349 research outputs found

    Facing difficult but unavoidable choices: Donor blood safety and the deferral of men who have sex with men

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    Blood service organizations employ various ways to ensure transfusion blood safety, including the testing of all donations for transfusion-transmissible infections (TTI) and the exclusion of donors who are at increased risk of a recent infection. As some TTIs are more common among men who have sex with men (MSM), many jurisdictions (temporarily) defer the donation of blood by sexually active MSM. This boils down to a categorical exclusion of a large group solely on the basis of their sexual orientation, which is seen as unduly discriminatory and stigmatizing. Blood service organizations in the U.K. and the Netherlands have recently changed their deferral policies for MSM. The problem of the MSM deferral involves a conflict between fundamental rights: the right of MSM to equal treatment and the right to health of the recipients of blood and blood products. We distinguish and discuss three broad alternative options to the current categorical deferral of MSM donations: (1) completely abandoning donor selection on the basis of sexual behavior, (2) individual risk assessment of the sexual activities of each potential donor, and (3) individual risk assessment of the sexual activities of MSM only. The new U.K. policy falls within the second category, and the new Dutch policy is in the third category. We argue that each approach comes with moral costs but that the most reasonable option is different from the policies of both the U.K. and the Netherlands

    Drivers for optimum sizing of wind turbines for offshore wind farms

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    Large-scale exploitation of offshore wind energy is deemed essential to provide its expected share to electricity needs of the future. To achieve the same, turbine and farm-level optimizations play a significant role. Over the past few years, the growth in the size of turbines has massively contributed to the reduction in costs. However, growing turbine sizes come with challenges in rotor design, turbine installation, supply chain, etc. It is, therefore, important to understand how to size wind turbines when minimizing the levelized cost of electricity (LCoE) of an offshore wind farm. Hence, this study looks at how the rated power and rotor diameter of a turbine affect various turbine and farm-level metrics and uses this information in order to identify the key design drivers and how their impact changes with setup. A multi-disciplinary design optimization and analysis (MDAO) framework is used to perform the analysis. The framework uses low-fidelity models that capture the core dependencies of the outputs on the design variables while also including the trade-offs between various disciplines of the offshore wind farm. The framework is used, not to estimate the LCoE or the optimum turbine size accurately, but to provide insights into various design drivers and trends. A baseline case, for a typical setup in the North Sea, is defined where LCoE is minimized for a given farm power and area constraint with the International Energy Agency 15 MW reference turbine as a starting point. It is found that the global optimum design, for this baseline case, is a turbine with a rated power of 16 MW and a rotor diameter of 236 m. This is already close to the state-of-the-art designs observed in the industry and close enough to the starting design to justify the applied scaling. A sensitivity study is also performed that identifies the design drivers and quantifies the impact of model uncertainties, technology/cost developments, varying farm design conditions, and different farm constraints on the optimum turbine design. To give an example, certain scenarios, like a change in the wind regime or the removal of farm power constraint, result in a significant shift in the scale of the optimum design and/or the specific power of the optimum design. Redesigning the turbine for these scenarios is found to result in an LCoE benefit of the order of 1 %–2 % over the already optimized baseline. The work presented shows how a simplified approach can be applied to a complex turbine sizing problem, which can also be extended to metrics beyond LCoE. It also gives insights into designers, project developers, and policy makers as to how their decision may impact the optimum turbine scale.</p

    Aeroservoelastic design definition of a 20 MW common research wind turbine model

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    Wind turbine upscaling is motivated by the fact that larger machines can achieve lower levelized cost of energy. However, there are several fundamental issues with the design of such turbines, and there is little public data available for large wind turbine studies. To address this need, we develop a 20 MW common research wind turbine design that is available to the public. Multidisciplinary design optimization is used to define the aeroservoelastic design of the rotor and tower subject to the following constraints: blade‐tower clearance, structural stresses, modal frequencies, tip‐speed and fatigue damage at several sections of the tower and blade. For the blade, the design variables include blade length, twist and chord distribution, structural thicknesses distribution and rotor speed at the rated. The tower design variables are the height, and the diameter distribution in the vertical direction. For the other components, mass models are employed to capture their dynamic interactions. The associated cost of these components is obtained by using cost models. The design objective is to minimize the levelized cost of energy. The results of this research show the feasibility of a 20 MW wind turbine and provide a model with the corresponding data for wind energy researchers to use in the investigation of different aspects of wind turbine design and upscaling. Copyright © 2016 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134256/1/we1970.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134256/2/we1970_am.pd

    Screening of post-mortem tissue donors for Coxiella burnetii infection after large outbreaks of Q fever in The Netherlands

