886 research outputs found

    Long XMM observation of the Narrow-Line Seyfert 1 galaxy IRAS13224-3809: rapid variability, high spin and a soft lag

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    Results are presented from a 500ks long XMM-Newton observation of the Narrow-Line Seyfert 1 galaxy IRAS13224-3809. The source is rapidly variable on timescales down to a few 100s. The spectrum shows strong broad Fe-K and L emission features which are interpreted as arising from reflection from the inner parts of an accretion disc around a rapidly spinning black hole. Assuming a power-law emissivity for the reflected flux and that the innermost radius corresponds to the innermost stable circular orbit, the black hole spin is measured to be 0.988 with a statistical precision better than one per cent. Systematic uncertainties are discussed. A soft X-ray lag of 100s confirms this scenario. The bulk of the power-law continuum source is located at a radius of 2-3 gravitational radii.Comment: 7 pages, 14 figures, submitted to MNRA

    Measuring Black Hole Spin using X-ray Reflection Spectroscopy

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    I review the current status of X-ray reflection (a.k.a. broad iron line) based black hole spin measurements. This is a powerful technique that allows us to measure robust black hole spins across the mass range, from the stellar-mass black holes in X-ray binaries to the supermassive black holes in active galactic nuclei. After describing the basic assumptions of this approach, I lay out the detailed methodology focusing on "best practices" that have been found necessary to obtain robust results. Reflecting my own biases, this review is slanted towards a discussion of supermassive black hole (SMBH) spin in active galactic nuclei (AGN). Pulling together all of the available XMM-Newton and Suzaku results from the literature that satisfy objective quality control criteria, it is clear that a large fraction of SMBHs are rapidly-spinning, although there are tentative hints of a more slowly spinning population at high (M>5*10^7Msun) and low (M<2*10^6Msun) mass. I also engage in a brief review of the spins of stellar-mass black holes in X-ray binaries. In general, reflection-based and continuum-fitting based spin measures are in agreement, although there remain two objects (GROJ1655-40 and 4U1543-475) for which that is not true. I end this review by discussing the exciting frontier of relativistic reverberation, particularly the discovery of broad iron line reverberation in XMM-Newton data for the Seyfert galaxies NGC4151, NGC7314 and MCG-5-23-16. As well as confirming the basic paradigm of relativistic disk reflection, this detection of reverberation demonstrates that future large-area X-ray observatories such as LOFT will make tremendous progress in studies of strong gravity using relativistic reverberation in AGN.Comment: 19 pages. To appear in proceedings of the ISSI-Bern workshop on "The Physics of Accretion onto Black Holes" (8-12 Oct 2012). Revised version adds a missing source to Table 1 and Fig.6 (IRAS13224-3809) and corrects the referencing of the discovery of soft lags in 1H0707-495 (which were in fact first reported in Fabian et al. 2009

    A Hard Look at NGC 5347: Revealing a Nearby Compton-thick AGN

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    Current measurements show that the observed fraction of Compton-thick (CT) active galactic nuclei (AGN) is smaller than the expected values needed to explain the cosmic X-ray background. Prior fits to the X-ray spectrum of the nearby Seyfert-2 galaxy NGC 5347 (z = 0.00792, D = 35.5 Mpc ) have alternately suggested a CT and Compton-thin source. Combining archival data from Suzaku, Chandra, and—most importantly—new data from NuSTAR, ... See full text for complete abstrac

    The safety of bivalirudin during elective percutaneous coronary interventions in heart transplant patients

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    Background: Bivalirudin has been shown to be safe and effective during percutaneous coronary interventions (PCI) of native coronary arteries in the REPLACE 2 trial. The safety of bivalirudin during PCIs in heart transplant patients is not known. Methods: Heart transplant patients who had undergone PCI of de novo lesions and received bivalirudin during the procedure were included in the study. Medical records were reviewed for the occurrence of death, myocardial infarction, target vessel revascularization or major bleeding up to 30 days after discharge. The results were compared with the REPLACE 2 trial and with a control group of heart transplant recipients who received heparin during their procedures. Results: There were 51 separate PCIs performed in 30 patients in the study group. The mean age was 56 &plusmn; 12 years and 6 (20%) were women. The control group consisted of 24 patients who had undergone 35 PCIs. There were no deaths, myocardial infarctions or target vessel revascularization during the follow-up period in the study group. The combined endpoint of death, myocardial infarctions, target vessel revascularization and major bleeding requiring two or more units of packed red blood cells occurred in 2 (3.9%) patients compared to 275 (9.2%) patients in the REPLACE 2 trial (p = 0.195) and 5 (14.3%) in the control group (p = 0.115). Conclusion: Bivalirudin is a safe antithrombotic medication to use during elective PCI in heart transplant patients with cardiac allograft vasculopathy. (Cardiol J 2007; 14: 458-462

