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- Galan, C., et al.
(författare)
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International observational campaigns of the last two eclipses in EE Cephei : 2003 and 2008/9
- 2012
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 544, s. A53-
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Tidskriftsartikel (refereegranskat)abstract
- Context. EECep is an unusual long-period (5.6 yr) eclipsing binary discovered during the mid-twentieth century. It undergoes almost-grey eclipses that vary in terms of both depth and duration at different epochs. The system consists of a Be type star and a dark dusty disk around an invisible companion. EECep together with the widely studied epsilon Aur are the only two known cases of long-period eclipsing binaries with a dark, dusty disk component responsible for periodic obscurations.Aims. Two observational campaigns were carried out during the eclipses of EECep in 2003 and 2008/9 to verify whether the eclipsing body in the system is indeed a dark disk and to understand the observed changes in the depths and durations of the eclipses.Methods. Multicolour photometric data and spectroscopic observations performed at both low and high resolutions were collected with several dozen instruments located in Europe and North America. We numerically modelled the variations in brightness and colour during the eclipses. We tested models with different disk structure, taking into consideration the inhomogeneous surface brightness of the Be star. We considered the possibility of disk precession.Results. The complete set of observational data collected during the last three eclipses are made available to the astronomical community. The 2003 and 2008/9 eclipses of EECep were very shallow. The latter is the shallowest among all observed. The very high quality photometric data illustrate in detail the colour evolution during the eclipses for the first time. Two blue maxima in the colour indices were detected during these two eclipses, one before and one after the photometric minimum. The first (stronger) blue maximum is simultaneous with a "bump" that is very clear in all the UBV(RI)(C) light curves. A temporary increase in the I-band brightness at the orbital phase similar to 0.2 was observed after each of the last three eclipses. Variations in the spectral line profiles seem to be recurrent during each cycle. The Na I lines always show at least three absorption components during the eclipse minimum and strong absorption is superimposed on the H alpha emission.Conclusions. These observations confirm that the eclipsing object in EECep system is indeed a dark, dusty disk around a low luminosity object. The primary appears to be a rapidly rotating Be star that is strongly darkened at the equator and brightened at the poles. Some of the conclusions of this work require verification in future studies: (i) a complex, possibly multi-ring structure of the disk in EECep; (ii) our explanation of the "bump" observed during the last two eclipses in terms of the different times of obscuration of the hot polar regions of the Be star by the disk; and (iii) our suggested period of the disk precession (similar to 11-12 P-orb) and predicted depth of about 2(m) for the forthcoming eclipse in 2014.
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- Dey, Lankeswar, et al.
(författare)
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Authenticating the Presence of a Relativistic Massive Black Hole Binary in OJ 287 Using Its General Relativity Centenary Flare : Improved Orbital Parameters
- 2018
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 866:1
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Tidskriftsartikel (refereegranskat)abstract
- Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission of gravitational waves (GWs). We show that observations associated with the binary black hole (BBH) central engine of blazar OJ 287 demand the inclusion of gravitational radiation reaction effects beyond the quadrupolar order. It turns out that even the effects of certain hereditary contributions to GW emission are required to predict impact flare timings of OJ 287. We develop an approach that incorporates this effect into the BBH model for OJ 287. This allows us to demonstrate an excellent agreement between the observed impact flare timings and those predicted from ten orbital cycles of the BBH central engine model. The deduced rate of orbital period decay is nine orders of magnitude higher than the observed rate in PSR 1913+16, demonstrating again the relativistic nature of OJ 287's central engine. Finally, we argue that precise timing of the predicted 2019 impact flare should allow a test of the celebrated black hole no-hair theorem at the 10% level.
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- Villforth, C., et al.
