Use of spot measurements for assessing residential ELF magnetic field exposure: a validity study

The purpose of this study was to evaluate residential short term "spot" measurements as surrogates for long term personal magnetic field (MF) exposure. In an epidemiological study on birth weight and pregnancy delay, MF exposure was assessed by taking five spot measurements in each room. For a subsample of 30 subjects 24 h personal MF measurements were made, and the following exposure metrics were calculated: 24 h arithmetic mean, 24 h median, percentage of time above 0.15 microT, and percentage of time above 0.29 microT. The 24 h exposure metrics were used as gold standards, when evaluating the validity of various summary measures calculated from spot measurements for assessing personal exposure. Based on Spearman correlation coefficient (r), specificity and sensitivity, the average of the spot measurements of a residence resulted in least exposure measurement error (misclassification). Also the above bed spot value correlated better with the 24 h metrics than any room average. Spot measurements performed about equally well in predicting different types of exposure metrics.     

Generalized character process models: estimating the genetic basis of traits that cannot be observed and that change with age or environmental conditions

The genetic analysis of characters that change as a function of some independent and continuous variable has received increasing attention in the biological and statistical literature. Previous work in this area has focused on the analysis of normally distributed characters that are directly observed. We propose a framework for the development and specification of models for a quantitative genetic analysis of function-valued characters that are not directly observed, such as genetic variation in age-specific mortality rates or complex threshold characters. We employ a hybrid Markov chain Monte Carlo algorithm involving a Monte Carlo EM algorithm coupled with a Markov chain approximation to the likelihood, which is quite robust and provides accurate estimates of the parameters in our models. The methods are investigated using simulated data and are applied to a large data set measuring mortality rates in the fruit fly, Drosophila melanogaster.     

Generalized linear mixture models for handling nonignorable dropouts in longitudinal studies

This paper presents a method for analysing longitudinal data when there are dropouts. In particular, we develop a simple method based on generalized linear mixture models for handling nonignorable dropouts for a variety of discrete and continuous outcomes. Statistical inference for the model parameters is based on a generalized estimating equations (GEE) approach (Liang and Zeger, 1986). The proposed method yields estimates of the model parameters that are valid when nonresponse is nonignorable under a variety of assumptions concerning the dropout process. Furthermore, the proposed method can be implemented using widely available statistical software. Finally, an example using data from a clinical trial of contracepting women is used to illustrate the methodology.     

The D' measure of overall gametic disequilibrium between pairs of multiallelic loci

Abstract The D ' coefficient is one of the most commonly used measures of the extent of gametic disequilibrium between multiallelic loci. It has been suggested that the range of the D ' measure of overall disequilibrium between pairs of multiallelic loci depends on allele frequencies, except under some very restricted conditions. Nevertheless, the problem of dependence of the range of D ' has not been characterized under a wide set of possible polymorphisms. Evaluation of the utility of D ' as a measure of the strength of overall disequilibrium between all possible pairs of alleles at two multiallelic loci requires better knowledge of its range than is currently available. In this work, the conditions of polymorphism under which the range of D ' is frequency independent are given. It is found that the range of D ' is more often independent of allelic frequencies than is commonly thought. Furthermore, the range of D ' undergoes only small fluctuations as a function of the polymorphisms at the loci. Numerical cases and microsatellite data from humans are used for illustration. These observations indicate that the D ' coefficient is a useful tool for the estimation and comparison of the extent of overall disequilibrium across pairs of multiallelic loci.     

