Which constructs can predict emotional exhaustion in a working population? A study into its determinants

The main objective of this study was to examine the psychosocial stress model developed by Taylor and Aspinwall with emotional exhaustion as the outcome variable. Respondents, 409 men and 346 women, who had a paid job for at least 20 hours per week, completed questionnaires concerning demographic variables, personality, temperament, work pressure, workload, perceived social support, appraisal, coping, and emotional exhaustion. Structural equation analyses provided only partial support for the validity of the model. First, on theoretical and statistical grounds, one more path linking external resources to social support was added. Second, contrary to expectations, coping styles did not predict emotional exhaustion. To conclude, when coping is measured retrospectively, it does not add to our understanding of emotional exhaustion. It is suggested that future studies should be longitudinal and include objective measures of stressors and psychosocial health outcomes in addition to self‐reports. Copyright © 2007 John Wiley & Sons, Ltd.     

Working‐correlation‐structure identification in generalized estimating equations

Selecting an appropriate working correlation structure is pertinent to clustered data analysis using generalized estimating equations (GEE) because an inappropriate choice will lead to inefficient parameter estimation. We investigate the well‐known criterion of QIC for selecting a working correlation structure, and have found that performance of the QIC is deteriorated by a term that is theoretically independent of the correlation structures but has to be estimated with an error. This leads us to propose a correlation information criterion (CIC) that substantially improves the QIC performance. Extensive simulation studies indicate that the CIC has remarkable improvement in selecting the correct correlation structures. We also illustrate our findings using a data set from the Madras Longitudinal Schizophrenia Study. Copyright © 2008 John Wiley & Sons, Ltd.     

Stochastic models for geriatric in-patient behaviour

Departments of geriatric medicine engage in two distinct formsof clinical activity: acute/rehabilitative and long-stay care.These are organizationally distinct and have very differentresource needs. Current hospital planning models, however, assumethat patients all move through the system at the same rate,thereby ignoring this effect of inherent heterogeneity in patientbehaviour. The present paper describes the movement of patientsthrough geriatric hospitals by a two-stage continuous-time Markovmodel, where the stages represent acute/rehabilitative and long-staypatients respectively. Patients are initially admitted to thefirst stage, from which they may depart from the system, bydeath or discharge, or move into the second stage, from whichthey eventually depart by death or discharge (unlikely). Admissionsare modelled in two ways: either as replacements for departuresor as a Poisson stream. Expressions for the distribution andmovement of numbers of patients are derived and evaluated fordata from a number of hospitals. Such an approach has the advantage,over previous crude models, of taking into account differenttypes of patients and introducing variability, thus making itpossible to extract variances as well as means of numbers ofgeriatric patients requiring hospital care.     

Statistical characterisation of bacterial wild-type MIC value distributions and the determination of epidemiological cut-off values

MIC distribution data were obtained from a variety of international sources, and pooled after selection by a defined criterion. Sixty-seven of these datasets were subjected to a range of statistical goodness-of-fit tests. The log-normal distribution was selected for subsequent modelling. Cumulative counts of MIC distribution data were fitted to the cumulative log-normal distribution using non-linear least squares regression for a range of data subsets from each antibiotic-bacterium combination. Estimated parameters in the regression were the number of isolates in the subset, and (the log(2) values of) the mean and standard deviation. Optimum fits for the cumulative log-normal curve were then used to determine the wild-type MIC range, determined by calculating the MICs associated with the lower and upper 0.1% of the distribution, rounding to the nearest two-fold dilution, and calculating the probabilities of values higher and lower than these values. When plotted logarithmically, histograms of MIC frequencies appeared normal (Gaussian), but standard goodness-of-fit tests showed that the two-fold dilution grouping of MICs fits poorly to a log-normal distribution, whereas non-linear regression gave good fits to population (histogram) log-normal distributions of log(2) MIC frequencies, and even better fits to log-normal cumulative distributions. Optimum fits were found when the difference between the estimated and true number of isolates in the fitted subset was minimal. Sixteen antibiotic-bacterium datasets were fitted using this technique, and the log(2) values of the means and standard deviations were used to determine the 0.1% and 99.9% wild-type cut-off values. When rounded to the nearest two-fold dilution, > or = 98.5% of MIC values fall within the cut-off value range. Non-linear regression fitting to a cumulative log-normal distribution is a novel and effective method for modelling MIC distributions and quantifying wild-type MIC ranges.     

三级综合医院护士在社区护理中的角色与作用

笔者分析了三级综合医院开展社区护理的必要性和可行性；阐述了三级综合医院护士在开展社区护理中承担的教育者和咨询者、服务者、协调者和合作者、观察和研究者多种角色；并提出三级综合医院护士在开展社区护理中所发挥的作用，包括：(1)向社区提供经验丰富的专科护士，提高社区护理质量；(2)为社区护士的培养提供师资队伍和培训基地；(3)开设日间病房，为病人提供方便的治疗及护理；(4)建立双向转诊的社区卫生服务网络，为社区提供持续的优质服务；(5)开展社区护理研究。     

Time-frequency analysis of heart murmurs. Part II: Optimisation of time-frequency representations and performance evaluation

The basic parameters of the spectrogram, the Choi-Williams, and the Bessel distributions are adjusted to provide the best time-frequency representations (TFRs) of the simulated murmur signals of mitral stenosis, mitral regurgitation, aortic stenosis, aortic regurgitation, and of two musical murmurs. The initial adjustment of the parameters of each TFR technique is performed by computing and minimising the relative averaged absolute error between the frequency contours at −3dB and −10dB of each TFR of the simulated murmurs and those of the theoretical distribution of the same signals. The results show that the spectrogram generally provides very good to excellent performance in representing the TFRs of stenotic and regurgitant murmurs. Improvements provided by the Choi-Williams and the Bessel distributions are minor but not systematic for the two signal-to-noise ratios tested (0 and 30 dB) and for the two frequency contours estimated. The Bessel and the Choi-Williams distributions provide the best performance for the musical murmurs. The study shows that although a single technique cannot be optimal for all six murmurs, the spectrogram using a Hamming window of 30 ms is an acceptable compromise to detect the six simutated heart murmurs.