| 1. |
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| 2. |
- Tjernström, Michael, et al.
(författare)
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The Arctic Summer Cloud Ocean Study (ASCOS) : overview and experimental design
- 2014
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 14:6, s. 2823-2869
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Tidskriftsartikel (refereegranskat)abstract
- The climate in the Arctic is changing faster than anywhere else on earth. Poorly understood feedback processes relating to Arctic clouds and aerosol-cloud interactions contribute to a poor understanding of the present changes in the Arctic climate system, and also to a large spread in projections of future climate in the Arctic. The problem is exacerbated by the paucity of research-quality observations in the central Arctic. Improved formulations in climate models require such observations, which can only come from measurements in situ in this difficult-to-reach region with logistically demanding environmental conditions. The Arctic Summer Cloud Ocean Study (ASCOS) was the most extensive central Arctic Ocean expedition with an atmospheric focus during the International Polar Year (IPY) 2007-2008. ASCOS focused on the study of the formation and life cycle of low-level Arctic clouds. ASCOS departed from Longyearbyen on Svalbard on 2 August and returned on 9 September 2008. In transit into and out of the pack ice, four short research stations were undertaken in the Fram Strait: two in open water and two in the marginal ice zone. After traversing the pack ice northward, an ice camp was set up on 12 August at 87 degrees 21' N, 01 degrees 29' W and remained in operation through 1 September, drifting with the ice. During this time, extensive measurements were taken of atmospheric gas and particle chemistry and physics, mesoscale and boundary-layer meteorology, marine biology and chemistry, and upper ocean physics. ASCOS provides a unique interdisciplinary data set for development and testing of new hypotheses on cloud processes, their interactions with the sea ice and ocean and associated physical, chemical, and biological processes and interactions. For example, the first-ever quantitative observation of bubbles in Arctic leads, combined with the unique discovery of marine organic material, polymer gels with an origin in the ocean, inside cloud droplets suggests the possibility of primary marine organically derived cloud condensation nuclei in Arctic stratocumulus clouds. Direct observations of surface fluxes of aerosols could, however, not explain observed variability in aerosol concentrations, and the balance between local and remote aerosols sources remains open. Lack of cloud condensation nuclei (CCN) was at times a controlling factor in low-level cloud formation, and hence for the impact of clouds on the surface energy budget. ASCOS provided detailed measurements of the surface energy balance from late summer melt into the initial autumn freeze-up, and documented the effects of clouds and storms on the surface energy balance during this transition. In addition to such process-level studies, the unique, independent ASCOS data set can and is being used for validation of satellite retrievals, operational models, and reanalysis data sets.
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| 3. |
- Padmanabhan, Sandosh, et al.
(författare)
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Genome-Wide Association Study of Blood Pressure Extremes Identifies Variant near UMOD Associated with Hypertension
- 2010
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Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 6:10
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Tidskriftsartikel (refereegranskat)abstract
- Hypertension is a heritable and major contributor to the global burden of disease. The sum of rare and common genetic variants robustly identified so far explain only 1%-2% of the population variation in BP and hypertension. This suggests the existence of more undiscovered common variants. We conducted a genome-wide association study in 1,621 hypertensive cases and 1,699 controls and follow-up validation analyses in 19,845 cases and 16,541 controls using an extreme case-control design. We identified a locus on chromosome 16 in the 59 region of Uromodulin (UMOD; rs13333226, combined P value of 3.6x10(-11)). The minor G allele is associated with a lower risk of hypertension (OR [95% CI]: 0.87 [0.84-0.91]), reduced urinary uromodulin excretion, better renal function; and each copy of the G allele is associated with a 7.7% reduction in risk of CVD events after adjusting for age, sex, BMI, and smoking status (H.R. = 0.923, 95% CI 0.860-0.991; p = 0.027). In a subset of 13,446 individuals with estimated glomerular filtration rate (eGFR) measurements, we show that rs13333226 is independently associated with hypertension (unadjusted for eGFR: 0.89 [0.83-0.96], p = 0.004; after eGFR adjustment: 0.89 [0.83-0.96], p = 0.003). In clinical functional studies, we also consistently show the minor G allele is associated with lower urinary uromodulin excretion. The exclusive expression of uromodulin in the thick portion of the ascending limb of Henle suggests a putative role of this variant in hypertension through an effect on sodium homeostasis. The newly discovered UMOD locus for hypertension has the potential to give new insights into the role of uromodulin in BP regulation and to identify novel drugable targets for reducing cardiovascular risk.
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| 4. |
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| 5. |
- Windahl, Sara H, 1971, et al.
