| 1. |
- Burisch, J., et al.
(författare)
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Environmental factors in a population-based inception cohort of inflammatory bowel disease patients in Europe : An ECCO-EpiCom study
- 2014
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Ingår i: Journal of Crohn's & Colitis. - : Oxford University Press. - 1873-9946 .- 1876-4479. ; 8:7, s. 607-616
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims: The incidence of inflammatory bowel disease (IBD) is increasing in Eastern Europe possibly due to changes in environmental factors towards a more "westernised" standard of Living. The aim of this study was to investigate differences in exposure to environmental factors prior to diagnosis in Eastern and Western European IBD patients.Methods: The EpiCom cohort is a population-based, prospective inception cohort of 1560 unselected IBD patients from 31 European countries covering a background population of 10.1 million. At the time of diagnosis patients were asked to complete an 87-item questionnaire concerning environmental factors.Results: A total of 1182 patients (76%) answered the questionnaire, 444 (38%) had Crohn's disease (CD), 627 (53%) ulcerative colitis (UC), and 111 (9%) IBD unclassified. No geographic differences regarding smoking status, caffeine intake, use of oral contraceptives, or number of first-degree relatives with IBD were found. Sugar intake was higher in CD and UC patients from Eastern Europe than in Western Europe while fibre intake was lower (p < 0.01). Daily consumption of fast food as well as appendectomy before the age of 20 was more frequent in Eastern European than in Western European UC patients (p < 0.01). Eastern European CD and UC patients had received more vaccinations and experienced fewer childhood infections than Western European patients (p < 0.01).Conclusions: In this European population-based inception cohort of unselected IBD patients, Eastern and Western European patients differed in environmental factors prior to diagnosis. Eastern European patients exhibited higher occurrences of suspected risk factors for IBD included in the Western lifestyle. (C) 2013 European Crohn's and Colitis Organisation. Published by Elsevier B.V. All rights reserved.
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| 2. |
- Liu, Jimmy Z, et al.
(författare)
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Dense genotyping of immune-related disease regions identifies nine new risk loci for primary sclerosing cholangitis.
- 2013
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Ingår i: Nature genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 45:6, s. 670-5
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Tidskriftsartikel (refereegranskat)abstract
- Primary sclerosing cholangitis (PSC) is a severe liver disease of unknown etiology leading to fibrotic destruction of the bile ducts and ultimately to the need for liver transplantation. We compared 3,789 PSC cases of European ancestry to 25,079 population controls across 130,422 SNPs genotyped using the Immunochip. We identified 12 genome-wide significant associations outside the human leukocyte antigen (HLA) complex, 9 of which were new, increasing the number of known PSC risk loci to 16. Despite comorbidity with inflammatory bowel disease (IBD) in 72% of the cases, 6 of the 12 loci showed significantly stronger association with PSC than with IBD, suggesting overlapping yet distinct genetic architectures for these two diseases. We incorporated association statistics from 7 diseases clinically occurring with PSC in the analysis and found suggestive evidence for 33 additional pleiotropic PSC risk loci. Together with network analyses, these findings add to the genetic risk map of PSC and expand on the relationship between PSC and other immune-mediated diseases.
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| 3. |
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| 4. |
- Arnason, T., et al.
(författare)
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Long-term rearing of Arctic charr Salvelinus alpinus under different salinity regimes at constant temperature
- 2014
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112. ; 85:4, s. 1145-1162
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Tidskriftsartikel (refereegranskat)abstract
- Arctic charr Salvelinus alpinus of the Holar strain (mean+/- s. e. body mass= 152.1+/-3.1g) were reared at four different salinity regimes at a constant temperature of 7.4 degrees C. Two groups were given a three-month acclimation in salinity 18 before the salinity was increased to either 25 or 29 (groups called A25 and A29), and two groups were reared in salinities 25 or 29 over the full experimental period of 409 days (groups called F25 and F29). In the first 3months, the A25 and A29 groups had the highest growth rates. By October 2011, there were no significant differences (two-way nested ANOVA, P> 0.05) in the mean body masses among A25, F25 and F29 (c. 1450 g), whereas A29 had a lower mean mass (1282 g). The growth in the last period from October 2011 to January 2012 was reduced by sexual maturation in the highest salinity regimes (A29 and F29), whereas fish in groups A25 and F25 showed high growth throughout the study. Males in all salinity groups had higher growth rates than females for the most part of the study, but the divergence between the sexes was most pronounced in the highest salinity regimes. All salinity groups showed distinct changes in Na+, K+-ATPase activity, with high activity in spring and summer, and lower activity in the autumn. Plasma sodium (Na+) levels were stable indicating that none of the experimental groups had problems in maintaining hydromineral balance during the study. While plasma leptin levels were not affected by salinity regimes, it was noted that these levels were 13-30% higher in fish with empty guts compared with those having food in their gut at the time of sampling. This suggests a link between leptin levels and food intake, indicating that this hormone may play a role in food intake and energy allocation in fishes.
