89 research outputs found

    Fibrosis progression under maintenance interferon in hepatitis C is better detected by blood test than liver morphometry

    Get PDF
    Summary.  We evaluated whether quantitative measurements of liver fibrosis with recently developed diagnostics outperform histological staging in detecting natural or interferon-induced changes. We compared Metavir staging, morphometry (area and fractal dimension) and six blood tests in 157 patients with chronic hepatitis C from two trials testing maintenance interferon for 96 weeks. Paired liver biopsies and blood tests were available for 101 patients, and there was a significant improvement in Metavir activity and a significant increase in blood tests reflecting fibrosis quantity in patients treated with interferon when compared with controls – all per cent changes in histological fibrosis measures were significantly increased in F1 vs F2–4 stages only in the interferon group. For the whole population studied between weeks 0 and 96, there was significant progression only in the area of fibrosis (AOF) (P = 0.026), FibroMeter (P = 0.020) and CirrhoMeter (P = 0.003). With regards to dynamic reproducibility, agreement was good (ric ≄ 0.72) only for Metavir fibrosis score, FibroMeter and CirrhoMeter. The per cent change in AOF was significantly higher than that of fractal dimension (P = 0.003) or Metavir fibrosis score (P = 0.015). CirrhoMeter was the only blood test with a change significantly higher than that of AOF (P = 0.039). AOF and two blood tests, reflecting fibrosis quantity, have high sensitivity and/or reproducibility permitting the detection of a small progression in liver fibrosis over two years. A blood test reflecting fibrosis quantity is more sensitive and reproducible than morphometry. The study also shows that maintenance interferon does not improve fibrosis, whatever its stage

    Decision support for disruption management on high frequency transit lines

    No full text
    Thesis: S.M., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 155-159).Incidents (due to equipment failures, passenger emergencies, infrastructure problems, human errors, etc.) routinely occur in metro systems. Such incidents can cause significant disruptions in service (from slowdown to full closure of the line), with serious impacts on passengers, especially in the core of high frequency lines operating near capacity. Disruption consists of two distinct phases. The incident phase is the period from the start of the incident to the moment when its cause has been resolved. The second phase of the disruption is the recovery, which starts at the end of the incident and lasts until normal service is restored. Dealing efficiently with disruptions is crucial and agencies use real-time control strategies to mitigate those impacts and improve performance. This thesis proposes an approach for supporting controllers decision-making in the recovery phase of disruption management. While the method is applied to the Piccadilly Line on the London Underground, It is applicable to other high frequency transit rail lines. After reviewing the main challenges controllers face during incident management and the main strategies they use, the thesis formulates the recovery phase problem as an optimization problem that integrates timetable revision and crew rescheduling (train reformation problem, TRP). The approach focuses on modeling common control strategies such as short-turning and train renumbering. It explicitly incorporates the scarcity of resources and associated constraints, especially with respect to crews. The method consists of two phases: the generation of a large number of candidate journeys; and the selection of the journeys (recovery timetable) that optimize some measure of performance, involving the effectiveness of the recovery and the passenger service. The model is first applied to an incident that happened on January 2014 on the Piccadilly Line. The actual controllers response is compared with the output of the train reformation problem, and a sensitivity analysis of the model parameters is performed. The results suggest that using more complex reformations and less short-turns may lead to better passenger service during the recovery phase. The train reformation problem is then applied to a hypothetical incident. The results support current practices that canceling trains during the incident phase enables a shorter and more efficient recovery.by Michel David Babany.S.M

    Reply

    No full text
    • 

    corecore