Comparison of some solution concepts for linear first-order hyperbolic differential equations with non-smooth coefficients

We discuss solution concepts for linear hyperbolic equations with coefficients of regularity below Lipschitz continuity. Thereby our focus is on theories which are based either on a generalization of the method of characteristics or on refined techniques concerning energy estimates. We provide a series of examples both as simple illustrations of the notions and conditions involved but also to show logical independence among the concepts.Comment: 35 page

Eliciting real cravings with virtual food: Using immersive technologies to explore the effects of food stimuli in virtual reality

In this paper, we explore the current technical possibilities of eating in virtual reality (VR) and show how this could be used to influence eating behaviors. Cue-based exposure therapy is a well-known method used to treat eating disorders. There are several benefits to using VR in combination with cue-based therapy. However, before VR-based cue-exposure can be used for therapeutic purposes, the ability of the VR environment to elicit craving responses in participants must be assessed. This was the objective of the first part of the study, where we assessed whether our VR environment elicited food craving responses in participants. Results showed that our VR environment elicited food craving responses: Salivation Magnitude, Food Craving State and Urge to Eat was significantly different from the neutral baseline. In addition, results showed that food cravings measured through the salivation magnitude in response to the virtual condition were not significantly different from the real condition, thus showing that VR had a comparable effect on producing food cravings. The second part of the study was conducted to determine whether the addition of olfactory and interaction cues in VR increased the development of food cravings. The results of this part showed that adding synthetic olfactory cues, paired with visual cues, to our system, provided a significant further increase in food cravings. Our results demonstrate that the use of food cues in VR can increase the development of food cravings and that it is possible to provide a simple yet convincing eating experience in VR. Inevitably, food interaction in VR is still underexplored territory and further research is needed to improve utility and application in disciplines related to food and eating

Using Virtual Reality to Enhance Food Technology Education

The use of Virtual Reality (VR) technology combined with 360-degree images and videos provide an opportunity for teachers to bring students into the classroom even when they are located somewhere else. During the COVID-19 lockdown and pandemic, with students across the world forced into home-based learning via remote teaching, a VR classroom shows potential as a tool for adding depth to their learning. The possibility of immersing students in a virtual environment could provide an answer to motivation and engagement issues for today’s students as well as a solution to some of the current constraints faced by teachers. In particular, VR has the potential to increase the time students are able to spend in (virtual) environments that are suitable for teaching and learning practical skills. With the cost of VR equipment reducing rapidly and the increasing quality of virtual experiences, it appears VR is on the tipping-point of becoming a regular part of school programmes.This article outlines the development and testing of a VR Classroom for the delivery of a food-based lesson with middle school students in a New Zealand school. Kitchens are a costly commodity for schools and the obvious health and safety issues make teaching practical cooking skills challenging. With a focus on student engagement and motivation, data is collected from observation of students using the virtual classroom and a post-test survey. Results show that students were highly motivated and perceived the VR classroom as fun to use

Design Insights to Support the Development of Effective Virtual Reality Nicotine and Vaping Dependency Therapy Scenarios for Future Telehealth

Vaping, or the use of electronic nicotine delivery systems (ENDS), has grown rapidly worldwide and is becoming an epidemic among youth in many countries. Invented as a method to help to quit smoking, ENDS are very popular, reaching increasing numbers of users and becoming a health concern. Virtual reality technology (VRT) represents an important tool for conducting addiction-associated interventions, including telemedicine. The design and quality of virtual reality scenarios (VRS) used for VR interventions are fundamental. How well VRS can replicate real-world scenarios has an impact on how realistic the VR immersion experiences are. Thus, VRS development influences therapeutic outcomes. VRT is used for interventions and treatments for smoking-related nicotine addiction but has yet to be validated for vaping-related disorders. Since vaping represents a technological step forward in nicotine consumption, the accurate contextualization of environments surrounding vapers is fundamental for developing advanced VR tools for the prevention and treatment of vaping disorders. Here, we present the results of focus group discussion with young vapers in New Zealand. The knowledge gained from this study will be used to design VRS for cue exposure and reactivity as a first step toward developing effective solutions for vaping disorders using VR interventions and telemedicine

Design Insights to Support the Development of Effective Virtual Reality Nicotine and Vaping Dependency Therapy Scenarios for Future Telehealth

Vaping, or the use of electronic nicotine delivery systems (ENDS), has grown rapidly worldwide and is becoming an epidemic among youth in many countries. Invented as a method to help to quit smoking, ENDS are very popular, reaching increasing numbers of users and becoming a health concern. Virtual reality technology (VRT) represents an important tool for conducting addiction-associated interventions, including telemedicine. The design and quality of virtual reality scenarios (VRS) used for VR interventions are fundamental. How well VRS can replicate real-world scenarios has an impact on how realistic the VR immersion experiences are. Thus, VRS development influences therapeutic outcomes. VRT is used for interventions and treatments for smoking-related nicotine addiction but has yet to be validated for vaping-related disorders. Since vaping represents a technological step forward in nicotine consumption, the accurate contextualization of environments surrounding vapers is fundamental for developing advanced VR tools for the prevention and treatment of vaping disorders. Here, we present the results of focus group discussion with young vapers in New Zealand. The knowledge gained from this study will be used to design VRS for cue exposure and reactivity as a first step toward developing effective solutions for vaping disorders using VR interventions and telemedicine