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| 5. |
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| 6. |
- Björnsson, H., et al.
(författare)
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Velocities in the plume of the 2010 Eyjafjallajökull eruption
- 2013
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Ingår i: Journal of Geophysical Research. - : American Geophysical Union (AGU). - 0148-0227 .- 2156-2202 .- 2169-897X. ; 118:20, s. 11698-11711
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Tidskriftsartikel (refereegranskat)abstract
- The eruption of the Icelandic volcano Eyjafjallajökull in the spring of 2010 lasted for 39 days with an explosive phase (14-18 April), an effusive phase (18 April to 4 May) and a phase with renewed explosive activity (5-17 May). Images every 5 s from a camera mounted 34 km from the volcano are available for most of the eruption. Applying the maximum cross-correlation method (MCC) on these images, the velocity structure of the eruption cloud has been mapped in detail for four time intervals covering the three phases of the eruption. The results show that on average there are updrafts in one part of the cloud and lateral motion or downdrafts in another. Even within the updraft part, there are alternating motions of strong updrafts, weak updrafts, and downward motion. These results show a highly variable plume driven by intermittent explosions. The results are discussed in the context of integral plume models and in terms of elementary parcel theory. Key Points Velocities in a volcanic cloud based on analysis of image data from the eruption Velocities in the eruption cloud are inhomogeneous and updrafts intermittent Intermittent updrafts are important for the dynamics and the lofting of ash.
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| 7. |
- Björnsson, Marcus A., et al.
(författare)
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A two-compartment effect site model describes the bispectral index after different rates of propofol infusion
- 2010
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Ingår i: Journal of Pharmacokinetics and Pharmacodynamics. - : Springer Science and Business Media LLC. - 1567-567X .- 1573-8744. ; 37:3, s. 243-255
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Tidskriftsartikel (refereegranskat)abstract
- Different estimates of the rate constant for the effect site distribution (k(e0)) of propofol, depending on the rate and duration of administration, have been reported. This analysis aimed at finding a more general pharmacodynamic model that could be used when the rate of administration is changed during the treatment. In a cross-over study, 21 healthy volunteers were randomised to receive a 1 min infusion of 2 mg/kg of propofol at one occasion, and a 1 min infusion of 2 mg/kg of propofol immediately followed by a 29 min infusion of 12 mg kg(-1) h(-1) of propofol at another occasion. Arterial plasma concentrations of propofol were collected up to 4 h after dosing, and BIS was collected before start of infusion and until the subjects were fully awake. The population pharmacokinetic-pharmacodynamic analysis was performed using NONMEM VI. A four-compartment PK model with time-dependent elimination and distribution described the arterial propofol concentrations, and was used as input to the pharmacodynamic model. A standard effect compartment model could not accurately describe the delay in the effects of propofol for both regimens, whereas a two-compartment effect site model significantly improved the predictions. The two-compartment effect site model included a central and a peripheral effect site compartment, possibly representing a distribution within the brain, where the decrease in BIS was linked to the central effect site compartment concentrations through a sigmoidal E-max model.
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| 8. |
- Björnsson, Marcus A., et al.