(författare)
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Estrogen receptor-alpha in osteocytes is important for trabecular bone formation in male mice
- 2013
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424. ; 110:6, s. 2294-2299
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Tidskriftsartikel (refereegranskat)abstract
- The bone-sparing effect of estrogen in both males and females is primarily mediated via estrogen receptor-alpha (ER alpha), encoded by the Esr1 gene. ER alpha in osteoclasts is crucial for the trabecular bone-sparing effect of estrogen in females, but it is dispensable for trabecular bone in male mice and for cortical bone in both genders. We hypothesized that ER alpha in osteocytes is important for trabecular bone in male mice and for cortical bone in both males and females. Dmp1-Cre mice were crossed with ER alpha(flox/flox) mice to generate mice lacking ER alpha protein expression specifically in osteocytes (Dmp1-ER alpha(-/-)). Male Dmp1-ER alpha(-/-) mice displayed a substantial reduction in trabecular bone volume (-20%, P < 0.01) compared with controls. Dynamic histomorphometry revealed reduced bone formation rate (-45%, P < 0.01) but the number of osteoclasts per bone surface was unaffected in the male Dmp1-ER alpha(-/-) mice. The male Dmp1-ER alpha(-/-) mice had reduced expression of several osteoblast/osteocyte markers in bone, including Runx2, Sp7, and Dmp1 (P < 0.05). Gonadal intact Dmp1-ER alpha(-/-) female mice had no significant reduction in trabecular bone volume but ovariectomized Dmp1-ER alpha(-/-) female mice displayed an attenuated trabecular bone response to supraphysiological E2 treatment. Dmp1-ER alpha(-/-) mice of both genders had unaffected cortical bone. In conclusion, ER alpha in osteocytes regulates trabecular bone formation and thereby trabecular bone volume in male mice but it is dispensable for the trabecular bone in female mice and the cortical bone in both genders. We propose that the physiological trabecular bone-sparing effect of estrogen is mediated via ER alpha in osteocytes in males, but via ER alpha in osteoclasts in females.
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| 6. |
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| 7. |
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| 8. |
- Börjesson, Anna E, et al.
(författare)
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Roles of transactivating functions 1 and 2 of estrogen receptor-alpha in bone.
- 2011
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 108:15, s. 6288-6293
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Tidskriftsartikel (refereegranskat)abstract
- The bone-sparing effect of estrogen is primarily mediated via estrogen receptor-α (ERα), which stimulates target gene transcription through two activation functions (AFs), AF-1 in the N-terminal and AF-2 in the ligand binding domain. To evaluate the role of ERα AF-1 and ERα AF-2 for the effects of estrogen in bone in vivo, we analyzed mouse models lacking the entire ERα protein (ERα(-/-)), ERα AF-1 (ERαAF-1(0)), or ERα AF-2 (ERαAF-2(0)). Estradiol (E2) treatment increased the amount of both trabecular and cortical bone in ovariectomized (OVX) WT mice. Neither the trabecular nor the cortical bone responded to E2 treatment in OVX ERα(-/-) or OVX ERαAF-2(0) mice. OVX ERαAF-1(0) mice displayed a normal E2 response in cortical bone but no E2 response in trabecular bone. Although E2 treatment increased the uterine and liver weights and reduced the thymus weight in OVX WT mice, no effect was seen on these parameters in OVX ERα(-/-) or OVX ERαAF-2(0) mice. The effect of E2 in OVX ERαAF-1(0) mice was tissue-dependent, with no or weak E2 response on thymus and uterine weights but a normal response on liver weight. In conclusion, ERα AF-2 is required for the estrogenic effects on all parameters evaluated, whereas the role of ERα AF-1 is tissue-specific, with a crucial role in trabecular bone and uterus but not cortical bone. Selective ER modulators stimulating ERα with minimal activation of ERα AF-1 could retain beneficial actions in cortical bone, constituting 80% of the skeleton, while minimizing effects on reproductive organs.
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| 9. |
- Börjesson, Anna E, et al.
(författare)
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The role of activation functions 1 and 2 of estrogen receptor-alpha for the effects of estradiol and selective estrogen receptor modulators in male mice
- 2013
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Ingår i: Journal of Bone and Mineral Research. - : Wiley. - 0884-0431 .- 1523-4681. ; 28:5, s. 1117-1126
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Tidskriftsartikel (refereegranskat)abstract
- Estradiol (E2) is important for male skeletal health and the effect of E2 is mediated via estrogen receptor (ER)-. This was demonstrated by the findings that men with an inactivating mutation in aromatase or a nonfunctional ER had osteopenia and continued longitudinal growth after sexual maturation. The aim of the present study was to evaluate the role of different domains of ER for the effects of E2 and selective estrogen receptor modulators (SERMs) on bone mass in males. Three mouse models lacking either ERAF-1 (ERAF-10), ERAF-2 (ERAF-20), or the total ER (ER/) were orchidectomized (orx) and treated with E2 or placebo. E2 treatment increased the trabecular and cortical bone mass and bone strength, whereas it reduced the thymus weight and bone marrow cellularity in orx wild type (WT) mice. These parameters did not respond to E2 treatment in orx ER/ or ERAF-20 mirx ERAF-10 mice were tissue-dependent, with a clear response in cortical bone parameters and bone marrow cellularity, but no response in trabecular bone. To determine the role of ERAF-1 for the effects of SERMs, we treated orx WT and ERAF-10 mice with raloxifene (Ral), lasofoxifene (Las), bazedoxifene (Bza), or vehicle. These SERMs increased total body areal bone mineral density (BMD) and trabecular volumetric BMD to a similar extent in orx WT mice. Furthermore, only Las increased cortical thickness significantly and only Bza increased bone strength significantly. However, all SERMs showed a tendency toward increased cortical bone parameters. Importantly, all SERM effects were absent in the orx ERAF-10 mice. In conclusion, ERAF-2 is required for the estrogenic effects on all evaluated parameters, whereas the role of ERAF-1 is tissue-specific. All evaluated effects of Ral, Las and Bza are dependent on a functional ERAF-1. Our findings might contribute to the development of bone-specific SERMs in males. (c) 2013 American Society for Bone and Mineral Research.
