Satisfactions and stresses in the sorting of mail

Abstract

The effects of two types of letter-sorting technology on job stress and satisfaction were compared. Manual sorting, which uses the traditional method of assigning letters to classified pigeon-holes, was judged to provide elements of discretion, autonomy, and social interaction which are largely absent in coding-desk work, in which a keyboard is used to enter postcodes. Between and within-subject methodology was used in the analysis of data from those engaged in sorting (n = 160). In addition, these groups were compared with supervisors (n = 36) and engineers (n = 26) also working in the sorting area.

The key findings were: (a) higher levels of satisfaction were found amongst manual sorters and those spending 50–75% of their time in code-sorting; (b) stress is closely related to satisfaction in the code-sort group but not in the manual group; (c) in manual groups and in supervisors stress was manifested in fatigue, but in the code-sort group stress took the form of anxiety. The results are discussed in terms of the impact of the type of work on fatigue, as well as on job stress and satisfaction.     

The Potential Effects of Recall Bias and Selection Bias on the Epidemiological Evidence for the Carcinogenicity of Glyphosate

Glyphosate is a widely used herbicide worldwide. The International Agency for Research on Cancer in 2015 declared that glyphosate is probably carcinogenic to humans, noting a positive association for non-Hodgkin lymphoma (NHL). The principal human data on glyphosate and NHL come from five case–control studies and two cohort studies. The case–control studies are at risk of recall bias resulting from information on exposure to pesticides being collected from cases and controls based on their memories. In addition, two of the case–control studies are additionally at risk of a form of selection bias that can exacerbate the effect of recall bias. Both biases are in the direction of making glyphosate appear carcinogenic. If odds ratios (ORs) are not biased and a pesticide plays no role in causing NHL, the probability that an OR for that pesticide is greater than 1.0 is approximately 0.5. The fractions of ORs for pesticides other than glyphosate that are greater than 1.0 in the case–control studies are 0.90 (n = 92), 0.90 (n = 152), 0.93 (n = 59), 0.76 (n = 140), and 0.53 (n = 54), the first two from studies that are at risk for both types of bias. In the two cohort studies, which are not subject to these biases, the comparable fractions for relative risks for all cancers are 0.51 (n = 70) and 0.48 (n = 158). These results comply closely with what would be expected if evidence for carcinogenicity of glyphosate in these studies results from statistical bias in the case–control studies.     

Heart rate and blood pressure in male police officers and clerical workers on workdays and non-workdays

Abstract

Male police officers from a city police station in Tasmania (n = 20) and a matched group of clerical workers (n = 20) monitored their heart rate, blood pressure and self-reported levels of stress and arousal over a two-week period. Measurements on workdays during which stressful events occurred were compared to non-event workdays and non-workdays. Two group differences were demonstrated, with the clerical workers reporting higher levels of stress, and the police officers reporting higher levels of arousal. Support was evident for the distinction between workdays and non-workdays, and support was demonstrated for differences between different types of workdays. Evidence suggested that restricting the time frame of such research may lead to results that are inaccurate or inconsistent because workdays differ in content.     

Minimizing the mean squared deviation from a common due date: unconstrained and constrained cases

The problem of minimizing the mean squared deviation (MSD) of completion times from a common due date in both unconstrained and constrained cases is addressed. It is shown that the unconstrained MDS function is unimodal for n ≤ 6, where n is the number of jobs. The constrained case is shown to be unimodular for n ≤ 3, The unconstrained case is shown, by counterexample, not to be unimodular for n = 8. The constrained case is shown not to be unimodular for n = 5. For the unimodular cases, a proposed search routine can find the optimum solution in less than three CPU seconds for n = 100. It provides an excellent heuristic solution otherwise. Computational results are shown in both cases.     

