| 1. |
- Anderbrant, Olle, et al.
(författare)
-
Release of sex pheromone and its precursors in the pine sawfly Diprion pini (Hym., Diprionidae)
- 2005
-
Ingår i: Chemoecology. - : Springer Science and Business Media LLC. - 0937-7409 .- 1423-0445. ; 15:3, s. 147-151
-
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.
|
|
| 2. |
|
|
| 3. |
- Bergström, Gunnar, et al.
(författare)
-
A comprehensive workplace intervention and its outcome with regard to lifestyle, health and sick leave : the AHA study
- 2008
-
Ingår i: Work. - 1051-9815 .- 1875-9270. ; 31:2, s. 167-180
-
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.
|
|
| 4. |
|
|
| 5. |
- Bergström, Gunnar, et al.
(författare)
-
Acceptanskriterier för repor och intryck i plaströr Accpetance criteria for scratches and indentations in plastic pipes
- 2009
-
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.
|
|
| 6. |
- Bergström, Gunnar, et al.
(författare)
-
Accpetance criteria for scratches and indentations in plastic pipes
- 2009
-
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.
|
|
| 7. |
|
|
| 8. |
- Bergström, Gunnar, et al.
(författare)
-
Direct burial of district heating pipe bends – A limited casing pipe temperature ap-proach
- 2003
-
Ingår i: Euroheat & Power - English Edition.
-
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.
|
|
| 9. |
|
|
| 10. |
- Bergström, Gunnar, et al.
(författare)
-
Does sickness presenteeism have an impact on future general health?
- 2009
-
Ingår i: International Archives of Occupational and Environmental Health. - Berlin : Springer. - 0340-0131 .- 1432-1246. ; 82:10, s. 1179-1190
-
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.
|
|
| 11. |
- Bergström, Gunnar, et al.
(författare)
-
Durability testing for 100 year lifetime for buried non-pressure plastic pipes
- 2006
-
Ingår i: Plastics Pipes XIII.
-
Konferensbidrag (refereegranskat)abstract
- For plastics pipes used for underground drainage and sewerage there is at present no internationally accepted method for the evaluation of durability. This makes it difficult to make an objective assessment for both new materials and new pipe designs entering the market. This paper presents a possible future structure of such a durability evaluation for nonpressure pipes. Based on an experimental study of pipes made from a filled and an unfilled PP material and one made from an HDPE material different damage mechanisms and changes in pipe characteristics were observed when the pipes were exposed to long-term deflection and long term (one-year) ageing at +95 °C. A CAED methodology is also described which was used to investigate the distribution and time dependence of pipe stresses.
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
|
|
| 15. |
|
|
| 16. |
- Bergström, Gunnar, Professor, et al.
(författare)
-
Long-term, non-specific spinal pain: reliable and valid subgroups of patients
- 2001
-
Ingår i: Behaviour Research and Therapy. - : Elsevier. - 0005-7967 .- 1873-622X. ; 39:1, s. 75-87
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to identify reliable and valid subgroups of spinal pain patients, using data from the Swedish version of the Multidimensional Pain Inventory (MPI-S). A second aim was to test the generalisability of the three patient profiles described in earlier studies on the MPI (”adaptive coper”, ”dysfunctional” and ”interpersonally distressed” patients). The study base consisted of two samples of individuals suffering from long-term, non-specific spinal pain and the results were validated across these samples. Cluster analysis was used to detect distinct groups of patients and the validity of these subgroups was evaluated on variables not used to generate the cluster solution. One subgroup was characterised by lower pain severity, lower interference with everyday activities, lower affective distress and higher life control than the other two subgroups. This patient profile was similar to the MPI adaptive coper patients. A second subgroup resembled the dysfunctional patient profile, thus displaying a worse adjustment to chronic pain than the AC patients. The third patient group reported significantly lower levels of social support from “significant others” than the other subgroups. This patient profile was similar to that of the interpersonally distressed patient group. Taken together, the results support the reliability, validity and generalisability of three subgroups of chronic pain patients derived from the MPI-S.
