Sampling Studies

抽样研究
  • 文章类型: Journal Article
    城市固体废物焚化炉(MSWI)不仅被认为是多氯二苯并二恶英/呋喃(PCDD/Fs)的最主要来源之一,但由于废物中存在溴化阻燃剂(BFR),也会产生大量的多溴二苯并对二恶英/呋喃(PBDD/Fs)。到目前为止,然而,MSWI附近环境中的PBDD/Fs及其相关风险的研究很少。基于为期一年的被动空气采样(PAS)方案,我们调查了已运行多年的大规模MSWI周围的机载PBDD/Fs和PCDD/Fs。随着远离MSWI,PBDD/Fs和PCDD/Fs的浓度在空间上呈下降趋势,确认MSWI对其环境空气中二恶英含量的影响。但其对PBDD/Fs的影响较小,因为PBDD/Fs的挥发性较低,因此气体浓度低于PCDD/Fs。与现有的机载PCDD/Fs和PBDD/Fs的全球数据相比,我们的MSWI附近的数据处于中等水平,尽管PAS样品在理论上仅代表气态二恶英的浓度。季节性数据表明,气象条件对MSWI周围空气中二恶英的浓度和来源产生了明显影响。至于PCDD/Fs,MSWI被诊断为最主要的来源,其次是当地交通和挥发/沉积。尽管前三个PBDD/F来源与多溴二苯醚有关,溴酚/溴苯,和交通车辆,分别。基于MSWI周围空气中二恶英的芳香烃受体激活的生物测定法衍生的TEQ比基于浓度的TEQ高一个或两个数量级,某些MSWI附近的相应致癌风险超过了美国EPA提出的可接受阈值(10-6~10-4),值得持续关注。
    Municipal solid waste incinerator (MSWI) not only is deemed one of the uppermost sources of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), but also produces substantial amount of polybrominated dibenzo-p-dioxins/furans (PBDD/Fs) owing to the existence of brominated flame retardants (BFRs) in the waste. So far, however, PBDD/Fs in the vicinal environments of MSWI and their associated risks remain rarely studied. Based on a one-year passive air sampling (PAS) scheme, we investigated airborne PBDD/Fs and PCDD/Fs around a large-scale MSWI that has been operated for multi-years. Both the concentrations of PBDD/Fs and PCDD/Fs showed spatially decreasing trends with the distance away from the MSWI, confirming the influence of the MSWI on the dioxin levels in its ambient air. But its influence on PBDD/Fs was less because PBDD/Fs exhibit lower volatility and therefore lower gaseous concentrations than PCDD/Fs. Compared to the existing global data of airborne PCDD/Fs and PBDD/Fs, our data of the MSWI vicinity were at medium levels, despite PAS samples only represent the concentrations of gaseous dioxins in theory. The seasonal data suggest that meteorological conditions exerted apparent influences over the concentrations and sources of airborne dioxins around the MSWI. As for PCDD/Fs, the MSWI was diagnosed as their uppermost source, followed by local traffic and volatilization/deposition. Whereas the top three PBDD/F sources were related to PBDEs, bromophenol/bromobenzene, and traffic vehicles, respectively. The bioassay-derived TEQs based on the aryl hydrocarbon receptor activation of airborne dioxins around the MSWI were one or two orders of magnitudes higher than their concentration-based TEQs, and the corresponding carcinogenic risks at some MSWI-vicinal sites exceeded the acceptable threshold proposed by the U. S. EPA (10-6 ∼ 10-4) and deserve continuous attention.
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  • 文章类型: Journal Article
    随着数据的快速膨胀,医疗领域的数据失衡问题日益突出,金融,网络,等。它通常使用过采样方法来求解。然而,大多数现有的过抽样方法随机抽样或仅对特定区域进行抽样,影响分类结果。为了解决上述限制,本研究提出了一种不平衡数据过采样方法,SD-KMSMOTE,基于少数样本的空间分布。增加了滤波器噪声预处理,考虑近邻样本的类别信息,并去除现有的少数类样本噪声。这些条件导致设计一种新的样品合成方法,并在此基础上构建了权重值的计算规则。综合考虑少数类样本的空间分布;对它们进行聚类,和包含有用信息的子集群被分配更大的权重值和更多的合成样本数量。实验结果表明,实验结果在精度方面优于现有方法,召回,F1得分,G-mean,和曲线下面积值的方法用于扩展医学等领域的不平衡数据集。
    With the rapid expansion of data, the problem of data imbalance has become increasingly prominent in the fields of medical treatment, finance, network, etc. And it is typically solved using the oversampling method. However, most existing oversampling methods randomly sample or sample only for a particular area, which affects the classification results. To solve the above limitations, this study proposes an imbalanced data oversampling method, SD-KMSMOTE, based on the spatial distribution of minority samples. A filter noise pre-treatment is added, the category information of the near-neighbouring samples is considered, and the existing minority class sample noise is removed. These conditions lead to the design of a new sample synthesis method, and the rules for calculating the weight values are constructed on this basis. The spatial distribution of minority class samples is considered comprehensively; they are clustered, and the sub-clusters that contain useful information are assigned larger weight values and more synthetic sample numbers. The experimental results show that the experimental results outperform existing methods in terms of precision, recall, F1 score, G-mean, and area under the curve values when the proposed method is used to expand the imbalanced dataset in the field of medicine and other fields.
