Positron lifetime study of an Al-1.7at.% Mg-1.1at.% Cu alloy

The behaviour of vacancies during isothermal ageing following quenching of an Al-1.7at.% Mg-1.1at.% Cu alloy has been studied by positron annihilation lifetime spectroscopy. The positron lifetime parameters vary in parallel with the Vickers hardness of the alloy, suggesting simultaneous migration of vacancies and changes in the size and concentration of vacancies containing clusters and dislocation loops. The results also explain the long hardness plateau observed previously in ageing experiments carried out between 100 and 240°C in terms of a continuous growth of Mg-Cu-vacancy clusters during ageing. The vacancy concentration of the clusters increases gradually until the setting in of the cluster Guinier-Preston-Bagaryatsky zone transformation.     

On the length scale of cyclic strain localization in fine-grained copper films

Fine-grained copper films on a flexible substrate were cyclically deformed under constant strain range control. It was found that cyclic dislocation plasticity through individual dislocation glide is still dominant at the submicrometer scale, while the ability of irreversible slip of dislocations gradually decreases and the damage was changed from extrusion-induced localization to cracking along grain boundary. Statistical evaluation of the mean spacing between slip bands and/or lines leads to a critical scale (～28 nm) below which dislocation-controlled cyclic strain localization would be shut down.     

Strain rate response of a Ni–Ti shape memory alloy after hydrogen charging

In this work, we investigate the susceptibility of Ni–Ti superelastic wires to the strain rates during tensile testing after hydrogen charging. Cathodic hydrogen charging is performed at a current density of 10?A/m² during 2–12?h in 0.9% NaCl solution and aged for 24?h at room temperature. Specimens underwent one cycle of loading-unloading reaching a stress value of 700 MPa. During loading, strain rates from 10^?6 to 5?×?10^?2?^?s^?1 have been achieved. After 8?h of hydrogen charging, an embrittlement has been detected in the tensile strain rate range of 10^?6 to 10^?4?s^?1. In contrast, no embrittlement has been detected for strain rates of 10^?3?s^?1 and higher. However, after 12?h of hydrogen charging and 24?h of annealing at room temperature, the embrittlement occurs in the beginning of the austenite-martensite transformation for all the studied strain rate values. These results show that for a range of critical amounts of diffused hydrogen, the embrittlement of the Ni–Ti superelastic alloy strongly depends on the strain rate during the tensile test. Moreover, it has been shown that this embrittlement occurs for low values of strain rates rather than the higher ones. This behaviour is attributed to the interaction between the diffused hydrogen and growth of the martensitic domain.     

The Demand–Control model and target's reports of bullying at work: A test within Spanish and Belgian blue-collar workers

The present study explores whether Karasek's Job Demand–Control (JDC) model's strain hypothesis can be applied to target's reports of bullying at work in matched samples of Spanish and Belgian blue-collar workers. In the Spanish sample, results reveal a positive main effect of workload and a negative main effect of autonomy. The relationship between workload and bullying is particularly strong under the condition of low autonomy (i.e., interaction), in line with Karasek's strain hypothesis. In the Belgian sample, results show a positive main effect of workload and a significant workload–autonomy interaction effect in accordance with the strain hypothesis. In sum, high strain jobs associate with target's reports of bullying in both the Spanish and Belgian sample. Karasek's JDC model may accordingly be extended to target's reports of bullying as a form of social behavioural strain. These findings furthermore enhance research in the realm of bullying at work by introducing a well-established theoretical framework to account for the relationship between workload, autonomy, and target's reports of bullying.     

Conflict of interest policies in science and medical journals: Editorial practices and author disclosures

This study examines the extent to which scientific and biomedical journals have adopted conflict of interest (COI) policies for authors, and whether the adoption and content of such policies leads to the publishing of authors’ financial interest disclosure statements by such journals. In particular, it reports the results of a survey of journal editors about their practices regarding COI disclosures. About 16 percent of 1396 highly ranked scientific and biomedical journals had COI policies in effect during 1997. Less than 1 percent of the articles published during that year in the journals with COI policies contained any disclosures of author personal financial interests while nearly 66 percent of the journals had zero disclosures of author personal financial interests. Nearly three fourths of journal editors surveyed usually publish author disclosure statements suggesting that low rates of personal financial disclosures are either a result of low rates of author financial interest in the subject matter of their publications or poor compliance by authors to the journals’ COI policies.     