Application of Whole-Genome Sequences and Machine Learning in Source Attribution of Salmonella Typhimurium

Prevention of the emergence and spread of foodborne diseases is an important prerequisite for the improvement of public health. Source attribution models link sporadic human cases of a specific illness to food sources and animal reservoirs. With the next generation sequencing technology, it is possible to develop novel source attribution models. We investigated the potential of machine learning to predict the animal reservoir from which a bacterial strain isolated from a human salmonellosis case originated based on whole-genome sequencing. Machine learning methods recognize patterns in large and complex data sets and use this knowledge to build models. The model learns patterns associated with genetic variations in bacteria isolated from the different animal reservoirs. We selected different machine learning algorithms to predict sources of human salmonellosis cases and trained the model with Danish Salmonella Typhimurium isolates sampled from broilers (n = 34), cattle (n = 2), ducks (n = 11), layers (n = 4), and pigs (n = 159). Using cgMLST as input features, the model yielded an average accuracy of 0.783 (95% CI: 0.77–0.80) in the source prediction for the random forest and 0.933 (95% CI: 0.92–0.94) for the logit boost algorithm. Logit boost algorithm was most accurate (valid accuracy: 92%, CI: 0.8706–0.9579) and predicted the origin of 81% of the domestic sporadic human salmonellosis cases. The most important source was Danish produced pigs (53%) followed by imported pigs (16%), imported broilers (6%), imported ducks (2%), Danish produced layers (2%), Danish produced cattle and imported cattle (<1%) while 18% was not predicted. Machine learning has potential for improving source attribution modeling based on sequence data. Results of such models can inform risk managers to identify and prioritize food safety interventions.     

Behavioral Self-Monitoring of Safety and Productivity in the Workplace: A Methodological Primer and Quantitative Literature Review

Workplace applications of behavioral self-monitoring (BSM) methods have been studied periodically for over 35 years, yet the literature has never been systematically reviewed. Recent occupational safety interventions including BSM resulted in relatively large behavior changes. Moreover, BSM methods are functional for addressing a broad range of occupational health psychology topics. Studies (n = 24) where workers self-monitored productivity or safety behaviors were reviewed and scored along dimensions relevant to research and practice. For intervention conditions (n = 38), standardized effect sizes ranged from 0.2 to 14.5 (weighted average d = 2.8). The results encourage the use of BSM in workplace interventions, but the literature has insufficiently addressed the isolated and additive effects of BSM, worker involvement and individual differences, assessment applications, and theory testing and development.     

Job stress,social support and health amongst shrimp fishermen

Abstract

Samples of shrimp fishermen (n = 211) and land-based workers (n = 99) drawn from a US Gulf Coast community are compared with regard to their degree of exposure to occupational stressors, level of social support, and extent of non-clinical depression and somatization. As hypothesized, shrimp fishermen report significantly greater levels of stressor exposure, support, depression and somatization at the zero-order level. At the multivariate level, with several covariates controlled, shrimpers report greater levels of stressor exposure, support and somatization. A model of the stress process which hypothesizes positive effects of stressors, and direct and indirect negative effects of social support on distress, is evaluated for each group. Occupational stressors predict as hypothesized, but social support does not. An explanation is offered which emphasizes the migratory character of shrimping as an occupation.     

Physiological Daily Inhalation Rates for Health Risk Assessment in Overweight/Obese Children,Adults, and Elderly

