Streamlines for Motion Planning in Underwater Currents

Motion planning for underwater vehicles must consider the effect of ocean currents. We present an efficient method to compute reachability and cost between sample points in sampling-based motion planning that supports long-range planning over hundreds of kilometres in complicated flows. The idea is to search a reduced space of control inputs that consists of stream functions whose level sets, or streamlines, optimally connect two given points. Such stream functions are generated by superimposing a control input onto the underlying current flow. A streamline represents the resulting path that a vehicle would follow as it is carried along by the current given that control input. We provide rigorous analysis that shows how our method avoids exhaustive search of the control space, and demonstrate simulated examples in complicated flows including a traversal along the east coast of Australia, using actual current predictions, between Sydney and Brisbane.Comment: 7 pages, 4 figures, accepted to IEEE ICRA 2019. Copyright 2019 IEE

Digital Intervention With Lifestyle Coach Support to Target Dietary and Physical Activity Behaviors of Adults With Nonalcoholic Fatty Liver Disease: Systematic Development Process of VITALISE Using Intervention Mapping

Background: Non-alcoholic fatty liver disease (NAFLD) is linked to excess calorie consumption, physical inactivity and being overweight. Patients with NAFLD can halt or decelerate progression, and potentially reverse their condition by changing their lifestyle behaviour. National and international guidelines recommend the use of lifestyle interventions, however there remains a discordance between published guidelines and clinical practice. This is primarily due to a lack of NAFLD-specific lifestyle interventions to support weight loss and improve liver function. Objective: To use Intervention Mapping to systematically develop a digital intervention to support patients with NAFLD to initiate and maintain changes to their dietary and physical activity behaviour to promote weight loss. Methods: Intervention Mapping consisted of 6 steps. A needs assessment with primary and secondary healthcare professionals and patients with NAFLD (step 1). Identification of the social cognitive determinants of change and behavioural outcomes of the intervention (step 2). Linking social cognitive determinants of behavioural outcomes with behaviour change techniques to effectively target dietary and physical activity behaviour (step 3). Step 4 involved the development of a prototype digital intervention that integrated the strategies from step 3, and the information content identified as important for improving knowledge and skills from steps 1 and 2. Step 5 involved development of an implementation plan with a digital provider of lifestyle behaviour change programmes to NHS patients using their delivery platform and lifestyle coaches. Finally, step 6 involved piloting the digital intervention with patients to obtain data on access, usability and content. Results: A digital intervention was developed consisting of eight modules, self-regulatory tools and provision of telephone support by trained lifestyle coaches to help facilitate behavioural intention, enactment and maintenance. A commercial provider of digital lifestyle behaviour change programmes enrolled 16 patients with NAFLD to the prototype intervention for 12 consecutive weeks. Eleven of the 16 participants successfully accessed the intervention and continued to engage with the content following initial log-in (on average four times over the piloting period). Most frequently accessed modules were “welcome to the programme”, “understanding NAFLD”, and “food and NAFLD”. Goal setting and self-monitoring tools were accessed on 22 occasions (four times per tool on average). Three out of eleven participants requested access to a lifestyle coach. Conclusions: Intervention Mapping provided a systematic methodological framework to guide a theory- and evidence-informed co-design intervention development process with patients and HCPs. The digital intervention with remote support by a lifestyle coach was acceptable to patients with NAFLD and feasible to deliver. Issues with initial access, optimisation of information content and promoting the value of remote lifestyle coach support require further development ahead of future research to establish intervention effectiveness

Lifestyle Behavior Change in Patients With Nonalcoholic Fatty Liver Disease:A Qualitative Study of Clinical Practice

Nonalcoholic fatty liver disease (NAFLD) is the most common liver condition worldwide and is linked largely to obesity and inactivity. Lifestyle modification is the primary treatment for NAFLD targeting dietary change, physical activity, and exercise to facilitate weight loss and weight loss maintenance. This has been shown to reduce steatosis and ameliorate steatohepatitis. European Clinical Practice Guidelines for the management of NAFLD highlight the importance of targeting lifestyle behavior change in all patients with NAFLD regardless of disease severity. These guidelines recommend combining dietary restriction and a progressive increase in aerobic exercise and resistance training with a focus on tailoring interventions to the individual patient. Practice guidelines published by the American Association for the Study of Liver Diseases recommend weight loss of at least 3% to 5% of body weight via hypocaloric diet or diet combined with increased physical activity but state that these lifestyle interventions should target patients with nonalcoholic steatohepatitis. Given the benefits of lifestyle behavior change, this study explored the perceptions surrounding clinical care as currently offered to patients with NAFLD. The aim of this study was to establish whether current provision of lifestyle behavior change support is sufficient, whether health care professionals believe they have the tools to target lifestyle behavior changes effectively, and how targeting diet and physical activity/exercise to facilitate weight loss and weight loss maintenance in practice can be improved from the perspective of health care professionals and patients

Intercomparison of shallow water bathymetry, hydro-optics, and benthos mapping techniques in Australian and Caribbean coastal environments

Science, resource management, and defense need algorithms capable of using airborne or satellite imagery to accurately map bathymetry, water quality, and substrate composition in optically shallow waters. Although a variety of inversion algorithms are available, there has been limited assessment of performance and no work has been published comparing their accuracy and efficiency. This paper compares the absolute and relative accuracies and computational efficiencies of one empirical and five radiative-transfer-based published approaches applied to coastal sites at Lee Stocking Island in the Bahamas and Moreton Bay in eastern Australia. These sites have published airborne hyperspectral data and field data. The assessment showed that (1) radiative-transfer-based methods were more accurate than the empirical approach for bathymetric retrieval, and the accuracies and processing times were inversely related to the complexity of the models used; (2) all inversion methods provided moderately accurate retrievals of bathymetry, water column inherent optical properties, and benthic reflectance in waters less than 13 m deep with homogeneous to heterogeneous benthic/substrate covers; (3) slightly higher accuracy retrievals were obtained from locally parameterized methods; and (4) no method compared here can be considered optimal for all situations. The results provide a guide to the conditions where each approach may be used (available image and field data and processing capability). A re-analysis of these same or additional sites with satellite hyperspectral data with lower spatial and radiometric resolution, but higher temporal resolution would be instructive to establish guidelines for repeatable regional to global scale shallow water mapping approaches