|
|
| 17. |
|
|
| 18. |
- Bergström, Gunnar
(författare)
-
The assessment and treatment of long-term, non-specific spinal pain : behavioural medicine, a cognitive-behavioural perspective
- 2000
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Matching treatment specifically to the needs of long-term, non-specific spinal pain (LTSP) patients might greatly enhance treatment efficacy, but the heterogeneity of patients has hindered this development. There is a wide array of treatments for LTSP. The scientific support for many treatments is, however, limited. Aims: The aims of this thesis were to: (a) evaluate a method for the assessment of psychosocial and behavioural factors in patients suffering from LTSP (studies I and II), (b) to evaluate whether reliable and valid patient groups could be identified among these patients (study III), (c) to evaluate the predictive validity of these subgroups regarding the outcome of a vocational rehabilitation programme (study IV) and, (b) to evaluate a behavioural medicine rehabilitation (BM) programme as a whole and divided into its two main components, behaviour-oriented physical therapy (PT) and cognitive behavioural therapy (CBT) (study V). Materials and Methods: Three samples of patients (sample 1, n = 682; sample 2, n = 235; sample 3, n = 273) suffering from LTSP were used. The Multidimensional Pain Inventory (MPI) was translated into Swedish (MPI-S) and used as a measure of psychosocial and behavioural factors in the patients' adjustment to pain. In the component analysis, patients were randomised to one of four alternatives (BM, PT, C13T or a "treatment-as-usual" control group (CG)). Results: The analyses showed that the factor structure, reliability, generalisability and construct validity of sections I and 2 of the MPI-S were acceptable between genders. However, section 3 was excluded from the MPI-S due to its weak validity. Subsequently, the MPI-S was used to identify three reliable and valid subgroups of patients across two of the patient samples. These subgroups were similar to the "dysfunctional" (DYS), "interpersonally distressed" (ID) and "adaptive coper" (AC) patient types described in earlier research. The MPI-S subgroup classification was shown to be predictive of total absence from work (sick-listing plus early retirement), utilisation of health care, and health-related quality of life over the 18-month follow-up period. However, subgroup affiliation was not predictive of the percentage of improved patients in the three patient groups. It was found in the component analysis that the active treatment conditions were superior to the CG condition in one or two of the three primary endpoints at the 18-month follow-up and that the positive effects were restricted to women. The results did not support the superiority of the complete BM programme over its main components, PT and C13T. Females in the CBT and PT groups had a significantly lower risk of being granted full-time early retirement and females in the CBT and BM groups reported a significantly better health-related quality of life over the 18-month follow-up period, than females in the CG. A non-significant positive trend towards both decreased total absence from work and improved health-related quality of life was demonstrated among males in the BM and PT conditions compared to the CG. Conclusions: The MPI-S (sections 1 and 2) is a reliable and valid instrument in the assessment of psychosocial and behavioural factors in LTSP patients and can be used as a tool to derive subgroups of patients which has been shown to be predictive of treatment outcome. For female LTSP patients, CBT was shown to decrease the risk of full-time early retirement and for improving the health-related quality of life. For male LTSP patients, the results indicated that BM or PT might be used as treatments for decreasing the total absence from work and improving the health-related quality of life. Further research is needed, however, regarding effective treatments for males.
|
|
| 19. |
- Bergström, Gunnar, Professor, et al.
(författare)
-
The impact of psychologically different patient groups on outcome after a vocational rehabilitation program for long-term spinal pain patients
- 2001
-
Ingår i: Pain. - : LWW. - 0304-3959 .- 1872-6623. ; 93:3, s. 229-237
-
Tidskriftsartikel (refereegranskat)abstract
- A better knowledge of differential treatment outcomes for subgroups of chronic spinal pain patients may, for instance, help clinicians in treatment planning or pain researchers in treatment outcome research. The purpose of this prospective study was to evaluate the predictive validity of a subgroup classification based on the Swedish version of the (West Haven Yale) Multidimensional Pain Inventory, the MPI-S. Patients referred to a vocational rehabilitation program were classified into one of three groups, labeled ‘adaptive copers’, ‘dysfunctional’ patients, and ‘interpersonally distressed’ patients, and followed over an 18-month follow-up period. The outcome variables were absence from work (defined as sick listing plus early retirement), general health status, and utilization of health care resources. To our knowledge, the predictive validity of the MPI subgroups has not been evaluated regarding sick listing and early retirement after rehabilitation. As hypothesized, the results showed that the ‘dysfunctional’ patient group had significantly more registered absences from work and reported higher utilization of health care, over the follow-up period compared to the ‘adaptive copers’. Furthermore, as hypothesized, the ‘interpersonally distressed’ and ‘dysfunctional’ patient groups report a poorer general health status than the ‘adaptive copers’ over the whole follow-up period. However, contrary to our hypothesis, the proportion of improved patients did not differ significantly between the subgroups. Altogether, the predictive validity of the MPI-S subgroup classification was mainly confirmed. The clinical implications of this study suggest that the matching of treatment to patient needs may enhance treatment outcome, reduce pain and suffering among chronic spinal pain patients and facilitate a better health economic allocation of treatment resources.
|
|
| 20. |
- Bergström, Gunnar, et al.
