| 41. |
- Leloudas, G., et al.
(författare)
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SN 2006oz : rise of a super-luminous supernova observed by the SDSS-II SN Survey
- 2012
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 541, s. A129-
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Tidskriftsartikel (refereegranskat)abstract
- Context. A new class of super-luminous transients has recently been identified. These objects reach absolute luminosities of M-u < -21, lack hydrogen in their spectra, and are exclusively discovered by non-targeted surveys because they are associated with very faint galaxies. Aims. We aim to contribute to a better understanding of these objects by studying SN 2006oz, a newly-recognized member of this class. Methods. We present multi-color light curves of SN 2006oz from the SDSS-II SN Survey that cover its rise time, as well as an optical spectrum that shows that the explosion occurred at z similar to 0.376. We fitted black-body functions to estimate the temperature and radius evolution of the photosphere and used the parametrized code SYNOW to model the spectrum. We constructed a bolometric light curve and compared it with explosion models. In addition, we conducted a deep search for the host galaxy with the 10 m GTC telescope. Results. The very early light curves show a dip in the g-and r-bands and a possible initial cooling phase in the u-band before rising to maximum light. The bolometric light curve shows a precursor plateau with a duration of 6-10 days in the rest-frame. A lower limit of M-u < -21.5 can be placed on the absolute peak luminosity of the SN, while the rise time is constrained to be at least 29 days. During our observations, the emitting sphere doubled its radius to similar to 2 x 10(15) cm, while the temperature remained hot at similar to 15 000 K. As for other similar SNe, the spectrum is best modeled with elements including O II and Mg II, while we tentatively suggest that Fe III might be present. The host galaxy is detected in gri with 25.74 +/- 0.19, 24.43 +/- 0.06, and 24.14 +/- 0.12, respectively. It is a faint dwarf galaxy with M-g = -16.9. Conclusions. We suggest that the precursor plateau might be related to a recombination wave in a circumstellar medium (CSM) and discuss whether this is a common property of all similar explosions. The subsequent rise can be equally well described by input from a magnetar or by ejecta-CSM interaction, but the models are not well constrained owing to the lack of post-maximum observations, and CSM interaction has difficulties accounting for the precursor plateau self-consistently. Radioactive decay is less likely to be the mechanism that powers the luminosity. The host is a moderately young and star-forming, but not a starburst, galaxy.
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| 45. |
- Taubenberger, S., et al.
(författare)
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SN2012dn from early to late times : 09dc-like supernovae reassessed
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 488:4, s. 5473-5488
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Tidskriftsartikel (refereegranskat)abstract
- As a candidate super-Chandrasekhar' or 09dc-like TypeIa supernova (SNIa), SN 2012dn shares many characteristics with other members of this remarkable class of objects but lacks their extraordinary luminosity. Here, we present and discuss the most comprehensive optical data set of this SN to date, comprised of a densely sampled series of early-time spectra obtained within the Nearby Supernova Factory project, plus photometry and spectroscopy obtained at the Very Large Telescope about 1yr after the explosion. The light curves, colour curves, spectral time series, and ejecta velocities of SN 2012dn are compared with those of other 09dc-like and normal SNeIa, the overall variety within the class of 09dc-like SNeIa is discussed, and new criteria for 09dc-likeness are proposed. Particular attention is directed to additional insight that the late-phase data provide. The nebular spectra show forbidden lines of oxygen and calcium, elements that are usually not seen in late-time spectra of SNeIa, while the ionization state of the emitting iron plasma is low, pointing to low ejecta temperatures and high densities. The optical light curves are characterized by an enhanced fading starting similar to 60d after maximum and very low luminosities in the nebular phase, which is most readily explained by unusually early formation of clumpy dust in the ejecta. Taken together, these effects suggest a strongly perturbed ejecta density profile, which might lend support to the idea that 09dc-like characteristics arise from a brief episode of interaction with a hydrogen-deficient envelope during the first hours or days after the explosion.
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| 46. |
- Theorell, Töres, et al.
(författare)
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Job strain in relation to body mass index : pooled analysis of 160 000 adults from 13 cohort studies
- 2012
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 272:1, s. 65-73
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Tidskriftsartikel (refereegranskat)abstract
- Job strain in relation to body mass index: pooled analysis of 160 000 adults from 13 cohort studies. J Intern Med 2012; 272: 6573. Background. Evidence of an association between job strain and obesity is inconsistent, mostly limited to small-scale studies, and does not distinguish between categories of underweight or obesity subclasses. Objectives. To examine the association between job strain and body mass index (BMI) in a large adult population. Methods. We performed a pooled cross-sectional analysis based on individual-level data from 13 European studies resulting in a total of 161 746 participants (49% men, mean age, 43.7 years). Longitudinal analysis with a median follow-up of 4 years was possible for four cohort studies (n = 42 222). Results. A total of 86 429 participants were of normal weight (BMI 18.524.9 kg m-2), 2149 were underweight (BMI < 18.5 kg m-2), 56 572 overweight (BMI 25.029.9 kg m-2) and 13 523 class I (BMI 3034.9 kg m-2) and 3073 classes II/III (BMI = 35 kg m-2) obese. In addition, 27 010 (17%) participants reported job strain. In cross-sectional analyses, we found increased odds of job strain amongst underweight [odds ratio 1.12, 95% confidence interval (CI) 1.001.25], obese class I (odds ratio 1.07, 95% CI 1.021.12) and obese classes II/III participants (odds ratio 1.14, 95% CI 1.011.28) as compared with participants of normal weight. In longitudinal analysis, both weight gain and weight loss were related to the onset of job strain during follow-up. Conclusions. In an analysis of European data, we found both weight gain and weight loss to be associated with the onset of job strain, consistent with a U-shaped cross-sectional association between job strain and BMI. These associations were relatively modest; therefore, it is unlikely that intervention to reduce job strain would be effective in combating obesity at a population level.
