201 research outputs found

    Sustainable inland transportation

    Get PDF
    Inland navigation is often mentioned as a ‘green’ alternative for the two other main inland transport modes: rail and road transport. In order to investigate the opportunities for inland navigation we first analyze the competitive position of inland navigation vis-àvis the other main inland transport modes. For that, we perform a comparative study on the current sustainability performance of the three modes. Second, through a case study, we analyze a recent initiative for sustainable innovation of inland navigation in order to assess the barriers and opportunities for improving the competitive position of sustainable inland navigation

    Semiparametric theory and empirical processes in causal inference

    Full text link
    In this paper we review important aspects of semiparametric theory and empirical processes that arise in causal inference problems. We begin with a brief introduction to the general problem of causal inference, and go on to discuss estimation and inference for causal effects under semiparametric models, which allow parts of the data-generating process to be unrestricted if they are not of particular interest (i.e., nuisance functions). These models are very useful in causal problems because the outcome process is often complex and difficult to model, and there may only be information available about the treatment process (at best). Semiparametric theory gives a framework for benchmarking efficiency and constructing estimators in such settings. In the second part of the paper we discuss empirical process theory, which provides powerful tools for understanding the asymptotic behavior of semiparametric estimators that depend on flexible nonparametric estimators of nuisance functions. These tools are crucial for incorporating machine learning and other modern methods into causal inference analyses. We conclude by examining related extensions and future directions for work in semiparametric causal inference

    Quantitative models for reverse logistics

    Get PDF
    This article surveys the recently emerged field of reverse logistics. The management of return flows induced by the various forms of reuse of products and materials in industrial production processes has received growing attentio

    Logistiek Biobased Economy: toekomstbeelden 2025 & agenda 2013-2017

    Get PDF
    Naast de afzetmogelijkheden van biobased producten (markten) en de technologische verwerkingsmogelijkheden, bepalen de beschikbaarheid, handel en logistiek in sterke mate de wijze waarop de biobased economy in Nederland zich zal ontwikkelen. Het is noodzakelijk in de komende jaren duurzame, economisch rendabele logistieke biomassaketens op te zetten. Op dit terrein bestaat nog veel onduidelijkheid. Het doel van het project is het vormen van: gedragen toekomstbeelden van de logistiek in de biobased economy in 2025 en een gedragen agenda met actiepunten voor 2013-2017 (ofwel waarmee moeten we starten in de eerstkomende 5 jaar om de toekomstbeelden te bereiken)

    Multicenter experience of upper extremity access in complex endovascular aortic aneurysm repair

    Get PDF
    Purpose: Upper extremity access (UEA) for antegrade cannulation of aortic side branches is a relevant part of endovascular treatment of complex aortic aneurysms and can be achieved using several techniques, sites, and sides. The purpose of this study was to evaluate different UEA strategies in a multicenter registry of complex endovascular aortic aneurysm repair (EVAR). Methods: In six aortic centers in the Netherlands, all endovascular aortic procedures from 2006 to 2019 were retrospectively reviewed. Patients who received UEA during complex EVAR were included. The primary outcome was a composite end point of any access complication, excluding minor hematomas. Secondary outcomes were access characteristics, access complications considered individually, access reinterventions, and incidence of ischemic cerebrovascular events. Results: A total of 417 patients underwent 437 UEA for 303 fenestrated/branched EVARs and 114 chimney EVARs. Twenty patients had bilateral, 295 left-sided, and 102 right-sided UEA. A total of 413 approaches were performed surgically and 24 percutaneously. Distal brachial access (DBA) was used in 89 cases, medial brachial access (MBA) in 149, proximal brachial access (PBA) in 140, and axillary access (AA) in 59 cases. No significant differences regarding the composite end point of access complications were seen (DBA: 11.3% vs MBA: 6.7% vs PBA: 13.6% vs AA: 10.2%; P =.29). Postoperative neuropathy occurred most after PBA (DBA: 1.1% vs MBA: 1.3% vs PBA: 9.3% vs AA: 5.1%; P =.003). There were no differences in cerebrovascular complications between access sides (right: 5.9% vs left: 4.1% vs bilateral: 5%; P =.75). Significantly more overall access complications were seen after a percutaneous approach (29.2% vs 6.8%; P =.002). In multivariate analysis, the risk for access complications after an open approach was decreased by male sex (odds ratio [OR]: 0.27; 95% confidence interval [CI]: 0.10-0.72; P =.009), whereas an increase in age per year (OR: 1.08; 95% CI: 1.004-1.179; P =.039) and diabetes mellitus type 2 (OR: 3.70; 95% CI: 1.20-11.41; P =.023) increased the risk. Conclusions: Between the four access localizations, there were no differences in overall access complications. Female sex, diabetes mellitus type 2, and aging increased the risk for access complications after a surgical approach. Furthermore, a percutaneous UEA resulted in higher complication rates than a surgical approach

    Results from a nationwide prospective registry on open surgical or endovascular repair of juxtarenal abdominal aortic aneurysms