(författare)
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Modelling of pain intensity and informative dropout in a dental pain model after naproxcinod, naproxen and placebo administration
- 2011
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Ingår i: British Journal of Clinical Pharmacology. - : Wiley. - 0306-5251 .- 1365-2125. ; 71:6, s. 899-906
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Tidskriftsartikel (refereegranskat)abstract
- AIMS To describe pain intensity (PI) measured on a visual analogue scale (VAS) and dropout due to request for rescue medication after administration of naproxcinod, naproxen or placebo in 242 patients after wisdom tooth removal. METHODS Non-linear mixed effects modelling was used to describe the plasma concentrations of naproxen, either formed from naproxcinod or from naproxen itself, and their relationship to PI and dropout. Goodness of fit was assessed by simultaneous simulations of PI and dropout. RESULTS Baseline PI for the typical patient was 52.7 mm. The PI was influenced by placebo effects, using an exponential model, and by naproxen concentrations using a sigmoid E-max model. Typical maximal placebo effect was a decrease in PI by 20.2%, with an onset rate constant of 0.237 h-1. EC50 was 0.135 mu mol l-1. A Weibull time-to-event model was used for the dropout, where the hazard was dependent on the predicted PI and by the PI at baseline. Since the dropout was not at random, it was necessary to include the simulated dropout in visual predictive checks (VPC) of PI. CONCLUSIONS This model describes the relationship between drug effects, PI and the likelihood of dropout after naproxcinod, naproxen and placebo administration. The model provides an opportunity to describe the effects of other doses or formulations, after dental extraction. VPC created by simultaneous simulations of PI and dropout provides a good way of assessing the goodness of fit when there is informative dropout.
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| 9. |
- Burisch, J., et al.
(författare)
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Health care and patients' education in a European inflammatory bowel disease inception cohort : an ECCO-EpiCom study
- 2014
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Ingår i: Journal of Crohn's & Colitis. - : Oxford University Press (OUP). - 1873-9946 .- 1876-4479. ; 8:8, s. 811-818
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims: The EpiCom study and inception cohort was initiated in 2010 in 31 centers from 14 Western and 8 Eastern European countries, covering a 10.1 million person background population. Our aim was to investigate whether there is a difference between Eastern and Western Europe in health care and education of patients with inflammatory bowel disease (IBD).Methods: A quality of care (QoC) questionnaire was developed in the EpiCom group consisting of 16 questions covering 5 items: time interval between the onset of symptoms and diagnosis, information, education, empathy and access to health care providers.Results: Of 1,515 patients, 947 (217 east/730 west) answered the QoC questionnaire. Only 23% of all patients had knowledge about IBD before diagnosis. In Eastern Europe, significantly more patients searched out information about IBD themselves (77% vs. 68%, p < 0.05), the main source was the Internet (92% vs. 88% p = 0.23). In Western Europe, significantly more patients were educated by nurses (19% vs. 1%, p < 0.05), while in Eastern Europe, gastroenterologists were easier to contact (80% vs. 68%, p < 0.05).Conclusion: Health care differed significantly between Eastern and Western Europe in all items, but satisfaction rates were high in both geographic regions. Because of the low awareness and the rising incidence of IBD, general information should be the focus of patient organizations and medical societies. In Western Europe IBD nurses play a very important role in reducing the burden of patient management. (c) 2014 European Crohn's and Colitis Organisation. Published by Elsevier B.V. All rights reserved.
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| 10. |
- Burisch, J., et al.
(författare)
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Health-related quality of life improves during one year of medical and surgical treatment in a European population-based inception cohort of patients with Inflammatory Bowel Disease : An ECCO-EpiCom study
- 2014
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Ingår i: Journal of Crohn's & Colitis. - Oxford, United Kingdom : Oxford University Press. - 1873-9946 .- 1876-4479. ; 8:9, s. 1030-1042
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Tidskriftsartikel (refereegranskat)abstract
- Background & Aims: Health-related quality of life (HRQoL) is impaired in patients with Inflammatory Bowel Disease (IBD). The aim was prospectively to assess and validate the pattern of HRQoL in an unselected, population-based inception cohort of IBD patients from Eastern and Western Europe.Methods: The EpiCom inception cohort consists of 1560 IBD patients from 31 European centres covering a background population of approximately 10.1 million. Patients answered the disease specific Short Inflammatory Bowel Disease Questionnaire (SIBDQ) and generic Short Form 12 (SF-12) questionnaire at diagnosis and after one year of follow-up.Results: In total, 1079 patients were included in this study. Crohn's disease (CD) patients mean SIBDQ scores improved from 45.3 to 55.3 in Eastern Europe and from 44.9 to 53.6 in Western Europe. SIBDQ scores for ulcerative colitis (UC) patients improved from 44.9 to 57.4 and from 48.8 to 55.7, respectively. UC patients needing surgery or biologicals had lower SIBDQ scores before and after compared to the rest, while biological therapy improved SIBDQ scores in CD. CD and UC patients in both regions improved all SF-12 scores. Only Eastern European UC patients achieved SF-12 summary scores equal to or above the normal population.Conclusion: Medical and surgical treatment improved HRQoL during the first year of disease. The majority of IBD patients in both Eastern and Western Europe reported a positive perception of disease-specific but not generic HRQoL. Biological therapy improved HRQoL in CD patients, while UC patients in need of surgery or biological therapy experienced lower perceptions of HRQoL than the rest.
