164 research outputs found

    Formal Verification of a Rover Anti-collision System

    Get PDF
    In this paper, we integrate inductive proof, bounded model checking, test case generation and equivalence proof techniques to verify an embedded system. This approach is implemented using Systerel Smart Solver (S3) toolset. It is applied to verify properties at system, software, and code levels. The verification process is illustrated on an anti-collision system (ARP for Automatic Rover Protection) implemented on-board a rover. Focus is placed on the verification of safety and functional properties and the proof of equivalence between the design model and the generated code

    Social technologies for online learning: theoretical and contextual issues

    Get PDF
    Three exemplars are presented of social technologies deployed in educational contexts: wikis; a photo-sharing environment; and a social bookmarking tool. Students were found to engage with the technologies selectively, sometimes rejecting them, in the light of their prior conceptions of education. Some students (a minority in all the studies) were unsympathetic to the educational philosophy underpinning the technology’s adoption. The paper demonstrates, through an examination of in-context use, the importance of socio-cultural factors in relation to education, and the non-deterministic nature of educational technology. The academic study of technology has increasingly called into question the deterministic views which are so pervasive in popular discourse and among policy makers. Instead, socio-cultural factors play a crucial role in shaping and defining technology and educational technology is no exception, as the examples in the paper show. The paper concludes by drawing out some implications of the examples for the use of social technologies in education

    The effectiveness and cost-effectiveness of a complex community sport intervention to increase physical activity: An interrupted time series design

    Get PDF
    © Author(s) (or their employer(s)) 2018. Objectives: An effectiveness and cost-effectiveness analyses of two-staged community sports interventions, taster sports sessions compared with portfolio of community sport sessions. Design: Quasi-experiment using an interrupted time series design. Setting: Community sports projects delivered by eight lead partners in London Borough of Hounslow, United Kingdom Participants: Inactive people aged 14 plus years (n=246) were recruited between May 2013–February 2014. Interventions: Community sports interventions delivered in two stages, 6-week programme of taster sport sessions (Stage1) and 6-week programme of portfolio of community sporting sessions delivered by trained coaches (Stage2). Primary and secondary outcome measures: Change in days with ≥30 min of self-reported vigorous intensity physical activity (PA), moderate intensity PA, walking, sport, subjective wellbeing, and EQ5D5L quality-adjusted life-years (QALYs) Methods: Interrupted time series analysis evaluated the effectiveness of the two sports programmes. Cost-effectiveness analysis compares Stage 2 with Stage 1 from a provider’s perspective, reporting outcomes of incremental cost per Quality Adjusted Life Year (QALY) (2015/16 price year). Uncertainty was assessed using deterministic and probabilistic sensitivity analyses. Results: Compared with Stage1, counterfactual change at 21 days in PA was lower for vigorous (log odds: -0.52; 95% CI -1, -0.03), moderate PA (-0.50; CI 0.94, -0.05) and sport (-0.56; CI -1.02, -0.10). Stage 2 increased walking (0.28; CI 0.3, 0.52). Effect overtime was similar. Counterfactual change at 21 days in wellbeing was positive particularly for ‘happiness’ (0.29; CI 0.06, 0.51). Stage2 was more expensive (£101 per participant) but increased QALYs (0.001; CI -0.034, 0.036). Cost per QALY for Stage2 was £50000 and has 29% chance of being cost effective (£30000 threshold). Conclusion: Community based sport interventions could increase PA among inactive people. Less intensive sports sessions may be more effective and cost-effective

    Cost-effectiveness of offering an area-level financial incentive on breast feeding: a within-cluster randomised controlled trial analysis