(författare)
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Variability and stability in blazar jets on time-scales of years : optical polarization monitoring of OJ 287 in 2005-2009
- 2010
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 402:3, s. 2087-2111
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Tidskriftsartikel (refereegranskat)abstract
- OJ 287 is a BL Lac object at redshift z = 0.306 that has shown double-peaked bursts at regular intervals of similar to 12 yr during the last similar to 40 yr. We analyse optical photopolarimetric monitoring data from 2005 to 2009, during which the latest double-peaked outburst occurred. The aim of this study is twofold: firstly, we aim to analyse variability patterns and statistical properties of the optical polarization light curve. We find a strong preferred position angle in optical polarization. The preferred position angle can be explained by separating the jet emission into two components: an optical polarization core and chaotic jet emission. The optical polarization core is stable on time-scales of years and can be explained as emission from an underlying quiescent jet component. The chaotic jet emission sometimes exhibits a circular movement in the Stokes plane. We find six such events, all on the time-scales of 10-20 d. We interpret these events as a shock front moving forwards and backwards in the jet, swiping through a helical magnetic field. Secondly, we use our data to assess different binary black hole models proposed to explain the regularly appearing double-peaked bursts in OJ 287. We compose a list of requirements a model has to fulfil to explain the mysterious behaviour observed in OJ 287. The list includes not only characteristics of the light curve but also other properties of OJ 287, such as the black hole mass and restrictions on accretion flow properties. We rate all existing models using this list and conclude that none of the models is able to explain all observations. We discuss possible new explanations and propose a new approach to understanding OJ 287. We suggest that both the double-peaked bursts and the evolution of the optical polarization position angle could be explained as a sign of resonant accretion of magnetic field lines, a 'magnetic breathing' of the disc.
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- McMurray, J. J. V., et al.
(författare)
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Dapagliflozin in Patients with Heart Failure and Reduced Ejection Fraction
- 2019
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Ingår i: New England Journal of Medicine. - 0028-4793 .- 1533-4406. ; 381:21, s. 1995-2008
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND In patients with type 2 diabetes, inhibitors of sodium-glucose cotransporter 2 (SGLT2) reduce the risk of a first hospitalization for heart failure, possibly through glucose-independent mechanisms. More data are needed regarding the effects of SGLT2 inhibitors in patients with established heart failure and a reduced ejection fraction, regardless of the presence or absence of type 2 diabetes.METHODS In this phase 3, placebo-controlled trial, we randomly assigned 4744 patients with New York Heart Association class II, III, or IV heart failure and an ejection fraction of 40% or less to receive either dapagliflozin (at a dose of 10 mg once daily) or placebo, in addition to recommended therapy. The primary outcome was a composite of worsening heart failure (hospitalization or an urgent visit resulting in intravenous therapy for heart failure) or cardiovascular death.RESULTS Over a median of 18.2 months, the primary outcome occurred in 386 of 2373 patients (16.3%) in the dapagliflozin group and in 502 of 2371 patients (21.2%) in the placebo group (hazard ratio, 0.74; 95% confidence interval [CI], 0.65 to 0.85; P<0.001). A first worsening heart failure event occurred in 237 patients (10.0%) in the dapagliflozin group and in 326 patients (13.7%) in the placebo group (hazard ratio, 0.70; 95% CI, 0.59 to 0.83). Death from cardiovascular causes occurred in 227 patients (9.6%) in the dapagliflozin group and in 273 patients (11.5%) in the placebo group (hazard ratio, 0.82; 95% CI, 0.69 to 0.98); 276 patients (11.6%) and 329 patients (13.9%), respectively, died from any cause (hazard ratio, 0.83; 95% CI, 0.71 to 0.97). Findings in patients with diabetes were similar to those in patients without diabetes. The frequency of adverse events related to volume depletion, renal dysfunction, and hypoglycemia did not differ between treatment groups.CONCLUSIONS Among patients with heart failure and a reduced ejection fraction, the risk of worsening heart failure or death from cardiovascular causes was lower among those who received dapagliflozin than among those who received placebo, regardless of the presence or absence of diabetes.
