Qualitative physics in virtual environments

In this paper, we describe a new approach to the creation of virtual environments, which uses qualitative physics to implement object behaviour. We adopted Qualitative Process Theory as a qualitative reasoning formalism, due to its representational properties (e.g., its orientation towards process ontologies and its explicit formulation of process’ pre-conditions). The system we describe is developed using a game engine and takes advantage of its event-based system to integrate qualitative process simulation in an interactive fashion. We use a virtual kitchen as a test environment. In this virtual world, we have implemented various behavioural aspects: physical object behaviour, complex device behaviour (appliances) and “alternative” (i.e. non-realistic) behaviours, which can all be simulated in user real-time. After a presentation of the system architecture and its implementation, we discuss example results from the prototype. This approach has potential applications in simulation and training, as well as in entertainment and digital arts. This work also constitutes a test case for the integration of an Artificial Intelligence technique into 3D user interfaces

The CaveUT system:Immersive entertainment based on a game engine

We describe recent developments in the CaveUT software, which supports immersive virtual reality installations based on the Unreal Tournament game engine. CaveUT implements several high-end VR features such as real-time stereoscopy with head and hand tracking. We demonstrate the use of CaveUT in the SAS Cube™, a PC-based CAVE™-like immersive four-screen display. One of the main advantages of the system is to support fully immersive VR while retaining the game engine’s advanced features for interaction and behavioral (or AI) systems. We illustrate the use of CaveUT on two installations: an artistic VR installation and an immersive interactive storytelling system

New behavioural approaches for virtual environments

We describe a new approach to the behaviour of 3D environments that supports the definition of physical processes and interactive phenomena. The work takes as a starting point the traditional event-based architecture that underlies most game engines. These systems discretise the environments' Physics by separating the objects' kinematics from the physical processes corresponding to objects interactions. This property has been used to insert a new behavioural layer, which implements AI-based simulation techniques. We introduce the rationale behind AI-based simulation and the techniques we use for qualitative Physics, as well as a new approach to world behaviour based on the induction of causal impressions. This is illustrated through several examples on a test environment. This approach has implications for the definition of complex world behaviour or non-standard physics, as required in creative applications

CaveUDK: a VR game engine middleware

Previous attempts at developing immersive versions of game engines have faced difficulties in achieving both overall high performance and preserving reusability of software developments. In this paper, we present a high-level VR middleware based on one of the most successful commercial game engines: the Unreal® Engine 3.0 (UE3). We describe a VR framework implemented as an extension to the Unreal® Development Kit (UDK) supporting CAVE"-like installations. Our approach relies on a distributed architecture reinforced by specific replication patterns to synchronize the user's point of view and interactions within a multi-screen installation. Our performance benchmarks indicated that our immersive port does not affect the game engine performance, even with complex real-time applications, such as fast-paced multiplayer First Person Shooter (FPS) games or high-resolution graphical environments with 2M+ polygons. A user study also demonstrated the capacity of our VR middleware to elicit high spatial presence while maintaining low cybersickness effects. With free distribution, we believe such a platform can support future Entertainment and VR research

The Role of Ultrasound Compared to Biopsy of Temporal Arteries in the Diagnosis and Treatment of Giant Cell Arteritis (TABUL): a diagnostic accuracy and cost-effectiveness study