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  • 文章类型: English Abstract
    Respondent-driven sampling (RDS) is a method of sampling specifically for hidden populations, often applied to transgender women, female sex workers, men who have sex with men, and other groups that are difficult to identify and contact because of stigma and legal constraints. However, this method is gradually applied to the general population. With the continuous improvement of RDS, studies find that the network size of RDS samples can be weighted to estimate the overall situation and population size. This article summarizes the current application progress of RDS in population size estimation and provides ideas for the development of RDS and the use of RDS to carry out relevant research.
    受访者驱动抽样(RDS)是一种专门针对隐匿人群的抽样方法,常用于跨性别者、暗娼、MSM等因耻辱感和法律制度的约束难以识别和接触的人群,并逐渐应用于一般人群。随着RDS的不断改进和完善,研究发现对RDS样本的社交网络规模赋予权重可以估计总体的情况及人群规模。本文对目前RDS在人群规模估计中的应用进展进行综述,为RDS的发展及使用该方法开展相关研究提供思路。.
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  • 文章类型: Journal Article
    Xinjiang is one of the areas in China with extremely severe iodine deficiency. The health of Xinjiang residents has been endangered for a long time. In order to provide reasonable suggestions for scientific iodine supplementation and improve the health and living standards of the people in Xinjiang, it is necessary to understand the spatial distribution of iodine content in drinking water and explore the influencing factors of spatial heterogeneity of water iodine content distribution.
    The data of iodine in drinking water arrived from the annual water iodine survey in Xinjiang in 2017. The distribution of iodine content in drinking water in Xinjiang is described from three perspectives: sampling points, districts/counties, and townships/streets. ArcGIS was used for spatial auto-correlation analysis, mapping the distribution of iodine content in drinking water and visualizing the distribution of Geographically Weighted Regression (GWR) model parameter. Kriging method is used to predict the iodine content in water at non-sampling points. GWR software was used to build GWR model in order to find the factors affecting the distribution of iodine content in drinking water.
    There are 3293 sampling points in Xinjiang. The iodine content of drinking water ranges from 0 to 128 μg/L, the median is 4.15 μg/L. The iodine content in 78.6% of total sampling points are less than 10 μg/L, and only that in the 3.4% are more than 40 μg/L. Among 1054 towns\' water samples in Xinjiang, 88.9% of the samples\' water iodine content is less than 10 μg/L. Among the 94 studied areas, the median iodine content in drinking water in 87 areas was less than 10 μg/L, those values in 7 areas were between 10-40 μg/L, and the distribution of water iodine content in Xinjiang shows clustered. The GWR model established had found that the effects of soil type and precipitation on the distribution of iodine content in drinking water were statistically significant.
    The iodine content of drinking water in Xinjiang is generally low, but there are also some areas which their drinking water has high iodine content. Soil type and precipitation are the factors affecting the distribution of drinking water iodine content, and are statistically significant (P<0.05).
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  • 文章类型: Journal Article
    Severe fever with thrombocytopenia syndrome (SFTS) is a novel tick-borne infectious disease caused by a new type of SFTS virus (SFTSV). Here, a longitudinal sampling study is conducted to explore the differences in transcript levels after SFTSV infection, and to characterize the transcriptomic and epigenetic profiles of hospitalized patients. The results reveal significant changes in the mRNA expression of certain genes from onset to recovery. Moreover, m6A-seq reveals that certain genes related with immune regulation may be regulated by m6A. Besides the routine tests such as platelet counts, serum ALT and AST levels testing, distinct changes in myocardial enzymes, coagulation function, and inflammation are well correlated with the clinical data and sequencing data, suggesting that clinical practitioners should monitor the above indicators to track disease progression and guide personalized treatment. In this study, the transcript changes and RNA modification may lend a fresh perspective to our understanding of the SFTSV and play a significant role in the discovery of drugs for effective treatment of this disease.