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| 10. |
- Börjesson, Anna E, et al.
(författare)
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The role of estrogen receptor-alpha in growth plate cartilage for longitudinal bone growth.
- 2010
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Ingår i: Journal of bone and mineral research. - : Wiley. - 1523-4681 .- 0884-0431. ; 25:12, s. 2414-24
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Tidskriftsartikel (refereegranskat)abstract
- Estrogens enhance skeletal growth during early sexual maturation while high estradiol levels during late puberty result in growth plate fusion in humans. Although the growth plates do not fuse directly after sexual maturation in rodents, a reduction in growth plate height is seen by treatment with a high dose of estradiol. It is unknown whether the effects of estrogens on skeletal growth are mediated directly via estrogen receptors (ERs) in growth plate cartilage and/or indirectly via other mechanisms such as the GH/IGF-I axis. To determine the role of ERalpha in growth plate cartilage for skeletal growth, we developed a mouse model with cartilage-specific inactivation of ERalpha. Although mice with total ERalpha inactivation displayed affected longitudinal bone growth associated with alterations in the GH/IGF-I axis, the skeletal growth was normal during sexual maturation in mice with cartilage-specific ERalpha inactivation. High dose estradiol treatment of adult mice reduced the growth plate height as a consequence of attenuated proliferation of growth plate chondrocytes in control mice but not in cartilage-specific ERalpha(-/-) mice. Adult cartilage-specific ERalpha(-/-) mice continued to grow after four months of age while growth was limited in control mice, resulting in increased femur length in one-year-old cartilage-specific ERalpha(-/-) mice compared with control mice. We conclude that during early sexual maturation ERalpha in growth plate cartilage is not important for skeletal growth. In contrast, it is essential for high dose estradiol to reduce the growth plate height in adult mice and for reduction of longitudinal bone growth in elderly mice. (c) 2010 American Society for Bone and Mineral Research.
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| 11. |
- Chambers, John C., et al.
(författare)
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Genetic loci influencing kidney function and chronic kidney disease
- 2010
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 42:5, s. 373-375
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Tidskriftsartikel (refereegranskat)abstract
- Using genome-wide association, we identify common variants at 2p12-p13, 6q26, 17q23 and 19q13 associated with serum creatinine, a marker of kidney function (P = 10(-10) to 10(-15)). Of these, rs10206899 (near NAT8, 2p12-p13) and rs4805834 (near SLC7A9, 19q13) were also associated with chronic kidney disease (P = 5.0 x 10(-5) and P = 3.6 x 10(-4), respectively). Our findings provide insight into metabolic, solute and drug-transport pathways underlying susceptibility to chronic kidney disease.
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| 12. |
- Ellinor, Patrick T., et al.
(författare)
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Meta-analysis identifies six new susceptibility loci for atrial fibrillation
- 2012
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 44:6, s. 88-670
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Tidskriftsartikel (refereegranskat)abstract
- Atrial fibrillation is a highly prevalent arrhythmia and a major risk factor for stroke, heart failure and death(1). We conducted a genome-wide association study (GWAS) in individuals of European ancestry, including 6,707 with and 52,426 without atrial fibrillation. Six new atrial fibrillation susceptibility loci were identified and replicated in an additional sample of individuals of European ancestry, including 5,381 subjects with and 10,030 subjects without atrial fibrillation (P < 5 x 10(-8)). Four of the loci identified in Europeans were further replicated in silico in a GWAS of Japanese individuals, including 843 individuals with and 3,350 individuals without atrial fibrillation. The identified loci implicate candidate genes that encode transcription factors related to cardiopulmonary development, cardiac-expressed ion channels and cell signaling molecules.
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| 13. |
- Fava, Cristiano, et al.
(författare)
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Vanin-1 T26I polymorphism, hypertension and cardiovascular events in two large urban-based prospective studies in Swedes.
- 2011
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Ingår i: Nutrition Metabolism and Cardiovascular Diseases. - : Elsevier BV. - 1590-3729 .- 0939-4753.