(författare)
-
The influence from pipe surface, weld beads and protective skins on long term failure times for PE butt fusion joints
- 2004
-
Ingår i: Plastics Pipes XII.
-
Konferensbidrag (refereegranskat)abstract
- When making creep tensile tests on butt fusion joints in PE pipes almost all failures emerge from the outside of the pipe. Results indicate an influence from the outside surface on the long term behaviour of butt fusion joints. It is a well established practice to scrape the outside surface of PE pipes when making electro-fusion joints. This study stress the question if scraping or bead removal is a positive thing also when making butt fusion joints. Using PE100 pipes butt fusion joints were made using different levels of surface scraping before the butt fusion and with and without removing the weld beads before testing. PE-pipes with an outside PP or PE-skin were also included with and without the skin. Tensile test pieces were cut parallel to the pipe axis centered over the butt fusion joint. The long term strength evaluation were made using a standard accelerated test procedure with the test pieces exposed to a 5 MPa tensile loading immersed in 80 °C water with 2 % Arkopal N100 surfactant. With outside weld beads left intact failure times 200 h to 400 h are normal. Leaving the inner beads but removing the outer beads increase failure times to 1000 h to 2000 h. Failure times for test pieces without weld beads approach 10000 h. Scraping of the pipe surface to a depth of 0.2 mm did not substantially change the failure-time above that for an unscraped surface. Removing 0.7 mm from the pipe surfaceincrease failure times to 2000 h to 3000 h. Outside weld beads and outside pipe surface clearly interact to lower the time to failure in accelerated creep tensile tests. Weld bead removal and scraping of outside pipe surface significantly increase failure times. The exact mechanism is not clear and the implication on butt fusion joint performance in service is not demonstrated but the results indicate possible ways to enhance safety margins when making butt fusion joints. The topic will be given further attention in coming studies.
|
|
| 21. |
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
|
|
| 25. |
|
|
| 26. |
|
|
| 27. |
|
|
| 28. |
- Forsaeus Nilsson, Stefan, 1972, et al.
(författare)
-
Brittle fracture in casing pipes
- 2006
-
Ingår i: 10th International Symposium on District Heating and Cooling.
-
Konferensbidrag (refereegranskat)
|
|
| 29. |
|
|
| 30. |
|
|
| 31. |
- Forsaeus Nilsson, Stefan, 1972, et al.
(författare)
-
Fuktmätning med pulsekometer
- 2005
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Detta projekt syftar till att undersöka vilka förutsättningar som finns att bygga upp ett larmsystem baserat på pulsekometermätningar där indikeringarna kan tolkas kvantitativt och därmed ger en säkrare bild av en fuktskadas omfattning. Projektarbetet har till största delen bestått av mätningar med pulsekometer för att utröna sambanden mellan ett fuktfels storlek och utslaget på mätinstrumentet. I viss utsträckning har även jämförande mätningar på samma fuktfel gjorts med olika pulsekometrar. Undersökningar har gjorts på en provledning i laboratorium på simulerade fuktfel med såväl ”rent” vatten i behållare och med porösa material uppfuktade till varierande grad. Studier har gjorts av hur mängden fukt och dess läge i förhållande till larmtråden påverkar mätresultaten. Dessutom har effekten av standardmässiga larmaktivatorer undersökts. Kompletterande mätningar har gjorts även på en verklig fjärrvärmeledning i Göteborg. Ofta används lik- eller växelströmsresistansen mellan tråd och medierör som larmindikator för när ett fuktfel föreligger. Emellertid är det inte så att fukt med automatik väsentligt sänker resistansnivån. Det finns inte heller någon entydig korrelation mellan mängden fukt och resistansnivån. Dock ökar systemets känslighet betydligt då larmfilt används. Sådana kan emellertid påverka systemets elektriska egenskaper så att goda pulsekometermätningar försvåras. Med pulsekometer kan ett fuktfel lokaliseras med god noggrannhet, men det är inte möjligt att utifrån den uppmätta pulsekokurvan dra några mera precisa slutsatser om hur långt fuktfelet sträcker sig längs ledningen. Däremot föreligger ett linjärt samband mellan mängden fukt direkt mellan larmtråd och stålrör och mätutslagets storlek, vilket i princip gör det möjligt att använda sig av pulsekometerteknik för kvantitativa mätningar. Det är dock svårt att indikera fukt som befinner sig vid sidan av larmtråden eller utanför denna, sett från stålröret. En möjlig vidareutveckling av dagens fuktövervakningssystem vore att använda sig av den diffusionsspärr av metallfolie på insidan mantelröret som flera rörtillverkare nu introducerar som ledare för spänningspulsen istället för dagens koppartråd. Det skulle göra att all fukt inuti rörkonstruktionen befann sig mellan ledaren och jordplanet och således vore synlig på pulsekokurvan. En förutsättning är dock fortfarande ett metalliskt medierör. Pulsekometrar av olika fabrikat fungerar efter samma princip men resultaten kan presenteras på olika sätt. Mätningarna ger dock samma information. Idag krävs att en erfaren operatör tolkar resultaten, men i princip torde det vara möjligt att behandla mätdata på ett sätt som gör att slutresultatet presenteras i ett standardiserat format. En överslagsmässig teoretisk analys av temperaturmätande fuktövervakningssystem visar att de är mindre känsliga än elektriska system, såtillvida att det krävs större mängder fukt innan de kan ge en säker reaktion.
