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751.
752.
To reduce maintenance costs, municipalities and schools are starting to replace natural grass fields with a new generation synthetic turf. Unlike Astro‐Turf, which was first introduced in the 1960s, synthetic field turf provides more cushioning to athletes. Part of this cushioning comes from materials like crumb rubber infill, which is manufactured from recycled tires and may contain a variety of chemicals. The goal of this study was to evaluate potential exposures from playing on artificial turf fields and associated risks to trace metals, semi‐volatile organic compounds (SVOCs), and polycyclic aromatic hydrocarbons (PAHs) by examining typical artificial turf fibers (n = 8), different types of infill (n = 8), and samples from actual fields (n = 7). Three artificial biofluids were prepared, which included: lung, sweat, and digestive fluids. Artificial biofluids were hypothesized to yield a more representative estimation of dose than the levels obtained from total extraction methods. PAHs were routinely below the limit of detection across all three biofluids, precluding completion of a meaningful risk assessment. No SVOCs were identified at quantifiable levels in any extracts based on a match of their mass spectrum to compounds that are regulated in soil. The metals were measurable but at concentrations for which human health risk was estimated to be low. The study demonstrated that for the products and fields we tested, exposure to infill and artificial turf was generally considered de minimus, with the possible exception of lead for some fields and materials. 相似文献
753.
Yoon-Suk Hwang 《Disability & Society》2014,29(10):1583-1600
Responding to the call for culturally informed research on autism spectrum (AS) to allow for the provision of appropriate services, this paper qualitatively explores the affective experience of five Korean learners identified with AS and cognitive difficulties by listening to their voices. The learners, supported by the use of visual aids and a choice of their preferred mode of communication, expressed the complexity of their inner experience that encompassed abilities as well as difficulties. The findings highlight the commonalities of experience between Korean and non-Korean individuals with AS, along with some aspects specific to the Korean cultural context. 相似文献
754.
Eunju Hwang 《Statistics》2017,51(4):844-861
This paper studies the stationary bootstrap applicability for realized covariations of high frequency asynchronous financial data. The stationary bootstrap method, which is characterized by a block-bootstrap with random block length, is applied to estimate the integrated covariations. The bootstrap realized covariance, bootstrap realized regression coefficient and bootstrap realized correlation coefficient are proposed, and the validity of the stationary bootstrapping for them is established both for large sample and for finite sample. Consistencies of bootstrap distributions are established, which provide us valid stationary bootstrap confidence intervals. The bootstrap confidence intervals do not require a consistent estimator of a nuisance parameter arising from nonsynchronous unequally spaced sampling while those based on a normal asymptotic theory require a consistent estimator. A Monte-Carlo comparison reveals that the proposed stationary bootstrap confidence intervals have better coverage probabilities than those based on normal approximation. 相似文献
755.
In recent years, attention on the issue of poverty in Singapore has been increasingly placed in the spotlight. This study examines the various types of attitudes among Singaporeans and how they are formed, relating them to the broader institutional context of Singapore. A mixed method design is employed where clusters or groups of attitudes are derived through the use of cluster analysis. Subsequently, discourses of poverty and welfare attitudes are construed through qualitative interviews with the aid of Foucauldian Discourse Analysis. Quantitative findings point to three clusters of attitudes: ‘Conservatives’, ‘Liberals’, and ‘Sui Generis’. Qualitative findings, however, show that ‘Sui Generis’ ultimately align themselves closer to either ‘Conservatives’ or ‘Liberals’ in their discourses of welfare. In fact, respondents in all three clusters reproduce state discourses, albeit in varying ways. In essence, this study explicates poverty and welfare attitudes as a product of social identities premised on subjective notions that are shaped by state discourses of meritocracy, self-reliance and anti-welfarism. It is thus argued that current socio-political constructions of poverty ensue a paucity of major welfare reform in the near future of Singapore. 相似文献
756.
757.
Robust tests for comparing scale parameters, based on deviances—absolute deviations from the median—are examined. Higgins (2004) proposed a permutation test for comparing two treatments based on the ratio of deviances, but the performance of this procedure has not been investigated. A simulation study examines the performance of Higgins’ test relative to other tests of scale utilizing deviances that have been shown in the literature to have good properties. An extension of Higgins’ procedure to three or more treatments is proposed, and a second simulation study compares its performance to other omnibus tests for comparing scale. While no procedure emerged as a preferred choice in every scenario, Higgins’ tests are found to perform well overall with respect to Type I error rate and power. 相似文献
758.
This study investigated the relationships between types of activity and quality of life (QOL) for older men and women at different ages. Based on cross-sectional data that included 220 community-dwelling elderly persons aged 65 and older in southern Taiwan, the results showed that the participation rates in many activities declined with age for both genders. Social activity and solitary leisure activity were significantly associated with QOL for old-old men, but not for young-old men. Only social activity was significantly associated with QOL for young-old women, but there was no significant association between any activity and QOL for old-old women. 相似文献
759.
Lawns are considered monocultures and lesser contributors to sustainability than diverse nature but are still a dominating green area feature and an important cultural phenomenon in cities. Lawns have esthetical values, provide playground, are potential habitat for species, contribute to carbon sequestration and water infiltration, but also increase pesticides, fertilization, are monocultures and costly to manage at the same time. To evaluate the potential impact of lawns, whether positive or negative, it is of interest to estimate the total lawn cover in cities and its change over time. This is not a straightforward process, e.g., because many lawns are small and covered by trees. In this study we review the existing literature of lawn cover in cities and the different methodologies used for cover estimation. We found both pros and cons with NDVI and LiDAR data as well as manually interpreted aerial photos. The total cover of lawns in three case study cities was estimated to 22.5%. By extrapolating these percentages to all Swedish cities lawn cover was estimated to 2589 km2 (0.6% of the terrestrial surface). The approximated total municipal management cost of lawns in all Swedish cities was 910,000,000 USD/ year. During 50 years lawn area almost doubled in relative cover and 56% of them were continuously managed. Since lawns constitute large parts of the urban greenery and are costly to manage it is highly relevant to consider their social, ecological and cultural value compared to alternatives, e.g., meadows with less intensive management. 相似文献
760.