| 1. |
- Anderbrant, Olle, et al.
(författare)
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Release of sex pheromone and its precursors in the pine sawfly Diprion pini (Hym., Diprionidae)
- 2005
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Ingår i: Chemoecology. - : Springer Science and Business Media LLC. - 0937-7409 .- 1423-0445. ; 15:3, s. 147-151
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Tidskriftsartikel (refereegranskat)abstract
- The first identification of a sex pheromone of a pine sawfly (Hymenoptera, Diprionidae) dates back almost thirty years. Since then, female-produced pheromones of over twenty diprionid species have been investigated by solvent extraction followed by separation and identification. However, no study has shown what the females actually release. Collection of airborne compounds using absorbtion on charcoal filter as well as solid phase microextraction (SPME) followed by analysis employing gas chromatography combined with mass spectrometry (GC-MS), revealed an unusual system in Diprion pini, in which the pheromone precursor alcohol, 3,7-dimethyl-2-tridecanol, is released together with acetic, propionic, butyric and isobutyric acids. The corresponding acetate, propionate and butyrate esters of 3,7-dimethyl-2-tridecanol were also found in the samples. All esters were electrophysiologically active, and the propionate and isobutyrate were attractive in trapping experiments. Based on these and earlier reported results, it seems that at least in part of its range, the pheromone response of D. pini is not very specific with regard to the functional group, as long as this is an ester.
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| 2. |
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| 3. |
- Bergström, Gunnar, et al.
(författare)
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A comprehensive workplace intervention and its outcome with regard to lifestyle, health and sick leave : the AHA study
- 2008
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Ingår i: Work. - 1051-9815 .- 1875-9270. ; 31:2, s. 167-180
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Tidskriftsartikel (refereegranskat)abstract
- This study is a prospective multicentre cohort study entitled Work and Health in the Processing and Engineering Industries, the AHA Study (AHA is the Swedish abbreviation for the study). Four large workplaces in Sweden participated during the years from 2000 to 2003. The present report has two objectives: (1) to present a comprehensive occupational health intervention programme and (2) to evaluate this programme with a focus on lifestyle (smoking and exercise), health related quality of life (HRQoL) and sick leave. Interventions were provided on an individual and group level, including evidence-based methods for four health/focus areas (individual level) and a group intervention based on a survey-feedback methodology. The analyses in this report were exclusively employed at an organizational level. The proportion of smokers decreased at three companies and the course of the HRQoL was advantageous at two of the companies as compared to a gainfully employed reference group. A significant decrease in sick leave was revealed at one company, whereas a break in an ascending sick-leave trend appeared at a second company as compared to their respective corporate groups. This comprehensive workplace intervention programme appears to have had positive effects on smoking habits, HRQoL and sick leave.
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| 4. |
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| 5. |
- Bergström, Gunnar, et al.
(författare)
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Acceptanskriterier för repor och intryck i plaströr Accpetance criteria for scratches and indentations in plastic pipes
- 2009
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Rapport (refereegranskat)abstract
- Development of materials and laying techniques have arisen the question how scratches and indentations in plastics pipes affect the strength and technical lifetime of pipelines. Scratches may occur both in the manufacturing of the pipes, in connection with the installation and subsequent maintenance. The problems in assessing the failure risk from scratches and indentations are similar for pipes used in gas and water distribution and in district heating applications. Therefore, a broad effort to identify the risks in relation to current pipe materials is technically and economically justified. The project has aimed to evaluate the effect of scratches and indentations on the technical lifetime of plastics pipes and to present criteria for maximum allowable depth of scratches and indentations. The study on pressure pipes focused on the conditions for scratched polyethylene pipes to achieve a lifetime of 50 years. It is noted that a scratch damage can not be judged solely on the basis of its depth and sharpness. To assess the impact of the scratch on the serviceability of the pipe, consideration must also be taken to the material from which the pipe was made and the safety factor used in the design. Extensive pressure tests show that pipes made of modern materials can withstand surface scratches to a higher degree than pipes of older materials. For pipes made of modern bimodal PE80 and PE100 materials, scratches up to 10% depth may be accepted without reduction of rated pressure. However, for pipes of older material, a reduction in pressure may be required already at smaller scratches. The study also indicates that for the same relative scratch depth, a greater reduction in pressure is required with increasing pipe dimension. The study on the non pressure pipes shows that the studied polypropylene pipes resist both deep scratches combined with ovalization and large indentations without any cracks penetrating the pipe wall. However, the extent and development of crazing and surface cracking vary with scratch depth, deformation level and material. The test pipes were subjected to extreme conditions very rarely or never occurring in practice. This suggests that small scratches at moderate ovalization and realistic indentations in temperatures around room temperature do not affect the lifetime of the pipes. One objective of the project was to develop a method for the evaluation of the scratch resistance of a pipe. In the proposed test method the force needed to produce a specified scratch is measured. This force is used as a relative measure of the scratch resistance of a pipe material when compared to other materials. In order to assess to what extent a scratch affects the lifetime of the pipe, the depth of the scratch must be estimated with reasonable accuracy. Since the scratch in many cases is found on existing pipelines the method must be suited for field use. To achieve that a simple instrument for scratch depth measurements was made and evaluated.
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| 6. |
- Bergström, Gunnar, et al.