|
|
| 32. |
|
|
| 33. |
- Forsaeus Nilsson, Stefan, 1972, et al.
(författare)
-
Grund förläggning av fjärrvärmeledningar
- 2006
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Tidigare studier inom programmet Värmegles Fjärrvärme har visat på att det går att minska investeringskostnaderna genom att effektivisera markarbetena vid läggning av fjärrvärmeledningar. Föreliggande projekt har studerat förutsättningarna för att minska läggningsdjupet i typiska villagator i värmeglesa områden utan att öka risken för skador på vare sig rör eller gata. En inventering gjordes av aktuella normer och anvisningar samt lokala föreskrifter från kommuner och energibolag gällande rörschaktens geometri, läggningsdjup, kringfyllningsmaterial, packningsgrad, dränering etc. Därutöver har energibolag och tekniska förvaltningar i ett antal svenska kommuner tillfrågats om vilka regler de följer. Det är i huvudsak endast de större kommunerna som har specifika krav på läggningsdjup i gatumark. På de flesta håll följer man Svensk Fjärrvärmes läggningsanvisningar och i mindre kommuner överlåter man i hög grad åt energibolagen att sköta frågan. I några kommuner finns överenskommelser mellan den kommunala förvaltningen och energibolaget att under vissa förutsättningar tillåta grundare förläggning, till exempel i Göteborg, Jönköping och Luleå. En analys av kostnaderna som är förknippade med markarbetena visade på att dessa kan minskas med närmare 30 % genom att minska läggningsdjupet från 600 mm till 350 mm. I ett fältförsök genomfördes mätningar i och kring fyra fjärrvärmerör av typ DN 2 × 32/160 som förlades 600 mm, 380 mm, 280 mm samt 180 mm under asfaltytan på en tungt och intensivt trafikerad fabriksgata. Återschaktning och asfaltering utfördes som för en typisk villagata i enlighet med Svensk Fjärrvärmes läggningsanvisningar. Under försökets gång har mätningar gjorts av rörens deformation, spårbildning i asfaltytan samt gatans bärighetsegenskaper. Rörens deformation har visat sig vara försumbar – oavsett vilket djup de läggs på. Detta tolkas som att fyllningen, om den är väl packad, tar upp huvuddelen av krafterna från trafikbelastningen genom valvverkan. Spårbildningen i gatan är däremot tydlig men tycks direkt avspegla sättningar i den nylagda fyllningen så att djupare fyllning ger större sättningar. En grundare rörförläggning medför därför mindre spårbildning i asfaltytan. Grundare förläggning medför något ökade värmeförluster, något större temperaturrörelser i systemet och en ökad risk för knäckning av ledningen uppåt genom överfyllnaden. Sådana aspekter får bedömas från fall till fall. Slutsatsen blir därmed att det tekniskt går att lägga fjärrvärmeledningar grundare i villagator om packningen av kringfyllningen utförs på ett bra sätt och man i övrigt följer de regelverk som finns. Det tycks också finnas goda förutsättningar för energibolagen att få acceptans för detta i sina kommuner.
|
|
| 34. |
|
|
| 35. |
- Forsaeus Nilsson, Stefan, 1972, et al.