Organizational response to recommendations based on a study of stress among correctional officers

A study was recently commissioned by the South Australian Government to study the nature and sources of stress among correctional (prison) officers. The paper reports on the key variables found to have significant predictive effects on strain (a composite measure comprising psychological distress, physical ill-health symptoms, job dissatisfaction, and work-home conflict). These included demographic variables (length of service, finances), personal variables (negative affectivity), work environment variables (work role ambiguity, institutional relationship concerns, inmate concerns, worktime concerns, low autonomy, and low involvement), and emotional suppression. Recommendations were formulated including: the appointment of a full-time mental health counselor, organizational and individual strategies aimed to improve supervisor support and management training, greater participation in organizational decision making, and post-shift debriefing. It was also suggested that in selecting correctional officers those displaying high levels of negative affectivity should be screened out. Finally, it was recommended that intervention should target the most vulnerable individuals, including shiftworkers, officers who had been employed in the organization the longest, officers currently on stress leave and officers, who have previously been on stress leave and have returned to work. The paper reports on the organizational response to the recommendations and the implications of the study are discussed in the context of ongoing surveillance and evaluation of the impact of intervention strategies.     

Effects of d-amphetamine and cocaine on strained ratio behavior in a repeated-acquisition task.

Pigeons acquired a different four-response chain each session by responding sequentially on three keys in the presence of four colors. When the fixed-ratio requirement for food presentation was five completions of the chain, d-amphetamine and cocaine disrupted the behavior. As the dose of each drug was increased, the overall response rate decreased, the overall accuracy was impaired (i,e., percent errors increased), and there was less within-session error reduction (acquisition). In contrast, when the fixed-ratio requirement was either 20 or 50 completions of the chain, certain doses of both drugs produced large increases in the overall response rate by eliminating the extended pausing (ratio strain) that was characteristic of the control sessions. These rate-increasing effects were accompanied by error-decreasing effects, both during acquisition and after the response chain had been acquired. Taken together, the results show that the effects of d-amphetamine and cocaine on behavior in a repeated-acquisition task can be modulated by manipulating the value of the fixed-ratio schedule maintaining the behavior.     

Work and nonwork stressors,negative affective states,and pain complaints among firefighters and paramedics

Prior research has suggested that occupational stressors may contribute to the etiology, progression, and chronicity of pain problems in workers. This study used anonymous survey methods to assess the prevalence and frequency of self-reported pain symptoms and their relationships to demographic variables, sources of occupational stressors, nonwork stressors and affective distress in a large sample (N2000) of employed career public sector firefighters and paramedics. The findings were consistent with those of previous studies of high strain workers. More than 95% of the firefighter/paramedic sample reported at least one pain complaint (using a 1 week assessment time frame). A hierarchical multiple regression analysis entering demographic, occupational, and nonwork stressors, as well as measures of negative affective states targeting total pain scores, yielded significant relationships. Five occupational stressors were associated with respondent pain complaints. The results also suggest that negative affective states mediated the relationships between work and nonwork variables, and pain complaint outcomes. The implications of these findings for the development of preventive interventions for firefighters and paramedics as well as other emergency service workers are considered.     

Coping and financial strain as predictors of mental illness in over‐ indebted individuals in Sweden

This cross‐sectional study examined psychological mechanisms in order to increase knowledge regarding mental illness amongst 561 over‐indebted individuals in Sweden. Differences were explored between individuals with probable clinical depression and/or anxiety and individuals without probable clinical depression and/or anxiety, considering objective measures of the debt, financial strain, coping strategies as well as sociodemographic variables. Furthermore, binary logistic regression analyses were performed in order to construct a model of predictors of mental illness. In order to collect the data, Hospital Anxiety and Depression Scale (HADS), Brief Coping Orientation to Problems Experienced (COPE_, as well as questions formulated by the research team, were used as measures. Prominent results showed that over‐indebted individuals with probable clinical depression and/or anxiety were younger, showed greater levels of financial strain, used adaptive coping strategies to a lesser extent, and maladaptive coping strategies to a greater extent. Additionally, financial strain, use of maladaptive and emotion‐focused coping, age and employment status were significant predictors of mental illness. These results put emphasis on the importance of adaptive coping as well as the psychological exposure of over‐indebted individuals.