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| 48. |
- Beard, Jessica H., et al.
(författare)
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Outcomes After Inguinal Hernia Repair With Mesh Performed by Medical Doctors and Surgeons in Ghana
- 2019
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Ingår i: JAMA Surgery. - : AMER MEDICAL ASSOC. - 2168-6254 .- 2168-6262. ; 154:9, s. 853-859
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Tidskriftsartikel (refereegranskat)abstract
- Key PointsQuestionWhat are the outcomes after mesh inguinal hernia repair performed by medical doctors compared with surgeons in Ghana? FindingsIn this cohort study of 242 men with primary reducible inguinal hernia, there was no significant difference in hernia recurrence at 1 year after inguinal hernia repair with mesh performed by medical doctors compared with surgeons (0.9% vs 2.8%). MeaningThis study shows that medical doctors can be trained to perform inguinal hernia repair with mesh in men with good results in a low-resource setting and appears to support surgical task sharing to combat the global burden of hernia disease. ImportanceInguinal hernia is the most common general surgical condition in the world. Although task sharing of surgical care with nonsurgeons represents one method to increase access to essential surgery, the safety and outcomes of this strategy are not well described for hernia repair. ObjectiveTo compare outcomes after inguinal hernia repair with mesh performed by medical doctors and surgeons in Ghana. Design, Setting, and ParticipantsThis prospective cohort study was conducted from February 15, 2017, to September 17, 2018, at the Volta Regional Hospital in Ho, Ghana. Following successful completion of a training course, 3 medical doctors and 2 surgeons performed inguinal hernia repair with mesh according to the Lichtenstein technique on 242 men with primary, reducible inguinal hernia. Main Outcomes and MeasuresThe primary end point was hernia recurrence at 1 year. The noninferiority limit was set at 5 percentage points. Secondary end points included postoperative complications at 2 weeks and patient satisfaction, pain, and self-assessed health status at 1 year. ResultsTwo-hundred forty-two patients were included; 119 men underwent operations performed by medical doctors and 123 men underwent operations performed by surgeons. Preoperative patient characteristics were similar in both groups. Two-hundred thirty-seven patients (97.9%) were seen at follow-up at 2 weeks, and 223 patients (92.1%) were seen at follow-up at 1 year. The absolute difference in recurrence rate between the medical doctor group (1 [0.9%]) and the surgeon group (3 [2.8%]) was -1.9 (1-tailed 95% CI, -4.8; Pamp;lt;.001), demonstrating noninferiority of the medical doctors. There were no statistically significant differences in postoperative complications (34 [29.1%] vs 29 [24.2%]), patient satisfaction (112 [98.2%] vs 108 [99.1%]), severe chronic pain (1 [0.9%] vs 4 [3.7%]), or self-assessed health (85.9 vs 83.7 of 100) for medical doctors and surgeons. Conclusions and RelevanceThis study shows that medical doctors can be trained to perform elective inguinal hernia repair with mesh in men with good results and high patient satisfaction in a low-resource setting. This finding supports surgical task sharing to combat the global burden of hernia disease. This cohort study compares the outcomes associated with inguinal hernia repair performed by medical doctors vs surgeons in Ghana.
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| 49. |
- Blander, M, et al.
(författare)
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Equilibrium Chemistry of Biomass Combustion: A Round-Robin Set of Calculations Using Available Computer Programs and Databases
- 2001
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Ingår i: Energy Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 15:2, s. 344-9
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Tidskriftsartikel (refereegranskat)abstract
- Equilibrium calculations of three problems regarding biomass combustion, at various levels of sophistication, were performed at six laboratories using seven combinations of computer programs and databases. The objective was to test the adequacy of the programs and databases for calculating both condensed and gas-phase behavior. The first problem was a simplified calculation for the combustion of a woodlike material with added sulfur to possibly form an ideal molten salt solution of potassium and calcium sulfate. The second and third problems were to simulate aspen wood and wheat straw combustion, respectively, and required a relatively sophisticated database on high-temperature solutions to describe condensed phases. All the participants performed calculations of the gas phases, which were reasonably accurate when their databases were adequate. For problem I, most of the participants were also able to calculate a reasonable set of condensed phases. However, for problems II and III, only four of the participants, using the two most sophisticated computer programs and databases, had the ability to produce rational results for the condensed phases. This round robin identified two computer programs and their associated databases that could prove useful for calculating the condensed-phase equilibrium chemistry of biomass combustion when coupled with experimental programs and the capability to expand databases as new experimental data become available. Such calculations can greatly enhance our understanding of the total equilibrium chemistry of biomass combustion.
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