994 resultados para Importance Sampling


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This paper estimates the marginal willingness-to-pay for attributes of a hypothetical HIV vaccine using discrete choice modeling. We use primary data from 326 respondents from Bangkok and Chiang Mai, Thailand, in 2008–2009, selected using purposive, venue-based sampling across two strata. Participants completed a structured questionnaire and full rank discrete choice modeling task administered using computer-assisted personal interviewing. The choice experiment was used to rank eight hypothetical HIV vaccine scenarios, with each scenario comprising seven attributes (including cost) each of which had two levels. The data were analyzed in two alternative specifications: (1) best-worst; and (2) full-rank, using logit likelihood functions estimated with custom routines in Gauss matrix programming language. In the full-rank specification, all vaccine attributes are significant predictors of probability of vaccine choice. The biomedical attributes of the hypothetical HIV vaccine (efficacy, absence of VISP, absence of side effects, and duration of effect) are the most important attributes for HIV vaccine choice. On average respondents are more than twice as likely to accept a vaccine with 99% efficacy, than a vaccine with 50% efficacy. This translates to a willingness to pay US$383 more for a high efficacy vaccine compared with the low efficacy vaccine. Knowledge of the relative importance of determinants of HIV vaccine acceptability is important to ensure the success of future vaccination programs. Future acceptability studies of hypothetical HIV vaccines should use more finely grained biomedical attributes, and could also improve the external validity of results by including more levels of the cost attribute.

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Prediction of the impact of suspended sediment on aquatic ecosystems requires adequate knowledge of sediment dynamics in surface waters. Often, studies reporting the response of aquatic biota to suspended sediment are concerned with concentrations, while catchment erosion studies often report sediment delivery as annual loads and yields, making the comparison to documented ecological impacts difficult. Similarly, the European Union Freshwater Fish Directive (FFD) (78/659/EC) stipulates a guideline value of 25mgl which should not be exceeded, with the exception of floods and droughts. In this respect, the significance of suspended sediment in two Irish rivers was assessed using turbidity sensors calibrated for suspended sediment. Sediment yields of 0.07 tonnes (t) hayear and 0.44thayear and annual FFD exceedance frequency of 8.3% and 17.8% were estimated for the two catchments. Contrasts in the frequency of exceedance events between both catchments was observed, yet duration was typically short (

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This article argues that to understand the use of evidence in policy, we need to examine how meanings and practices in the civil service shape what is accepted as knowledge, and how differences between the beliefs and values of the academy and the polity can impede the flow and transfer of knowledge. It considers the importance of social context and shared meanings in legitimating knowledge. Who counts as legitimate knowledge providers has expanded and here the role of stakeholder groups and experiential knowledge is of particular interest. How hierarchy, anonymity, and generalist knowledge within the civil service mediate the use of evidence in policy is examined. The difference in values and ideology of the civil service and the academy has implications for how academic research is interpreted and used to formulate policy and for its position in knowledge power struggles. There are particular issues about the social science nature of evidence to inform rural policy being mediated in a government department more used to dealing with natural science knowledge. This article is based on participant observation carried out in a UK Department of Agriculture and Rural Development. © 2013 The Author. Sociologia Ruralis © 2013 European Society for Rural Sociology.

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Background: The majority of women (71%) who undergo BRCA1/2 testing—designed to identify genetic mutations associated with increased risk of cancer—receive results that are termed ‘ambiguous’ or ‘uninformative negative’. How women interpret these results and the association with numerical ability was examined. Methods: In this study, 477 women at increased risk for breast and ovarian cancer were recruited via the Cancer Genetics Network. They were presented with information about the four different possible BRCA1/2 test results—positive, true negative, ambiguous and uninformative negative—and asked to indicate which of six options represents the best response. Participants were then asked which treatment options they thought a woman receiving the results should discuss with her doctor. Finally, participants completed measures of objective and subjective numeracy. Results: Almost all of the participants correctly interpreted the positive and negative BRCA1/2 genetic test results. However, they encountered difficulties interpreting the uninformative and ambiguous BRCA1/2 genetic test results. Participants were almost equally likely to think either that the woman had learned nothing from the test result or that she was as likely to develop cancer as the average woman. Highly numerate participants were more likely to correctly interpret inconclusive test results (ambiguous, OR = 1.62; 95% CI [1.28, 2.07]; p < 0.001; uninformative, OR = 1.40; 95% CI [1.10, 1.80]). Discussion: Given the medical and psychological ramifications of genetic testing, healthcare professionals should consider devoting extra effort to ensuring proper comprehension of ambiguous and uninformative negative test results by women. Copyright © 2014 John Wiley & Sons, Ltd.

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Objectives: To explore children's views on microneedle use for this population, particularly as an alternative approach to blood sampling, in monitoring applications, and so, examine the acceptability of this approach to children.

Methods: Focus groups were conducted with children (aged 10-14 years) in a range of schools across Northern Ireland. Convenience sampling was employed, i.e. children involved in a university-directed community-outreach project (Pharmacists in Schools) were recruited.