(författare)
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Accpetance criteria for scratches and indentations in plastic pipes
- 2009
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Rapport (refereegranskat)abstract
- Development of materials and laying techniques have arisen the question how scratches and indentations in plastics pipes affect the strength and technical lifetime of pipelines. Scratches may occur both in the manufacturing of the pipes, in connection with the installation and subsequent maintenance. The problems in assessing the failure risk from scratches and indentations are similar for pipes used in gas and water distribution and in district heating applications. Therefore, a broad effort to identify the risks in relation to current pipe materials is technically and economically justified. The project has aimed to evaluate the effect of scratches and indentations on the technical lifetime of plastics pipes and to present criteria for maximum allowable depth of scratches and indentations. The study on pressure pipes focused on the conditions for scratched polyethylene pipes to achieve a lifetime of 50 years. It is noted that a scratch damage can not be judged solely on the basis of its depth and sharpness. To assess the impact of the scratch on the serviceability of the pipe, consideration must also be taken to the material from which the pipe was made and the safety factor used in the design. Extensive pressure tests show that pipes made of modern materials can withstand surface scratches to a higher degree than pipes of older materials. For pipes made of modern bimodal PE80 and PE100 materials, scratches up to 10% depth may be accepted without reduction of rated pressure. However, for pipes of older material, a reduction in pressure may be required already at smaller scratches. The study also indicates that for the same relative scratch depth, a greater reduction in pressure is required with increasing pipe dimension. The study on the non pressure pipes shows that the studied polypropylene pipes resist both deep scratches combined with ovalization and large indentations without any cracks penetrating the pipe wall. However, the extent and development of crazing and surface cracking vary with scratch depth, deformation level and material. The test pipes were subjected to extreme conditions very rarely or never occurring in practice. This suggests that small scratches at moderate ovalization and realistic indentations in temperatures around room temperature do not affect the lifetime of the pipes. One objective of the project was to develop a method for the evaluation of the scratch resistance of a pipe. In the proposed test method the force needed to produce a specified scratch is measured. This force is used as a relative measure of the scratch resistance of a pipe material when compared to other materials. In order to assess to what extent a scratch affects the lifetime of the pipe, the depth of the scratch must be estimated with reasonable accuracy. Since the scratch in many cases is found on existing pipelines the method must be suited for field use. To achieve that a simple instrument for scratch depth measurements was made and evaluated.
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| 7. |
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| 8. |
- Bergström, Gunnar, et al.
(författare)
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Direct burial of district heating pipe bends – A limited casing pipe temperature ap-proach
- 2003
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Ingår i: Euroheat & Power - English Edition.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The direct burial of district heating pipe bends, i.e., without the use of expansionabsorbing elements, has reportedly frequently been done withoutany observed pipe-line damage. This in spite of current design principles,predicting so large stresses on a directly buried L bend that the techniqueshould be avoided. A reason for the lack of correspondence between practicalexperience and design theory is the difficulties in formulating relevantcriteria for tolerable stresses and deformations in the pipe. Conservative designlimits are traditionally used, particularly regarding allowable stresses inthe PUR foam.An alternative method for design with respect to the PUR foam may bedeveloped based on the idea that the deformation of the PUR foam, and thusalso the displacement of the steel pipe relative to the casing pipe, must belimited only to avoid overheating of the polyethylene. The factors influencingthe deformation of the PUR foam is mainly a question of the temperatureinduced steel pipe displacement versus the stiffness and strength of thebackfill material. When the loading properties of the PUR foam and thebackfill material are known, the relationship between the steel pipe displacementand the PUR foam deformation is defined. Thus also a relation betweena specified thermal motion of the steel pipe and the resulting maximumtemperature on the casing pipe is established. This makes it possible touse the maximum casing pipe temperature as a design value.The conclusion using this approach is that the laying of bends directly inthe ground should be possible with normal backfill materials and compactionconditions. Certain care must be taken, though, when bends are laid invery stiff and strong backfill, where high reaction pressures may develop. Ingeneral, the risk for pipeline damage is minimised if directly buried bendsare laid in only moderately compacted backfill.
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| 9. |
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| 10. |
- Bergström, Gunnar, et al.
(författare)
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Does sickness presenteeism have an impact on future general health?
- 2009
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Ingår i: International Archives of Occupational and Environmental Health. - Berlin : Springer. - 0340-0131 .- 1432-1246. ; 82:10, s. 1179-1190
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The primary aim of this prospective study was to investigate whether working despite illness, so called "sickness presenteeism", has an impact on the future general health of two different working populations during a follow-up period of 3 years.METHODS: The study was based on two bodies of data collected at a number of Swedish workplaces from 1999 to 2003. The first material comprised 6,901 employees from the public sector and the second 2,862 subjects from the private sector. A comprehensive survey was issued three times: at baseline, after 18 months and after 3 years. Apart from the explanatory variable sickness presenteeism, several potential confounders were considered. The outcome variable was good/excellent versus fair/poor self-reported health.RESULTS: Sickness presenteeism at baseline was consistently found to heighten the risk of fair/poor health at both the 18-month and 3-year follow ups even after adjusting for the detected confounders.CONCLUSIONS: To the best of the authors' knowledge, this study is the first to show that sickness presenteeism appears to be an independent risk factor for future fair/poor general health.
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