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| 11. |
- Cheng, J. C. P., et al.
(författare)
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A service oriented framework for construction supply chain integration
- 2010
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Ingår i: Automation in Construction. - : Elsevier BV. - 0926-5805. ; 19:2, s. 245-260
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Tidskriftsartikel (refereegranskat)abstract
- The benefits of integrating and coordinating supply chain partners have been well recognized in many industries. In the construction industry, supply chain integration is technically challenging due to the high fragmentation of the industry. Information, applications, and services are loosely distributed among participants with a wide range of hardware and software capabilities. In addition, participants are often unwilling to share information because the temporary nature of construction projects often impedes the establishment of trust. A secure, modular, and flexible system that can aggregate scattered information and share that information across applications is, therefore, highly desirable. We have prototyped a service oriented, web-based system that can provide both these capabilities. Called the SC Collaborator, this system facilitates the flexible coordination of construction supply chains by leveraging web services, web portal, and open source technologies. These technologies enable the SC Collaborator system to provide an economical and customizable tool for integrating supply chain partners with a wide range of computing capabilities. This paper describes the overall architecture and the features of the system. Two example scenarios are included to demonstrate the potential of SC Collaborator in integrating and managing information from project partners. The first scenario is an e-Procurement example whereas the second is a rescheduling scenario based on the data from a completed project in Sweden. (C) 2009 Elsevier B.V. All rights reserved.
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| 12. |
- Cheng, J. C. P., et al.
(författare)
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Modeling and monitoring of construction supply chains
- 2010
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Ingår i: Advanced Engineering Informatics. - : Elsevier BV. - 1474-0346. ; 24:4, s. 435-455
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Tidskriftsartikel (refereegranskat)abstract
- The planning and management of supply chains require properly specifying the participating members and the relationships among them. Construction supply chains usually consist of numerous participants and are complex in structure Representing construction supply chains using a network model can help understand the complexity, support re-configuration, identify the bottlenecks, and prioritize company's resources, as well as add values to the management of construction projects. Using a case example on the mechanical, electrical and plumbing (MEP) processes in a construction project, this paper demonstrates the modeling of construction supply chains using the Supply Chain Operations Reference (SCOR) framework developed by the Supply Chain Council (SCC). The SCOR modeling framework provides a structured and systematic way to model and decompose a supply chain from conceptual representation to process element specificatjavascript:dropdown_help('field-abstract')ion. The SCOR framework is commonly used by corporations for strategic planning of their supply chains This paper further presents a model-based service oriented framework that leverages the SCOR models for performance monitoring of construction supply chains. In the supply chain management and monitoring framework each supply chain process element is implemented as a discrete web service component The framework is built on a service oriented collaborative system. namely SC Collaborator, that we have developed using web service technology, open standards, and open source technologies.
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| 13. |
- Desai, Neel, et al.
(författare)
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Anatomic single- versus double-bundle ACL reconstruction: a meta-analysis.
- 2014
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Ingår i: Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA. - : Springer Science and Business Media LLC. - 1433-7347. ; 22:5, s. 1009-1023
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Tidskriftsartikel (refereegranskat)abstract
- To determine whether anatomic double-bundle anterior cruciate ligament (ACL) reconstruction compared to anatomic single-bundle ACL reconstruction more effectively restored antero-posterior (A-P) laxity, rotatory laxity and reduced frequency of graft rupture. Our hypothesis was that anatomic double-bundle ACL reconstruction results in superior rotational knee laxity and fewer graft ruptures due to its double-bundle tension pattern, compared with anatomic single-bundle ACL reconstruction.
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| 14. |
- Froiland, E., et al.