(författare)
-
Läckagevägar för markvatten i skarvisolering
- 2005
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Att ett tätt och sprickfritt rörskum innebär en betydelsefull barriär mot utifrån inträngande vatten har påvisats i tidigare undersökningar. Men det har också uppmärksammats att skarvskummets cellstruktur i gränsskiktet mot rörskummet ofta är betydligt grövre än i skarvskummet i övrigt. Det föreliggande projektet har avsett att klarlägga om en grövre cellstruktur i gränsskiktet mot rörskummet kan utgöra en oönskad transportväg för inträngande markvatten vid ett läckage genom skarvtätningen. Resultaten visar att utförandet av skarvskumningen avgör vilken täthet gränsskiktet får. Skumning mot ett renskalat rörskum visar sig ge klart högre säkerhet mot vattenläckage än det normala förfarandet att skumma mot befintlig yta. Undersökningarna utfördes efter ett schema där olika kombinationer av rörskum, skarvskum och förbehandlingar studerades. Gränsskiktets vattengenomsläpplighet uppmättes på sju olika skarvar med inalles fjorton olika kombinationer av gränsskikt. Dessutom karaktäriserades skarvskummen genom uppmätning av densitet, cellstorlek och andelen slutna celler. Skarvutförandet varierades på flera olika sätt. Både rör med väderexponerade ändytor rör med helt eller delvis renskalade ändytor och rör med ändgavlar användes. Vidare har enkelrör i både DN 50, DN 65 och DN 300-dimension och dubbelrör DN 2×40 använts. Fyra av skarvarna skummades vid rumstemperatur, en i låg temperatur och två med hög temperatur på medieröret. Resultaten visar att samtliga gränsskikt mot renkapade ändytor var täta, vatten passerade dessa prov endast genom ångdiffusion. När det gäller gränsskikten mot lagrade ändytor visade sig endast ett av proven vara tätt, övriga läckte i olika grad. De prover som innehöll ändgavlar visade sig vara täta på skarvskumsidan men otäta på rörskumsidan. Några tydliga skillnader mellan rör av olika dimension och mellan enkel- och dubbelrör har inte framkommit. Inte heller har några påtagliga skillnader kunnat påvisas mellan skarvar skummade vid hög temperatur och skarvar skummade vid rumstemperatur. Däremot tycks gränsskikt som skummas i låg temperatur bli tätare. Vid jämförelser av läckagehastigheter tyder resultaten på att grövre cellstrukturer i gränsskikten ger snabbare läckage. Samtidigt kan konstateras att grövre cellstruktur också bildas mot renskalade ändytor utan att föranleda något läckage. Detta tyder på att stora celler i sig inte är orsaken, men påskyndar läckage i de fall det uppstår. En överslagsmässig analys baserad på perkolationsteori antyder att PUR-skum som uppfyller kraven i SS-EN 253 avseende andelen slutna celler teoretiskt inte skall kunna vara vattengenomsläppligt. Den viktigaste slutsatsen av de genomförda studierna är att de bästa skarvskumningsresultaten uppnås om ändytorna renskalas före skumning. På så vis blir vidhäftningen i gränsskiktet maximal och risken för läckage genom detsamma minimal. Därför rekommenderas att vikten av att ändytorna renskalas för skumning lyfts fram i Svensk Fjärrvärmes Läggningsanvisningar och i tillverkarnas montageanvisningar. Det är även viktigt att skarvmontörer i sin utbildning blir tydligt informerade om vikten av att ändytorna är renskalade för att bästa resultat skall uppnås.
|
|
| 36. |
|
|
| 37. |
|
|
| 38. |
- Forsaeus Nilsson, Stefan, 1972, et al.
(författare)
-
Spröda brott i mantelrör
- 2005
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Vid ett flertal tillfällen har Rapid Crack Propagation (RCP) inträffat i mantelröret hos stora fjärrvärmerör. RCP är ett mycket snabbt sprickförlopp där sprickan drivs fram av ringdragspänningar i mantelröret. Det är ett problem framför allt vid arbete på rören i låga temperaturer. Dels blir mantelrörsmaterialet sprödare då det kyls ned, och dels gör en temperatursänkning att ringdragspänningar byggs in i mantelröret då det förhindras att dra ihop sig av stålrör och PUR-skum. RCP-sprickor i fjärrvärmemantelrör har dokumenterats vid temperaturer kring –18 °C men sannolikt har fenomenet inträffat i enstaka fall redan vid några grader under noll. Tre olika polyetenmaterial utvärderades med avseende på risken för spröda brott i mantelrör. Dels ett unimodalt material av PE80-kvalitet som har använts i stor utsträckning tidigare, dels ett modernare unimodalt PE80-material som används emellanåt idag och slutligen ett bimodalt PE80-material av en kvalitet som för närvarande används av de flesta tillverkare. Generellt sett är modernare material avsevärt tåligare med avseende på spröda brott då det är en viktig utvecklingsparameter hos råmaterialtillverkarna. Provningar genomfördes på polyetenrör av både stor (upp till 630 mm diameter) och liten (160 mm) dimension. Ett hanteringsprov genomfördes där rören kyldes ned och bearbetades med elverktyg på samma sätt som sker i fält. Här uppstod ett RCP-brott vid –25 °C under skärarbete med vinkelslip på ett rör med diameter 500 mm av det modernare unimodala PE80 materialet. Samma material sprack även vid slagprovning enligt SS-EN 253 vid –20 °C på