators about substance use and smoking, alcohol and drug service utilisation, and alcohol and drug hospitalisations are presented in the Substance use section. These indicators are important for overall wellbeing, growth, and long-term health of children and young people and inextricably linked to other wellbeing measures presented in the 2019 report.
The United Nations Convention on the Rights of the Child establishes that every child is deserving of a state-level commitment towards the promotion of their social, spiritual and mental wellbeing, as well as towards their protection from all forms of violence and harm.2 The section on Safety and Security provides an overview of indicators relating to the protection of children and young people in Aotearoa, including information about assault and self-harm.
Supporting and adding value to the lives of children and young people with cancer is an important part of planning and funding decisions and is presented in the section on Cancer.
The report appendices describe the processes used in compiling information for these reports, including the methods used to develop evidence for good practice, and the statistical methods used in the data analyses. The appendices give further information about the data sources used for the indicators in the report, explanation about classification of ethnicity and social and material deprivation, and a list of the clinical codes relevant to each indicator.
In summary, the 2019 report on health and wellbeing of under-25 year olds presents data and interpretation on a set of relevant indicators extracted from national health datasets. The data used were the most recent available at the time of writing, and provide a snapshot of achievements and challenges in these areas. This report cannot address questions that require outpatient data, as these are not yet available at a national level. Developing systems that can provide a fuller picture of outpatient and primary health care data is important to inform child health service planning at national and DHB levels. The NZCYES is liaising with the Ministry of Health as they develop and roll out a patient flow system that will include primary care and outpatient data
Health and wellbeing of under-25 year olds in MidCentral and Whanganui 2019
No full textIn this report the New Zealand Child and Youth Epidemiology Service (NZCYES) presents information to assist in the planning and funding of services that can collectively improve, promote and protect the health and wellbeing of children and young people aged under-25 years. This is the final of three age-based reports: indicators presented in 2017 had a focus on the first five years of life, and the 2018 report had a focus on the health and wellbeing of under-15 year olds.
Data for the indicators presented in this report were extracted in 2019 from a range of routinely collected national datasets. The report provides an analysis of the most recent data available for each indicator at the time of writing. Unadjusted rates should be interpreted in light of the differing patterns in age structure, ethnic composition, social and material deprivation in each DHB and in Aotearoa overall. Evidence for good practice is presented for each section, compiled from published scholarly literature and from publicly available guidelines, policies, and reports. Where possible, the evidence for good practice includes discussion of equity issues relevant to each indicator, to inform service planning and delivery.
The two review topics included in this report were selected by DHB representatives: Alcohol use in young people by Lee Smith and Promoting mental wellbeing in schools by Judith Adams and Georgia Richardson. These two sections of the report can inform strategies to promote health and wellbeing for all young people. Intervention and treatment services, supportive environments, and healthy cultural norms around drinking are some key components to addressing hazardous alcohol consumption in Aotearoa’s youngest generations. Through school-based initiatives, services can support the mental wellbeing of children and adolescents and thus invest in their long-term flourishing.
Navigating sexual and reproductive health is important to the lives of many young people. Information on reproductive planning and pregnancy rates can provide an indication about the accessibility of services and provide an indication about the future social and economic participation of this generation of young people and the sustainability of the overall population and economy.1 These indicators are presented in the section on Reproductive health.
The section on Mental Health presents information on the prevalence of selected mental health diagnoses in young people, the mental health services utilised by young people and the hospitalisations of young people that are associated with mental health issues.
Selected indicators about substance use and smoking, alcohol and drug service utilisation, and alcohol and drug hospitalisations are presented in the Substance use section. These indicators are important for overall wellbeing, growth, and long-term health of children and young people and inextricably linked to other wellbeing measures presented in the 2019 report.
The United Nations Convention on the Rights of the Child establishes that every child is deserving of a state-level commitment towards the promotion of their social, spiritual and mental wellbeing, as well as towards their protection from all forms of violence and harm.2 The section on Safety and Security provides an overview of indicators relating to the protection of children and young people in Aotearoa, including information about assault and self-harm.
Supporting and adding value to the lives of children and young people with cancer is an important part of planning and funding decisions and is presented in the section on Cancer.
The report appendices describe the processes used in compiling information for these reports, including the methods used to develop evidence for good practice, and the statistical methods used in the data analyses. The appendices give further information about the data sources used for the indicators in the report, explanation about classification of ethnicity and social and material deprivation, and a list of the clinical codes relevant to each indicator.