(författare)
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Seasonal appetite regulation in the anadromous Arctic charr: Evidence for a role of adiposity in the regulation of appetite but not for leptin in signalling adiposity
- 2012
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Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480. ; 178:2, s. 330-337
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate whether the seasonal feeding cycle of the anadromous Arctic charr (Salvelinus alpinus) is regulated by a lipostatic mechanism and if leptin (Lep) might act as an endocrine signal of adiposity. Offspring of anadromous Arctic charr with a body mass of 121 g were divided into two treatment groups; one was given feed in excess from March to November. and the other was fasted between April and early June and fed in excess thereafter. In the continuously fed group there was an 8-fold increase in body mass, and a doubling of percentage body fat, from March to August, after which there was no further increase. Fish in the other group lost weight and body fat during fasting, but grew rapidly on being fed, and had partially compensated for their deficit in body mass by August. Differences in percentage body fat between treatment groups were eliminated by August. providing evidence for a lipostatic regulation of feeding and energy homeostasis in Arctic charr. Neither liver total LepA gene expression nor plasma Lep concentrations correlated positively with fish adiposity, so there was no evidence that Lep acts as a signal of adiposity in this species. On the other hand, there was a strong increase in liver LepA1 gene expression at the end of the fasting period, concomitant with fat mobilization and increased plasma glucose, indicating that LepA1 may play a role in regulating metabolic processes associated with fasting. (C) 2012 Elsevier Inc. All rights reserved.
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| 15. |
- Janols, Helena, et al.
(författare)
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Heterogeneity among septic shock patients in a set of immunoregulatory markers.
- 2014
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Ingår i: European Journal of Clinical Microbiology & Infectious Diseases. - : Springer Science and Business Media LLC. - 1435-4373 .- 0934-9723. ; 33:3, s. 313-324
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Tidskriftsartikel (refereegranskat)abstract
- Immune activation is a regular feature of sepsis, but the incidence and nature of the ensuing inflammation-resolving and immunosuppressive component is less well understood. In this study, we compared immunoregulatory markers on blood leukocytes from patients with Gram-negative or Gram-positive sepsis or septic shock, and compared this to blood from patients with severe virosis or healthy controls. To this end, blood from 32 patients with sepsis, including ten cases with shock, and 12 patients with severe virosis were analysed by flow cytometry for the expression levels of monocyte HLA-DR, CD11c, CD14 and CD40, and for frequencies of CD163(+)-suppressive monocytes, HLA-DR(+) or CD40(+)-activated T cells and Tregs. Plasma cytokine levels were analysed as a functional measurement. Signs of immunosuppression dominated in the septic shock and Gram-positive sepsis groups, whereas monocyte activation was common in Gram-negative sepsis patients without shock. However, the main finding was the large inter-individual variation of immune activation and immunosuppression, with no correlation to prognosis among the shock patients. The pronounced inter-individual variation in the analysed monocyte and lymphocyte markers forms a strong argument that, when immunomodulatory treatment is considered in a sepsis patient, it should be personalised and guided by a detailed immune status assessment.
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| 16. |
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| 17. |
- Jönsson, Elisabeth, 1968, et al.
(författare)
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Ghrelin decreases food intake in juvenile rainbow trout (Oncorhynchus mykiss) through the central anorexigenic corticotropin-releasing factor system
- 2010
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Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480. ; 166:166, s. 39-46
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Tidskriftsartikel (refereegranskat)abstract
- Ghrelin stimulates pituitary growth hormone (GH) release, and has a key role in the regulation of food intake and adiposity in vertebrates. To investigate the central effect of native rainbow trout ghrelin (rtghrelin) on food intake in rainbow trout, as well as its possible mode of action, four groups of fish received a single injection into the third brain ventricle (i.c.v. injection): (1) control group (physiological saline) (2) ghrelin-treated group (2.0 ng rtghrelin g bwt−1), (3) group given the corticotropin-releasing hormone receptor antagonist α-helical CRF 9–41 (ahCRF) (4.0 ng g bwt−1) and (4) group receiving the same dose of both ghrelin and ahCRF. Food intake was assessed 1 h after treatment. In addition, the presence of the GHS-R (the ghrelin receptor) in the rainbow trout CNS was examined with Western blot. To investigate peripheral effects of ghrelin, rainbow trout received an intraperitoneal cholesterol-based implant with or without rtghrelin, and daily food intake was measured during 14 days. Weight and length were measured at the start and termination of the experiment and specific growth rates were calculated. Mesenteric fat stores, muscle and liver lipid content were analysed after the treatment period. Central ghrelin injections decreased food intake compared with controls, and treatment with ahCRF abolished the ghrelin-effect. Western blot analysis of the GHS-R revealed a single band at around 60 kDa in pituitary, hypothalamus, brain and stomach. Long-term peripheral ghrelin treatment decreased daily food intake compared with controls. This was reflected in a ghrelin-induced decrease in weight growth rate (p < 0.06). There was no effect of ghrelin on plasma GH levels or tissue fat stores. The conclusion from this study is that the GHS-R is indicated in the CNS in rainbow trout and that ghrelin may act there as an anorexigenic hormone, through a CRF-mediated pathway. Elevated peripheral ghrelin levels also seem to lead to decreased feed intake in the longer term.
