A predictive study of emotional labor and turnover

The current study examined how the emotional labor strategies of deep acting and surface acting directly influence emotional exhaustion and turnover intentions, and indirectly impact actual turnover among a sample of bank tellers. Turnover data were collected from organizational records 6 months after participants responded to a survey that measured emotional labor strategies, emotional exhaustion, and turnover intentions. Results showed that turnover intentions mediated the relationship between deep acting and actual turnover. Additionally, surface acting had indirect effects on turnover through emotional exhaustion and turnover intentions. Copyright © 2009 John Wiley & Sons, Ltd.     

Antibiotic degradation during manure composting

On-farm manure management practices, such as composting, may provide a practical and economical option for reducing antibiotic concentrations in manure before land application, thereby minimizing the potential for environmental contamination. The objective of this study was to quantify degradation of chlortetracycline, monensin, sulfamethazine, and tylosin in spiked turkey (Meleagris gallopavo) litter during composting. Three manure composting treatments were evaluated: a control treatment (manure pile with no disturbance or adjustments after initial mixing), a managed compost pile (weekly mixing and moisture content adjustments), and vessel composting. Despite significant differences in temperature, mass, and nutrient losses between the composting treatments and the control, there was no difference in antibiotic degradation among the treatments. Chlortetracycline concentrations declined rapidly during composting, whereas monensin and tylosin concentrations declined gradually in all three treatments. There was no degradation of sulfamethazine in any of treatments. At the conclusion of the composting period (22-35 d), there was >99% reduction in chlortetracycline, whereas monensin and tylosin reduction ranged from 54 to 76% in all three treatments. Assuming first-order decay, the half-lives for chlortetracycline, monensin, and tylosin were 1, 17, and 19 d, respectively. These data suggest that managed compositing in a manure pile or in a vessel is not better than the control treatment in degrading certain antibiotics in manure. Therefore, low-level manure management, such as stockpiling, after an initial adjustment of water content may be a practical and economical option for livestock producers in reducing antibiotic levels in manure before land application.     

Mortality Risk in Pediatric Motor Vehicle Crash Occupants: Accounting for Developmental Stage and Challenging Abbreviated Injury Scale Metrics

Objective: Survival risk ratios (SRRs) and their probabilistic counterpart, mortality risk ratios (MRRs), have been shown to be at odds with Abbreviated Injury Scale (AIS) severity scores for particular injuries in adults. SRRs have been validated for pediatrics but have not been studied within the context of pediatric age stratifications. We hypothesized that children with similar motor vehicle crash (MVC) injuries may have different mortality risks (MR) based upon developmental stage and that these MRs may not correlate with AIS severity.

Methods: The NASS-CDS 2000–2011 was used to define the top 95% most common AIS 2+ injuries among MVC occupants in 4 age groups: 0–4, 5–9, 10–14, and 15–18 years. Next, the National Trauma Databank 2002–2011 was used to calculate the MR (proportion of those dying with an injury to those sustaining the injury) and the co-injury-adjusted MR (MR_MAIS) for each injury within 6 age groups: 0–4, 5–9, 10–14, 15–18, 0–18, and 19+ years. MR differences were evaluated between age groups aggregately, between age groups based upon anatomic injury patterns and between age groups on an individual injury level using nonparametric Wilcoxon tests and chi-square or Fisher's exact tests as appropriate. Correlation between AIS and MR within each age group was also evaluated.

Results: MR and MR_MAIS distributions of the most common AIS 2+ injuries were right skewed. Aggregate MR of these most common injuries varied between the age groups, with 5- to 9-year-old and 10- to 14-year-old children having the lowest MRs and 0- to 4-year-old and 15- to 18-year-old children and adults having the highest MRs (all P <.05). Head and thoracic injuries imparted the greatest mortality risk in all age groups with median MR_MAIS ranging from 0 to 6% and 0 to 4.5%, respectively. Injuries to particular body regions also varied with respect to MR based upon age. For example, thoracic injuries in adults had significantly higher MR_MAIS than such injuries among 5- to 9-year-olds and 10- to 14-year-olds (P =.04; P <.01). Furthermore, though AIS was positively correlated with MR within each age group, less correlation was seen for children than for adults. Large MR variations were seen within each AIS grade, with some lower AIS severity injuries demonstrating greater MRs than higher AIS severity injuries. As an example, MR_MAIS in 0- to 18-year-olds was 0.4% for an AIS 3 radius fracture versus 1.4% for an AIS 2 vault fracture.

Conclusions: Trauma severity metrics are important for outcome prediction models and can be used in pediatric triage algorithms and other injury research. Trauma severity may vary for similar injuries based upon developmental stage, and this difference should be reflected in severity metrics. The MR-based data-driven determination of injury severity in pediatric occupants of different age cohorts provides a supplement or an alternative to AIS severity classification for pediatric occupants in MVCs.     

Age- and Sex-Specific Thorax Finite Element Model Development and Simulation

Objective: The shape, size, bone density, and cortical thickness of the thoracic skeleton vary significantly with age and sex, which can affect the injury tolerance, especially in at-risk populations such as the elderly. Computational modeling has emerged as a powerful and versatile tool to assess injury risk. However, current computational models only represent certain ages and sexes in the population. The purpose of this study was to morph an existing finite element (FE) model of the thorax to depict thorax morphology for males and females of ages 30 and 70 years old (YO) and to investigate the effect on injury risk.

Methods: Age- and sex-specific FE models were developed using thin-plate spline interpolation. In order to execute the thin-plate spline interpolation, homologous landmarks on the reference, target, and FE model are required. An image segmentation and registration algorithm was used to collect homologous rib and sternum landmark data from males and females aged 0–100 years. The Generalized Procrustes Analysis was applied to the homologous landmark data to quantify age- and sex-specific isolated shape changes in the thorax. The Global Human Body Models Consortium (GHBMC) 50th percentile male occupant model was morphed to create age- and sex-specific thoracic shape change models (scaled to a 50th percentile male size). To evaluate the thoracic response, 2 loading cases (frontal hub impact and lateral impact) were simulated to assess the importance of geometric and material property changes with age and sex.

Results: Due to the geometric and material property changes with age and sex, there were observed differences in the response of the thorax in both the frontal and lateral impacts. Material property changes alone had little to no effect on the maximum thoracic force or the maximum percent compression. With age, the thorax becomes stiffer due to superior rotation of the ribs, which can result in increased bone strain that can increase the risk of fracture. For the 70-YO models, the simulations predicted a higher number of rib fractures in comparison to the 30-YO models. The male models experienced more superior rotation of the ribs in comparison to the female models, which resulted in a higher number of rib fractures for the males.

Conclusion: In this study, age- and sex-specific thoracic models were developed and the biomechanical response was studied using frontal and lateral impact simulations. The development of these age- and sex-specific FE models of the thorax will lead to an improved understanding of the complex relationship between thoracic geometry, age, sex, and injury risk.     

Changes in physicochemical forms of lead and cadmium added to freshwater

Transformation of physicochemical forms of cadmium and lead added at 1 μ/L to Lake Michigan water have been studied by anodic stripping voltammetry. Unfiltered, 0.45 μ membrane filtered, ultrafiltered, and UV irradiated ultrafiltered samples were used to differentiate metal binding by particulate, colloidal, and dissolved organic matter. The reaction of added metal with colloids and particles is rapid. Their reaction with soluble organic matter is slow, requiring 1 to 2 days for complexation of one-half the added metal.