| 1. |
- Agardh, Emilie E, et al.
(författare)
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Work stress and low sense of coherence is associated with type 2 diabetes in middle-aged Swedish women.
- 2003
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Ingår i: Diabetes Care. - : American Diabetes Association. - 0149-5992 .- 1935-5548. ; 26:3, s. 719-24
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The risk of type 2 diabetes is suggested to be increased for individuals exposed to stress. We analyzed the association of work stress by high demands, low decision latitude, and job strain (combination of high demands and low decision latitude) with type 2 diabetes. We also studied low sense of coherence (SOC) (a factor for successful coping with stressors) in association with type 2 diabetes. Finally, we investigated the combination of SOC and demands or SOC and decision latitude in association with the disease. RESEARCH DESIGN AND METHODS: This cross-sectional study recruited 4821 healthy Swedish women (aged 35-56 years) residing in five municipalities in the Stockholm area. An oral glucose tolerance test identified 52 women with type 2 diabetes. Relative risks (RRs) with 95% CIs were estimated in a logistic multiple regression analysis. RESULTS: No association was found between high demands and type 2 diabetes (RR 1.1 [CI 0.5-2.2]). Low decision latitude was associated with type 2 diabetes with a RR of 2.2 (1.0-4.8). The RR of type 2 diabetes with low SOC was 3.7 (1.2-11.2). The combination of low SOC and low decision latitude was associated with type 2 diabetes with a RR of 2.6 (1.2-5.7). Homeostasis model assessment revealed an association of 4.2 (1.2-15.0) between low SOC and insulin resistance. CONCLUSIONS: This study provided new evidence that stress factors such as low decision latitude at work and low SOC were associated with type 2 diabetes in middle-aged Swedish women.
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| 2. |
- Hergens, Maria-Pia, et al.
(författare)
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Use of Scandinavian Moist Smokeless Tobacco (Snus) and the Risk of Atrial Fibrillation
- 2014
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Ingår i: Epidemiology. - 1044-3983 .- 1531-5487. ; 25:6, s. 872-876
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Snus is a smokeless tobacco product, widely used among Swedish men and increasingly so elsewhere. There is debate as to whether snus is an acceptable "harm-reduction" tobacco product. Since snus use delivers a dose of nicotine equivalent to cigarettes, and has been implicated in cardiac arrhythmia because of associations with sudden cardiovascular death, a relation with atrial fibrillation is plausible and important to investigate.METHODS:: To assess the relation between use of snus and risk of atrial fibrillation, we carried out a pooled analysis of 7 prospective Swedish cohort studies. In total, 274,882 men, recruited between 1978 and 2004, were followed via the National Patient Register for atrial fibrillation. Primary analyses were restricted to 127,907 never-smokers. Relative risks were estimated using Cox proportional hazard regression.RESULTS:: The prevalence of snus use was 25% among never-smokers. During follow-up, 3,069 cases of atrial fibrillation were identified. The pooled relative risk of atrial fibrillation was 1.07 (95% confidence interval = 0.97-1.19) in current snus users, compared with nonusers.CONCLUSION:: Findings from this large national pooling project indicate that snus use is unlikely to confer any important increase in risk of atrial fibrillation.
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| 3. |
- Agardh, Emilie E, et al.
(författare)
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Explanations of socioeconomic differences in excess risk of type 2 diabetes in Swedish men and women.
- 2004
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Ingår i: Diabetes Care. - : American Diabetes Association. - 0149-5992 .- 1935-5548. ; 27:3, s. 716-21
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: We investigated to what extent socioeconomic differences in type 2 diabetes risk could be explained by established risk factors (obesity, physical inactivity, smoking, and heredity) and psychosocial factors (low decision latitude at work and low sense of coherence). RESEARCH DESIGN AND METHODS: This cross-sectional study comprised 3,128 healthy Swedish men and 4,821 women, aged 35-56 years, living in the Stockholm area. An oral glucose tolerance test identified 55 men and 52 women with type 2 diabetes. The relative contribution of established and psychosocial factors to socioeconomic differences in diabetes risk was assessed by comparing analyses with adjustment for different sets of these factors. RESULTS: The relative risks (RRs) for type 2 diabetes in middle and low socioeconomic groups in men were 2.4 (95% CI 1.0-5.3) and 2.9 (1.5-5.7), respectively, and in women 3.2 (1.5-6.6) and 2.7 (1.3-5.9), respectively. In men, the RRs decreased to 1.9 (0.8-4.4) and 2.1 (1.0-4.2) after adjustment for established risk factors; no further change was found when psychosocial factors were included. In women, the RRs changed to 2.4 (1.1-5.2) and 1.6 (0.7-3.8) by including established risk factors and to 2.3 (1.0-5.1) and 1.9 (0.8-4.3) by inclusion of psychosocial factors. After adjustment for both established and psychosocial factors, the RRs were 1.4 (0.6-3.6) and 1.0 (0.4-2.5), respectively. CONCLUSIONS: In men, the excess risk of type 2 diabetes was partly explained by established risk factors (36-42%), whereas psychosocial factors had no effect. In women, most of the socioeconomic differences in type 2 diabetes were explained by simultaneous adjustment for established risk factors and psychosocial factors (81-100%).
