Change and stability: Within-person life satisfaction over a 20-year period using data from the HUNT survey
SCANDINAVIAN JOURNAL OF PUBLIC HEALTH
Authors: Lysberg, Frode; Bjerregaard Bertelsen, Tomas; Lysberg, Cathrine; Hoie, Magnhild; Espnes, Geir Arild; Innstrand, Siw Tone
Abstract
Background:The aim of the present study was to investigate within-person life satisfaction (LS) dynamics for two age groups, 20-29 and 30-39 years, from 1984 to 1986 and to follow them over a 20-year period.Methods:Data from 1984 to 2008 were extracted from the large, prospective, longitudinal North-Trondelag Health Study (HUNT), Norway. This paper includes data from more than 14,500 persons. Data were analysed using logistic regression, and LS dynamics were modelled using gender, time and self-rated health.Results:The analyses revealed that about 20% of people in these age groups had a stable level in LS, also known as set point. Long-term LS change, defined as > 2 SDs, was reported for 9% and 6% of people in the youngest and oldest age groups, respectively. A large proportion of more than 70% of people had fluctuations in their LS over a 20-year period. A significant decrease in within-person LS was seen for the age groups from 1984-86 to 1995-97 where a significant increase appeared from 1995-97 to 2006-08. For the initial 20-29 age group, the odds of having a higher score increased by 34%, and for the initial 30-39 age group, the within-person LS increase was 81%. Self-rated health was the most crucial variable influencing within-person LS.Conclusions:These findings suggest that a significant proportion of the responders had a long-term within-person LS change over the 20-year period.
Applicability of an anionic-nonionic surfactant in p-cresol contaminated soil washing: Finding the optimal mixing ratio
JOURNAL OF ENVIRONMENTAL HEALTH SCIENCE AND ENGINEERING
Authors: Mohebban, Ali; Yaghoobzadeh, Peyman; Gitipour, Saeid; Abdollahinejad, Mahdi; Delarestaghi, Reza Maleki; Ramezani, Mostafa
Abstract
In this study, the parameters influencing p-cresol removal efficiency in soil washing method were investigated. Primarily, extraction efficiencies of three Tween series surfactants (Tween 20, Tween 60, Tween 80) with 10 mM concentration were compared. Tween 80 showed the best results since its value (55%) was 4% and 13% higher than that of Tween 60 and Tween 20. The impact of mixed surfactant on extraction rate was examined by employing a mixture of Tween 80 and one anionic surfactant (sodium dodecyl sulfate) with different molar ratio as the main washing solution. The results denoted that the molar ratio of 3:2 (SDS:Tween80) could enhance the extraction rate up to 38% compared to using SDS and Tween 80 alone. Regarding the initial p-cresol concentration in the collected sample, the cleanup level (390 mg/kg) could only be achieved using the mixed-surfactant. Thus, the minimum required surfactant concentrations to hit the target level was calculated to be 3.54 g/L of Tween 80 and 2.105 g/L of SDS (molar ratio of 0.27 SDS:Tween80). Studying the role of surfactant concentration indicated that its increment from 10 mM to 20 mM, which is way above all the reagents' critical micelle concentration (CMC), does not affect the removal rate considerably. The same results were obtained comparing the effect of washing time in three different levels (30 min, 60 min and 90 min). However, temperature showed to be a more significant parameter as it could enhance the results up to 20% (for SDS).