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND AIMS: Vanin-1 (gene name VNN1) is an enzyme with pantetheinase activity generating the amino-thiol cysteamine which is implicated in the regulation of red-ox status through its effect on glutathione. We tested the hypothesis that the rs2294757 VNN1 T26I polymorphism could affect blood pressure (BP) levels, hypertension prevalence, and risk of incident cardiovascular events. METHODS AND RESULTS: The VNN1 T26I polymorphism was genotyped in 5664 participants of the cardiovascular cohort of the "Malmö Diet and Cancer" (MDC-CVA) study and successively in 17874 participants of the "Malmö Preventive project"(MPP). The incidence of cardiovascular events was monitored for an average of nearly 12 years of follow-up in the MDC-CVA and for 25 years in the MPP. Both before and after adjustment for sex, age and BMI in the MDC-CVA the polymorphism had a mild lowering effect on diastolic BP and hypertension, especially in females. However in MPP no effect on BP phenotypes was detectable. Before and after adjustment for major cardiovascular risk factors, the hazard ratio for incident ischemic stroke and coronary events in the MDC-CVA was not significantly different in carriers of different genotypes. CONCLUSIONS: Our data do not support a major role for the VNN1 T26I variant in determining BP level and incident ischemic events.
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| 14. |
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| 15. |
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| 16. |
- Gao, H., et al.
(författare)
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Serum selenium in relation to measures of glucose metabolism and incidence of Type 2 diabetes in an older Swedish population
- 2014
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Ingår i: Diabetic Medicine. - : Wiley. - 0742-3071 .- 1464-5491. ; 31:7, s. 787-793
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Tidskriftsartikel (refereegranskat)abstract
- Aims The relation between selenium status and risk of Type2 diabetes is controversial. We aimed to evaluate associations of serum selenium, a marker of dietary selenium, with measures of glucose metabolism and risk of diabetes. Methods We used data from a population-based, longitudinal cohort of 1925 Swedish men who were 50years old and did not have diabetes at baseline in the 1970s. At baseline, an intravenous glucose tolerance test was performed and, at a follow-up examination after 20years, an oral glucose tolerance test and a hyperinsulinaemic euglycaemic clamp for the assessment of insulin sensitivity were conducted. Results At baseline, the mean (standard deviation) selenium concentration was 75.6 (14.3) g/l. During 20years of follow-up, 88 incident cases of diabetes occurred in 1024 participants with follow-up data. Baseline serum selenium levels were not associated with risk of diabetes (odds ratio1.06; 95%CI 0.83-1.38). Higher selenium levels were associated with lower early insulin response (standardized -0.08; 95%CI -0.14 to -0.03) at baseline after adjusting for potential confounders, but not with any other measures of -cell function or insulin sensitivity at baseline or follow-up. The association with early insulin response was non-significant after taking multiple testing into account. Conclusions Our results do not support a role of dietary selenium in the development of disturbances in glucose metabolism or diabetes in older individuals.
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| 17. |
- Holmgren, Gustav, et al.
(författare)
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Long-Term Chronic Toxicity Testing Using Human Pluripotent Stem Cell-Derived Hepatocytes
- 2014
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Ingår i: Drug Metabolism and Disposition. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0090-9556 .- 1521-009X. ; 42:9, s. 1401-1406
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Tidskriftsartikel (refereegranskat)abstract
- Human pluripotent stem cells (hPSC) have the potential to become important tools for the establishment of new models for in vitro drug testing of, for example, toxicity and pharmacological effects. Late-stage attrition in the pharmaceutical industry is to a large extent caused by selection of drug candidates using nonpredictive preclinical models that are not clinically relevant. The current hepatic in vivo and in vitro models show clear limitations, especially for studies of chronic hepatotoxicity. For these reasons, we evaluated the potential of using hPSC-derived hepatocytes for long-term exposure to toxic drugs. The differentiated hepatocytes were incubated with hepatotoxic compounds for up to 14 days, using a repeated-dose approach. The hPSC-derived hepatocytes became more sensitive to the toxic compounds after extended exposures and, in addition to conventional cytotoxicity, evidence of phospholipidosis and steatosis was also observed in the cells. This is, to the best of our knowledge, the first report of a long-term toxicity study using hPSC-derived hepatocytes, and the observations support further development and validation of hPSC-based toxicity models for evaluating novel drugs, chemicals, and cosmetics.
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| 18. |
- Huang, X, et al.