Background: Giant cell arteritis (GCA) is a relatively common form of primary systemic vasculitis, which, if left untreated, can lead to permanent sight loss. We compared ultrasound as an alternative diagnostic test with temporal artery biopsy, which may be negative in 9–61% of true cases. Objective: To compare the clinical effectiveness and cost-effectiveness of ultrasound with biopsy in diagnosing patients with suspected GCA. Design: Prospective multicentre cohort study. Setting: Secondary care. Participants: A total of 381 patients referred with newly suspected GCA. Main outcome measures: Sensitivity, specificity and cost-effectiveness of ultrasound compared with biopsy or ultrasound combined with biopsy for diagnosing GCA and interobserver reliability in interpreting scan or biopsy findings. Results: We developed and implemented an ultrasound training programme for diagnosing suspected GCA. We recruited 430 patients with suspected GCA. We analysed 381 patients who underwent both ultrasound and biopsy within 10 days of starting treatment for suspected GCA and who attended a follow-up assessment (median age 71.1 years; 72% female). The sensitivity of biopsy was 39% [95% confidence interval (CI) 33% to 46%], which was significantly lower than previously reported and inferior to ultrasound (54%, 95% CI 48% to 60%); the specificity of biopsy (100%, 95% CI 97% to 100%) was superior to ultrasound (81%, 95% CI 73% to 88%). If we scanned all suspected patients and performed biopsies only on negative cases, sensitivity increased to 65% and specificity was maintained at 81%, reducing the need for biopsies by 43%. Strategies combining clinical judgement (clinician’s assessment at 2 weeks) with the tests showed sensitivity and specificity of 91% and 81%, respectively, for biopsy and 93% and 77%, respectively, for ultrasound; cost-effectiveness (incremental net monetary benefit) was £485 per patient in favour of ultrasound with both cost savings and a small health gain. Inter-rater analysis revealed moderate agreement among sonographers (intraclass correlation coefficient 0.61, 95% CI 0.48 to 0.75), similar to pathologists (0.62, 95% CI 0.49 to 0.76). Limitations: There is no independent gold standard diagnosis for GCA. The reference diagnosis used to determine accuracy was based on classification criteria for GCA that include clinical features at presentation and biopsy results. Conclusion: We have demonstrated the feasibility of providing training in ultrasound for the diagnosis of GCA. Our results indicate better sensitivity but poorer specificity of ultrasound compared with biopsy and suggest some scope for reducing the role of biopsy. The moderate interobserver agreement for both ultrasound and biopsy indicates scope for improving assessment and reporting of test results and challenges the assumption that a positive biopsy always represents GCA. Future work: Further research should address the issue of an independent reference diagnosis, standards for interpreting and reporting test results and the evaluation of ultrasound training, and should also explore the acceptability of these new diagnostic strategies in GCA. Funding: he National Institute for Health Research Health Technology Assessment programme

Does the approach to economic evaluation in health care depend on culture, values, and institutional context?

There is a fairly strong case to argue that culture, values, and institutional context have an influence on the use of HTA and economic evaluation in health care, either directly, or indirectly through the impact on the organization of the health care system. Therefore, this observation may be useful both in explaining the different approaches to the use of economic evaluation between countries and in determining the most appropriate use of economic evaluation for other countries yet to adopt the approach

Acidithiobacillus ferrooxidans metabolism: from genome sequence to industrial applications

<p>Abstract</p> <p>Background</p> <p><it>Acidithiobacillus ferrooxidans </it>is a major participant in consortia of microorganisms used for the industrial recovery of copper (bioleaching or biomining). It is a chemolithoautrophic, γ-proteobacterium using energy from the oxidation of iron- and sulfur-containing minerals for growth. It thrives at extremely low pH (pH 1–2) and fixes both carbon and nitrogen from the atmosphere. It solubilizes copper and other metals from rocks and plays an important role in nutrient and metal biogeochemical cycling in acid environments. The lack of a well-developed system for genetic manipulation has prevented thorough exploration of its physiology. Also, confusion has been caused by prior metabolic models constructed based upon the examination of multiple, and sometimes distantly related, strains of the microorganism.</p> <p>Results</p> <p>The genome of the type strain <it>A. ferrooxidans </it>ATCC 23270 was sequenced and annotated to identify general features and provide a framework for <it>in silico </it>metabolic reconstruction. Earlier models of iron and sulfur oxidation, biofilm formation, quorum sensing, inorganic ion uptake, and amino acid metabolism are confirmed and extended. Initial models are presented for central carbon metabolism, anaerobic metabolism (including sulfur reduction, hydrogen metabolism and nitrogen fixation), stress responses, DNA repair, and metal and toxic compound fluxes.</p> <p>Conclusion</p> <p>Bioinformatics analysis provides a valuable platform for gene discovery and functional prediction that helps explain the activity of <it>A. ferrooxidans </it>in industrial bioleaching and its role as a primary producer in acidic environments. An analysis of the genome of the type strain provides a coherent view of its gene content and metabolic potential.</p