Modeling long-term average exposure in occupational exposure-response analysis

OBJECTIVES: Estimates of long-term average exposure to occupational hazards are often imprecise because intraindividual variability in exposure can be large and exposure is usually based on one or few measurements. One potential result is bias of exposure-response relationships. The possibility was studied of a more valid measure of exposure being obtained by modeling exposure and consequently increasing the number of days with exposure estimates, using simple measurable exposure surrogates. METHODS: In a group of 198 Dutch pig farmers, exposure to endotoxins was measured on one workday in summer and one day in winter. Farmers recorded activity patterns during one week in both seasons, and farm characteristics were evaluated. Relationships between farm characteristics and activities and log-transformed measured exposure levels were quantified in a multiple regression analysis. Exposure was estimated for 14 d with known activity patterns. RESULTS: The ratio of intraindividual and interindividual variance in log-transformed measured exposure was 4.7. Given this ratio, the true regression coefficient of lung function on exposure would potentially be attenuated by 70%. The variance ratio for predicted exposures was only 1.2, and the potential attenuation by variation in exposure estimates was decreased to 8%. There was no relationship between lung function and measured exposure. Modeled long-term average exposure was inversely related to base-line lung function; it reached statistical significance for asymptomatic farmers. CONCLUSIONS: The results suggest that the presented strategy offers a possibility to minimize measurement effort in occupational epidemiologic studies, without apparent loss of statistical power.     

Medically compromised patients, Part II. Current trends in zidovudine chemoprophylaxis post HIV exposure

Zidovudine chemoprophylaxis is commonly offered to health care workers post exposure to HIV. The use of this therapy appears to have escalated since the early 1990s in spite of the lack of consensus science. This paper presents the results of a survey of 15 academic health care centers representing the major cities whose aggregate AIDS cases accounted for 81 percent of the reported cases in the United States. Thirteen of the 15 institutions have a zidovudine chemoprophylaxis protocol in place. With the efficacy and risks of prophylactic zidovudine still in question, health care workers should establish their positions on this therapy prior to facing an occupational exposure.     

Sex differences and age trends in occupational preference and occupational prestige.

Studied sex differences and age trends in the relationship of occupational preferences and aversions and occupational prestige in 1,531 male and 988 female middle- and upper-middle-class 9-17 yr old Ss to test the hypothesis that females learn early to avoid high-prestige occupations. Rank-order correlation coefficients between empirically established prestige rankings and preference and aversion rankings were calculated separately for each sex at each age. The relationships between preference and prestige were positive and stronger for the males than for the females; those between aversion and prestige were positive and stronger for females than for males. Sign tests for both relationships were significant. It is concluded that males learn to prefer prestigious occupations; females learn to avoid them. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

数据库技术的发展及趋势

数据库技术已发展戚为一项十分重要的技术，在很多领域得到了广泛的应用。概括的介绍了数据库发展的历史发展现状及发展趋势。     

Behavioral determinants of occupational exposure to chemical agents.

Used the passive-active dimension of the job demand–control model (T. Theorell and R. A. Karasek, see record 83:28881) to examine the impact of behavioral factors on the exposure to and actual uptake of airborne lead in 2 lead exposed populations of male workers (18 from an electric accumulator factors and 18 from a lead smeltery) and to ascertain work-related determinants of hygienic behavior. Environmental exposure was assessed by measurement of the concentration of lead dust in ambient air at the workplace, and the intake of lead was assessed by measurement of the lead in blood level. In the work environment of Ss in active jobs, lower concentrations of lead in air were measures, but higher levels of lead in blood were observed in these workers. The opposite was true of workers in passive jobs. Differences in hygienic behavior (e.g., use of protective equipment) at work may explain these results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A systematic review of the literature on patient priorities for general practice care. Part 1: Description of the research domain

To make health care more responsive to patient needs, insight into patient priorities is needed. A systematic literature review, using electronic and manual searches, was made of studies on patient priorities with regard to primary health care. Data-extraction was performed by two researchers, followed by systematic analyses of study features. 57 studies were included. The aspects of care and methods used showed a wide variation. Aspects most often included were "informativeness", "humaneness" and "competence/accuracy". Based on an analysis of 19 studies, the following aspects were seen by patients as most important in more than 50% of the studies that included them: "humaneness", "competence/accuracy", "patients' involvement in decisions", "time for care", "other aspects of availability/accessibility", "informativeness", "exploring patients' needs", "other aspects of relation and communication" and "availability of special services".     

Cocaine exposure causes long-term increases in impulsive choice.

In this study, the authors examined the long-term effects of prior exposure to cocaine on a delay-discounting task commonly used to measure impulsive choice. Male Long-Evans rats received daily intraperitoneal injections of 30 mg/kg cocaine HCl or saline for 14 days. Following 3 weeks of withdrawal, rats began training. On each trial, rats were given a choice between 2 levers. A press on 1 lever resulted in immediate delivery of a single 45-mg food pellet, and a press on the other resulted in delivery of 4 pellets after a delay period. Impulsive choice was defined as preference for the small immediate over the large delayed reward. Three months after treatment, cocaine-exposed rats displayed increased impulsive choice behavior. They also showed less anticipatory responding (entries into the food trough) during the delays prior to reward delivery, indicating that the enhanced impulsive choice in these rats may be related to deficits in bridging the delay between response and reward. These data demonstrate that cocaine exposure can cause enduring increases in impulsive choice behavior, consistent with observations in human subjects with drug addictions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Description and psychometric evaluation of the Youth Counseling Impact Scale.