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| 4. |
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| 5. |
- Ahlbom, Anders, 1993
(författare)
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Hydrothermal Depolymerisation of Kraft Lignin: The Influence of Capping Agents and Residence Time
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lignin, the aromatic macromolecule found in wood and other lignocellulosic biomass, is envisioned as a future renewable source of aromatic compounds that can be used as, for example, chemicals, fuel additives and resins. A way in which this can be realised is by depolymerising the lignin once it has been isolated from the lignocellulosic biomass. Hydrothermal methods that employ water as a reaction medium are suggested as ways of accomplishing this. However, reactive fragments prone to repolymerisation, indeed char formation, are formed during depolymerisation, causing operational difficulties in the process as well as yield losses of the desired components. The suggestion has been made to add chemicals, i.e. capping agents, to scavenge the reactive components in order to mitigate these issues. Careful selection of reaction parameters, such as residence time and temperature, is also crucial for the process. In this work, the depolymerisation of softwood kraft lignin has been investigated under hydrothermal conditions, with additions isopropanol, glycerol and guaiacol, to investigate their potential of functioning as capping agents. A customised batch reactor (99 ml) enabling swift heating of the reaction mixture was employed at 290-335 °C and 250 bar with low residence times (1-12 min). The result of the hydrothermal depolymerisation of lignin was an aqueous suspension with a strong smoky odour. No apparent separate liquid organic phase was formed, although a char fraction precipitated. Characterisation of the products indicated a rapid depolymerisation of the lignin, since inter-unit ether linkages were cleaved, which was later followed by a slower repolymerisation. Additions of isopropanol, glycerol and guaiacol, reduced the weight average molecular weights (Mw) of the product fractions. Only isopropanol appeared to be able to reduce the amount of char formed from the lignin. Subsequent aftertreatment of the product would be required to obtain a usable product.
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| 6. |
- Ahlbom, Anders, 1993
(författare)
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Hydrothermal Liquefaction of Kraft Lignin - The influence of capping agents and residence time
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the context of exploring alternatives to replace fossil resources, lignin has been acknowledged as a renewable source of various aromatic compounds that have the potential of being precursors to chemicals as well as fuel additives. Originating from lignocellulosic biomass such as wood, lignin is an amorphous polymer with a high content of aromatic units and, in order to harness these units, it must be depolymerised. A major problem with current depolymerisation techniques, however, is that lignin repolymerises after being depolymerised, and forms an undesirable char fraction. The addition of capping agents and fine-tuning the reaction conditions can be used to mitigate such formation of char. This work has investigated the depolymerisation of kraft lignin in hydrothermal conditions under varying temperatures (290-335 °C), residence times (1-12 min) and charges of isopropanol (IPA/dry lignin, 0-4.9) which, aside from being a co-solvent, was hypothesised as acting as a capping agent. The influence of these reaction parameters on the molecular weights, yields and elemental compositions of the products was studied, along with changes in the molecular structure compared to the starting lignin. The product is a suspension of solid material, i.e. char, in an aqueous phase and thus any desired organic liquid phase requires extraction from the aqueous product. While the yield of char increased with temperature and residence time, it decreased with increasing isopropanol loading, suggesting that the isopropanol does in fact act as a capping agent. Most of the lignin forms a water-soluble fraction that precipitates when the aqueous product phase is acidified, thereby forming the precipitated solids fraction (PS). The components remaining dissolved after acidification of the product phase are known as acid soluble organics (ASO). A portion of the ASO fraction was aromatic monomers, with guaiacol dominating: this result was expected since the lignin was sourced from softwood. The amount of such monomers increased with residence time in the reactor. Molecular weight analyses showed a rapid depolymerisation of the lignin within 1 min of hydrothermal liquefaction (HTL) treatment via a significant decrease in the molecular weight of all product fractions: char, PS and ASO. Moreover, the carbon-oxygen inter-unit linkages were found to break in this timeframe as well. The repolymerisation reactions started to exceed depolymerisation between residence times of 4 and 12 min, causing the weight average molecular weight (Mw) to increase again. Although minimising the residence time allows the char yield and Mw to be kept low, more monomers were formed at longer residence times. This calls for careful tuning of the residence time in the HTL of kraft lignin.
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| 7. |
- Ahlbom, Anders, et al.
(författare)
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Occupational magnetic field exposure and myocardial infarction incidence.