såväl liten som stor dimension. Den bimodala polyetenvarianten klarade båda provningarna utan brott. En serie slagprov genomfördes på rör med diameter 160 mm med en egenutvecklad provningsmetodik med avsikten att ringa in kritiska temperaturer och temperaturspänningsnivåer vid vilka man bör iaktta särskild försiktighet. Resultaten visar att det bimodala polyetenmaterial som provats är så tåligt med avseende på spröda brott att det knappast är förknippat med någon större risk att hantera dem i normalt vinterklimat. Det äldre materialet, som sprack vid hanteringsprov och slagprov enligt SS-EN 253, är dock betydligt känsligare och en spänningsanalys visar att det, för stora dimensioner, finns en påtaglig risk för sprödbrott redan vid temperaturer några grader under noll. Slagsegheten hos de olika materialen har också utvärderats med sk Charpyslagprovning, som provningsmässigt är betydligt enklare att genomföra än slagprov i fullskala på hela rör. Även här var syftet att bestämma en kritisk omslagstemperatur mellan segt och sprött beteende. Tydliga skillnader kunde ses mellan de olika polyetenkvaliteterna. Sannolikt finns en korrelation mellan resultaten från Charpyprov och rörslagprov. Emellertid saknas statistiskt underlag för att dra några kvantitativa slutsatser, men med mer underlag skulle metoden troligtvis kunna användas för klassificering och kravgränser.
|
|
| 39. |
|
|
| 40. |
|
|
| 41. |
- Hedenström, Erik, et al.
(författare)
-
Sex pheromone of the pine sawfly, Gilpinia pallida: Chemical identification, synthesis, and biological activity
- 2006
-
Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 32:11, s. 2525-2541
-
Tidskriftsartikel (refereegranskat)abstract
- We present the identification of the sex pheromone in the pine sawfly, Gilpinia pallida, including analysis of the female pheromone content, male antennal response and attraction in the field, and synthesis of the most active pheromone component. Several 3,7-dimethyl-2-alkanols were identified from female whole-body extracts, including some compounds with a 2R configuration. This is the first observation of such compounds in a pine sawfly species. Antennae of male G. pallida responded strongly in electroantennograph (EAG) recordings to the (2S,3R,7R)-isomers of the propionates of 3,7-dimethyl-2-tridecanol, 3,7-dimethyl-2-tetradecanol, and 3,7-dimethyl-2-pentadecanol, as well as to the acetates of the tri- and pentadecanols (the acetate of the tetradecanol was not tested). The propionate of (2S,3R,7R)-3,7-dimethyl-2-tetradecanol caught more males in the field than the corresponding isomer of tri- or pentadecanol. We suggest that the (2S,3R,7R)-isomer of 3,7-dimethyl-2-tetradecanol is likely the main sex pheromone precursor in G. pallida, with a subsidiary role for the (2S,3R,7R)-isomer of the tridecanol. Preparation of highly pure (2R,3R,7R)- and (2S,3R,7R)-stereoisomers of 3,7-dimethyl-2-tetradecanol, including the biological active esters, was performed via chemoenzymatic methods and is described in detail.
|
|
| 42. |
|
|
| 43. |
- Jensen, Irene B., et al.
(författare)
-
A randomized controlled component analysis of a behavioral medicine rehabilitation program for chronic spinal pain: are the effects dependent on gender?
- 2001
-
Ingår i: Pain. - : LWW. - 0304-3959 .- 1872-6623. ; 91:1, s. 65-78
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to evaluate the outcome of a behavioral medicine (BM) rehabilitation program and the outcome of its two main components, compared to a ‘treatment-as-usual’ control group (CG). The study employed a 4×4 repeated-measures design with four groups and four assessment periods (pre-treatment, post-treatment, 6-month follow-up, and 18-month follow-up). The group studied consisted of subjects on sick leave identified in a nationwide health insurance scheme in Sweden. After inclusion, the subjects were randomized to one of four conditions, which were: (1) behavior-oriented physical therapy (PT); (2) cognitive behavioral therapy (CBT); (3) BM rehabilitation consisting of PT+CBT (BM); (4) a ‘treatment-as-usual’ CG. The treatments were given over a period of 4 weeks, PT and CBT on a part-time basis and BM on a full-time basis. Outcome variables were sick leave, early retirement, and health-related quality of life (measured using the Short Form Health Survey, SF-36). The results showed that the risk of being granted full-time early retirement was significantly lower for females in PT and CBT compared to the CG during the 18-month follow-up period. However, the total absence from work (sick listing plus early retirement) in days over the 18-month follow-up period was not significantly different in the CG compared to the treatments. On the SF-36, women in CBT and BM reported a significantly better health-related quality of life than women in the CG at the 18-month follow-up. No significant differences for men were found on the SF-36 scales. In conclusion, the results revealed gender differences in the outcome of the treatments and that the components of this BM program yielded as good results as the whole program.
