From visuomotor control to latent space planning for robot manipulation

Deep visuomotor control is emerging as an active research area for robot manipulation. Recent advances in learning sensory and motor systems in an end-to-end manner have achieved remarkable performance across a range of complex tasks. Nevertheless, a few limitations restrict visuomotor control from being more widely adopted as the de facto choice when facing a manipulation task on a real robotic platform. First, imitation learning-based visuomotor control approaches tend to suffer from the inability to recover from an out-of-distribution state caused by compounding errors. Second, the lack of versatility in task definition limits skill generalisability. Finally, the training data acquisition process and domain transfer are often impractical. In this thesis, individual solutions are proposed to address each of these issues. In the first part, we find policy uncertainty to be an effective indicator of potential failure cases, in which the robot is stuck in out-of-distribution states. On this basis, we introduce a novel uncertainty-based approach to detect potential failure cases and a recovery strategy based on action-conditioned uncertainty predictions. Then, we propose to employ visual dynamics approximation to our model architecture to capture the motion of the robot arm instead of the static scene background, making it possible to learn versatile skill primitives. In the second part, taking inspiration from the recent progress in latent space planning, we propose a gradient-based optimisation method operating within the latent space of a deep generative model for motion planning. Our approach bypasses the traditional computational challenges encountered by established planning algorithms, and has the capability to specify novel constraints easily and handle multiple constraints simultaneously. Moreover, the training data comes from simple random motor-babbling of kinematically feasible robot states. Our real-world experiments further illustrate that our latent space planning approach can handle both open and closed-loop planning in challenging environments such as heavily cluttered or dynamic scenes. This leads to the first, to our knowledge, closed-loop motion planning algorithm that can incorporate novel custom constraints, and lays the foundation for more complex manipulation tasks

Explorations of structure and choice in taxing capital gains: New Zealand tax experts' perspectives

This study explores the key issues, aspects, and attributes concerning capital gains tax (CGT) to enable the formulation of policy guidelines that might be used if a CGT were considered in New Zealand. It contends that the development of the New Zealand’s policy on taxing capital gains has continued in a somewhat ad hoc and inconsistent fashion. The lack of a uniform approach to capital gains taxation has resulted in detailed, but complex, legislation which leads to “policy inconsistencies and unintended incentives built into the tax structure” (Oliver, 2001, pp. 80 – 81). The study bridges the divide between theoretical analysis of CGT and implementation issues on operating a CGT. It attempts to address one primary research question and an associated secondary question. The primary research question is: should capital gains be taxed more comprehensively than at present? As a start, it examines the two important issues surrounding income definition and the capital/income distinction. In this regard, the research first attempts to identify the definition(s) of capital gains from the New Zealand perspective(s). This is followed by investigating the key areas of the tax system in order to seek the best way of taxing capital gains. This study also attempts to address the secondary research question, i.e., why (or why not) do the tax experts favour (or oppose) a comprehensive CGT? In this respect, this study identifies 23 factors/issues that are related to the tax experts’ attitudes towards a particular form of a CGT model (i.e., current hybrid approach, a realisation-based CGT or an accrual-based CGT). A mixed-methods design has been adopted in this study involving both a quantitative (survey) and a qualitative (interview) method in analysing the data to determine the tax experts’ overall perceptions of a CGT in New Zealand and the CGT adoption factors which influenced them. One important finding of the comparative analyses was that all tax experts generally agreed that the lack of a comprehensive CGT could provide more significant tax planning opportunities. However, many tax experts did not support the comprehensive income concept as they disagreed with the benefits derived from the gains in horizontal equity through adopting a CGT. This study has identified several important policy issues and reviewed their implication for the adoption of a CGT in New Zealand. The finding of the study revealed that the tax experts strongly supported the exemption of the gains on disposal of a taxpayer’s main residence and the tax preference for inflation adjustment. Another important policy issue is the implementation of an accrual-based CGT. Most tax experts considered a realisation-based CGT would be better than an accrual one. In particular, they were concerned about the liquidity problems and the compliance costs involved in an accrual-based CGT regime i.e., the annual valuation of all assets. These findings represent a first step towards a theoretical CGT framework. It is hoped that the knowledge gained in this study would give a greater understanding into the practical decision-making process that could result in a better public acceptance for a tax reform

Association between vitamin D and cardiovascular disease: Findings from a national study

ABSTRACT Introduction Many studies have investigated the association between vitamin D and cardiovascular disease (CVD), but literature has shown various results. The aim of this study was to investigate the role of vitamin D in CVD. Methods Data source The data were obtained from the 2015-2018 National Health and Nutrition Examination Survey database and included adults aged 20 years and older with a history of CVD. Descriptive statistics for participants’ demographics, vitamin D levels, CVD status, and risk factors were reported. Chi-square tests and t-tests were performed to examine differences in participant characteristics among those who had CVD and did not have CVD. Regression models were used to explore the association between vitamin D levels and CVD. Results A total of 9,825 participants took part in this study with an average age of 50.28 years. Majority were female (52.1%) and Non-Hispanic White (34%). Most had normal vitamin D levels (64.8%) and had never been told that they had CVD (89.5%). Individuals with vitamin D deficiency or insufficiency had a higher likelihood of having CVD than those with normal vitamin D levels. Conclusions Both vitamin D deficiency and insufficiency were associated with an increased risk of CVD. Healthcare professionals may consider recommending the intake of vitamin D supplements to improve and prevent cardiovascular health in adults. Keywords: Vitamin D, cardiovascular disease, healthcare, supplements Word count: 24