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    BACKGROUND: After the largest outbreaks of Q fever ever recorded in history occurred in the Netherlands, concern arose that Coxiella may be transmitted via donated tissues of latent or chronically infected donors. The Dutch Health Council recently advised to screen tissue donors, donating high risk tissues, for Coxiella infection. METHODS: After validation of an enzyme immunoassay (EIA) test for IgG antibodies against phase 2 of C. burnetii for use on post-mortem samples, serum samples of 1033 consecutive Dutch post-mortem tissue donors were tested for IgG antibodies against phase 2 of C. burnetii. Confirmation of reactive results was done by immunofluorescence assay (IFA). All available tissues (corneas, heart valves, skin and bone marrow) from donors with IgG reactivity were tested for presence of Coxiella DNA by PCR. Risk factors for IgG reactivity were investigated. RESULTS: After validation of the tests for use on post-mortem samples, 50/1033 donors (4.8%) screened positive for phase 2 anti-Coxiella IgG by EIA, and 31 were confirmed by IFA (3.0%). One donor showed a serological profile compatible with chronic infection. All tested tissues (25 corneas, 6 heart valves, 4 skin and 3 bone marrow) from donors with IgG reactivity tested negative for the presence of Coxiella DNA. Except for living in a postal code area with a high number of Q fever notifications, no risk factors for IgG reactivity were found. CONCLUSIONS: The strong correlation between notifications and seroprevalence confirms that the used assays are sufficiently specific for use on post-mortem samples, although one has to be aware of differences between batches. Thus, this study provides a validated method for screening tissue donors for infection with Coxiella burnetii that can be used in future outbreaks

    Pulmonary arterial hypertension associated with pulmonary arteriovenous malformations and pulmonary veno-occlusive disease:A devastating combination

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    We describe a case of an adolescent male with the rare combination of pulmonary arterial hypertension (PAH) and pulmonary arteriovenous malformations (PAVM's) without confirmed hereditary hemorrhagic telangiectasia (HHT). The patient showed clinical deterioration on standard vasodilator therapy, leading us to question our initial diagnosis. Post-mortem evaluation confirmed the presence of pulmonary veno-occlusive disease of which no conclusive signs were recognized at diagnostic work-up. This case demonstrates the heterogeneity in the diseases causing PAH and shows that an unexpected treatment response should alert the physician to question the original diagnosis

    Risk factors for hepatitis E virus seropositivity in Dutch blood donors

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    Background: A marked increase of hepatitis E cases has recently been observed in the Netherlands. Causes of the (re-)emergence of hepatitis E virus (HEV) and exact sources and routes of transmission of HEV infection are currently unknown. We aimed to identify risk factors for HEV seropositivity. Methods: Using the Wantai EIA, 2100 plasma samples of blood donors from all over the Netherlands aged 18-70 years were tested for anti-HEV IgG antibodies. A questionnaire on socio-demographic characteristics, health, and potential risk factors for HEV exposure was sent to these participants. Results: The overall IgG-seroprevalence was 31% (648/2100) and increased with age. Several food products were independently associated with IgG-seropositivity in a multivariate analysis adjusting for age and gender among 1562 participants who completed the questionnaire: traditional Dutch dry raw sausages called "cervelaat", "fijnkost", "salami" and "salametti" which are generally made from raw pork and beef (aOR 1.5; 95%CI 1.2-1.9), frequent consumption of bovine steak (aOR 1.3; 95%CI 1.0-1.7), and frequent consumption of smoked beef (aOR 1.3 95%CI 1.0-1.7). Although not frequently reported, contact with contaminated water was also a risk factor for seropositivity (aOR 2.5; 95%CI 1.5-4.4). Lower seroprevalence was associated with eating raspberries, going out for dinner, and contact with wild animals and dogs. Conclusion: Several pork food products, mainly dry raw sausages, and contact with contaminated water were associated with past HEV infection in the Netherlands. Further investigation is needed into the prevalence and infectivity of HEV in these risk factor food products, as well as investigation of the production methods and possible origin of HEV-contamination within these sausages, e.g. very small amounts of pork liver, pig-derived blood products as food additive, or the pork muscle tissue

    Fluorescence Lifetime Imaging Microcopy of Extravasating Cancer Cells in the Mouse Microenvironment

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    Objective. To determine (i) whether early viral kinetics or other markers during a modified treatment regimen are predictors of treatment outcome and (ii) whether fast responders can be treated for 24 weeks, without compromising the sustained virologic response (SVR) rate. Material and methods. One hundred "difficult-to-treat'' chronic hepatitis C patients (46 previous non-responders/relapsers (any genotype), 54 treatment-naive patients genotypes 1 and 4) were treated with triple antiviral induction therapy: amantadine hydrochloride and ribavirin, combined with 6 weeks interferon alfa-2b induction (weeks 1-2: 18 MU/day, weeks 3-4: 9 MU/day, weeks 5-6: 6 MU/day), thereafter combined with weekly peginterferon alfa-2b. Fast responders (>= 3 log(10) HCV RNA decline at week 4) were randomized to 24 or 48 weeks. Slow responders (= or = 5 IU/mL at week 16 became non-SVR. In previous non-responders/relapsers, the predictive value for SVR was 83% if HCV RNA was = 5 IU/mL at week 8 became non-SVR. Conclusions. With high-dose interferon induction, SVR and non-SVR can be predicted reliably within 16 weeks. Fast responders can be treated for 24 weeks, and SVR is independent of baseline viral load in fast responders
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