109 research outputs found

    Manufacturing flow line systems: a review of models and analytical results

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    The most important models and results of the manufacturing flow line literature are described. These include the major classes of models (asynchronous, synchronous, and continuous); the major features (blocking, processing times, failures and repairs); the major properties (conservation of flow, flow rate-idle time, reversibility, and others); and the relationships among different models. Exact and approximate methods for obtaining quantitative measures of performance are also reviewed. The exact methods are appropriate for small systems. The approximate methods, which are the only means available for large systems, are generally based on decomposition, and make use of the exact methods for small systems. Extensions are briefly discussed. Directions for future research are suggested.National Science Foundation (U.S.) (Grant DDM-8914277

    [F-18]FDG-PET/CT to prevent futile surgery in indeterminate thyroid nodules: a blinded, randomised controlled multicentre trial

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    Purpose To assess the impact of an [F-18]FDG-PET/CT-driven diagnostic workup to rule out malignancy, avoid futile diagnostic surgeries, and improve patient outcomes in thyroid nodules with indeterminate cytology.Methods In this double-blinded, randomised controlled multicentre trial, 132 adult euthyroid patients with scheduled diagnostic surgery for a Bethesda III or IV thyroid nodule underwent [F-18]FDG-PET/CT and were randomised to an [F-18] FDG-PET/CT-driven or diagnostic surgery group. In the [F-18]FDG-PET/CT-driven group, management was based on the [F-18]FDG-PET/CT result: when the index nodule was visually [F-18]FDG-positive, diagnostic surgery was advised; when [F-18]FDG-negative, active surveillance was recommended. The nodule was presumed benign when it remained unchanged on ultrasound surveillance. In the diagnostic surgery group, all patients were advised to proceed to the scheduled surgery, according to current guidelines. The primary outcome was the fraction of unbeneficial patient management in one year, i.e., diagnostic surgery for benign nodules and active surveillance for malignant/borderline nodules. Intention-to-treat analysis was performed. Subgroup analyses were performed for non-Hurthle cell and Hurthle cell nodules.Results Patient management was unbeneficial in 42% (38/91 [95% confidence interval [CI], 32-53%]) of patients in the [F-18] FDG-PET/CT-driven group, as compared to 83% (34/41 [95% CI, 68-93%]) in the diagnostic surgery group (p < 0.001). [F-18]FDG-PET/CT-driven management avoided 40% (25/63 [95% CI, 28-53%]) diagnostic surgeries for benign nodules: 48% (23/48 [95% CI, 33-63%]) in non-Hurthle cell and 13% (2/15 [95% CI, 2-40%]) in I-Liable cell nodules (p = 0.02). No malignant or borderline tumours were observed in patients under surveillance. Sensitivity, specificity, negative and positive predictive value, and benign call rate (95% CI) of [F-18]FDG-PET/CT were 94.1% (80.3-99.3%), 39.8% (30.0-50.2%), 95.1% (83.5-99.4%), 35.2% (25.4-45.9%), and 31.1% (23.3-39.7%), respectively.Conclusion An [F-18]FDG-PET/CT-driven diagnostic workup of indeterminate thyroid nodules leads to practice changing management, accurately and oncologically safely reducing futile surgeries by 40%. For optimal therapeutic yield, application should be limited to non-Hurthle cell nodules.Imaging- and therapeutic targets in neoplastic and musculoskeletal inflammatory diseas

    Verstrikt in eigen complexiteit - het relaas van een zorgverzekeraar.

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    Concept-guided development of ICT use in ‘traditional’ and ‘innovative’ primary schools: what types of ICT use do schools develop?

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    The fit between existing educational practices and promoted classroom use of information and communication technologies is increasingly recognized as a factor in successful integration of such technologies in classroom practice. Using a descriptive multiple-case study design, we characterize the types of information and communication technology (ICT) use resulting from a 'concept-guided' approach in five schools. Teachers at schools characterized as having a 'traditional' or an 'innovative' school concept were supported in designing and implementing ICT-enhanced learning arrangements that fit their schools' educational concept. In the traditional schools, ICT was primarily applied to extend and support the use of standard teaching materials in mostly teacher-directed activities. The innovative schools on the other hand used ICT tools primarily to support open-ended activities with a lot of input from the pupils. All five schools expected ICT to increase pupils' motivation, improve learning results, promote self-directed learning, and enable differentiation between pupils. Yet underneath these goals, we find distinct differences in expectations between the two school types. © 2011 Blackwell Publishing Ltd
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