原子吸收光谱法测定牡蛎中铅的测量不确定度评定

目的评定原子吸收光谱法测定牡蛎中铅的测量不确定度。方法根据JF 1059-1999《测量不确定度评定与表示》,分析不确定度主要分量。应用Excel软件,发挥其函数功能。结果分析和识别了分析过程中的不确定度来源,较为全面地评定了测量不确定度。结论识别出测定过程中的关键环节,应在关键环节上严格质量控制,降低测量不确定度。该法对原子荧光光谱法,电感耦合等离子发射光谱法和原子吸收光谱法等测定结果的不确定度评定具有参考作用。     

CODMn指数测量不确定度评定

随着对外开放力度的加大,特别是加入WTO后,对实验室特别是第三方实验室检测能力的要求越来越高,实验室间的竞争愈趋激烈,实验室的国家认可工作更显其重要性。而实验室国家认可中不确定度的评定是一个不可忽视的内容。我们试图对水中CODMn指数测量不确定度评定进行初步探讨,数学模型采用分项替代法简化成便于运算的数学形式进行了尝试。     

工作场所空气中甲苯溶剂解吸气相色谱法测定的不确定度评定

目的建立工作场所空气中甲苯的溶剂解吸气相色谱法测定的不确定度评定方法,通过控制这些因素提高检测结果的置信度和准确性。方法依据中华人民共和国国家计量技术规范JJF1059-1999《测量不确定度评定与表示》和中国金属学会推荐的技术和方法CCM010100-2006《化学仪器分析测量结果不确定度评定导则》。结果甲苯不确定度主要来源:①测量重复性的不确定度;②标准溶液配制过程的不确定度;③标准曲线的变动性的不确定度;④采样过程的不确定度;⑤解吸效率的不确定度;⑥样品解吸的不确定度。取包含因子k=2,扩展不确定度为U=1.7540×2≈3.51mg/m3。结论该不确定度评定方法对甲苯的溶剂解吸气相色谱法检测过程的质量控制意义十分重大,是提高检测结果的置信度和准确性的保证。     

重量分析测量不确定度评定的探讨

测量不确定度是与测量结果相关联的参数,表征合理地赋予被测量值的分散性。一切测量结果都不可避免地具有不确定度[1],在化学分析中,它反映了测量结果的质量,不确定度越小,测量结果的质量越好,水平越高,使用价值越大[2];反之,测量结果的质量越差。测量不确定度的评定非常重要,若评定不当,过大或过小都有可能给生产和生活带来不可估量的影响[3]。重量法是化学分析中的一类经典方法[4],通过对食品中灰分测定的不确定度评定,讨论重量分析的不确定度评定方法。1测定方法按国标方法GB/T5009.4-2003对某食品中的灰分进行测定[5],其测定步骤如下:…     

γ能谱仪测量40K的两种分析法的不确定度比较

目的进行γ能谱仪测量~(40)K的相对比较法和效率曲线法的不确定度评定。方法根据两种分析法的计算过程建立不确定度评定模型,分析不确定度来源,并进行标准不确定度和扩展不确定度的计算。结果γ能谱仪测量~(40)K结果的相对比较法和效率曲线法的准确度评价,分别为1.01和1.02,扩展不确定度评定结果分别为(1464±70)Bq/kg,k=2;以及(1456±68)Bq/kg,k=2;两种分析方法的准确度和不确定度评定结果基本一致,且标准源活度的偏差,是两种分析方法不确定度的主要来源。结论两种方法均可对日常γ能谱仪测量结果的不确定度进行有效评定。     