Physiological daily inhalation rates reported in our previous study for normal‐weight subjects 2.6–96 years old were compared to inhalation data determined in free‐living overweight/obese individuals (n = 661) aged 5–96 years. Inhalation rates were also calculated in normal‐weight (n = 408), overweight (n = 225), and obese classes 1, 2, and 3 adults (n = 134) aged 20–96 years. These inhalation values were based on published indirect calorimetry measurements (n = 1,069) and disappearance rates of oral doses of water isotopes (i.e., ²H₂O and H₂¹⁸O) monitored by gas isotope ratio mass spectrometry usually in urine samples for an aggregate period of over 16,000 days. Ventilatory equivalents for overweight/obese subjects at rest and during their aggregate daytime activities (28.99 ± 6.03 L to 34.82 ± 8.22 L of air inhaled/L of oxygen consumed; mean ±  SD) were determined and used for calculations of inhalation rates. The interindividual variability factor calculated as the ratio of the highest 99th percentile to the lowest 1st percentile of daily inhalation rates is higher for absolute data expressed in m³/day (26.7) compared to those of data in m³/kg‐day (12.2) and m³/m²‐day (5.9). Higher absolute rates generally found in overweight/obese individuals compared to their normal‐weight counterparts suggest higher intakes of air pollutants (in μg/day) for the former compared to the latter during identical exposure concentrations and conditions. Highest absolute mean (24.57 m³/day) and 99th percentile (55.55 m³/day) values were found in obese class 2 adults. They inhale on average 8.21 m³ more air per day than normal‐weight adults.     

Risk Communication,Values Clarification,and Vaccination Decisions

Many health‐related decisions require choosing between two options, each with risks and benefits. When presented with such tradeoffs, people often make choices that fail to align with scientific evidence or with their own values. This study tested whether risk communication and values clarification methods could help parents and guardians make evidence‐based, values‐congruent decisions about children's influenza vaccinations. In 2013–2014 we conducted an online 2×2 factorial experiment in which a diverse sample of U.S. parents and guardians (n = 407) were randomly assigned to view either standard information about influenza vaccines or risk communication using absolute and incremental risk formats. Participants were then either presented or not presented with an interactive values clarification interface with constrained sliders and dynamic visual feedback. Participants randomized to the risk communication condition combined with the values clarification interface were more likely to indicate intentions to vaccinate (β = 2.10, t(399) = 2.63, p < 0.01). The effect was particularly notable among participants who had previously demonstrated less interest in having their children vaccinated against influenza (β = –2.14, t(399) = –2.06, p < 0.05). When assessing vaccination status reported by participants who agreed to participate in a follow‐up study six months later (n = 116), vaccination intentions significantly predicted vaccination status (OR = 1.66, 95%CI (1.13, 2.44), p < 0.05) and rates of informed choice (OR = 1.51, 95%CI (1.07, 2.13), p < 0.012), although there were no direct effects of experimental factors on vaccination rates. Qualitative analysis suggested that logistical barriers impeded immunization rates. Risk communication and values clarification methods may contribute to increased vaccination intentions, which may, in turn, predict vaccination status if logistical barriers are also addressed.     

Improved algorithms for largest cardinality 2-interval pattern problem

The 2-INTERVAL PATTERN problem is to find the largest constrained pattern in a set of 2-intervals. The constrained pattern is a subset of the given 2-intervals such that any pair of them are R-comparable, where model . The problem stems from the study of general representation of RNA secondary structures. In this paper, we give three improved algorithms for different models. Firstly, an O(n{log} n +L) algorithm is proposed for the case , where is the total length of all 2-intervals (density d is the maximum number of 2-intervals over any point). This improves previous O(n ²log n) algorithm. Secondly, we use dynamic programming techniques to obtain an O(nlog n + dn) algorithm for the case R = { <, ⊏ }, which improves previous O(n ²) result. Finally, we present another algorithm for the case with disjoint support(interval ground set), which improves previous O(n ²□n) upper bound. A preliminary version of this article appears in Proceedings of the 16th Annual International Symposium on Algorithms and Computation, Springer LNCS, Vol. 3827, pp. 412–421, Hainan, China, December 19–21, 2005.     