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  • 文章类型: Journal Article
    证据表明,年龄相关性黄斑变性(AMD)与过敏性疾病的先前存在有关;然而,文献中的大规模研究是有限的。使用台湾的国民健康保险数据库进行了一项病例对照研究,以描述病前过敏性疾病与AMD之间的关系。建立了纳入2000年至2013年新的成人AMD病例的资格标准。我们将诊断年定义为指数年。年龄-,性别-,从同一数据库中提取的索引年份匹配的对照。病例对照比为1:4。对于所有参与者,从1996年到索引年的所有病前状况都有记录。二元logistic回归用于描述与AMD发生相关的因素。AMD组包括10,911名患者,对照组由43,644人组成。AMD患者与病前变态反应性疾病显著相关(aOR1.54,95%CI1.47-1.61),特别是过敏性结膜炎(aOR2.07,95%CI1.94-2.20),过敏性鼻炎(aOR1.32,95%CI1.25-1.39),哮喘(aOR0.99,95%CI0.93-1.06),和特应性皮炎(aOR1.04,95%CI0.94-1.17)。进一步的分析表明,并发过敏性疾病较多的患者与AMD的相关性高于并发疾病较少的患者。每年因过敏性疾病就诊次数较多的患者与AMD的相关性也高于就诊次数较少的患者。AMD与病前过敏性疾病显著相关。必须进一步调查潜在的机制。
    Evidence indicates that age-related macular degeneration (AMD) is associated with the prior presence of allergic diseases; however, large-scale studies in the literature are limited. A case-control study was conducted to describe the relationship between premorbid allergic diseases and AMD using Taiwan\'s National Health Insurance database. Eligibility criteria for inclusion of new adult AMD cases from 2000 to 2013 were set up. We defined the year of diagnosis as the index year. Age-, gender-, index year- matched controls who were drawn from the same database. The case control ratio was 1:4. For all participants, all premorbid conditions staring 1996 to index year were documented. Binary logistic regression was used to describe factors related to AMD occurrence. The AMD group consisted of 10,911 patients, and the comparison group consisted of 43,644 individuals. Patients with AMD showed significant associations with premorbid allergic diseases (aOR 1.54, 95% CI 1.47-1.61), specifically with allergic conjunctivitis (aOR 2.07, 95% CI 1.94-2.20), allergic rhinitis (aOR 1.32, 95% CI 1.25-1.39), asthma (aOR 0.99, 95% CI 0.93-1.06), and atopic dermatitis (aOR 1.04, 95% CI 0.94-1.17). Further analyses indicated that patients with more concurrent allergic diseases have higher associations with AMD than those with fewer concurrent diseases. Patients with more annual medical visits for their allergic diseases also showed higher associations with AMD than those with fewer visits. AMD is significantly associated with premorbid allergic diseases. The underlying mechanisms must be further investigated.
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  • 文章类型: Journal Article
    The negative air ion (NAI) concentration is an essential indicator of air quality and atmospheric pollution. The NAI concentration can be used to monitor air quality on a regional scale and is commonly determined using field measurements. However, obtaining these measurements is time-consuming. In this paper, the relationship between remotely sensed surface parameters (such as land surface temperature, normalized difference vegetation index (NDVI), and leaf area index) obtained from MODIS data products and the measured NAI concentration using a stepwise regression method was analyzed to estimate the spatial distribution of the NAI concentration and verify the precision. The results indicated that the NAI concentration had a negative correlation with temperature, leaf area index (LAI), and gross primary production while it exhibited a positive correlation with the NDVI. The relationship between land surface temperature and the NAI concentration in the Daxing\'anling region is expressed by the regression equation of y = -35.51x1 + 11206.813 (R2 = 0.6123). Additionally, the NAI concentration in northwest regions with high forest coverage was higher than that in southeast regions with low forest coverage, suggesting that forests influence the air quality and reduce the impact of environmental pollution. The proposed inversion model is suitable for evaluating the air quality in Daxing\'anling and provides a reference for air quality evaluation in other areas. In the future, we will expand the quantity and distribution range of sampling points, conduct continuous observations of NAI concentrations and environmental parameters in the research areas with different land-use types, and further improve the accuracy of inversion results to analyze the spatiotemporal dynamic changes in NAI concentration and explore the possibility of expanding the application areas of NAI monitoring.
