| 1. |
- Pablo, H., et al.
(författare)
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epsilon Lupi : measuring the heartbeat of a doubly magnetic massive binary with BRITE Constellation
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966. ; 488:1, s. 64-77
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Tidskriftsartikel (refereegranskat)abstract
- epsilon Lupi A is a binary system consisting of two main-sequence early B-type stars Aa and Ab in a short period, moderately eccentric orbit. The close binary pair is the only doubly magnetic massive binary currently known. Using photometric data from the BRITE Constellation we identify a modest heartbeat variation. Combining the photometry with radial velocities of both components we determine a full orbital solution including empirical masses and radii. These results are compared with stellar evolution models as well as interferometry and the differences discussed. We also find additional photometric variability at several frequencies, finding it unlikely these frequencies can be caused by tidally excited oscillations. We do, however, determine that these signals are consistent with gravity mode pulsations typical for slowly pulsating B stars. Finally we discuss how the evolution of this system will be affected by magnetism, determining that tidal interactions will still be dominant.
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| 2. |
- Zwintz, K., et al.
(författare)
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beta Cas : The first ffi Scuti star with a dynamo magnetic field
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP SCIENCES S A. - 0004-6361 .- 1432-0746. ; 643
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Tidskriftsartikel (refereegranskat)abstract
- Context. F-type stars are characterised by several physical processes such as different pulsation mechanisms, rotation, convection, diffusion, and magnetic fields. The rapidly rotating delta Scuti star beta Cas can be considered as a benchmark star to study the interaction of several of these effects.Aims. We investigate the pulsational and magnetic field properties of beta Cas. We also determine the star's apparent fundamental parameters and chemical abundances.Methods. Based on photometric time series obtained from three different space missions (BRITE-Constellation, SMEI, and TESS), we conduct a frequency analysis and investigate the stability of the pulsation amplitudes over four years of observations. We investigate the presence of a magnetic field and its properties using spectropolarimetric observations taken with the Narval instrument by applying the least-squares deconvolution and Zeeman-Doppler imaging techniques.Results. The star beta Cas shows only three independent p-mode frequencies down to the few ppm-level; its highest amplitude frequency is suggested to be an n=3, l=2, m=0 mode. Its magnetic field structure is quite complex and almost certainly of a dynamo origin. The atmosphere of beta Cas is slightly deficient in iron peak elements and slightly overabundant in C, O, and heavier elements.Conclusions. Atypically for delta Scuti stars, we can only detect three pulsation modes down to exceptionally low noise levels for beta Cas. The star is also one of very few delta Scuti pulsators known to date to show a measurable magnetic field and the first delta Scuti star with a dynamo magnetic field. These characteristics make beta Cas an interesting target for future studies of dynamo processes in the thin convective envelopes of F-type stars, the transition region between fossil and dynamo fields, and the interaction between pulsations and magnetic field.
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| 3. |
- Pieniowski, E, et al.
(författare)
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Early versus delayed surgery for acute cholecystitis as an applied treatment strategy when assessed in a population-based cohort
- 2014
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Ingår i: Digestive surgery. - : S. Karger AG. - 1421-9883 .- 0253-4886. ; 31:3, s. 169-176
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Tidskriftsartikel (refereegranskat)abstract
- <b><i>Background:</i></b> The aims of this study were to describe the surgical management of acute cholecystitis (AC) in a well-defined population-based patient cohort, in particular adherence to and outcome of the early open/laparoscopic cholecystectomy (EC/ELC) strategy. <b><i>Methods:</i></b> The medical records of all patients residing in Stockholm County who were treated for AC during 2003 and 2008 were reviewed according to a standardized protocol. <b><i>Results:</i></b> In 2003, 799 patients were admitted 850 times for AC, and the respective figures for 2008 were 833 and 919. The number of patients who underwent EC/ELC increased from 42.9% in 2003 to 47.4% in 2008. In multivariate regression analysis adjusting for age, gender, severity of cholecystitis, maximal CRP and maximal WBC, EC/ELC was associated with shorter operation time but higher perioperative blood loss when compared to delayed open/laparoscopic cholecystectomy (DC/DLC). The odds ratio for completing the procedure laparoscopically was significantly higher in DC/DLC when adjusting for the same covariates. There were no significant differences in peri- or postoperative complications between the groups. <b><i>Conclusion:</i></b> Strategies should be implemented in order to secure a more evidence-based approach to the surgical treatment of AC.
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| 4. |
- Popowicz, A, et al.