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- Weigert, A, et al.
(författare)
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Influence of gender and age on haemodialysis practices: a European multicentre analysis
- 2020
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Ingår i: Clinical kidney journal. - : Oxford University Press (OUP). - 2048-8505 .- 2048-8513. ; 13:2, s. 217-224
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundWomen of all ages and elderly patients of both genders comprise an increasing proportion of the haemodialysis population. Worldwide, significant differences in practice patterns and treatment results exist between genders and among younger versus older patients. Although efforts to mitigate sex-based differences have been attempted, significant disparities still exist.MethodsThis retrospective cohort study included all 1247 prevalent haemodialysis patients in DaVita units in Portugal (five dialysis centres, n = 730) and Poland (seven centres, n = 517). Demographic data, dialysis practice patterns, vascular access prevalence and the achievement of a variety of Kidney Disease: Improving Global Outcomes (KDIGO) treatment targets were evaluated in relation to gender and age groups.ResultsBody weight and the prescribed dialysis blood flow rate were lower in women (P < 0.001), whereas treated blood volume per kilogram per session was higher (P < 0.01), resulting in higher single-pool Kt/V in women than in men (P < 0.001). Haemoglobin was significantly higher in men (P = 0.01), but the proportion of patients within target range (10–12 g/dL) was similar. Men more often had an arteriovenous fistula than women (80% versus 73%; P < 0.01) with a similar percentage of central venous catheters. There were no gender-specific differences in terms of dialysis adequacy, anaemia parameters or mineral and bone disorder parameters, or in the attainment of KDIGO targets between women and men >80 years of age.ConclusionsThis large, multicentre real-world analysis indicates that haemodialysis practices and treatment targets are similar for women and men, including the most elderly, in DaVita haemodialysis clinics in Europe.
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- Adamson, Carly, et al.
(författare)
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Liver Tests and Outcomes in Heart Failure with Reduced Ejection Fraction : Findings from DAPA-HF.
- 2022
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Ingår i: European journal of heart failure. - : Wiley. - 1388-9842 .- 1879-0844. ; 24:10, s. 1856-1868
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Reflecting both increased venous pressure and reduced cardiac output, abnormal liver tests are common in patients with severe heart failure and are associated with adverse clinical outcomes. We aimed to investigate the prognostic significance of abnormal liver tests in ambulatory patients with heart failure with reduced ejection fraction (HFrEF), explore any treatment interaction between bilirubin and sodium- glucose cotransporter 2 (SGLT2) inhibitors and examine change in liver tests with SGLT2 inhibitor treatment. METHODS AND RESULTS: We explored these objectives in the Dapagliflozin And Prevention of Adverse outcomes in Heart Failure (DAPA-HF) trial, with focus on bilirubin. We calculated the incidence of cardiovascular death or worsening heart failure by bilirubin tertile. Secondary cardiovascular outcomes were examined, along with the change in liver tests at the end-of-study visit. Baseline bilirubin was available in 4720 patients (99.5%). Participants in the highest bilirubin tertile (T3) have more severe HFrEF (lower left ventricular ejection fraction, higher N-terminal pro-B-type natriuretic peptide [NT-proBNP] and worse New York Heart Association class), had a greater burden of atrial fibrillation but less diabetes. Higher bilirubin (T3 vs. T1) was associated with worse outcomes even after adjustment for other predictive variables, including NT-proBNP and troponin T (adjusted hazard ratio for the primary outcome 1.73 [95% confidence interval 1.37-2.17], p $<$ 0.001; and 1.52 [1.12-2.07], p = 0.01 for cardiovascular death). Baseline bilirubin did not modify the benefits of dapagliflozin. During follow-up, dapagliflozin had no effect on liver tests. CONCLUSION: Bilirubin concentration was an independent predictor of worse outcomes but did not modify the benefits of dapagliflozin in HFrEF. Dapagliflozin was not associated with change in liver tests. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov NCT03036124.