    Oral antiplatelet therapy in diabetes mellitus and the role of prasugrel: an overview

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    Diabetics have a prothrombotic state that includes increased platelet reactivity. This contributes to the less favorable clinical outcomes observed in diabetics experiencing acute coronary syndromes as well as stable coronary artery disease. Many diabetics are relatively resistant to or have insufficient response to several antithrombotic agents. In the setting of percutaneous coronary intervention, hyporesponsiveness to clopidogrel is particularly common among diabetics. Several strategies have been examined to further enhance the benefits of oral antiplatelet therapy in diabetics. These include increasing the dose of clopidogrel, triple antiplatelet therapy with cilostazol, and new agents such as prasugrel. The large TRITON TIMI 38 randomized trial compared clopidogrel to prasugrel in the setting of percutaneous coronary intervention for acute coronary syndromes. The diabetic subgroup (n = 3146) experienced considerable incremental benefit with a 4.8% reduction in cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke at 15-month follow-up with prasugrel treatment. Among diabetics on insulin this combined endpoint was reduced by 7.9% at 15 months. Major bleeding was not increased in the diabetic subgroup. This confirms the general hypothesis that more potent oral antiplatelet therapy can partially overcome the prothrombotic milieu and safely improve important clinical outcomes in diabetics

    A blurred reflection interpretation for the intermediate flux state in Mrk 335

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    As part of a long-term monitoring campaign of Mrk 335, deep XMM–Newton observations catch the narrow-line Seyfert 1 galaxy (NLS1) in a complex, intermediate flux interval as the active galaxy is transiting from low to high flux. Other works on these same data examined the general behaviour of the NLS1 and the conditions of its warm absorber. The analysis presented here demonstrates the X-ray continuum and timing properties can be described in a self-consistent manner adopting a blurred reflection model without any need to invoke partial covering. The rapid spectral variability appears to be driven by changes in the shape of the primary emitter that is illuminating the inner accretion disc around a rapidly spinning black hole (a > 0.7). While light bending is certainly prominent, the rather constant emissivity profile and break radius obtained in our spectral fitting suggest that the blurring parameters do not change as would be expected if the primary source varies its distance from the disc. Instead changes could be intrinsic to the power-law component. One possibility is that material in an unresolved jet above the disc falls to combine with material at the base of the jet producing the changes in the primary emitter (spectral slope and flux) without changing its distance from the disc

    Comparison of ethanol septal reduction therapy with surgical myectomy for the treatment of hypertrophic obstructive cardiomyopathy

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    AbstractOBJECTIVESThis study was designed to compare the hemodynamic efficacy of nonsurgical septal reduction therapy (NSRT) by intracoronary ethanol with standard therapy (surgical myectomy) for the treatment of hypertrophic obstructive cardiomyopathy (HOCM).BACKGROUNDNonsurgical septal reduction therapy has gained interest as a new treatment modality for patients with drug-refractory symptoms of HOCM; however, its benefits in comparison to surgery are unknown.METHODSForty-one consecutive NSRT patients at Baylor College of Medicine with one-year follow-up were compared with age- and gradient-matched septal myectomy patients at the Mayo Clinic. All patients had left ventricular outflow obstruction with a resting gradient ≥40 mm Hg and none had concomitant procedures.RESULTSThere were no baseline differences in New York Heart Association class, severity of mitral regurgitation, use of cardiac medications or exercise capacity. One death occurred during NSRT because of dissection of the left anterior descending artery. At one year, all improvements in both groups were similar. After surgical myectomy, more patients were on medications (p < 0.05) and there was a higher incidence of mild aortic regurgitation (p < 0.05). After NSRT, the incidence of pacemaker implantation for complete heart block was higher (22% vs. 2% in surgery; p = 0.02). However, seven of the nine pacemakers in the NSRT group were implanted before a modified ethanol injection technique and the use of contrast echocardiography.CONCLUSIONSNonsurgical septal reduction therapy resulted in a significantly higher incidence of complete heart block, but the risk was reduced with contrast echocardiography and slow ethanol injection. Surgical myectomy resulted in a significantly higher incidence of mild aortic regurgitation. Nonsurgical septal reduction therapy, guided by contrast echocardiography, is an effective procedure for treating patients with HOCM. The hemodynamic and functional improvements at one year are similar to those of surgical myectomy