(författare)
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Cholecystostomy as Bridge to Surgery and as Definitive Treatment or Acute Cholecystectomy in Patients with Acute Cholecystitis
- 2016
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Ingår i: Gastroenterology research and practice. - : Hindawi Limited. - 1687-6121 .- 1687-630X. ; 2016, s. 3672416-
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Tidskriftsartikel (refereegranskat)abstract
- Purpose.Percutaneous cholecystostomy (PC) has increasingly been used as bridge to surgery as well as sole treatment for patients with acute cholecystitis (AC). The aim of the study was to assess the outcome after PC compared to acute cholecystectomy in patients with AC.Methods.A review of medical records was performed on all patients residing in Stockholm County treated for AC in the years 2003 and 2008.Results.In 2003 and 2008 altogether 799 and 833 patients were admitted for AC. The number of patients treated with PC was 21/799 (2.6%) in 2003 and 50/833 (6.0%) in 2008. The complication rate (Clavien-Dindo ≥ 2) was 4/71 (5.6%) after PC and 135/736 (18.3%) after acute cholecystectomy. Mean (standard deviation) hospital stay was 11.4 (10.5) days for patients treated with PC and 5.1 (4.3) days for patients undergoing acute cholecystectomy. After adjusting for age, gender, Charlson comorbidity index, and degree of cholecystitis, the hospital stay was significantly longer for patients treated with PC than for those undergoing acute cholecystectomy (P<0.001) but the risk for intervention-related complications was found to be significantly lower (P=0.001) in the PC group.Conclusion.PC can be performed with few serious complications, albeit with a longer hospital stay.
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| 5. |
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| 6. |
- Weiss, W. W., et al.
(författare)
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New BRITE-Constellation observations of the roAp star α Cir⋆
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP SCIENCES S A. - 0004-6361 .- 1432-0746. ; 642
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Tidskriftsartikel (refereegranskat)abstract
- Context. Chemically peculiar (CP) stars with a measurable magnetic field comprise the group of mCP stars. The pulsating members define the subgroup of rapidly oscillating Ap (roAp) stars, of which alpha Cir is the brightest member. Hence, alpha Cir allows the application of challenging techniques, such as interferometry, very high temporal and spectral resolution photometry, and spectroscopy in a wide wavelength range, that have the potential to provide unique information about the structure and evolution of a star.Aims. Based on new photometry from BRITE-Constellation, obtained with blue and red filters, and on photometry from WIRE, SMEI, and TESS we attempt to determine the surface spot structure of alpha Cir and investigate pulsation frequencies.Methods. We used photometric surface imaging and frequency analyses and Bayesian techniques in order to quantitatively compare the probability of different models.Results. BRITE-Constellation photometry obtained from 2014 to 2016 is put in the context of space photometry obtained by WIRE, SMEI, and TESS. This provides improvements in the determination of the rotation period and surface features (three spots detected and a fourth one indicated). The main pulsation frequencies indicate two consecutive radial modes and one intermediate dipolar mode. Advantages and problems of the applied Bayesian technique are discussed.
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| 7. |
- Popowicz, A, et al.
(författare)
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Management of Common Bile Duct Stones Encountered During Cholecystectomy in Patients With Previous Gastric Bypass
- 2021
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Ingår i: Frontiers in surgery. - : Frontiers Media SA. - 2296-875X. ; 8, s. 789231-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Rapid weight loss following gastric bypass (GBP) predisposes to the development of gallstones, and in those who develop gallstone disease there is a high prevalence of common bile duct stones (CBDS). Furthermore, in these patients, CBDS are difficult to extract due to the altered upper gastrointestinal anatomy following GBP. The aim of the present study was to assess outcome after various management methods applied in the counties of Stockholm and Uppsala, Sweden.Methods: Data from the Swedish Register for Gallstone Surgery and ERCP (GallRiks) and the Swedish Obesity Surgery Register (SoReg) were crossmatched to identify all patients who had undergone gallstone surgery after GBP, where CBDS were found at intraoperative cholangiography, in the Stockholm and Uppsala counties 2009–2013. A retrospective review of patient records was performed for all patients identified.Results: In all, 55 patients were identified. These were managed as follows: expectancy (N = 11); transgastric ERCP (N = 2); laparoscopic choledochotomy (N = 3); open choledochotomy (N = 5); transcystic stone extraction (N = 12); and other approach (N = 13). In nine cases, data on management could not be found. There were nine cases of minor postoperative complication. No retained stones were registered. The operation time was longer for transgastric ERCP (p = 0.002), and the postoperative stay was longer following open and laparoscopic choledochotomy (p < 0.001). There was no statistically significant difference between any of the methods regarding the incidence of postoperative complications (p = 0.098).Discussion: Further development of techniques for managing CBDS discovered in patients undergoing cholecystectomy after previous GBP are needed, as well as more comparative studies with greater statistical power.
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