Regulatory Perspectives on the Significance of Ecological Changes as Reported in Ecological Risk Assessments

A broad range of perspectives exists regarding the interpretation of potentially adverse ecological changes in ecological risk assessments conducted under Superfund and RCRA. While USEPA's Proposed Guidelines for Ecological Risk Assessment recommend determining whether predicted changes are adverse based on the nature of effects, intensity of effects, spatial scale, temporal scale, and potential for recovery, the guidelines do not provide specific stan dards for judging adversity. Hence, implementation of the proposed guide lines varies with each risk manager's subjective judgments regarding the relative importance of each of these five criteria. In an effort to increase consistency in the scientific interpretation of ecological risk assessments, the following practices are recommended. First, measures of effects should focus on levels of ecological organization that are more complex than the individual organ ism. Second, multiple lines of evidence should be evaluated for each assessment endpoint. Third, bioequivalence testing should be used in place of traditional statistical testing (e.g., Student t-test) because the goal of bioequivalence testing is to answer the biologically relevant question of whether measurements differ by, at most, a biologically small amount. Fourth, in defining biologically small differences, site-specific and species specific conditions should be considered to the greatest extent possible. Fifth, where the outcomes of multiple lines of evidence contradict one another, the risk assessor should employ a quantitative approach to weighing the evidence based on the scientific defensibility of each measure of effect.     

Survey of electromagnetic field exposure in bedrooms of residences in lower Austria

Previous investigations of exposure to electric, magnetic, or electromagnetic fields (EMF) in households were either about electricity supply EMFs or radio frequency EMFs (RF‐EMFs). We report results from spot measurements at the bedside that comprise electrostatic fields, extremely low‐frequency electric fields (ELF‐EFs), extremely low‐frequency magnetic fields (ELF‐MFs), and RF‐EMFs. Measurements were taken in 226 households throughout Lower Austria. In addition, effects of simple reduction measures (e.g., removal of clock radios or increasing their distance from the bed, turning off Digital Enhanced Cordless Telecommunication (DECT) telephone base stations) were assessed. All measurements were well below International Commission on Non‐Ionizing Radiation Protection (ICNIRP) guideline levels. Average night‐time ELF‐MFs (long‐term measurement from 10 pm to 6 am, geometric mean over households) above 100 nT were obtained in 2.3%, and RF‐EMFs above 1000 µW/m² in 7.1% of households. Highest ELF‐EFs were primarily due to lamps beside the bed (max = 166 V/m), and highest ELF‐MFs because of transformers of devices (max = 1030 nT) or high current of power lines (max = 380 nT). The highest values of RF‐EMFs were caused by DECT telephone base stations (max = 28979 µW/m²) and mobile phone base stations (max = 4872 µW/m²). Simple reduction measures resulted in an average decrease of 23 nT for ELF‐MFs, 23 V/m for ELF‐EFs, and 246 µW/m² for RF‐EMFs. A small but statistically significant correlation between ELF‐MF exposure and overall RF‐EMF levels of R = 0.16 (P = 0.008) was computed that was independent of type (flat, single family) and location (urban, rural) of houses. Bioelectromagnetics 31:200–208, 2010. © 2009 Wiley‐Liss, Inc.     

医师资格考试存在的问题分析及对策探讨

医师资格考试对于提高医师的素质,保证医疗质量至关重要。通过专家访谈,了解目前医师资格考试存在的问题,并提出相应的管理对策,以促进医师资格考试制度不断完善。     

Morningness–eveningness and performance-based emotional intelligence

The aim of the present article is to determine whether recently shown positive relationships between self-reported emotional intelligence (EI) and morningess preference exist when EI is measured with an ability-based test. In two studies (study 1: N = 206 and study 2: N = 184), we applied two different morningness–eveningness questionnaires and a performance test of EI consisting of four dimensions (perception, understanding, assimilation, managing). The two studies provided similar results indicating that “night owls” have higher EI than “larks”; specifically, evening-oriented subjects showed greater ability in emotion perception and understanding, as compared to morning-oriented individuals. The obtained results were in line with hitherto existing research on chronotype and general intelligence. The results provide further evidence for a cognitive character of ability-based EI and accentuate its different nature when compared to self-reported EI. The main findings are discussed in terms of evolutionary theories of circadian preferences, EI and mental abilities.