In summary, the 2019 report on health and wellbeing of under-25 year olds presents data and interpretation on a set of relevant indicators extracted from national health datasets. The data used were the most recent available at the time of writing, and provide a snapshot of achievements and challenges in these areas. This report cannot address questions that require outpatient data, as these are not yet available at a national level. Developing systems that can provide a fuller picture of outpatient and primary health care data is important to inform child health service planning at national and DHB levels. The NZCYES is liaising with the Ministry of Health as they develop and roll out a patient flow system that will include primary care and outpatient data
Health and wellbeing of under-25 year olds in the South Island 2019
No full textIn this report the New Zealand Child and Youth Epidemiology Service (NZCYES) presents information to assist in the planning and funding of services that can collectively improve, promote and protect the health and wellbeing of children and young people aged under-25 years. This is the final of three age-based reports: indicators presented in 2017 had a focus on the first five years of life, and the 2018 report had a focus on the health and wellbeing of under-15 year olds.
Data for the indicators presented in this report were extracted in 2019 from a range of routinely collected national datasets. The report provides an analysis of the most recent data available for each indicator at the time of writing. Unadjusted rates should be interpreted in light of the differing patterns in age structure, ethnic composition, social and material deprivation in each DHB and in Aotearoa overall. Evidence for good practice is presented for each section, compiled from published scholarly literature and from publicly available guidelines, policies, and reports. Where possible, the evidence for good practice includes discussion of equity issues relevant to each indicator, to inform service planning and delivery.
The two review topics included in this report were selected by DHB representatives: Alcohol use in young people by Lee Smith and Promoting mental wellbeing in schools by Judith Adams and Georgia Richardson. These two sections of the report can inform strategies to promote health and wellbeing for all young people. Intervention and treatment services, supportive environments, and healthy cultural norms around drinking are some key components to addressing hazardous alcohol consumption in Aotearoa’s youngest generations. Through school-based initiatives, services can support the mental wellbeing of children and adolescents and thus invest in their long-term flourishing.
Navigating sexual and reproductive health is important to the lives of many young people. Information on reproductive planning and pregnancy rates can provide an indication about the accessibility of services and provide an indication about the future social and economic participation of this generation of young people and the sustainability of the overall population and economy.1 These indicators are presented in the section on Reproductive health.
The section on Mental Health presents information on the prevalence of selected mental health diagnoses in young people, the mental health services utilised by young people and the hospitalisations of young people that are associated with mental health issues.
Selected indicators about substance use and smoking, alcohol and drug service utilisation, and alcohol and drug hospitalisations are presented in the Substance use section. These indicators are important for overall wellbeing, growth, and long-term health of children and young people and inextricably linked to other wellbeing measures presented in the 2019 report.
The United Nations Convention on the Rights of the Child establishes that every child is deserving of a state-level commitment towards the promotion of their social, spiritual and mental wellbeing, as well as towards their protection from all forms of violence and harm.2 The section on Safety and Security provides an overview of indicators relating to the protection of children and young people in Aotearoa, including information about assault and self-harm.
Supporting and adding value to the lives of children and young people with cancer is an important part of planning and funding decisions and is presented in the section on Cancer.
The report appendices describe the processes used in compiling information for these reports, including the methods used to develop evidence for good practice, and the statistical methods used in the data analyses. The appendices give further information about the data sources used for the indicators in the report, explanation about classification of ethnicity and social and material deprivation, and a list of the clinical codes relevant to each indicator.
In summary, the 2019 report on health and wellbeing of under-25 year olds presents data and interpretation on a set of relevant indicators extracted from national health datasets. The data used were the most recent available at the time of writing, and provide a snapshot of achievements and challenges in these areas. This report cannot address questions that require outpatient data, as these are not yet available at a national level. Developing systems that can provide a fuller picture of outpatient and primary health care data is important to inform child health service planning at national and DHB levels. The NZCYES is liaising with the Ministry of Health as they develop and roll out a patient flow system that will include primary care and outpatient data
Textiles and compression of the lower limb
No full textCompression is a common therapy for management of chronic disease, including oedema of the lower limb. Modern compression interventions exert pressure on the lower limb through use of one or more materials which exert pressure against the limb over time. Where these materials are textiles, they range from elastic to inelastic, and are produced using knitting, weaving, or other textile technologies which can be manipulated to control performance properties. The radius of curvature at any cross-section of the lower limb (i.e. calf (gastrocnemius), tibial crest (anterior edge of the tibia bone)) is irregular, and differs among individuals and populations. Thus, understanding of both the materials/textiles and the human body is needed if the most appropriate compression device and treatment strategy is to be used. Neither is independent of the other.