    Get PDF
    Objective To provide the first estimate of the cost-effectiveness of financial incentive for breastfeeding intervention compared with usual care. Design Within-cluster (‘ward’-level) randomised controlled trial cost-effectiveness analysis (trial registration number ISRCTN44898617). Setting Five local authority districts in the North of England. Participants 5398 mother-infant dyads (intervention arm), 4612 mother-infant dyads (control arm). Interventions Offering a financial incentive (over a 6-month period) on breast feeding to women living in areas with low breastfeeding prevalence (<40% at 6–8 weeks). Main outcome measures Babies breast fed (receiving breastmilk) at 6–8 weeks, and cost per additional baby breast fed. Methods Costs were compared with differences in area-level data on babies’ breast fed in order to estimate a cost per additional baby breast fed and the quality-adjusted life year (QALY) gains required over the lifetime of babies to justify intervention cost. Results In the trial, the total cost of providing the intervention in 46 wards was £462 600, with an average cost per ward of £9989 and per baby of £91. At follow-up, area-level breastfeeding prevalence at 6–8 weeks was 31.7% (95% CI 29.4 to 34.0) in control areas and 37.9% (95% CI 35.0 to 40.8) in intervention areas. The adjusted difference between intervention and control was 5.7 percentage points (95% CI 2.7 to 8.6; p<0.001), resulting in 10 (95% CI 6 to 14) more additional babies breast fed in the intervention wards (39 vs 29). The cost per additional baby breast fed at 6–8 weeks was £974. At a cost per QALY threshold of £20 000 (recommended in England), an additional breastfed baby would need to show a QALY gain of 0.05 over their lifetime to justify the intervention cost. If decision makers are willing to pay £974 (or more) per additional baby breast fed at a QALY gain of 0.05, then this intervention could be cost-effective. Results were robust to sensitivity analyses. Conclusion This study provides information to help inform public health guidance on breast feeding. To make the economic case unequivocal, evidence on the varied and long-term health benefits of breast feeding to both the baby and mother and the effectiveness of financial incentives for breastfeeding beyond 6–8 weeks is require

    Short-term and long-term cost-effectiveness of a pedometer-based exercise intervention in primary care: a within-trial analysis and beyond-trial modelling

    Get PDF
    Abstract Objectives A short-term and long-term cost-effectiveness analysis (CEA) of two pedometer-based walking interventions compared with usual care. Design (A) Short-term CEA: parallel three-arm cluster randomised trial randomised by household. (B) Long-term CEA: Markov decision model. Setting Seven primary care practices in South London, UK. Participants (A) Short-term CEA: 1023 people (922 households) aged 45–75 years without physical activity (PA) contraindications. (b) Long-term CEA: a cohort of 100 000 people aged 59–88 years. Interventions Pedometers, 12-week walking programmes and PA diaries delivered by post or through three PA consultations with practice nurses. Primary and secondary outcome measures Accelerometer-measured change (baseline to 12 months) in average daily step count and time in 10 min bouts of moderate to vigorous PA (MVPA), and EQ-5D-5L quality-adjusted life-years (QALY). Methods Resource use costs (£2013/2014) from a National Health Service perspective, presented as incremental cost-effectiveness ratios for each outcome over a 1-year and lifetime horizon, with cost-effectiveness acceptability curves and willingness to pay per QALY. Deterministic and probabilistic sensitivity analyses evaluate uncertainty. Results (A) Short-term CEA: At 12 months, incremental cost was £3.61 (£109)/min in ≥10 min MVPA bouts for nurse support compared with control (postal group). At £20 000/QALY, the postal group had a 50% chance of being cost saving compared with control. (B) Long-term CEA: The postal group had more QALYs (+759 QALYs, 95% CI 400 to 1247) and lower costs (−£11 million, 95% CI −12 to −10) than control and nurse groups, resulting in an incremental net monetary benefit of £26 million per 100 000 population. Results were sensitive to reporting serious adverse events, excluding health service use, and including all participant costs. Conclusions Postal delivery of a pedometer intervention in primary care is cost-effective long term and has a 50% chance of being cost-effective, through resource savings, within 1 year. Further research should ascertain maintenance of the higher levels of PA, and its impact on quality of life and health service use.This research was supported by the Health Technology Assessment (HTA) Programme, National Institute for Health Research (project number HTA 10/32/02 ISRCTN42122561)

    PACE-UP (Pedometer and consultation evaluation--UP)--a pedometer-based walking intervention with and without practice nurse support in primary care patients aged 45-75 years: study protocol for a randomised controlled trial.