(författare)
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Serum fatty acid patterns, insulin sensitivity and the metabolic syndrome in individuals with chronic kidney disease
- 2014
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 275:1, s. 71-83
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The causes of the multiple metabolic disorders of individuals with chronic kidney disease (CKD) are not fully known. We investigated the relationships between dietary fat quality, the metabolic syndrome (MetS), insulin sensitivity and inflammation in individuals with CKD.SUBJECTS: Two population-based surveys were conducted in elderly Swedish individuals (aged 70 years) with serum cystatin C-estimated glomerular filtration rate <60 mL min(-1) /1.73 m(2) : the Uppsala Longitudinal Study of Adult Men (ULSAM) and the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) surveys. The present population comprised 274 men and 187 subjects (63% women) from the ULSAM and PIVUS cohorts, respectively.DESIGN: Factor analyses of serum fatty acids were used to evaluate dietary fat quality. Insulin sensitivity was measured by homeostasis model assessment of insulin resistance (IR) and, in ULSAM, also by euglycaemic clamp.RESULTS: Factor analyses generated two fatty acid patterns of (i) low linoleic acid (LA)/high saturated fatty acid (SFA) or (ii) high n-3 polyunsaturated fatty acid (n-3 PUFA) levels. In both surveys, the low LA/high SFA pattern increased the odds of having MetS [adjusted odds ratio 0.60 [95% confidence interval (CI) 0.44-0.81] and 0.45 (95% CI 0.30-0.67) per SD decrease in factor score in the ULSAM and PIVUS surveys, respectively] and was directly associated with both IR and C-reactive protein. The n-3 PUFA pattern was not consistently associated with these risk factors.CONCLUSIONS: A serum fatty acid pattern reflecting low LA and high SFA was strongly associated with MetS, IR and inflammation in two independent surveys of elderly individuals with CKD. At present, there are no specific dietary guidelines for individuals with CKD; however, these findings indirectly support current recommendations to replace SFAs with PUFAs from vegetable oils.
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| 19. |
- Martin, M., et al.
(författare)
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Cloud condensation nuclei closure study on summer arctic aerosol
- 2011
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:22, s. 11335-11350
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Tidskriftsartikel (refereegranskat)abstract
- We present an aerosol - cloud condensation nuclei (CCN) closure study on summer high Arctic aerosol based on measurements that were carried out in 2008 during the Arctic Summer Cloud Ocean Study (ASCOS) on board the Swedish ice breaker Oden. The data presented here were collected during a three-week time period in the pack ice (> 85 degrees N) when the icebreaker Oden was moored to an ice floe and drifted passively during the most biological active period into autumn freeze up conditions. CCN number concentrations were obtained using two CCN counters measuring at different supersaturations. The directly measured CCN number concentration was then compared with a CCN number concentration calculated using both bulk aerosol mass composition data from an aerosol mass spectrometer (AMS) and aerosol number size distributions obtained from a differential mobility particle sizer, assuming kappa-Kohler theory, surface tension of water and an internally mixed aerosol. The last assumption was supported by measurements made with a hygroscopic tandem differential mobility analyzer (HTDMA) for particles > 70 nm. For the two highest measured supersaturations, 0.73 and 0.41 %, closure could not be achieved with the investigated settings concerning hygroscopicity and density. The calculated CCN number concentration was always higher than the measured one for those two supersaturations. This might be caused by a relative larger insoluble organic mass fraction of the smaller particles that activate at these supersaturations, which are thus less good CCN than the larger particles. On average, 36% of the mass measured with the AMS was organic mass. At 0.20, 0.15 and 0.10% supersaturation, closure could be achieved with different combinations of hygroscopic parameters and densities within the uncertainty range of the fit. The best agreement of the calculated CCN number concentration with the observed one was achieved when the organic fraction of the aerosol was treated as nearly water insoluble (kappa(org) = 0.02), leading to a mean total kappa, kappa(tot), of 0.33 +/- 0.13. However, several settings led to closure and kappa(org) = 0.2 is found to be an upper limit at 0.1% supersaturation. kappa(org) <= 0.2 leads to a kappa(tot) range of 0.33 +/- 013 to 0.50 +/- 0.11. Thus, the organic material ranges from being sparingly soluble to effectively insoluble. These results suggest that an increase in organic mass fraction in particles of a certain size would lead to a suppression of the Arctic CCN activity.
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| 20. |
- Mauritsen, T., et al.
(författare)
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Aerosols indirectly warm the Arctic
- 2010
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- On average, airborne aerosol particles cool the Earth's surface directly by absorbing and scattering sunlight and indirectly by influencing cloud reflectivity, life time, thickness or extent. Here we show that over the central Arctic Ocean, where there is frequently a lack of aerosol particles upon which clouds may form, a small increase in aerosol loading may enhance cloudiness thereby likely causing a climatologically significant warming at the ice-covered Arctic surface. Under these low concentration conditions cloud droplets grow to drizzle sizes and fall, even in the absence of collisions and coalescence, thereby diminishing cloud water. Evidence from a case study suggests that interactions between aerosol, clouds and precipitation could be responsible for attaining the observed low aerosol concentrations.
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| 21. |
- Mauritsen, T., et al.
(författare)
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An Arctic CCN-limited cloud-aerosol regime
- 2011
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:1, s. 165-173
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Tidskriftsartikel (refereegranskat)abstract
- On average, airborne aerosol particles cool the Earth's surface directly by absorbing and scattering sunlight and indirectly by influencing cloud reflectivity, life time, thickness or extent. Here we show that over the central Arctic Ocean, where there is frequently a lack of aerosol particles upon which clouds may form, a small increase in aerosol loading may enhance cloudiness thereby likely causing a climatologically significant warming at the ice-covered Arctic surface. Under these low concentration conditions cloud droplets grow to drizzle sizes and fall, even in the absence of collisions and coalescence, thereby diminishing cloud water. Evidence from a case study suggests that interactions between aerosol, clouds and precipitation could be responsible for attaining the observed low aerosol concentrations.