Prop-oriented world rotation: enabling passive haptic feedback by aligning real and virtual objects in virtual reality

Passive haptics have long been used to enhance the user’s experience in virtual reality (VR). However, creating props to be used in a virtual environment can be a complicated and lengthy process. Current research looks to create passive haptic props based on the layout of, or objects in, the user’s real environment. However, we identify three key limitations of current research. Firstly, procedural generation introduces many unknown variables into the design process, which complicates applying such techniques to scenarios requiring knowledge of the virtual environment’s layout ahead of time. Furthermore, such techniques limit the size and dimensions of the virtual space to that of the real space. Lastly, current research necessitates pre-scanning or real-time scanning of the user’s real environment, often requiring specialist equipment and expertise, thus limiting its generalisability. This research proposes PropOrientedWorldRotation, a technique that attempts to answer the aforementioned limitations and simplify the process of adding haptic feedback to VR applications. We implemented this technique in a demonstration game and give an overview of the steps taken to apply the technique in a real context. We analysed the demonstration system’s performance and conducted an initial user evaluation in three different physical environments. While our stress test of the system’s performance highlights the necessity for certain optimisations in complex environments, our initial user feedback suggests that users experienced a stronger sense of presence and feelings of safety in our passive haptics-enhanced environment. Hence, we conclude that our proposal has the potential to enhance experiences in VR with haptic feedback

Ex-Cit XR: Expert-elicitation and validation of Extended Reality visualisation and interaction techniques for disengaging and transitioning users from immersive virtual environments

This research explores visualisation and interaction techniques to disengage users from immersive virtual environments (IVEs) and transition them back to the Augmented Reality mode in the real world. To gain a better understanding and novel ideas, we invited eleven Extended Reality (XR) experts to participate in an elicitation study to design such techniques for disengagement. From the elicitation study, we elicited a total of 132 techniques for four different scenarios of IVEs: Narrative-driven, Social-platform, Adventure Sandbox, and Fast-paced Battle experiences. Through extracted keywords and thematic analysis, we classified the elicited techniques into six categories of Activities, Breaks, Cues, Degradations, Notifications, and Virtual Agents. We shared our analyses on users’ intrinsic motivation to engage in different experiences, subjective ratings of four design attributes in designing the disengagement techniques, Positive and Negative Affect Schedules, and user preference. In addition, we gave the design patterns found and illustrated the exemplary user cases of Ex-Cit XR. Finally, we conducted an online survey to preliminarily validate our design recommendations. We proposed the SPINED behavioural manipulation spectrum for XR disengagement to guide how the systems can strategically escalate to disengage users from an IVE

Advancing prosociality in extended reality: systematic review of the use of embodied virtual agents to trigger prosocial behaviour in extended reality

Attention has increasingly been focused on the potential of Extended Reality (XR) and Embodied Virtual Agents (EVAs) to significantly influence human behaviour. While an expanding body of literature explores the individual impacts of XR and EVAs, there is a noticeable gap in the literature regarding their combined influence on eliciting prosocial behaviour in humans. The purpose of this systematic review is to explore this intersection, offering insights into their multifaceted effects on human prosocial behaviour and the implications for future research and development of EVAs in XR. Our systematic review adopted a scoping approach due to the limited number of studies directly focused on EVAs (i.e., autonomously computer-controlled entities). Despite this, we observed the use of various forms of virtual characters (VCs) to elicit prosocial behaviour. An in-depth analysis of 15 selected studies indicates complex patterns in how XR and VCs affect users’ prosocial behaviour and interactions. Our review suggests that there is promising potential for EVAs to promote prosocial behaviour. However, further research is necessary to identify the design and interaction-related attributes that enhance the effectiveness of these technologies, particularly for socially interactive EVAs in XR environments

Deciphering sources of PET signals in the tumor microenvironment of glioblastoma at cellular resolution

Various cellular sources hamper interpretation of positron emission tomography (PET) biomarkers in the tumor microenvironment (TME). We developed an approach of immunomagnetic cell sorting after in vivo radiotracer injection (scRadiotracing) with three-dimensional (3D) histology to dissect the cellular allocation of PET signals in the TME. In mice with implanted glioblastoma, translocator protein (TSPO) radiotracer uptake per tumor cell was higher compared to tumor-associated microglia/macrophages (TAMs), validated by protein levels. Translation of in vitro scRadiotracing to patients with glioma immediately after tumor resection confirmed higher single-cell TSPO tracer uptake of tumor cells compared to immune cells. Across species, cellular radiotracer uptake explained the heterogeneity of individual TSPO-PET signals. In consideration of cellular tracer uptake and cell type abundance, tumor cells were the main contributor to TSPO enrichment in glioblastoma;however, proteomics identified potential PET targets highly specific for TAMs. Combining cellular tracer uptake measures with 3D histology facilitates precise allocation of PET signals and serves to validate emerging novel TAM-specific radioligands