- 2004
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Ingår i: Epidemiology. - : Ovid Technologies (Wolters Kluwer Health). - 1044-3983 .- 1531-5487. ; 15:4, s. 403-8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Studies on healthy volunteers have seen reduced heart rate variability after exposure to extremely low-frequency electric and magnetic fields (EMF). Because reduced heart rate variability has been linked to cardiovascular disease risk, it has been hypothesized that exposure to EMF might increase the risk of cardiovascular disease. One epidemiologic study has shown increased mortality from cardiovascular conditions in utility workers with elevated exposure to magnetic fields, but several other epidemiologic studies have failed to confirm this result. We tested the hypothesis that occupational EMF exposure increases the risk of myocardial infarction in a large population-based case-control study of myocardial infarction, with detailed information on potential confounders. METHODS: We used data from the SHEEP study, which is a population-based case-control study of acute myocardial infarction in Stockholm. Occupational EMF exposure was based on job titles 1, 5, and 10 years before diagnosis. We used 2 approaches to classify exposure: first, specific individual job titles with presumed elevated EMF exposure, and second, classification of subjects according to a job-exposure matrix. RESULTS: We found no increased risk of myocardial infarction in subjects classified as having elevated EMF exposure. For the highest exposure category of > or = 0.3 microT according to the job-exposure matrix, the adjusted relative risk was = 0.57 (95% confidence interval = 0.36-0.89). CONCLUSIONS: The results of this study do not support the hypothesis that occupational EMF exposure increases the risk of myocardial infarction.
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| 8. |
- Ahlbom, Anders, 1993, et al.
(författare)
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On the hydrothermal depolymerisation of kraft lignin using glycerol as a capping agent
- 2023
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 1437-434X .- 0018-3830. ; 77:3, s. 159-169
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Tidskriftsartikel (refereegranskat)abstract
- Depolymerisation of kraft lignin under hydrothermal conditions was investigated at short residence times (1–12 min) with glycerol being used as a capping agent. The weight average molecular weight (M w) of the products decreased within the first minute of residence time, with the inter-unit ether linkages breaking accordingly. Furthermore, the M w of the product fractions decreased at increasing residence times, while the char yield increased. Short residence times thus appear to be beneficial for mitigating the formation of char. Also, addition of NaOH reduced the yield of char. Although the addition of glycerol caused a decrease in the M w of the products, it seemed to increase the yield of char and therefore might not be a suitable capping agent for kraft lignin depolymerisation.
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| 9. |
- Ahlbom, Anders, et al.
(författare)
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Radiofrequency electromagnetic fields and risk of disease and ill health - Research during the last ten years
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The focus of this report is electromagnetic fields of the type that occur in connection with mobile telephony, so called radio frequency (RF) fields and the possibility that exposure to such fields poses a risk of disease or ill health. The purpose is to describe what was known ten years ago, what we have learned during the past decade, and where we stand today. TEN YEARS AGOThe mechanism of interaction between RF fields and the human body was established long ago and is increased temperature of exposed tissue (compare microwave ovens). Methods for measurements of the fields in the air were developed early but the data on distribution of the absorbed energy in the human body was still restricted. Data regarding sources and levels of exposure to the population was limited because systematic measurements had not been conducted. A considerable number of provocation studies on exposure to fields of lower frequencies (related to electric power and computer screens) had already been conducted and had not found any evidence of an association to symptoms (headache, vertigo, dizziness, concentration difficulties, insomnia) but the corresponding information about RF fields and occurrence of symptoms was scarce. Few and methodologically limited epidemiological studies had been conducted on RF field exposure and cancer.WHAT WAS LEARNED DURING THE PAST TEN YEARSExtensive research on various aspects of RF fields has been conducted during the last ten years and the knowledge database has increased considerably. Simulation models have improved our knowledge about how the fields and the energy are distributed in the body. Mobile, so called, exposimeters have been developed for use in epidemiological studies. Many more measurements have been conducted to increase our knowledge about sources and level of exposure to the population. More than 15 provocation studies (single or double blind) have been conducted on symptoms attributed to exposure to RF fields. These studies have not been able to demonstrate that people experience symptoms or sensations more often when the fields are turned on than when they are turned off. One longitudinal study has looked at frequency of symptoms in relation to environmental exposure and this study found no association between exposure and symptoms. A considerable number of studies on cancer, and in particular brain tumor, were presented. As a consequence there exist now very useful data including methodological results that can be used in the interpretation of this research. With a small number of exceptions the available results are all negative and taken together with new methodological understandings the overall interpretation is that these do not provide support for an association between mobile telephony and brain tumor risk. In addition, national cancer statistics are very useful sources of information because mobile phone usage has increased so quickly. Had mobile phone use and brain cancer risk been associated it would have been visible as an increasing trend in national cancer statistics. But brain cancer rates are not increasing. WHERE WE STAND TODAYWe now know much more about measurements and absorption of RF fields and also about sources of exposure to the population and levels of exposure. A considerable number of provocation studies on RF exposure and symptoms have been unable to show any association. Overall, the data on brain tumor and mobile telephony do not support an effect of mobile phone use on tumor risk, in particular when taken together with national cancer trend statistics throughout the world. Research on mobile telephony and health started without a biologically or epidemiologically based hypothesis about possible health risks. Instead the inducement was an unspecific concern related to a new and rapidly spreading technology. Extensive research for more than a decade has not detected anything new regarding interaction mechanisms between radiofrequency fields and the human body and has found no evidence for health risks below current exposure guidelines. While absolute certainty can never be achieved, nothing has appeared to suggest that the since long established interaction mechanism of heating would not suffice as basis for health protection.
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