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| 22. |
- Saini, G., et al.
(författare)
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'happy on norflurazon' (hon) mutations implicate perturbance of plastid homeostasis with activating stress acclimatization and changing nuclear gene expression in norflurazon-treated seedlings
- 2011
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Ingår i: Plant Journal. - 0960-7412. ; 65:5, s. 690-702
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Tidskriftsartikel (refereegranskat)abstract
- P>Various mutant screens have been undertaken to identify constituents involved in the transmission of signals from the plastid to the nucleus. Many of these screens have been performed using carotenoid-deficient plants grown in the presence of norflurazon (NF), an inhibitor of phytoene desaturase. NF-treated plants are bleached and suppress the expression of nuclear genes encoding chloroplast proteins. Several genomes uncoupled (gun) mutants have been isolated that de-repress the expression of these nuclear genes. In the present study, a genetic screen has been established that circumvents severe photo-oxidative stress in NF-treated plants. Under these modified screening conditions, happy on norflurazon (hon) mutants have been identified that, like gun mutants, de-repress expression of the Lhcb gene, encoding a light-harvesting chlorophyll protein, but, in contrast to wild-type and gun mutants, are green in the presence of NF. hon mutations disturb plastid protein homeostasis, thereby activating plastid signaling and inducing stress acclimatization. Rather than defining constituents of a retrograde signaling pathway specifically associated with the NF-induced suppression of nuclear gene expression, as proposed for gun, hon mutations affect Lhcb expression more indirectly prior to initiation of plastid signaling in NF-treated seedlings. They pre-condition seedlings by inducing stress acclimatization, thereby attenuating the impact of a subsequent NF treatment.
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| 23. |
- Shupe, M. D., et al.
(författare)
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Cloud and boundary layer interactions over the Arctic sea ice in late summer
- 2013
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 13:18, s. 9379-9399
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Tidskriftsartikel (refereegranskat)abstract
- Observations from the Arctic Summer Cloud Ocean Study (ASCOS), in the central Arctic sea-ice pack in late summer 2008, provide a detailed view of cloud-atmosphere-surface interactions and vertical mixing processes over the sea-ice environment. Measurements from a suite of ground-based remote sensors, near-surface meteorological and aerosol instruments, and profiles from radiosondes and a helicopter are combined to characterize a week-long period dominated by low-level, mixed-phase, stratocumulus clouds. Detailed case studies and statistical analyses are used to develop a conceptual model for the cloud and atmosphere structure and their interactions in this environment. Clouds were persistent during the period of study, having qualities that suggest they were sustained through a combination of advective influences and in-cloud processes, with little contribution from the surface. Radiative cooling near cloud top produced buoyancy-driven, turbulent eddies that contributed to cloud formation and created a cloud-driven mixed layer. The depth of this mixed layer was related to the amount of turbulence and condensed cloud water. Coupling of this cloud-driven mixed layer to the surface boundary layer was primarily determined by proximity. For 75% of the period of study, the primary stratocumulus cloud-driven mixed layer was decoupled from the surface and typically at a warmer potential temperature. Since the near-surface temperature was constrained by the ocean-ice mixture, warm temperatures aloft suggest that these air masses had not significantly interacted with the sea-ice surface. Instead, back-trajectory analyses suggest that these warm air masses advected into the central Arctic Basin from lower latitudes. Moisture and aerosol particles likely accompanied these air masses, providing necessary support for cloud formation. On the occasions when cloud-surface coupling did occur, back trajectories indicated that these air masses advected at low levels, while mixing processes kept the mixed layer in equilibrium with the near-surface environment. Rather than contributing buoyancy forcing for the mixed-layer dynamics, the surface instead simply appeared to respond to the mixed-layer processes aloft. Clouds in these cases often contained slightly higher condensed water amounts, potentially due to additional moisture sources from below.
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| 24. |
- Sjögren, Anna-Karin, 1980, et al.
(författare)
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Monozygotic twins discordant for intermittent allergic rhinitis differ in mRNA and protein levels
- 2012
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Ingår i: Allergy. European Journal of Allergy and Clinical Immunology. - : John Wiley and Sons. - 0105-4538 .- 1398-9995. ; 67:6, s. 831-833
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Tidskriftsartikel (refereegranskat)abstract
- Monozygotic (MZ) twins discordant for complex diseases may help to find disease mechanisms that are not due to genetic variants. Intermittent allergic rhinitis (IAR) is an optimal disease model because it occurs at defined time points each year, owing to known external antigens. We hypothesized that MZ twins discordant for IAR could help to find gene expression differences that are not dependent on genetic variants. We collected blood outside of the season from MZ twins discordant for IAR, challenged their peripheral blood mononuclear cells (PBMC) with pollen allergen in vitro, collected supernatants and isolated CD4+ T cells. We identified disease-relevant mRNAs and proteins that differed between the discordant MZ twins. By contrast, no differences in microRNA expression were found. Our results indicate that MZ twins discordant for IAR is an optimal model to identify disease mechanisms that are not due to genetic variants.