Binary Mixtures of Polycyclic Aromatic Hydrocarbons Display Nonadditive Mixture Interactions in an In Vitro Liver Cell Model

Polycyclic aromatic hydrocarbons (PAHs) have been labeled contaminants of concern due to their carcinogenic potential, insufficient toxicological data, environmental ubiquity, and inconsistencies in the composition of environmental mixtures. The Environmental Protection Agency is reevaluating current methods for assessing the toxicity of PAHs, including the assumption of toxic additivity in mixtures. This study was aimed at testing mixture interactions through in vitro cell culture experimentation, and modeling the toxicity using quantitative structure‐activity relationships (QSAR). Clone‐9 rat liver cells were used to analyze cellular proliferation, viability, and genotoxicity of 15 PAHs in single doses and binary mixtures. Tests revealed that many mixtures have nonadditive toxicity, but display varying mixture effects depending on the mixture composition. Many mixtures displayed antagonism, similar to other published studies. QSARs were then developed using the genetic function approximation algorithm to predict toxic activity both in single PAH congeners and in binary mixtures. Effective concentrations inhibiting 50% of the cell populations were modeled, with R² = 0.90, 0.99, and 0.84, respectively. The QSAR mixture algorithms were then adjusted to account for the observed mixture interactions as well as the mixture composition (ratios) to assess the feasibility of QSARs for mixtures. Based on these results, toxic addition is improbable and therefore environmental PAH mixtures are likely to see nonadditive responses when complex interactions occur between components. Furthermore, QSAR may be a useful tool to help bridge these data gaps surrounding the assessment of human health risks that are associated with PAH exposures.     

Consumption of Fish and Shrimp from Southeast Louisiana Poses No Unacceptable Lifetime Cancer Risks Attributable to High‐Priority Polycyclic Aromatic Hydrocarbons

Following oil spills such as the Deepwater Horizon accident (DWH), contamination of seafood resources and possible increased health risks attributable to consumption of seafood in spill areas are major concerns. In this study, locally harvested finfish and shrimp were collected from research participants in southeast Louisiana and analyzed for polycyclic aromatic hydrocarbons (PAHs). PAHs are some of the most important chemicals of concern regarding oil‐spill‐contaminated seafood resources during and following oil spills. Some PAHs are considered carcinogens for risk assessment purposes, and currently, seven of these can be combined in lifetime cancer risk assessments using EPA approaches. Most PAHs were not detected in these samples (minimum detection limits ranged from 1.2 to 2.1 PPB) and of those that were detected, they were generally below 10 PPB. The pattern of detected PAHs suggested that the source of these chemicals in these seafood samples was not a result of direct contact with crude oil. Lifetime cancer risks were assessed using conservative assumptions and models in a probabilistic framework for the seven carcinogenic PAHs. Lifetime health risks modeled using this framework did not exceed a 1/10,000 cancer risk threshold. Conservative, health‐protective deterministic estimates of the levels of concern for PAH chemical concentration and seafood intake rates were above the concentrations and intake rates modeled under this probabilistic framework. Taken together, consumption of finfish and shrimp harvested from southeast Louisiana following the DWH does not pose unacceptable lifetime cancer risks from these seven carcinogenic PAHs even for the heaviest possible consumers.     

Emotions,Trust, and Perceived Risk: Affective and Cognitive Routes to Flood Preparedness Behavior

Despite the prognoses of the effects of global warming (e.g., rising sea levels, increasing river discharges), few international studies have addressed how flood preparedness should be stimulated among private citizens. This article aims to predict Dutch citizens’ flood preparedness intentions by testing a path model, including previous flood hazard experiences, trust in public flood protection, and flood risk perceptions (both affective and cognitive components). Data were collected through questionnaire surveys in two coastal communities (n= 169, n= 244) and in one river area community (n= 658). Causal relations were tested by means of structural equation modeling (SEM). Overall, the results indicate that both cognitive and affective mechanisms influence citizens’ preparedness intentions. First, a higher level of trust reduces citizens’ perceptions of flood likelihood, which in turn hampers their flood preparedness intentions (cognitive route). Second, trust also lessens the amount of dread evoked by flood risk, which in turn impedes flood preparedness intentions (affective route). Moreover, the affective route showed that levels of dread were especially influenced by citizens’ negative and positive emotions related to their previous flood hazard experiences. Negative emotions most often reflected fear and powerlessness, while positive emotions most frequently reflected feelings of solidarity. The results are consistent with the affect heuristic and the historical context of Dutch flood risk management. The great challenge for flood risk management is the accommodation of both cognitive and affective mechanisms in risk communications, especially when most people lack an emotional basis stemming from previous flood hazard events.     