    Get PDF
    Background: Juxtarenal abdominal aortic aneurysms (JRAAAs) can be treated either with open surgical repair (OSR) including suprarenal clamping or by complex endovascular aneurysm repair (cEVAR). In this study, we present the comparison between the short-term mortality and complications of the elective JRAAA treatment modalities from a national database reflecting daily practice in the Netherlands. Methods: All patients undergoing elective JRAAA open repair or cEVAR (fenestrated EVAR or chimney EVAR) between January 2016 and December 2018 registered in the Dutch Surgical Aneurysm Audit (DSAA) were eligible for inclusion. Descriptive perioperative variables and outcomes were compared between patients treated with open surgery or endovascularly. Adjusted odds ratios for short-term outcomes were calculated by logistic regression analysis. Results: In all, 455 primary treated patients with JRAAAs could be included (258 OSR, 197 cEVAR). Younger patients and female patients were treated more often with OSR vs cEVAR (72 ± 6.1 vs 76 ± 6.0; P < .001 and 22% vs 15%; P = .047, respectively). Patients treated with OSR had significantly more major and minor complications as well as a higher chance of early mortality (OSR vs cEVAR, 45% vs 21%; P < .001; 34% vs 23%; P = .011; and 6.6% vs 2.5%; P = .046, respectively). After logistic regression with adjustment for confounders, patients who were treated with OSR showed an odds ratio of 3.64 (95% confidence interval [CI], 2.25-5.89; P < .001) for major complications compared with patients treated with cEVAR, and for minor complications, the odds ratios were 2.17 (95% CI, 1.34-3.53; P = .002) higher. For early mortality, the odds ratios were 3.79 (95% CI, 1.26-11.34; P = .017) higher after OSR compared with cEVAR. Conclusions: In this study, after primary elective OSR for JRAAA, the odds for major complications, minor complications, and short-term mortality were significantly higher compared with cEVAR

    Toward Transplantation of Liver Organoids: From Biology and Ethics to Cost-effective Therapy

    Get PDF
    Liver disease is a common cause of morbidity and mortality, and many patients would benefit from liver transplantation. However, because of a shortage of suitable donor livers, even of those patients who are placed on the donor liver waiting list, many do not survive the waiting time for transplantation. Therefore, alternative treatments for end-stage liver disease need to be explored. Recent advances in organoid technology might serve as a solution to overcome the donor liver shortage in the future. In this overview, we highlight the potential of organoid technology for cell therapy and tissue engineering approaches. Both organoid-based approaches could be used as treatment for end-stage liver disease patients. Additionally, organoid-based cell therapy can also be used to repair liver grafts ex vivo to increase the supply of transplantable liver tissue. The potential of both approaches to become clinically available is carefully assessed, including their clinical, ethical, and economic implications. We provide insight into what aspects should be considered further to allow alternatives to donor liver transplantation to be successfully clinically implemented

    Case Study of Semaglutide and Cardiovascular Outcomes: An Application of the Causal Roadmap to a Hybrid Design for Augmenting an RCT Control Arm with Real-World Data

    Get PDF
    Introduction: Increasing interest in real-world evidence has fueled the development of study designs incorporating real-world data (RWD). Using the Causal Roadmap, we specify three designs to evaluate the difference in risk of major adverse cardiovascular events (MACE) with oral semaglutide versus standard-of-care: 1) the actual sequence of non-inferiority and superiority randomized controlled trials (RCTs), 2) a single RCT, and 3) a hybrid randomizedexternal data study. Methods: The hybrid design considers integration of the PIONEER 6 RCT with RWD controls using the experiment-selector cross-validated targeted maximum likelihood estimator. We evaluate 95% confidence interval coverage, power, and average patient-time during which participants would be precluded from receiving a glucagon-like peptide-1 receptor agonist (GLP1-RA) for each design using simulations. Finally, we estimate the effect of oral semaglutide on MACE for the hybrid PIONEER 6-RWD analysis. Results: In simulations, Designs 1 and 2 performed similarly. The tradeoff between decreased coverage and patient-time without the possibility of a GLP1-RA for Designs 1 and 3 depended on the simulated bias. In real data analysis using Design 3, external controls were integrated in 84% of cross-validation folds, resulting in an estimated risk difference of -1.53%-points (95% CI -2.75%-points to -0.30%-points). Conclusions: The Causal Roadmap helps investigators to minimize potential bias in studies using RWD and to quantify tradeoffs between study designs. The simulation results help to interpret the level of evidence provided by the real data analysis in support of the superiority of oral semaglutide versus standard-of-care for cardiovascular risk reduction

    The influence of multidisciplinary team meetings on treatment decisions in advanced bladder cancer

    Get PDF
    Objectives: To investigate the role of specialised genitourinary multidisciplinary team meetings (MDTMs) in decision-making and identify factors that influence the probability of receiving a treatment plan with curative intent for patients with muscle invasive bladder cancer (MIBC). Patients and methods: Data relating to patients with cT2-4aN0/X-1 M0 urothelial cell carcinoma, diagnosed between November 2017 and October 2019, were selected from the nationwide, population-based Netherlands Cancer Registry (‘BlaZIB study’). Curative treatment options were defined as radical cystectomy (RC) with or without neoadjuvant chemotherapy, chemoradiation or brachytherapy. Multilevel logistic regression analyses were used to examine the association between MDTM factors and curative treatment advice and how this advice was followed. Results: Of the 2321 patients, 2048 (88.2%) were discussed in a genitourinary MDTM. Advanced age (&gt;80 years) and poorer World Health Organization performance status (score 1–2 vs 0) were associated with no discussion (P &lt; 0.001). Being discussed was associated with undergoing treatment with curative intent (odds ratio [OR] 3.0, 95% confidence interval [CI] 1.9–4.9), as was the involvement of a RC hospital (OR 1.70, 95% CI 1.09–2.65). Involvement of an academic centre was associated with higher rates of bladder-sparing treatment (OR 2.05, 95% CI 1.31–3.21). Patient preference was the main reason for non-adherence to treatment advice. Conclusions: For patients with MIBC, the probability of being discussed in a MDTM was associated with age, performance status and receiving treatment with curative intent, especially if a representative of a RC hospital was present. Future studies should focus on the impact of MDTM advice on survival data.</p
    • …
    corecore