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  • 文章类型: Journal Article
    依赖于结果的抽样设计,如病例对照或病例队列设计,因其出色的成本效益而被广泛用于流行病学研究。在这篇文章中,我们提出并开发了一种平滑加权Gehan估计方程方法,用于在一般故障时间结果相关采样方案下的加速故障时间模型中进行推断。所提出的估计方程是连续可微的,可以通过标准的数值方法求解。除了开发所提出的估计器的渐近性质外,我们还通过最大化重要测试的幂函数,在所提出的设计中提出并研究了一种新的基于功率的子样本分配标准。仿真结果表明,所提出的估计器比其他现有的竞争估计器更有效,并且基于功率的最佳子样本分配将提供ODS设计,该设计可为暴露效果的测试提供改进的功率。我们使用来自挪威母婴队列研究的数据集说明了所提出的方法,以评估全氟烷基物质暴露与女性生育能力之间的关系。
    Outcome-dependent sampling designs such as the case-control or case-cohort design are widely used in epidemiological studies for their outstanding cost-effectiveness. In this article, we propose and develop a smoothed weighted Gehan estimating equation approach for inference in an accelerated failure time model under a general failure time outcome-dependent sampling scheme. The proposed estimating equation is continuously differentiable and can be solved by the standard numerical methods. In addition to developing asymptotic properties of the proposed estimator, we also propose and investigate a new optimal power-based subsamples allocation criteria in the proposed design by maximizing the power function of a significant test. Simulation results show that the proposed estimator is more efficient than other existing competing estimators and the optimal power-based subsamples allocation will provide an ODS design that yield improved power for the test of exposure effect. We illustrate the proposed method with a data set from the Norwegian Mother and Child Cohort Study to evaluate the relationship between exposure to perfluoroalkyl substances and women\'s subfecundity.
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  • 文章类型: Journal Article
    In the face of the global pandemic of coronavirus disease-2019 (COVID-19), people\'s adherence to precautionary behavioral measures (e.g. social distancing) largely influences the effectiveness of those measures in containing the spread of the coronavirus. The present study aims at testing the applicability of the health belief model (HBM) and generalised social beliefs (i.e. social axioms) to explore strategies for promoting adherence to COVID-19 precautionary measures.
    We conducted a telephone survey with a two-step stratified random sampling method and obtained a probability sample of 616 adults in Macao, China (18-87 years old; 60.9% women) in April 2020.
    Our participants showed stronger adherence to some COVID-19 precautionary measures (e.g. face mask wearing; 96.4%) but not others (e.g. social distancing; 42.3%). Their adherence to those measures was found to be significantly associated with four HBM factors and two social axioms, after controlling for gender, age, and years of education.
    The HBM and the generalised social beliefs of social cynicism and reward for application can be applied to understanding adherence to precautionary measures against COVID-19. Strategies based on beliefs were proposed to facilitate the promotion of precautionary measures.
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  • 文章类型: Journal Article
    Since its outbreak in January 2020, COVID-19 has quickly spread worldwide and has become a global pandemic. Social media platforms have been recognized as important tools for health-promoting practices in public health, and the use of social media is widespread among the public. However, little is known about the effects of social media use on health promotion during a pandemic such as COVID-19.
    In this study, we aimed to explore the predictive role of social media use on public preventive behaviors in China during the COVID-19 pandemic and how disease knowledge and eHealth literacy moderated the relationship between social media use and preventive behaviors.
    A national web-based cross-sectional survey was conducted by a proportionate probability sampling among 802 Chinese internet users (\"netizens\") in February 2020. Descriptive statistics, Pearson correlations, and hierarchical multiple regressions were employed to examine and explore the relationships among all the variables.
    Almost half the 802 study participants were male (416, 51.9%), and the average age of the participants was 32.65 years. Most of the 802 participants had high education levels (624, 77.7%), had high income >¥5000 (US $736.29) (525, 65.3%), were married (496, 61.8%), and were in good health (486, 60.6%). The average time of social media use was approximately 2 to 3 hours per day (mean 2.34 hours, SD 1.11), and the most frequently used media types were public social media (mean score 4.49/5, SD 0.78) and aggregated social media (mean score 4.07/5, SD 1.07). Social media use frequency (β=.20, P<.001) rather than time significantly predicted preventive behaviors for COVID-19. Respondents were also equipped with high levels of disease knowledge (mean score 8.15/10, SD 1.43) and eHealth literacy (mean score 3.79/5, SD 0.59). Disease knowledge (β=.11, P=.001) and eHealth literacy (β=.27, P<.001) were also significant predictors of preventive behaviors. Furthermore, eHealth literacy (P=.038) and disease knowledge (P=.03) positively moderated the relationship between social media use frequency and preventive behaviors, while eHealth literacy (β=.07) affected this relationship positively and disease knowledge (β=-.07) affected it negatively. Different social media types differed in predicting an individual\'s preventive behaviors for COVID-19. Aggregated social media (β=.22, P<.001) was the best predictor, followed by public social media (β=.14, P<.001) and professional social media (β=.11, P=.002). However, official social media (β=.02, P=.597) was an insignificant predictor.
    Social media is an effective tool to promote behaviors to prevent COVID-19 among the public. Health literacy is essential for promotion of individual health and influences the extent to which the public engages in preventive behaviors during a pandemic. Our results not only enrich the theoretical paradigm of public health management and health communication but also have practical implications in pandemic control for China and other countries.
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