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| 18. |
- Raven, P. A., et al.
(författare)
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Growth and endocrine effects of recombinant bovine growth hormone treatment in non-transgenic and growth hormone transgenic coho salmon
- 2012
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Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480. ; 177:1, s. 143-152
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Tidskriftsartikel (refereegranskat)abstract
- To examine the relative growth, endocrine, and gene expression effects of growth hormone (GH) transgenesis vs. GH protein treatment, wild-type non-transgenic and GH transgenic coho salmon were treated with a sustained-release formulation of recombinant bovine GH (bGH; Posilac(TM)). Fish size, specific growth rate (SGR), and condition factor (CF) were monitored for 14 weeks, after which endocrine parameters were measured. Transgenic fish had much higher growth, SGR and CF than non-transgenic fish, and bGH injection significantly increased weight and SGR in non-transgenic but not transgenic fish. Plasma salmon GH concentrations decreased with bGH treatment in non-transgenic but not in transgenic fish where levels were similar to controls. Higher GH mRNA levels were detected in transgenic muscle and liver but no differences were observed in GH receptor (GHR) mRNA levels. In non-transgenic pituitary. GH and GHR mRNA levels per mg pituitary decreased with bGH dose to levels seen in transgenic salmon. Plasma IGF-I was elevated with bGH dose only in non-transgenic fish, while transgenic fish maintained an elevated level of IGF-I with or without bGH treatment. A similar trend was seen for liver IGF-I mRNA levels. Thus, bGH treatment increased fish growth and influenced feedback on endocrine parameters in non-transgenic but not in transgenic fish. A lack of further growth stimulation of GH transgenic fish suggests that these fish are experiencing maximal growth stimulation via GH pathways. Crown Copyright (C) 2012 Published by Elsevier Inc. All rights reserved.
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| 19. |
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| 20. |
- Schulze, S., et al.
(författare)
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GRB 120422A/SN 2012bz : Bridging the gap between low- and high-luminosity gamma-ray bursts
- 2014
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 566
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Tidskriftsartikel (refereegranskat)abstract
- Context. At low redshift, a handful of gamma-ray bursts (GRBs) have been discovered with luminosities that are substantially lower (L-iso less than or similar to 10(48.5) erg s(-1)) than the average of more distant ones (L-iso greater than or similar to 10(49.5) erg s(-1)). It has been suggested that the properties of several low-luminosity (low-L) GRBs are due to shock break-out, as opposed to the emission from ultrarelativistic jets. This has led to much debate about how the populations are connected. Aims. The burst at redshift z = 0.283 from 2012 April 22 is one of the very few examples of intermediate-L GRBs with a gamma-ray luminosity of L-iso similar to 10(49.6-49.9) erg s(-1) that have been detected up to now. With the robust detection of its accompanying supernova SN 2012bz, it has the potential to answer important questions on the origin of low-and high-L GRBs and the GRB-SN connection. Methods. We carried out a spectroscopy campaign using medium-and low-resolution spectrographs with 6-10-m class telescopes, which covered a time span of 37.3 days, and a multi-wavelength imaging campaign, which ranged from radio to X-ray energies over a duration of similar to 270 days. Furthermore, we used a tuneable filter that is centred at H alpha to map star-formation in the host and the surrounding galaxies. We used these data to extract and model the properties of different radiation components and fitted the spectral energy distribution to extract the properties of the host galaxy. Results. Modelling the light curve and spectral energy distribution from the radio to the X-rays revealed that the blast wave expanded with an initial Lorentz factor of Gamma(0) similar to 50, which is a low value in comparison to high-L GRBs, and that the afterglow had an exceptionally low peak luminosity density of less than or similar to 2 x 10(30) erg s(-1) Hz(-1) in the sub-mm. Because of the weak afterglow component, we were able to recover the signature of a shock break-out in an event that was not a genuine low-L GRB for the first time. At 1.4 hr after the burst, the stellar envelope had a blackbody temperature of k(B)T similar to 16 eV and a radius of similar to 7 x 10(13) cm (both in the observer frame). The accompanying SN 2012bz reached a peak luminosity of M-V = -19.7 mag, which is 0.3 mag more luminous than SN 1998bw. The synthesised nickel mass of 0.58 M-circle dot, ejecta mass of 5.87 M-circle dot, and kinetic energy of 4.10x10(52) erg were among the highest for GRB-SNe, which makes it the most luminous spectroscopically confirmed SN to date. Nebular emission lines at the GRB location were visible, which extend from the galaxy nucleus to the explosion site. The host and the explosion site had close-to-solar metallicity. The burst occurred in an isolated star-forming region with an SFR that is 1/10 of that in the galaxy's nucleus. Conclusions. While the prompt gamma-ray emission points to a high-L GRB, the weak afterglow and the low Gamma(0) were very atypical for such a burst. Moreover, the detection of the shock break-out signature is a new quality for high-L GRBs. So far, shock break-outs were exclusively detected for low-L GRBs, while GRB 120422A had an intermediate L-iso of similar to 10(49.6-49.9) erg s(-1). Therefore, we conclude that GRB 120422A was a transition object between low-and high-L GRBs, which supports the failed-jet model that connects low-L GRBs that are driven by shock break-outs and high-L GRBs that are powered by ultra-relativistic jets.