Using Public Feedback and Competitive Rewards to Increase the Safe Driving of Pizza Deliverers

Abstract

This study investigated the effects of a safe driving competition facilitated by publicly-posted individual feedback. The turn-signal use, safety-belt use, and complete intersection stopping of 82 pizza deliverers were observed at two experimental and three control stores, as well as among the civilian population. After baseline observations, pizza deliverers received posted weekly individual feedback on their turn-signal use (at Store A) or complete intersection stops (at Store B). The deliverers' safe driving scores were posted individually on a vertical scale along with their names. Each week the deliverer with the highest average performance was rewarded with a free vehicle-maintenance coupon. Turn-signal use among drivers at Store A (n= 24) increased 22 percentage points from baseline to the intervention phase which was maintained into the withdrawal phase. Complete intersection stopping among drivers at Store B (n= 21) increased 17 percentage points from baseline to the intervention phase and was maintained into the withdrawal phase. Although the winners of the weekly competitions had the greatest increase in performance, non-winners also increased their instances of safe driving during the competition.     

Polynomially solvable cases of the constant rank unconstrained quadratic 0-1 programming problem

In this paper we consider the constant rank unconstrained quadratic 0-1 optimization problem, CR-QP01 for short. This problem consists in minimizing the quadratic function 〈x, Ax〉 + 〈c, x〉 over the set {0,1} ⁿ where c is a vector in ℝ ⁿ and A is a symmetric real n × n matrix of constant rank r. We first present a pseudo-polynomial algorithm for solving the problem CR-QP01, which is known to be NP-hard already for r = 1. We then derive two new classes of special cases of the CR-QP01 which can be solved in polynomial time. These classes result from further restrictions on the matrix A. Finally we compare our algorithm with the algorithm of Allemand et al. (2001) for the CR-QP01 with negative semidefinite A and extend the range of applicability of the latter algorithm. It turns out that neither of the two algorithms dominates the other with respect to the class of instances which can be solved in polynomial time.     

Understanding the Relationship Between Direct Experience and Risk Perception of Natural Hazards

Risk perception has been largely examined in studies that have aimed to explain and predict preparedness behavior in the context of natural hazards. Findings from studies on the relationship between previous experience, preparedness, and risk perception in disaster situations have been inconsistent. Hence, the main goal of this work was to explore the influence of physical and emotional experience on risk perception regarding natural hazards. This study was conducted in a statistically representative sample of the city of Iquique, in northern Chile (n = 701), who completed a survey one month after the occurrence of an earthquake and tsunami (8.2 Mw). The survey assessed the experience and preparation actions of survivors in relation to this event. Using a structural equation model, we examined nine proposed relationships, six of which were significant. The final model had an adequate fit (χ² = 752.23, df = 283, comparative fit index [CFI] = 0.90, root mean square error of approximation [RMSEA] = 0.049). Direct experience showed the greatest influence on risk perception: while direct physical experience (i.e., the physical and material consequences associated with the earthquake) maintained a direct positive effect on risk perception, direct emotional experience (i.e., the fear of experiencing an earthquake) produced an indirect positive effect (through worry). Emotional experience, however, did not directly influence current preparedness and risk perception. Implications for understanding the relationship between risk perception and direct experience are discussed.     