    Guided digital health intervention for depression in Lebanon: randomised trial

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    &lt;jats:sec&gt;&lt;jats:title&gt;Background&lt;/jats:title&gt;&lt;jats:p&gt;Most people with mental disorders in communities exposed to adversity in low-income and middle-income countries (LMICs) do not receive effective care. Digital mental health interventions are scalable when digital access is adequate, and can be safely delivered during the COVID-19 pandemic.&lt;/jats:p&gt;&lt;/jats:sec&gt;&lt;jats:sec&gt;&lt;jats:title&gt;Objective&lt;/jats:title&gt;&lt;jats:p&gt;To examine the effects of a new WHO-guided digital mental health intervention, Step-by-Step, supported by a non-specialist helper in Lebanon, in the context of concurring economic, humanitarian and political crises, a large industrial disaster and the COVID-19 pandemic.&lt;/jats:p&gt;&lt;/jats:sec&gt;&lt;jats:sec&gt;&lt;jats:title&gt;Methods&lt;/jats:title&gt;&lt;jats:p&gt;We conducted a single-blind, two-arm pragmatic randomised trial, comparing guided Step-by-Step with enhanced care as usual (ECAU) among people suffering from depression and impaired functioning. Primary outcomes were depression (Patient Health Questionnaire 9 (PHQ-9)) and impaired functioning (WHO Disability Assessment Schedule-12 (WHODAS)) at post-treatment.&lt;/jats:p&gt;&lt;/jats:sec&gt;&lt;jats:sec&gt;&lt;jats:title&gt;Findings&lt;/jats:title&gt;&lt;jats:p&gt;680 people with depression (PHQ-9&amp;gt;10) and impaired functioning (WHODAS&amp;gt;16) were randomised to Step-by-Step or ECAU. Intention-to-treat analyses showed effects on depression (standardised mean differences, SMD: 0.71; 95% CI: 0.45 to 0.97), impaired functioning (SMD: 0.43; 95% CI: 0.21 to 0.65), post-traumatic stress (SMD: 0.53; 95% CI: 0.27 to 0.79), anxiety (SMD: 0.74; 95% CI: 0.49 to 0.99), subjective well-being (SMD: 0.37; 95% CI: 0.12 to 0.62) and self-identified personal problems (SMD: 0.56; 95% CI 0.29 to 0.83). Significant effects on all outcomes were retained at 3-month follow-up.&lt;/jats:p&gt;&lt;/jats:sec&gt;&lt;jats:sec&gt;&lt;jats:title&gt;Conclusions&lt;/jats:title&gt;&lt;jats:p&gt;Guided digital mental health interventions can be effective in the treatment of depression in communities exposed to adversities in LMICs, although some uncertainty remains because of high attrition.&lt;/jats:p&gt;&lt;/jats:sec&gt;&lt;jats:sec&gt;&lt;jats:title&gt;Clinical implications&lt;/jats:title&gt;&lt;jats:p&gt;Guided digital mental health interventions should be considered for implementation in LMICs.&lt;/jats:p&gt;&lt;/jats:sec&gt;&lt;jats:sec&gt;&lt;jats:title&gt;Trial registration number&lt;/jats:title&gt;&lt;jats:p&gt;ClinicalTrials.gov &lt;jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="clintrialgov" xlink:href="NCT03720769"&gt;NCT03720769&lt;/jats:ext-link&gt;.&lt;/jats:p&gt;&lt;/jats:sec&gt

    Evidence for a dynamic corona in the short-term time lags of black hole X-ray binary MAXI J1820+070

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    \ua9 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.In X-ray observations of hard state black hole X-ray binaries (BHXRBs), rapid variations in accretion disc and coronal power-law emission are correlated and show Fourier-frequency-dependent time lags. On short (0.1 s) time-scales, these lags are thought to be due to reverberation and therefore may depend strongly on the geometry of the corona. Low-frequency quasi-periodic oscillations (QPOs) are variations in X-ray flux that have been suggested to arise because of geometric changes in the corona, possibly due to general relativistic Lense-Thirring precession. Therefore, one might expect the short-term time lags to vary on the QPO time-scale. We performed novel spectral-timing analyses on Neutron Star Interior Composition ExploreR observations of the BHXRB MAXI J1820+070 during the hard state of its outburst in 2018 to investigate how the short-term time lags between a disc-dominated and a coronal power-law-dominated energy band vary on different time-scales. Our method can distinguish between variability due to the QPO and broad-band noise, and we find a linear correlation between the power-law flux and lag amplitude that is strongest at the QPO frequency. We also introduce a new method to resolve the QPO signal and determine the QPO phase dependence of the flux and lag variations, finding that both are very similar. Our results are consistent with a geometric origin of QPOs, but also provide evidence for a dynamic corona with a geometry varying in a similar way over a broad range of time-scales, not just the QPO time-scale
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