Prevalence of chronic fatigue syndrome in metropolitan, urban, and rural Georgia

© 2007 Reeves et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Time spent on work-related activities, social activities and time pressure as intermediary determinants of health disparities among elderly women and men in 5 European countries: a structural equation model

Background Psychosocial factors shape the health of older adults through complex inter-relating pathways. Besides socioeconomic factors, time use activities may explain gender inequality in self-reported health. This study investigated the role of work-related and social time use activities as determinants of health in old age. Specifically, we analysed whether the impact of stress in terms of time pressure on health mediated the relationship between work-related time use activities (i.e. housework and paid work) on self-reported health. Methods We applied structural equation models and a maximum-likelihood function to estimate the direct and indirect effects of psychosocial factors on health using pooled data from the Multinational Time Use Study on 11,168 men and 14,295 women aged 65+ from Italy, Spain, UK, France and the Netherlands. Results The fit indices for the conceptual model indicated an acceptable fit for both men and women. The results showed that socioeconomic status (SES), demographic factors, stress and work-related time use activities after retirement had a significant direct influence on self-reported health among the elderly, but the magnitude of the effects varied by gender. Social activities had a positive impact on self-reported health but had no significant impact on stress among older men and women. The indirect standardized effects of work-related activities on self-reported health was statistically significant for housework (β = − 0.006; P  0.05 among women), which implied that the paths from paid work and housework on self-reported health via stress (mediator) was very weak because their indirect effects were close to zero. Conclusions Our findings suggest that although stress in terms of time pressure has a direct negative effect on health, it does not indirectly influence the positive effects of work-related time use activities on self-reported health among elderly men and women. The results support the time availability hypothesis that the elderly may not have the same time pressure as younger adults after retirement

Pre-Survey Text Messages (SMS) Improve Participation Rate in an Australian Mobile Telephone Survey: An Experimental Study

Mobile telephone numbers are increasingly being included in household surveys samples. As approach letters cannot be sent because many do not have address details, alternatives approaches have been considered. This study assesses the effectiveness of sending a short message service (SMS) to a random sample of mobile telephone numbers to increase response rates. A simple random sample of 9000 Australian mobile telephone numbers: 4500 were randomly assigned to be sent a pre-notification SMS, and the remaining 4500 did not have a SMS sent. Adults aged 18 years and over, and currently in paid employment, were eligible to participate. American Association for Public Opinion Research formulas were used to calculated response cooperation and refusal rates. Response and cooperation rate were higher for the SMS groups (12.4% and 28.6% respectively) than the group with no SMS (7.7% and 16.0%). Refusal rates were lower for the SMS group (27.3%) than the group with no SMS (35.9%). When asked, 85.8% of the pre-notification group indicated they remembered receiving a SMS about the study. Sending a pre-notification SMS is effective in improving participation in population-based surveys. Response rates were increased by 60% and cooperation rates by 79%

Piezoelectric field and its influence on the pressure behavior of the light emission from GaN/AlGaN strained quantum wells

We have studied the influence of hydrostatic pressure on the light emission from a strained GaN/AlGaN multiquantum well system. We have found that the pressure coefficients of the photoluminescence peak energies are dramatically reduced with respect to that of GaN energy gap and this reduction is a function of the quantum well thickness. The decrease of the light emission pressure coefficient may be as large as 30% for a 32 monolayer (8 nm) thick quantum well. We explain this effect by the hydrostatic-pressure-induced increase of the piezoelectric field in quantum structures. Model calculations based on the k x p method and linear elasticity theory reproduce the experimental results well, demonstrating that this increase may be explained by small anisotropy of the wurtzite lattice of GaN and a specific interplay of elastic constants and values of the piezoelectric tensor. (C) 2001 American Institute of Physics

Large built-in electric field and its influence on the pressure behavior of the light emission from GaN/AlGaN strained quantum wells

Influence of hydrostatic pressure on the light emission from strained GaN/AlGaN multi-quantum-well systems has been studied, Pressure coefficients of the photoluminescence peak energies show a strong reduction with respect to that of the GaN energy ? ap and this reduction is a function of the quantum-well thickness. The decrease of the light emission pressure coefficient may be almost 40% for a 32 monolayer (8 nm) thick quantum well in comparison with a 4 monolayer well. We explain this effect by a hydrostatic-pressure-induced increase of the piezoelectric field in the GaN/AlGaN quantum structures