|
|
| 44. |
- Jensen, Irene B., et al.
(författare)
-
Assessing the Needs of Patients in Pain: A Matter of Opinion?
- 2000
-
Ingår i: Spine. - : LWW. - 0362-2436 .- 1528-1159. ; 25:21, s. 2816-2823
-
Tidskriftsartikel (refereegranskat)abstract
- Study Design. A prospective cohort study including patients with nonspecific spinal pain was performed.Objectives. To investigate whether the use of expert judgment in routine practice can provide a basis for reliable decision making concerning the need for intervention in patients with spinal pain and their ability to benefit from treatment.Summary of Background Data. A wide range of instruments and techniques are used to assess and treat patients with spinal pain. Many instruments are used without being clinimetrically tested.Methods. A questionnaire concerning the patients’ need of treatment and their potential to assimilate it was sent to experts in the health care arena: physicians, physical therapists, social insurance officers. The experts included were those connected with patients participating in a larger outcome study. Two cohorts of patients (sample 1, n = 217; sample 2, n = 257) were followed for 6 and 12 months, during which time the patients’ health and work status were mapped.Results. No acceptable agreement was found between any of the experts’ ratings of patients’ needs and potential for rehabilitation. Logistic regression showed that the experts’ judgments were based almost solely on the age of the patient. The prediction analyses showed that the most consistent predictor of the patients’ status at the 6-month follow-up assessment was the patients’ own belief in the existence of effective treatments and their perceived ability for learning to cope with the condition.Conclusions. Expert judgment as exercised in routine practice cannot be used as basis for reliable decision making concerning the need of the patient with spinal pain for intervention and the patient’s ability to benefit from treatment.
|
|
| 45. |
|
|
| 46. |
- Knudsen, Jette, 1961-, et al.
(författare)
-
Trends in floral scent chemistry in pollination syndromes : floral scent composition in hummingbird-pollinated taxa
- 2004
-
Ingår i: Botanical journal of the Linnean Society. - London : Academic Press. - 0024-4074 .- 1095-8339. ; 146:2, s. 191-199
-
Tidskriftsartikel (refereegranskat)abstract
- We studied an assemblage of 17 species of bird-pollinated Ecuadorian plants (from 14 angiosperm families), including taxa pollinated by short-billed (trochiline) and sickle-billed (hermit) hummingbirds. Hummingbirds are widely supposed to ignore fragrance while visiting flowers. We collected floral headspace odours in order to test the general prediction that specialist hummingbird-pollinated flowers are scentless. In nine out of 17 of these species we failed to detect any odours using gas chromatography-mass spectrometry (GC-MS), whereas the remaining eight species produced trace levels of volatile compounds. Most of these odour compounds were of terpenoid or lipoxygenase derivation and are commonly emitted by vegetative as well as floral plant tissues. Further studies will be required to determine whether these weak odours attract alternative pollinators, repel enemies or represent vestiges of a scented ancestry.
|
|
| 47. |
- Lundh, Karin, et al.
