A method for acquiring random range uncertainty probability distributions in proton therapy.

In treatment planning we depend upon accurate knowledge of geometric and range uncertainties. If the uncertainty model is inaccurate then the plan will produce under-dosing of the target and/or overdosing of OAR. We aim to provide a method for which centre and site-specific population range uncertainty due to inter-fraction motion can be quantified to improve the uncertainty model in proton treatment planning. Daily volumetric MVCT data from previously treated radiotherapy patients has been used to investigate inter-fraction changes to water equivalent path-length (WEPL). Daily image-guidance scans were carried out for each patient and corrected for changes in CTV position (using rigid transformations). An effective depth algorithm was used to determine residual range changes, after corrections had been applied, throughout the treatment by comparing WEPL within the CTV at each fraction for several beam angles. As a proof of principle this method was used to quantify uncertainties for inter-fraction range changes for a sample of head and neck patients of [Formula: see text] mm, [Formula: see text] mm and overall [Formula: see text] mm. For prostate [Formula: see text] mm, [Formula: see text] mm and overall [Formula: see text] mm. The choice of beam angle for head and neck did not affect the inter-fraction range error significantly; however this was not the same for prostate. Greater range changes were seen using a lateral beam compared to an anterior beam for prostate due to relative motion of the prostate and femoral heads. A method has been developed to quantify population range changes due to inter-fraction motion that can be adapted for the clinic. The results of this work highlight the importance of robust planning and analysis in proton therapy. Such information could be used in robust optimisation algorithms or treatment plan robustness analysis. Such knowledge will aid in establishing beam start conditions at planning and for establishing adaptive planning protocols.This work was funded by a Medical Research Council Studentship to the University of Cambridge (G1000384). Dr S. Holloway is currently supported by a Cancer Research UK Centres Network Accelerator Award Grant (A21993) to the ART-NET consortium

Modeling and formal verification of gaming storylines

Video games are becoming more and more interactive with increasingly complex plots. These plots typically involve multiple parallel storylines that may converge and diverge based on player actions. This may lead to situations that are inconsistent or impassable. Current techniques for planning and testing game plots involve naive means such as text documents, spreadsheets, and critical path testing. Recent academic research [1] [2] [3] examines the design planning problems, but neglect testing and verification of the possible plot lines. These complex plots have thus until now been handled inadequately due to a lack of a formal methodology and tools to support them. In this dissertation, we describe how we develop methods to 1) characterize storylines (SChar), 2) define a storyline description language (SDL), and 3) create a storyline verification tool based in formal verification techniques (StoCk) that use our SDL as input. SChar (Storyline Characterization) help game developers characterize the category of story line they are working on (e.g. linear, branching and plot) through a tool that give a set of guided questions. Our SDL allows its users to describe storylines in a consistent format similar to how they reason about storylines, but in such a way that it can be used for formal verification. StoCk accepts storylines, described in SDL, to be formally verified using SPIN for errors. StoCk is also examined in three common use cases found in the gaming industry used as a tool 1) during storyline creation 2) during quality assurance and 3) during storyline implementation. The combination of SChar, SDL, and StoCk provides designers, writers, and developers a novel methodology and tools to verify consistency in large and complex game plots.Electrical and Computer Engineerin

Mobilizing learning: mobile Web 2.0 scenarios in tertiary education

Based upon three years of mobile learning (mlearning) projects, a major implementation project has been developed for integrating the use of mobile web 2.0 tools across a variety of departments and courses in a tertiary education environment. A participatory action research methodology guides and informs the project. The project is based upon an explicit social constuctivist pedagogy, focusing on student collaboration, and the sharing and critique of student-generated content using freely available web 2.0 services. These include blogs, social networks, location aware (geotagged) image and video sharing, instant messaging, microblogging etc… Students and lecturers are provided with either an appropriate smartphone and/or a 3G capable netbook to use as their own for the duration of the project. Keys to the projects success are the level of pedagogical and technical support, and the level of integration of the tools into the courses – including assessment and lecturer modelling of the use of the tools. The projects are supported by an intentional community of practice model, with the researcher taking on the role of the “technology steward”. The paper outlines three different scenarios illustrating how this course integration is being achieved, establishing a transferable model of mobile web 2.0 integration and implementation. The goal is to facilitate a student-centred, collaborative, flexible, context-bridging learning environment that empowers students as content producers and learning context generators, guided by lecturers who effectively model th

Boundary element methods in the prediction of the acoustic damping of ship whipping vibrations

Damping of ship whipping vibrations following a slam due to wave impact is traditionally assumed to be primarily of material or structural origin. However, several mechanisms of energy dissipation to the surrounding water exist, including gravity and acoustic waves. Neither transports much energy for the lowest frequency modes, in which the acoustic wavelength may be an order or magnitude greater than the ship length whereas the gravity wavelength is at least an order of magnitude shorter than the ship beam. However, the acoustic damping ratio increases as the fourth power of frequency, becoming significant for higher frequency modes

Influence network linkages across implementation strategy conditions in a randomized controlled trial of two strategies for scaling up evidence-based practices in public youth-serving systems.

BackgroundGiven the importance of influence networks in the implementation of evidence-based practices and interventions, it is unclear whether such networks continue to operate as sources of information and advice when they are segmented and disrupted by randomization to different implementation strategy conditions. The present study examines the linkages across implementation strategy conditions of social influence networks of leaders of youth-serving systems in 12 California counties participating in a randomized controlled trial of community development teams (CDTs) to scale up use of an evidence-based practice.MethodsSemi-structured interviews were conducted with 38 directors, assistant directors, and program managers of county probation, mental health, and child welfare departments. A web-based survey collected additional quantitative data on information and advice networks of study participants. A mixed-methods approach to data analysis was used to create a sociometric data set (n = 176) to examine linkages between treatment and standard conditions.ResultsOf those network members who were affiliated with a county (n = 137), only 6 (4.4%) were directly connected to a member of the opposite implementation strategy condition; 19 (13.9%) were connected by two steps or fewer to a member of the opposite implementation strategy condition; 64 (46.7%) were connected by three or fewer steps to a member of the opposite implementation strategy condition. Most of the indirect steps between individuals who were in different implementation strategy conditions were connections involving a third non-county organizational entity that had an important role in the trial in keeping the implementation strategy conditions separate. When these entities were excluded, the CDT network exhibited fewer components and significantly higher betweenness centralization than did the standard condition network.ConclusionAlthough the integrity of the RCT in this instance was not compromised by study participant influence networks, RCT designs should consider how influence networks may extend beyond boundaries established by the randomization process in implementation studies.Trial registrationNCT00880126