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- Crespo-Leiro, Maria G., et al.
(författare)
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European Society of Cardiology Heart Failure Long-Term Registry (ESC-HF-LT): 1-year follow-up outcomes and differences across regions
- 2016
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Ingår i: European Journal of Heart Failure. - : WILEY-BLACKWELL. - 1388-9842 .- 1879-0844. ; 18:6, s. 613-625
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Tidskriftsartikel (refereegranskat)abstract
- AimsThe European Society of Cardiology Heart Failure Long-Term Registry (ESC-HF-LT-R) was set up with the aim of describing the clinical epidemiology and the 1-year outcomes of patients with heart failure (HF) with the added intention of comparing differences between participating countries. Methods and resultsThe ESC-HF-LT-R is a prospective, observational registry contributed to by 211 cardiology centres in 21 European and/or Mediterranean countries, all being member countries of the ESC. Between May 2011 and April 2013 it collected data on 12440 patients, 40.5% of them hospitalized with acute HF (AHF) and 59.5% outpatients with chronic HF (CHF). The all-cause 1-year mortality rate was 23.6% for AHF and 6.4% for CHF. The combined endpoint of mortality or HF hospitalization within 1year had a rate of 36% for AHF and 14.5% for CHF. All-cause mortality rates in the different regions ranged from 21.6% to 36.5% in patients with AHF, and from 6.9% to 15.6% in those with CHF. These differences in mortality between regions are thought reflect differences in the characteristics and/or management of these patients. ConclusionThe ESC-HF-LT-R shows that 1-year all-cause mortality of patients with AHF is still high while the mortality of CHF is lower. This registry provides the opportunity to evaluate the management and outcomes of patients with HF and identify areas for improvement.
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- Dewan, Pooja, et al.
(författare)
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Effects of Dapagliflozin in Heart Failure with Reduced Ejection Fraction and Chronic Obstructive Pulmonary Disease : An Analysis of DAPA-HF.
- 2021
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Ingår i: European journal of heart failure. - : Wiley. - 1388-9842 .- 1879-0844. ; 23:4, s. 632-643
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Chronic obstructive pulmonary disease (COPD) is an important comorbidity in heart failure (HF) with reduced ejection fraction (HFrEF), associated with worse outcomes and often suboptimal treatment because of under-prescription of beta-blockers. Consequently, additional effective therapies are especially relevant in patients with COPD. The aim of this study was to examine outcomes related to COPD in a post hoc analysis of the Dapagliflozin And Prevention of Adverse-outcomes in Heart Failure (DAPA-HF) trial. METHODS AND RESULTS: We examined whether the effects of dapagliflozin in DAPA-HF were modified by COPD status. The primary outcome was the composite of an episode of worsening HF or cardiovascular death. Overall, 585 (12.3%) of the 4744 patients randomized had a history of COPD. Patients with COPD were more likely to be older men with a history of smoking, worse renal function, and higher baseline N-terminal pro B-type natriuretic peptide, and less likely to be treated with a beta-blocker or mineralocorticoid receptor antagonist. The incidence of the primary outcome was higher in patients with COPD than in those without [18.9 (95% confidence interval 16.0-22.2) vs. 13.0 (12.1-14.0) per 100 person-years; hazard ratio (HR) for COPD vs. no COPD 1.44 (1.21-1.72); P $<$ 0.001]. The effect of dapagliflozin, compared with placebo, on the primary outcome, was consistent in patients with [HR 0.67 (95% confidence interval 0.48-0.93)] and without COPD [0.76 (0.65-0.87); interaction P-value 0.47]. CONCLUSIONS: In DAPA-HF, one in eight patients with HFrEF had concomitant COPD. Participants with COPD had a higher risk of the primary outcome. The benefit of dapagliflozin on all pre-specified outcomes was consistent in patients with and without COPD. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov ID NCT03036124.
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