(författare)
-
Ageing and wear in polymeric child articles
- 2008
-
Rapport (refereegranskat)abstract
- Ageing and wear in polymeric child articles This report targets child use and care articles, toys and playground equipment. These products will in this report collectively be referred to as ‘child articles’. It is the authors’ experience that polymers are getting more and more frequent in child articles, probably since they are cheaper and in many ways easier to process than metals. This is not an unwanted development in itself, but the choice of material has to be carefully made since the material properties of polymers vary greatly depending on the type and amount of additives and this can not be assessed visually. In addition they degrade with time due to environmental influence. To verify the properties of a polymer the material has to be tested. One of the challenges with polymers is that they all have a limited lifetime. They degrade over time and might lose almost all their strength, leading to material failure and, in the worst case scenario, accidents. It is a fact that accidents happen due to material failure, although it is hard to trace the true cause in accident statistics. In this report the term ‘ageing’ will be used for chemical degradation of the material structure due to light and/or heat exposure and ‘wear’ refers to mechanical degradation as a result of mechanical stress and contact. The current regulation covers property changes in polymers during the lifetime of a product insufficiently, if at all. Ageing of materials is virtually non-existing in existing child article standards. During its life a product is subjected to all kinds of environmental factors which more or less lead to reduction of function of the product. All products get worn, in one way or another, when used and the surrounding environment affects the material of the product. These effects are greater or lesser depending on usage and the harshness of the surrounding environment, as well as material choice and other qualities of the product. Therefore the material and processing have to be chosen based on the knowledge of the environment in which the product will be used as well as the expected lifetime. This process is called environmental design or environmental engineering. In order to simplify the material selection process when a product is developed, it is recommended to compose a material qualification system for child articles. This system can preferably be based on existing systems from other industries. This study recommends that the requirements and test methods proposed in Chapter 5 are considered when new standards for child articles are being developed or when existing standards are being revised. It is also recommended to perform a risk analysis to identify the hazards of a product.
|
|
| 48. |
- Mandenius, Carl-Fredrik, 1954-, et al.
(författare)
-
Monitoring of influenza virus hemagglutinin in process samples using weak affinity ligands and surface plasmon resonance
- 2008
-
Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 623, s. 66-75
-
Tidskriftsartikel (refereegranskat)abstract
- Surface plasmon resonance (SPR) was used to screen the interaction between a variety of affinity ligands and hemagglutinin (HA) from human influenza virus, with the aim of identifying low affinity ligands useful for the development of a rapid bioanalytical sensor. Three sialic acid-based structures and four lectins were evaluated as sensor ligands. The sialic acid-based ligands included a natural sialic acid-containing glycoprotein, human α1-acid glycoprotein (α1-AGP), and two synthetic 6′-sialyllactose-conjugates, with varying degree of substitution. The interaction of HA with the four lectin-based ligands, concanavalin A (Con A), wheat germ agglutinin (WGA), Maackia amurensis lectin (MAL), and Sambucus nigra agglutinin (SNA), showed a wide variation of affinity strengths. Affinity and kinetics data were estimated. Strong affinities were observed for Con A, WGA, α1-AGP, and a 6′-sialyllactose-conjugate with a high substitution degree, and low affinities were observed for MAL and a 6′-sialyllactose-conjugate with low substitution. The main objective, to identify a low affinity ligand which could be used for on-line monitoring and product quantification, was met by a 6′-sialyllactose–ovalbumin conjugate that had 0.6 mol ligand per mol carrier protein. The apparent affinity of this ligand was estimated to be 1.5 ± 0.03 μM (KD) on the SPR surface. Vaccine process samples containing HA were analyzed in the range 10–100 μg HA mL−1 and correlated with single-radial immunodiffusion. The coefficient of variation on the same chip was between 0.010 and 0.091.
|
|
| 49. |
|
|
| 50. |
- Peterson, Ulla, et al.
(författare)
-
Burnout and physical and mental health among Swedish healthcare workers
- 2008
-
Ingår i: Journal of Advanced Nursing. - : Wiley. - 0309-2402 .- 1365-2648. ; 62:1, s. 84-95
-
Tidskriftsartikel (refereegranskat)abstract
- Aim. This paper is a report of a study to investigate how burnout relates to self-reported physical and mental health, sleep disturbance, memory and lifestyle factors. Background. Previous research on the possible relationship between lifestyle factors and burnout has yielded somewhat inconsistent results. Most of the previous research on possible health implications of burnout has focused on its negative impact on mental health. Exhaustion appears to be the most obvious manifestation of burnout, which also correlates positively with workload and with other stress-related outcomes. Method. A cross-sectional study was conducted, using questionnaires sent to all employees in a Swedish County Council (N = 6118) in 2002. The overall response rate was 65% (n = 3719). A linear discriminant analysis was used to look for different patterns of health indicators and lifestyle factors in four burnout groups (non-burnout, disengaged, exhausted and burnout). Results. Self-reported depression, anxiety, sleep disturbance, memory impairment and neck- and back pain most clearly discriminated burnout and exhausted groups from disengaged and non-burnout groups. Self-reported physical exercise and alcohol consumption played a minor role in discriminating between burnout and non-burnout groups, while physical exercise discriminated the exhausted from the disengaged group. Conclusion. Employees with burnout had most symptoms, compared with those who experienced only exhaustion, disengagement from work or no burnout, and the result underlines the importance of actions taken to prevent and combat burnout.
|
|