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| 25. |
- Sjögren, Erik, et al.
(författare)
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Optimized Experimental Design for the Estimation of Enzyme Kinetic Parameters : An Experimental Evaluation
- 2012
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Ingår i: Drug Metabolism And Disposition. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0090-9556 .- 1521-009X. ; 40:12, s. 2273-2279
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Tidskriftsartikel (refereegranskat)abstract
- A set of compounds (n = 30), including traditional cytochrome P450 substrates and compounds from AstraZeneca's compound library, was used in an experimental evaluation of an optimal design approach (ODA) for the estimation of enzyme kinetic parameters (CLint, V-max, and K-m). A depletion method previously shown to provide reliable results, the multiple depletion curves method (MDCM), was used as reference. Experiments were conducted with human liver microsomes, and samples were analyzed using liquid chromatography-tandem mass spectrometry. CLint estimated with the ODA were in >90% of the cases within a 2-fold difference compared with MDCM estimates. In addition, good agreement was generally seen for V-max and K-m estimates between the two methods as >80% of the estimates were within or almost within a 2-fold difference. The variability in V-max and K-m estimates were generally higher than for CLint estimates. In addition, decreased substrate turnover considerably increased the variability in V-max and Km estimates, whereas only a modest increase was observed for CLint estimates. The experimental design of using multiple starting concentrations for the estimation of enzyme kinetics was shown to be appropriate even when there was a limitation to the number of samples. The method allowed for good estimates of CLint and also for V-max and K-m in many cases. Hence, this approach is a good alternative for the estimation of enzyme kinetic parameters, especially if enzyme saturation and an assessment of a potential risk for nonlinear metabolism are of interest.
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| 26. |
- Sjögren, Lena, et al.
(författare)
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Ancient Eleutherna. Sector 1, vol 1
- 2011
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Ingår i: Classical Review. - 0009-840X .- 1464-3561. ; 61:1, s. 316-316
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Recension (refereegranskat)
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| 27. |
- Sjögren, Lena, et al.
(författare)
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Corrosion resistance of stainless steel pipes in soil
- 2011
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Ingår i: Materials and corrosion - Werkstoffe und Korrosion. - : Wiley. - 0947-5117 .- 1521-4176. ; 62:4, s. 299-309
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Tidskriftsartikel (refereegranskat)abstract
- To be able to give safe recommendations concerning the choice of suitable stainless steel grades for pipelines to be buried in various soil environments, a large research programme, including field exposures of test specimens buried in soil in Sweden and in France, has been performed. Resistance against external corrosion of austenitic, super austenitic, lean duplex, duplex and super duplex steel grades in soil has been investigated by laboratory tests and field exposures. The grades included have been screened according to their critical pitting-corrosion temperature and according to their time-to-re-passivation after the passive layer has been destroyed locally by scratching. The field exposures programme, being the core of the investigation, uses large specimens: 2 m pipes and plates, of different grades. The exposure has been performed to reveal effects of aeration cells, deposits or confined areas, welds and burial depth. Additionally, investigations of the tendency of stainless steel to corrode under the influence of alternating current (AC) have been performed, both in the laboratory and in the field. Recommendations for use of stainless steels under different soil conditions are given based on experimental results and on operating experiences of existing stainless steel pipelines in soil. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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| 28. |
- Sjögren, Peter, et al.
(författare)
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MANUFACTURING ASPECTS OF OFFSHORE FABRICATION AND INSTALLATION
- 2014
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Ingår i: International Journal of Maritime Engineering. - 1479-8751 .- 1740-0716. ; 156, s. 277-284
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Tidskriftsartikel (refereegranskat)abstract
- The research presented in this paper aim at identifying research commonalities between shipbuilding, offshore fabrication practices and manufacturing. As part of an exploratory effort a literature review and a case study of two offshore structures projects were performed. Research concerning shipbuilding and offshore fabrication, together with literature from other industries in construction, larger engineering projects and traditional manufacturing was reviewed. The two offshore structures projects were analyzed by means of interviews and complemented by direct observations and document reviews. The study concludes that there are gaps in the research concerned with holistic perspectives on the fabrication and installation phases of shipbuilding and offshore projects. The number of actors involved in any project of this magnitude increase barriers and communication interfaces. The dynamic nature of these types of projects was also observed and the changeability should always be a accounted factor when dealing with projects of this sort. The interviews held as part of the verification of observed phenomena in literature was limited to two projects and a single company and actors perceptions. However the collected data served well in being complementary to the literature review. It could be the task of academia to patch the gaps for overall project success, in the cases where single industry actors simply cannot see the benefit or do not have the recourses to fill them themselves. This study combines findings from traditional manufacturing industries, shipbuilding, offshore structures fabrication and large engineering projects in general.