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| 21. |
- Sundt-Hansen, L., et al.
(författare)
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Growth hormone reduces growth in free-living Atlantic salmon fry
- 2012
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463. ; 26:4, s. 904-911
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Tidskriftsartikel (refereegranskat)abstract
- 1. Although life-history theory predicts that juvenile growth rates should be high, there is substantial evidence that most juveniles grow below their physiological maximum. The endocrine system plays an important role in the determination of fundamental life-history traits, and hormones often serve as a link between an organisms environment and the expression of a trait. Particularly, growth is a life-history trait, which is strongly associated with growth hormone (GH) in fish, as well as most vertebrates. 2. To elucidate trade-offs related to elevated GH in fish in a natural environment, we experimentally administrated GH exogenously to juvenile Atlantic salmon using sustained-release GH implants, at an earlier ontogenetic stage than previously achieved (1.5 months). We assessed the effects on growth, dispersal and survival in contrasting environments. 3. Exogenous GH treatment increased the growth rate when fish were fed ad libitum in captivity. However, in a natural stream, GH treatment had a significant negative effect on growth and no apparent effect on survival or dispersal. This contrasts with previous studies conducted at later developmental stages, which show either a positive growth effect or no effect of elevated GH levels. 4. This study shows that environmental conditions strongly affect the response to GH and that under some natural conditions, it may also reduce growth. We suggest that the endogenous plasma GH levels may be maximizing growth during early, but not later, juvenile stages in nature.
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| 22. |
- Wild, J. A., et al.
(författare)
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Midnight sector observations of auroral omega bands
- 2011
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 116, s. A00I30-
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Tidskriftsartikel (refereegranskat)abstract
- We present observations of auroral omega bands on 28 September 2009. Although generally associated with the substorm recovery phase and typically observed in the morning sector, the features presented here occurred just after expansion phase onset and were observed in the midnight sector, dawnward of the onset region. An all-sky imager located in northeastern Iceland revealed that the omega bands were similar to 150 x 200 km in size and propagated eastward at similar to 0.4 km s(-1) while a colocated ground magnetometer recorded the simultaneous occurrence of Ps6 pulsations. Although somewhat smaller and slower moving than the majority of previously reported omega bands, the observed structures are clear examples of this phenomenon, albeit in an atypical location and unusually early in the substorm cycle. The THEMIS C probe provided detailed measurements of the upstream interplanetary environment, while the Cluster satellites were located in the tail plasma sheet conjugate to the ground-based all-sky imager. The Cluster satellites observed bursts of 0.1-3 keV electrons moving parallel to the magnetic field toward the Northern Hemisphere auroral ionosphere; these bursts were associated with increased levels of field-aligned Poynting flux. The in situ measurements are consistent with electron acceleration via shear Alfven waves in the plasma sheet similar to 8 R-E tailward of the Earth. Although a one-to-one association between auroral and magnetospheric features was not found, our observations suggest that Alfven waves in the plasma sheet are responsible for field-aligned currents that cause Ps6 pulsations and auroral brightening in the ionosphere. Our findings agree with the conclusions of earlier studies that auroral omega bands have a source mechanism in the midtail plasma sheet.
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