酶联免疫法测量动物尿液中克仑特罗含量的不确定度分析

目的分析和评定酶联免疫法测量动物尿液中克仑特罗含量的不确定度。方法分析影响测量不确定的各种因素,评估各影响量的大小,包括从校正曲线计算试样浓度,稀释倍数,配制标准溶液的重复性和可靠性,以及动物尿液的测量重复性等。结果在校正曲线范围内(0～8ng/mL)内插计算试样的浓度时,合成不确定度不大于8%;置信概率为95%的扩展不确定度不大于16%。外推至10～12ng/mL时,合成不确定度不大于20%;置信概率为95%的扩展不确定度不大于40%。结论酶联免疫法测量动物尿液中克仑特罗含量的不确定度主要来源为从校正曲线内插或外插计算的试样测量不确定度、样品稀释引起的不确定度和样品重复测量的不确定度。     

火焰法——原子吸收测定蔬菜中铜的测量不确定度分析

对火焰法——原子吸收测定蔬菜中铜的分析方法的测量不确定度进行了分析,建立了测量过程中各分量的数学模型,并识别了测量过程中不确定度来源,估算了各不确定度分量对总不确定度的影响,确定了测量结果的置信区间,给出蔬菜中铜的含量及其置信区间为1.05±0.39 mg/kg(k=2)。     

高效液相色谱法测定血浆中维生素A的测量结果的不确定度评价

目的对高效液相色谱法测定血浆中维生素A的测量结果的不确定度进行评定,确定引入测量不确定度的主要来源,以便在检测工作中引起重视并予以纠正。方法分析测量不确定度的来源,建立数学模型,通过血浆样品检测来计算测定结果的扩展不确定度。结果高效液相色谱法测定血浆中维生素A含量引入的扩展不确定度为0.0282μg/ml。结论最小二乘法拟合曲线产生的不确定度在该法中影响最大,样品重复性测定和前处理过程中的回收率也是测量不确定度的主要来源,故在样品测定时应对其加以控制。     

放射工作人员热释光个人剂量测量不确定度评定

目的为保证放射工作人员热释光个人剂量测量数据的准确性,评定其不确定度。方法分析不确定度来源,通过计算给出不确定度。结果 相对扩展不确定度为8.2%。结论个人剂量测量不确定度主要受刻度因子、探测器重复性和发光系统偏差3个分量的影响。     

工作场所空气中乙酸测定结果的不确定度评定

目的进行空气中乙酸测定结果不确定度的评定,为检测工作提供质量保证。方法根据测量不确定度的评定原理和测定方法来进行评定,并对测定结果进行完整描述。结果方法的合成标准不确定度为13.26%,乙酸浓度为41.36mg/m3,其扩展不确定度是10.96 mg/m3。结论该法的不确定度主要来源于工作曲线的拟合,解吸效率,采样器、温度和气压引起采样体积误差、标准溶液的配制及气相色谱仪等方面。     

Disability: a model and measurement technique.

Current methods of ranking or scoring disability tend to be arbitrary. A new method is put forward on the hypothesis that disability progresses in regular, cumulative patterns. A model of disability is defined and tested with the use of Guttman scale analysis. Its validity is indicated on data from a survey in the community and from postsurgical patients, and some factors involved in scale variation are identified. The model provides a simple measurement technique and has implications for the assessment of individual disadvantage, for the prediction of progress in recovery or deterioration, and for evaluation of the outcome of treatment regimes.     

结核分枝杆菌菌悬液光密度值与菌落计数的关联性

目的建立一种基于光密度值计算结核分枝杆菌菌落数的可靠方法。方法利用低频超声和玻璃珠研磨两种方法制备H37Ra菌悬液,菌悬液2倍梯度稀释后,分别测定各个稀释度菌悬液在600 nm处的光密度值（OD600值）,并分析OD600值与稀释倍数曲线,确定最佳的菌悬液制备方法,OD600线性范围,以及OD600值与CFU关联曲线。结果OD600值为0.1～0.6,线性范围内OD600值与稀释倍数线性回归分析结果显示,玻璃珠研磨法和低频超声法相关系数（R2）分别为0.98、1.00,均呈良好的相关性,且低频超声法比玻璃珠研磨法的相关性好,其菌液分散更均匀。OD600值与CFU值线性回归分析结果显示,玻璃珠研磨法和低频超声法回归方程分别是：CFU=2.35×107×OD600+4.42×105、CFU=3.26×107×OD600+6.89×105。结论低频超声法是一种较好的结核分枝杆菌菌悬液制备方法,结合OD600值测定,可成为一种可靠、快速的结核分枝杆菌定量方法。     