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| 29. |
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| 30. |
- Sjögren, Peter, et al.
(författare)
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SEMI-SUBMERSIBLE GRAVITY BASED HYBRID STRUCTURE – AN ALTERNATIVE TO JACKET AND TOPSIDE PLATFORMS
- 2014
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Ingår i: Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE, vol. 8B, 2014. - 9780791845516
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Konferensbidrag (refereegranskat)abstract
- The aim of this research is to present the result from a case study comparing a semi-submersible gravity based hybrid structure and a jacket topside structure for two offshore wind farm converter station projects. The cases are analyzed from a transportation and installation perspective. Converter stations enable the conversion from alternating to direct current, more efficiently bringing generated wind energy to shore. Out of the project process phases e.g. planning, engineering, fabrication, transport, installation and commissioning; transportation and installation are two of the most demanding during offshore platform projects. The weight and size of an offshore platform require specialized equipment, vessels and marine contractors’ expertise to be transported and installed. The risks associated with transportation and installation (T&I) operations are related to health, safety and environment, and T&I operations are also sensitive to any disturbance e.g. accidents and delays. Many interdependencies between disciplines in the project execution process may result in consequential and immediate impact, should an activity not follow the plan and thus the risk of cost overruns increases. In an attempt to circumvent risks related to heavy lifts offshore and consequently mitigate the corresponding risks, a new platform concept has been developed a Norwegian EPC –company and a Swiss converter station manufacturer, a semi-submersible gravity based hybrid, SSGBH. The subjects presented in this paper include the general principles of the SSGBH concept and in what way risk associated with T&I operations are reduced. This paper present the platform concepts, data gathered from interviews, archival data and direct observations. Their pros and cons are presented in an objective way, while concluding that platform concepts of this kind are and should be highly customized, as should the concept selection.
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| 31. |
- Sjögren, Per, et al.
(författare)
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Simple advice on lifestyle habits and long-term changes in biomarkers of inflammation and vascular adhesion in healthy middle-aged men
- 2010
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Ingår i: European Journal of Clinical Nutrition. - : Springer Science and Business Media LLC. - 0954-3007 .- 1476-5640. ; 64:12, s. 1450-1456
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Tidskriftsartikel (refereegranskat)abstract
- Background/Objectives: Lifestyle habits, vascular function and inflammation are components in the development of cardiovascular disease (CVD). We investigated whether simple advice on dietary and exercise habits given (at a single time point) to hypercholesterolemic men affects circulating biomarkers of inflammation and vascular adhesion. Subjects/Methods: In total, 157 men (age 46 +/- 5 years) with mild hypercholesterolemia were randomized to four intervention groups, diet (D, n = 40), exercise (E, n 39), diet and exercise (DE, n 39) or controls (C, n 39) and serum concentrations of C-reactive protein (CRP), interleukin-6 (IL-6), soluble intercellular adhesion molecule 1 (sICAM-1), soluble vascular cell adhesion molecule 1 (sVCAM-1) and soluble E-selectin (sE-selectin) were quantified at baseline and after a 6-month intervention period. Results: The intervention applied in this study, that is, simple advice on lifestyle changes given at a single time point, had a modest effect on inflammatory biomarkers and soluble vascular adhesion molecules. The most apparent alterations were found for individuals in group DE, who responded with significant reductions in sICAM-1, -28 (-41 to -14 mg/l) and sE-selectin, -3.6 (-6.9 to -0.3 mu g/l) after 6 months. None of the groups had altered their concentrations of sVCAM-1, CRP or IL-6 significantly after the intervention. In all individuals combined, we found changes in apolipoprotein B (apoB) to predict alterations in sICAM-1 (beta = 0.21) and sE-selectin (beta = 0.26), independently of changes in inflammation and other adhesion molecules. Conclusions: These observations indicate that even small efforts to improve diet and physical activity can influence biomarkers of vascular function in individuals at increased risk for CVD. ApoB was identified as an important determinant of this improvement, which adds further support to the notion of apoB as a critical target in cardiovascular prevention.
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| 32. |
- Sjögren, Peter, et al.
(författare)
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THE IMPORTANCE OF INFORMATION TRANSFER BETWEEN PROJECT PHASES
- 2013
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Ingår i: 3rd International Conference on Ship & Offshore Technology - India 2013 ICSOT-13.
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Konferensbidrag (refereegranskat)abstract
- This research investigates the subject of current shipbuilding practices and two offshore structures projects, focusing on information transfer between project process phases. Large construction projects, as offshore structures, are often subjected to substantial economic and environmental risks. A holistic approach to the project execution could help mitigate some of the problems that yards, engineering firms and marine contractors face today. Research has been conducted into the area of EPC offshore structures projects and the need for predictability, shortened lead times and increased flexibility. The literature study performed as background to this research, shows that there are few studies covering information management between offshore structures project phases. A case study was performed to further explore and enrich the empirical findings. Concluding that information is insufficient between project phases, looking ahead, the question is raised: In what way can information be improved between project phases?
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