Current understanding of pressure generated by conventional lower limb compression products such as bandages and stockings is based on Laplace’s law. According to this law, the larger the radius of a cylinder, the larger is the wall tension required to withstand a given internal fluid pressure. This theory has been interpreted mathematically with several researchers modifying the Laplace model to better estimate the interface pressure on skin of a lower limb. These estimates have been checked against conventional compression products but not air pneumatic compression devices (PCD), nor have they been checked against models of varying radii.
An air pneumatic compression device consists of an inflatable bladder/s that encircles the lower limb. Investigation into effects of air pneumatic devices as part of sustained compression therapy has led to the conclusion that compression treatment does indeed, offer benefits. However, participants in human trials have been shown to resist or abandon compression treatments due to discomfort and low sensorial acceptability of the treatment involved. These findings suggest pneumatic compression devices need to create a satisfactory environment if the treatment is to be effectively employed. Thus, the aim of this investigation was to develop a theoretical model to predict the pressure exerted by an air pneumatic compression device on an irregularly shaped lower limb, and design a compression device which can create a satisfactory environment on the oedematous lower leg.
Two theoretical models, first considering the lower leg as circular in shape, and second as elliptic in shape were developed to predict the pressure generation by an air pneumatic compression device. In order to validate the model, compression sleeves for three positions on a lower leg manikin were fabricated. A pressure instrument for measuring the effect of the compression sleeves on this leg manikin was developed. The theoretical model developed for an elliptic shaped lower leg predicted the pressure more accurately than that predicted by the circular shape.
Two approaches to development of the textile-based compression device were taken: creation of a tubular braided structure, and creation of a multi-layered textile/silicone structure.
The experimental set-up for characterising the materials included (a) single layers of two next-to-skin knit fabrics in both relaxed and extended conditions, (b) two layers of silicone, and (c) a multi-layered assembly with and without vents (each next-to-skin extended fabric in combination with two layers of silicone). Key performance properties in question included thermal and water-vapour resistance, water-vapour and air permeability, and drying rate. Next-to-skin fabrics were examined in a relaxed form and also in arrangements simulating use: that is, fabric extension during use was measured in the length and width directions for three different locations on a lower leg manikin. Specimens in these locations were cut, stretched, and fitted to a pre-prepared frame simulating arrangement during use. When testing multi-layer ensembles, one layer of extended next-to-skin fabric (technical face uppermost), and two layers of silicone were stacked on each other, with silicone layers placed uppermost. To determine the effect of vent variables i.e. shape, size, and number of vents on fabric properties, vent variables were optimised. Results for single-layer fabric (relaxed and extended arrangements), and multi-layer assembly with and without vents were examined.
As expected structural properties of the knits (thickness, mass) dominated thermal resistance in the multi-layered assembly and the silicone layers rendered the multi-layered assembly impermeable to water-vapour. Results confirmed the need for some form of ventilation to manage water-vapour from a user’s skin to the environment. By creating the eighteen circular vents with 314 mm2 area of each vent across the silicone layers, the water-vapour resistance of the multi-layer assembly dropped significantly from non-detectable values (very high) to below ~300 m2Pa/W for the multi-layer assembly with the heavy weight fabric and ~225 m2Pa/W for multi-layer assembly with the light weight fabric.
Recommendations are made: i.e. examine the effect of different thickness of silicone on performance properties of multi-layer assemblies, examine the friction between human skin and layers of multi-layer assemblies, human trials of sensory and thermo-physiological performance properties of newly developed pneumatic compression device, and re-consider the tubular braids with different compositions of yarns and structures
Young Chinese and Functional Foods for Mobility Health: Perceptions of Importance, Trust, and Willingness to Purchase and Pay a Premium
No full textConsumers’ desire to enhance diet and health has become a driver for the development of functional food products. China, with one of the largest markets in the world, offers huge potential for these foods. In the context of functional foods, specifically related to mobility health, this study aimed to understand Chinese consumers’ perceptions of the importance of these foods, trust, and willingness to purchase and pay a premium for such foods. A mixed-methodological approach using both focus groups and a survey was used to collect data from Chinese living in New Zealand. Findings show Chinese consumers place a high level of importance on their mobility health. Level of importance increased when asked about the believed importance of this area later in life. Key factors influencing Chinese consumers’ willingness to purchase functional foods were also identified: the carrier/nutrient combination; trust in the product’s country of origin and in the various institutions that may be involved in the production of functional food products; trust in both the product brand and how it is advertised; health motivation; and price. The study offers the food industry insights into the development and marketing of mobility-related functional foods targeted to this market
It’s not just about the destination, but also the journey: Reflections on research with Indigenous women food growers
No full textcultural values, aspirations, and tikanga (protocols). While the research explored how Māori women are reclaiming the food system and promoting agroecology, food self-reliance, and alternative visions based on Māori cultural values and traditions, this article is a reflective work based on my experiential learning through the process of utilizing a participatory methodology and kaupapa Māori. Nonetheless, I touch upon key research findings. The vastly opposing worldviews between Indigenous women promoting agroecological farming and the industrial model of food production are representative of the conflicting values of an Indigenous versus an academic worldview. In this paper, I set out a series of reflections on working with Indigenous Māori women within a research context; the challenges and tribulations that were overcome; as well as how kaupapa Māori, an Indigenous methodology, expands on participatory research
Impact of sugar-sweetened beverage taxes on price, import and sale volumes in an island: interrupted time series analysis
No full textObjective
To evaluate the impact of changes in import tariffs on sweetened beverages.