奈替米星血药浓度、血清杀菌活性与给药方案的相关性研究

目的通过测定奈替米星(乙基西梭霉素，NTM)不同给药方案的血药浓度及血清杀菌活性(SBA)，观察与其不同给药方案的疗效与副作用，探讨其血药浓度和血清杀菌活性与给药方案的相关性，优选其最佳给药方案。方法血药浓度用TDX(荧光偏振免疫法)测定；SBA以微量稀释法测定；患者分成OD组(oncedaily)和TD(twicedaily)组以观察临床疗效和不良反应。结果OD给予NTM，其谷浓度均低于2μg／ml，且较TD给药有显著性降低(P<0.05)，而其峰浓度较TD给药则有显著性增高(P<0.01)；除铜绿假单胞菌外，NTM对其他3种菌峰时SBA均≥1∶8，经Wilcoxon秩和检验，较TD给药有显著性增强；OD给药组患者给药前后Cr、BUN没有变化，而TD给药组患者用药后较用药前Cr有显著性增高(P<0.05)。结论NTMOD比TD给药能够获得较高的峰浓度与杀菌活性，较低的谷浓度。     

Several methods to investigate relative attribute impact in stated preference experiments

There is growing use of discrete choice experiments (DCEs) to investigate preferences for products and programs and for the attributes that make up such products and programs. However, a fundamental issue overlooked in the interpretation of many choice experiments is that attribute parameters estimated from DCE response data are confounded with the underlying subjective scale of the utilities, and strictly speaking cannot be interpreted as the relative "weight" or "impact" of the attributes, as is frequently done in the health economics literature. As such, relative attribute impact cannot be compared using attribute parameter size and significance. Instead, to investigate the relative impact of each attribute requires commensurable measurement units; that is, a common, comparable scale. We present and demonstrate empirically a menu of five methods that allow such comparisons: (1) partial log-likelihood analysis; (2) the marginal rate of substitution for non-linear models; (3) Hicksian welfare measures; (4) probability analysis; and (5) best-worst attribute scaling. We discuss the advantages and disadvantages of each method and suggest circumstances in which each is appropriate.     

Factor substitution in nursing homes

This paper studies factor substitution in one important sector: the nursing home industry. Specifically, we measure the extent to which nursing homes substitute materials for labor when labor becomes relatively more expensive. From a policy perspective, factor substitution in this market is important because materials-intensive methods of care are associated with greater risks of morbidity and mortality among nursing home residents. Studying longitudinal data from 1991 to 2000 on nearly every nursing home in the United States, we use the method of instrumental variables (IV) to address measurement error in nursing home wages. The results from the IV models yield evidence of factor substitution: higher nursing home wages are associated with greater use of psychoactive drugs and lower quality.     

Individual Behavioral Reactions in the Context of Food Sensitivities in Children with Attention-Deficit/Hyperactivity Disorder before and after an Oligoantigenic Diet

The influence of food intake on behavior problems of children with Attention-Deficit/Hyperactivity Disorder (ADHD) was already described in the early 20th century. Eliminating food components by using the Oligoantigenic Diet (OD) leads to reduction of ADHD symptoms for more than two-thirds of patients. The aim of our study was to reveal how to identify foods having an impact on ADHD symptomatology. Therefore, 28 children with ADHD participating in this uncontrolled, open trial were examined before and after a restricted elimination diet. They kept a daily 24-h recall nutrition and behavior journal and filled out the abbreviated Conners’ scale (ACS) to identify foods which increased ADHD symptoms. The study was completed by 16 children (13 m/3 f). After four weeks of elimination diet the individual food sensitivities were identified in a reintroduction phase. A repetitive increase of ADHD symptoms by at least two points in ACS after food introduction hints at food sensitivity. Twenty-seven food sensitivity reactions were identified. Most of the participants were sensitive to more than one food. Food intolerances could not be identified without preceding OD. The combination of OD and subsequent food challenge appears as a valid method to identify individual food sensitivity in ADHD.     