The present article describes and evaluates the Youth Counseling Impact Scale (YCIS; L. Bickman et al., 2007), a recently developed therapeutic process measure that assesses youths' perceptions of the impact individual mental health counseling sessions have on their thoughts, feelings, and behaviors. This measure is intended for frequent use in the mental health treatment of youths aged 11–18. It provides a general Impact score as well as two subscale scores: Insight and Change. Five hundred youths receiving mental health services participated in this investigation. Classical test theory, item response theory, confirmatory factor nalysis, and analyses of the relationship of the YCIS with other scales were used to evaluate the research questions. The results suggest that, overall, the YCIS is a well-functioning scale with good psychometric properties. The proposed model for 1 primary general factor of impact and 2 secondary factors (Insight and Change) fit the data well. Specific weaknesses of the scale are discussed, and possible improvements are suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Comprehensive Model of the Electroslag Remelting Process: Description and Validation

Electroslag remelting (ESR) is widely used for the production of high-value-added alloys such as special steels or nickel-based superalloys. Because of high trial costs and the complexity of the mechanisms involved, trial-and-error-based approaches are not well suited for fundamental studies or for optimization of the process. Consequently, a transient-state numerical model has been developed that accounts for electromagnetic phenomena and coupled heat and momentum transfers in an axisymmetrical geometry. The model simulates the continuous growth of the electroslag-remelted ingot through a mesh-splitting method. In addition, solidification of the metal is modeled by an enthalpy-based technique. A turbulence model is implemented to compute the motion of liquid phases (slag and metal), while the mushy zone is described as a porous medium the permeability of which varies with the liquid fraction, thus enabling accurate calculation of solid/liquid interaction. The coupled partial differential equations (PDEs) are solved using a finite-volume technique. The computed results are compared to the experimental observation of an industrial remelted ingot; the melt pool depth and shape, in particular, are investigated, in order to validate the model. These results provide valuable information about the process performance and the influence of the operating parameters. In this way, we present an example of a model used as a support in analyzing the influence of the electrode fill ratio. This article is based on a presentation given at the International Symposium on Liquid Metal Processing and Casting (LMPC 2007), which occurred in September 2007 in Nancy, France.     

Monitoring of occupational exposure to 1-butanol by diffusive sampling and urinalysis

This study was designed to define the relationship between different combinations of prosthetic head diameters, neck lengths, and acetabular containment angles, and range of motion before component impingement. Three cadaveric pelves with attached lower limbs were mounted in their correct anatomic position. Acetabular and modular femoral stems were inserted into each of the six hips. For each combination of femoral head diameter, neck length, and acetabular liner overhang, the range of motion to impingement was measured in flexion, extension, abduction, adduction, external rotation, internal rotation, and internal rotation with 90 degrees hip flexion. These experiments suggest that the maximum range of motion before impingement can be attained by increasing the prosthetic head diameter and avoiding longer neck lengths with skirts. Acetabular liners with greater overhang decrease motion in all planes except flexion when the overhang is positioned posteriorly.     

An investigation of systematic changes in occupational exposure

Nonstationary behavior in occupational exposure was examined among a number of job groups from different industries. A change in the mean level of exposure between two survey periods was evaluated by applying mixed-effects models. Overall, differences between surveys were observed in slightly more than one-third of the industries analyzed and in about one-quarter of the total number of comparisons performed. Exposures in the majority of cases decreased in the later survey. Further analyses examined the impact of nonstationary exposures on the estimation of the between- and within-worker components of variance. When changes in the mean exposure level were detected, point estimates of the variance components generated under the mixed model were compared with those estimates obtained under the one-way random-effects model, which assumes that the mean exposure level remains constant over time. The results indicate that the magnitude of the bias in the variance component estimates can be substantial when the misspecified model is applied. It is concluded that, in the absence of changes known to affect exposure, data collected within a year are likely to result in relatively valid inferences about mean and variance parameters using models that assume stationarity; for periods extending beyond a year, systematic changes in exposure are more likely to occur. Thus, exposure assessment strategies should be designed so that sufficient data are collected among groups of workers to investigate systematic changes and to ensure that appropriate statistical models are applied. In this way, occupational hygienists will be able to make reliable inferences about the underlying distribution of exposures pertinent to each occupational group.     

Endoesthetics. Part 1: Intra-radicular rehabilitation

The flared canal, whether due to age, carious extension, pulpal pathology or endodontic access, presents a restorative management problem. Intra-radicular rehabilitation prior to post fabrication and/or cementation, increases the chance for operative success. This is the first in a series of articles that introduces the concept of esthetic considerations in post-endodontic restorative therapy.     

Accidental occupational exposure of intravenous nurses to human immunodeficiency virus. Anticipating the consequences

The relationship of parental history of high blood pressure (HBP) to blood pressure (BP) was estimated in three Japanese population samples, totalling 591 men and women aged 20-59 years, from the INTERSALT study. Parental history of HBP was defined as reported HBP by their father and/or mother. With adjustment for antihypertensive medication, body mass index, alcohol intake, and Na/K ratio in 24-h urine, for participants with a parental history of HBP compared to those without a history, BP was higher for three to four age-sex strata, both for systolic and diastolic pressure (SBP, DBP), by 3.3 to 6.8 and 2.7 to 5.5 mm Hg respectively, with four of these six positive associations statistically significant. This finding was stronger for persons aged 40-59 than for those aged 20-39. These data support the judgment that for persons with a parental history of HBP, BP is apt to increase more with age due to combined effects of genetic and environmental factors. Such people especially need to control their lifestyles carefully, including to maintain an optimal intake of salt (eg, <70 mmol/day) and a high potassium intake, to avoid high alcohol consumption, and keep weight moderate, for the prevention of hypertension.