    Get PDF
    BACKGROUND: Most adults do not achieve the 150 minutes weekly of at least moderate intensity activity recommended for health. Adults' most common physical activity (PA) is walking, light intensity if strolling, moderate if brisker. Pedometers can increase walking; however, most trials have been short-term, have combined pedometer and support effects, and have not reported PA intensity. This trial will investigate whether pedometers, with or without nurse support, can help less active 45-75 year olds to increase their PA over 12 months. METHODS/DESIGN: DESIGN: Primary care-based 3-arm randomized controlled trial with 12-month follow-up and health economic and qualitative evaluations. PARTICIPANTS: Less active 45-75 year olds (n = 993) will be recruited by post from six South West London general practices, maximum of two per household and households randomised into three groups. Step-count and time spent at different PA intensities will be assessed for 7 days at baseline, 3 and 12 months by accelerometer. Questionnaires and anthropometric assessments will be completed. INTERVENTION: The pedometer-alone group will be posted a pedometer (Yamax Digi-Walker SW-200), handbook and diary detailing a 12-week pedometer-based walking programme, using targets from their baseline assessment. The pedometer-plus-support group will additionally receive three practice nurse PA consultations. The handbook, diary and consultations include behaviour change techniques (e.g., self-monitoring, goal-setting, relapse prevention planning). The control group will receive usual care. OUTCOMES: Changes in average daily step-count (primary outcome), time spent sedentary and in at least moderate intensity PA weekly at 12 months, measured by accelerometry. Other outcomes include change in body mass index, body fat, self-reported PA, quality of life, mood and adverse events. Cost-effectiveness will be assessed by the incremental cost of the intervention to the National Health Service and incremental cost per change in step-count and per quality adjusted life year. Qualitative evaluations will explore reasons for trial non-participation and the interventions' acceptability. DISCUSSION: The PACE-UP trial will determine the effectiveness and cost-effectiveness of a pedometer-based walking intervention delivered by post or practice nurse to less active primary care patients aged 45-75 years old. Approaches to minimise bias and challenges anticipated in delivery will be discussed

    A hazard analysis method for systematic identification of safety requirements for user interface software in medical devices

    Get PDF
    © Springer International Publishing AG (outside the US) 2017. Formal methods technologies have the potential to verify the usability and safety of user interface (UI) software design in medical devices, enabling significant reductions in use errors and consequential safety incidents with such devices. This however depends on comprehensive and verifiable safety requirements to leverage these techniques for detecting and preventing flaws in UI software that can induce use errors. This paper presents a hazard analysis method that extends Leveson’s System Theoretic Process Analysis (STPA) with a comprehensive set of causal factor categories, so as to provide developers with clear guidelines for systematic identification of use-related hazards associated with medical devices, their causes embedded in UI software design, and safety requirements for mitigating such hazards. The method is evaluated with a case study on the Gantry-2 radiation therapy system, which demonstrates that (1) as compared to standard STPA, our method allowed us to identify more UI software design issues likely to cause use-related hazards; and (2) the identified UI software design issues facilitated the definition of precise, verifiable safety requirements for UI software, which could be readily formalized in verification tools such as Prototype Verification System (PVS).- U.S. Food and Drug Administration(NORTE-01-0145-FEDER-000016)Sandy Weininger (FDA), Scott Thiel (Navigant Consulting, Inc.), Michelle Jump (Stryker), Stefania Gnesi (ISTI/CNR) and the CHI+MED team (www.chi-med.ac.uk) provided useful feedback and inputs. Paolo Masci’s work is supported by the North Portugal Regional Operational Programme (NORTE 2020) under the PORTUGAL 2020 Partnership Agreement, and by the European Regional Development Fund (ERDF) within Project “NORTE-01-0145-FEDER-000016”.info:eu-repo/semantics/publishedVersio
    corecore