Repeated measurement sampling in genetic association analysis with genotyping errors

Genotype misclassification occurs frequently in human genetic association studies. When cases and controls are subject to the same misclassification model, Pearson's chi-square test has the correct type I error but may lose power. Most current methods adjusting for genotyping errors assume that the misclassification model is known a priori or can be assessed by a gold standard instrument. But in practical applications, the misclassification probabilities may not be completely known or the gold standard method can be too costly to be available. The repeated measurement design provides an alternative approach for identifying misclassification probabilities. With this design, a proportion of the subjects are measured repeatedly (five or more repeats) for the genotypes when the error model is completely unknown. We investigate the applications of the repeated measurement method in genetic association analysis. Cost-effectiveness study shows that if the phenotyping-to-genotyping cost ratio or the misclassification rates are relatively large, the repeat sampling can gain power over the regular case-control design. We also show that the power gain is not sensitive to the genetic model, genetic relative risk and the population high-risk allele frequency, all of which are typically important ingredients in association studies. An important implication of this result is that whatever the genetic factors are, the repeated measurement method can be applied if the genotyping errors must be accounted for or the phenotyping cost is high.     

Uncertainty of measurement for competitive and indirect ELISAs

A method for the estimation of the uncertainty of measurements for Gaussian outcomes of enzyme-linked immunosorbent assay (ELISA) is described using competitive and indirect foot and mouth disease (FMD) ELISAs. Assay repeatability was determined by random effects analysis of variance, and the normality of the residuals was checked. The standard errors of the individual predicted values were transformed into confidence intervals around the corresponding observed values and further transformed into probabilities of being above/below a cut-off. Logistic regression models were subsequently used to interpolate probability values for the whole range of possible assay values. The uncertainty of measurement of a test result was finally defined as the probability of not observing the same qualitative test result when retesting the same sample. For the competitive ELISA any sample with a percent inhibition 4% above the cut-off value had an uncertainty level (probability of a negative result in the case of retest) below 5%. In the indirect ELISA with a cut-off OD of 0.1, the uncertainty was below 5% for any sample with a normalised OD value above 0.22.     

Texture-Modified Diet for Improving the Management of Oropharyngeal Dysphagia in Nursing Home Residents: An Expert Review

This paper provides evidence-based and, when appropriate, expert reviewed recommendations for long-stay residents who are prescribed texture-modified diets (TMDs), with the consideration that these residents are at high risk of worsening oropharyngeal dysphagia (OD), malnutrition, dehydration, aspiration pneumonia, and OD-associated mortality, poorer quality of life and high costs. Nestlé Health Science funded an initial virtual meeting attended by all authors, in which the unmet needs and subsequent recommendations for OD management were discussed. The opinions, results, and recommendations detailed in this paper are those of the authors, and are independent of funding sources. OD is common in nursing home (NH) residents, and is defined as the inability to initiate and perform safe swallowing. The long-stay NH resident population has specific characteristics marked by a shorter life expectancy relative to community-dwelling older adults, high prevalence of multimorbidity with a high rate of complications, dementia, frailty, disability, and often polypharmacy. As a result, OD is associated with malnutrition, dehydration, aspiration pneumonia, functional decline, and death. Complications of OD can potentially be prevented with the use of TMDs. This report presents expert opinion and evidence-informed recommendations for best practice on the nutritional management of OD. It aims to highlight the practice gaps between the evidence-based management of OD and real-world patterns, including inadequate dietary provision and insufficient staff training. In addition, the unmet need for OD screening and improvements in therapeutic diets are explored and discussed. There is currently limited empirical evidence to guide practice in OD management. Given the complex and heterogeneous population of long-stay NH residents, some ‘best practice’ approaches and interventions require extensive efficacy testing before further changes in policy can be implemented.