Design
Interrupted time series analysis examined sweetened beverage tariff increases of 40% to 60% in 2008 and to 75% in 2012; and an approximately 11% decrease in 2014 when an excise tax replaced the tariff. Post-tax trends were compared with a counterfactual modelled on the pre-tax trend for: quarterly price of an indicator beverage, monthly beverage import volumes (both 2001 to 2017), and quarterly sales volumes (2012 to 2017). In a controlled analysis taxed beverage imports were compared to a sugary snacks control.
Setting
Cook Islands
Participants NA
Results
In the first year, the 2008 tariff increased the price of the selected indicator soft drink by 7.3% (CI: 6.3% to 8.3%) but after the 2012 tariff increase it decreased by 13.9% (CI: -14.9% to -12.8%). At the same time the import volumes of taxed beverages decreased by 13.2% (CI: -38.1% to 17.8%) and 2.9% (CI: -41.6% to 72.5%) respectively; and decreased by 24.8% (CI: -36.9 to -9.8) and 10.2% (CI: -37.1 to 37.5) in the controlled analysis. After the 2014 tax decrease, the price of the indicator soft drink decreased by 23.6% (CI: -26.0% to -21.1%), sweetened beverage imports increased by 4.5% (CI: -39.5% to 156.0%), and sales of full-sugar soft drinks increased by 31% (CI: -21% to 243%).
Conclusions
The increased import tariffs on sweetened beverages appeared to be effective for reducing import volumes, but this was partly reversed by the reduced tax/tariff in 2014.Peer Reviewe
Subjective well-being buffers the effects of social exclusion and expression of in-group favouritism in real groups
No full textHuman beings are social animals. People need to connect with one another in order to thrive and survive. Yet people are socially excluded by others on a daily basis. A growing body of research reveals that such outcomes can (a) thwart the basic psychological needs of self-esteem, meaning, control and belonging and (b) promote negative outcomes such as prejudice, hostility and in-group favouritism. In spite of such findings, it is also true that not everyone, who experiences exclusion or ostracism, will become depressed or respond negatively to others via hostility and prejudice. As it stands we know little about the factors that determine reactions to ostracism. The primary aim of this thesis was to redress this issue by assessing the extent to which subjective well-being might serve as buffer in reducing the negative effects of ostracism on psychological needs and in-group favouritism. To this end four experiments were conducted.
Study 1, sought to examine the link between well-being and in-group favouritism amongst men and women. The results showed that, (a) low baseline levels of subjective well-being were associated with greater patterns of in-group favouritism and (b) greater patterns of in-group favouritism led to increased levels of well-being.
Study 2, sought to examine the link between well-being and in-group favouritism, following threat manipulated through progressive ostracism amongst minimal groups. The findings revealed that participants tended to show in-group favouritism regardless of psychological threat, and that people with high well-being showed more in-group favouritism.
Study 3 compared the differences in psychological threat as a function of progressive ostracism as opposed to constant ostracism. The data suggest that the latter was more psychologically threatening. Although there were no differences in perceived exclusion between the two methods of ostracism, participants subjected to constant ostracism reported lower levels of control and meaningful existence.
Study 4 used constant ostracism to subsequently test the extent to which subjective well-being, in the context of exposure to pleasant media, buffered the expression of in-group favouritism and threats to psychological needs. The findings indicate that (a) the in-group was evaluated less favourably than the out-group, and the more excluded participants felt, the lower they rated the in-group and (b) exposure to pleasant media content, prior to ostracism feedback served to buffer psychological needs. Ostracised participants with higher (as opposed to lower) well-being, reported higher levels of control and meaningful existence when exposed to pleasant media content