Approximating the Independence Number and the Chromatic Number in Expected Polynomial Time

The independence number of a graph and its chromatic number are known to be hard to approximate. Due to recent complexity results, unless coRP = NP, there is no polynomial time algorithm which approximates any of these quantities within a factor of n ^1– for graphs on n vertices.We show that the situation is significantly better for the average case. For every edge probability p = p(n) in the range n ^–1/2+ p 3/4, we present an approximation algorithm for the independence number of graphs on n vertices, whose approximation ratio is O((np)^1/2/log n) and whose expected running time over the probability space G(n, p) is polynomial. An algorithm with similar features is described also for the chromatic number.A key ingredient in the analysis of both algorithms is a new large deviation inequality for eigenvalues of random matrices, obtained through an application of Talagrand's inequality.     

Reducing Overconfidence in the Interval Judgments of Experts

Elicitation of expert opinion is important for risk analysis when only limited data are available. Expert opinion is often elicited in the form of subjective confidence intervals; however, these are prone to substantial overconfidence. We investigated the influence of elicitation question format, in particular the number of steps in the elicitation procedure. In a 3‐point elicitation procedure, an expert is asked for a lower limit, upper limit, and best guess, the two limits creating an interval of some assigned confidence level (e.g., 80%). In our 4‐step interval elicitation procedure, experts were also asked for a realistic lower limit, upper limit, and best guess, but no confidence level was assigned; the fourth step was to rate their anticipated confidence in the interval produced. In our three studies, experts made interval predictions of rates of infectious diseases (Study 1, n = 21 and Study 2, n = 24: epidemiologists and public health experts), or marine invertebrate populations (Study 3, n = 34: ecologists and biologists). We combined the results from our studies using meta‐analysis, which found average overconfidence of 11.9%, 95% CI [3.5, 20.3] (a hit rate of 68.1% for 80% intervals)—a substantial decrease in overconfidence compared with previous studies. Studies 2 and 3 suggest that the 4‐step procedure is more likely to reduce overconfidence than the 3‐point procedure (Cohen's d = 0.61, [0.04, 1.18]).     

The role of stress and social support in Sick Building Syndrome

Sick Building Syndrome (SBS) involves seemingly healthy individuals experiencing long-lasting symptoms of physical distress in their work settings and is estimated to exist in 20 to 30% of all work settings in the USA. We examined differences in stress, social support and both physical and psychological symptoms reported by hospital personnel working in known SBS sites in Halifax, Nova Scotia (n = 297) with control employees working in relatively SBS-free settings (n = 228). We found that employees reporting that their health had been affected by the building in which they worked and those complaining of poor air quality were more likely to be found in SBS locations. In addition, those people with higher levels of organizational support and marginally higher levels of union support were also more likely to be found in SBS locations. Further analyses revealed that employees with higher role overload and greater family support, but lower levels of organizational support were more likely to report that their own health had been adversely affected by their place of work. Perceptions of poor air quality were predicted by higher levels of role conflict, role overload, and organizational stress and lower levels of organizational support. These results suggest that SBS may not be solely dependent on environmental factors.     

Patterns of conflict and enrichment in work-family balance: A three-dimensional typology

Abstract

A four-dimensional typology of work-family balance (WFB) that has previously been reported was tested in four samples: Finnish nurses (n=662), Slovenian nurses (n=667), Finnish health and social care workers (n=1493) and Finnish service sector employees (n=827). Latent profile analyses identified three rather than four types of WFB in each sample. In line with the four-dimensional typology, a Beneficial type (56% to 70% of the participants), experiencing high work-to-family and family-to-work enrichment (WFE and FWE) and low work-to-family and family-to-work conflict (WFC and FWC), and an Active type (15% to 20%), experiencing high WFC, FWC, WFE and FWE, emerged; however, the Harmful and Passive types were not identified. Instead, a Contradictory type (16% to 53%), experiencing high WFC and low WFE in combination with low FWC and high FWE, was found. The Beneficial type showed higher subjective well-being than the Contradictory and Active types, the latter showing higher vigour at work but also higher psychological strain and lower life satisfaction than the Contradictory type. These findings support the view that WFB is not a single state or continuum, but manifests itself in diverse combinations of WFC, FWC, WFE and FWE.