Key findings: A total of 86 children participated in 13 focus groups across seven schools in Northern Ireland. A widespread disapproval for blood sampling was evident, with pain, blood and traditional needle visualisation particularly unpopular aspects. In general, microneedles had greater visual acceptability and caused less fear. A patch-based design enabled minimal patient awareness of the monitoring procedure, with personalised designs, e.g. cartoon themes, favoured. Children's concerns included possible allergy and potential inaccuracies with this novel approach; however, many had confidence in the judgement of healthcare professionals if deeming this technique appropriate. They considered paediatric patient education critical for acceptance of this new approach and called for an alternative name, without any reference to 'needles'.

Conclusions: The findings presented here support the development of blood-free, minimally invasive techniques and provide an initial indication of microneedle acceptability in children, particularly for monitoring purposes. A proactive response to these unique insights should enable microneedle array design to better meet the needs of this end-user group. Further work in this area is recommended to ascertain the perspectives of a purposive sample of children with chronic conditions who require regular monitoring. © 2013 Royal Pharmaceutical Society.

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With its origins in the trick films of the 1890s and early 1900s, British science fiction film has a long history. While Things to Come (1936) is often identified as significant for being written by H.G.Wells, one of the fathers of science fiction as a genre, the importance of the interactions between media in the development of British science fiction film are often set aside. This chapter examines the importance of broadcast media to film-making in Britain, focusing on the 1950s as a period often valourised in writings about American science fiction, to the detriment of other national expressions of the genre. This period is key to the development of the genre in Britain, however, with the establishment of television as a popular medium incorporating the development of domestic science fiction television alongside the import of American products, together with the spread of the very term ‘science fiction’ through books, pulps and comics as well as radio, television and cinema. It was also the time of a backlash against the perceived threat of American soft cultural power embodied in the attractive shine of science fiction with its promise of a bright technological future. In particular, this chapter examines the significance of the relationship between the BBC television and radio services and the film production company Hammer, which was responsible for multiple adaptations of BBC properties, including a number of science fiction texts. The Hammer adaptation of the television serial The Quatermass Experiment proved to be the first major success for the company, moving it towards its most famous identity as producer of horror texts, though often horror with an underlying scientific element, as with their successful series of Frankenstein films. This chapter thus argues that the interaction between film and broadcast media in relation to science fiction was crucial at this historical juncture, not only in helping promote the identities of filmmakers like Hammer, but also in supporting the identity of the BBC and its properties, and in acting as a nexus for the then current debates on taste and national identity.

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Accretion disk winds are thought to produce many of the characteristic features seen in the spectra of active galactic nuclei (AGNs) and quasi-stellar objects (QSOs). These outflows also represent a natural form of feedback between the central supermassive black hole and its host galaxy. The mechanism for driving this mass loss remains unknown, although radiation pressure mediated by spectral lines is a leading candidate. Here, we calculate the ionization state of, and emergent spectra for, the hydrodynamic simulation of a line-driven disk wind previously presented by Proga & Kallman. To achieve this, we carry out a comprehensive Monte Carlo simulation of the radiative transfer through, and energy exchange within, the predicted outflow. We find that the wind is much more ionized than originally estimated. This is in part because it is much more difficult to shield any wind regions effectively when the outflow itself is allowed to reprocess and redirect ionizing photons. As a result, the calculated spectrum that would be observed from this particular outflow solution would not contain the ultraviolet spectral lines that are observed in many AGN/QSOs. Furthermore, the wind is so highly ionized that line driving would not actually be efficient. This does not necessarily mean that line-driven winds are not viable. However, our work does illustrate that in order to arrive at a self-consistent model of line-driven disk winds in AGN/QSO, it will be critical to include a more detailed treatment of radiative transfer and ionization in the next generation of hydrodynamic simulations.

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Soil gas emissions of methane and carbon dioxide on brownfield sites are usually attributed to anthropogenic activities; however geogenic sources of soil gas are often not considered during site investigation and risk management strategies. This paper presents a field study at a redeveloped brownfield site on a flood plain to identify accumulations of methane biogas trapped in underlying sediments. The investigation is based on a multidisciplinary approach using direct multi-level sampling measurements and Earth resistivity tomography . Resistivity imaging was applied to evaluate the feasibility of identifying the size and spatial continuity of soil gas accumulations in anthropogenic and naturally occurring deposits. As a result, biogas accumulations are described within both anthropogenic deposits and pristine organic sediments. This result is important to identify the correct approaches to identify and manage risks associated with soil gas emissions on brownfield and pristine sites. The organic-rich sediments in Quaternary fluvial environments of São Paulo Basin in particular the Tietê River, biogas reservoirs can be generated and trapped beneath geogenic and anthropogenic layers, potentially requiring the management of brownfield developments across this region.

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Despite adherence to strict standards of care in preparation for intravitreal injections, endophthalmitis can still occur. This article focuses on endophthalmitis and the importance of povidone-iodine in pre-procedure antisepsis. An overview of endophthalmitis and an examination of the benefits of povidone-iodine in ocular aseptic technique for the prevention of post-procedure endophthalmitis are provided. The misconceptions that patients and health practitioners may have in relation to povidone-iodine hypersensitivity are also explored.