Disk, Corona, Jet Connection in the Intermediate State of MAXI J1820+070 Revealed by NICER Spectral-timing Analysis

We analyze five epochs of Neutron star Interior Composition Explorer (NICER) data of the black hole X-ray binary MAXI J1820+070 during the bright hard-to-soft state transition in its 2018 outburst with both reflection spectroscopy and Fourier-resolved timing analysis. We confirm the previous discovery of reverberation lags in the hard state, and find that the frequency range where the (soft) reverberation lag dominates decreases with the reverberation lag amplitude increasing during the transition, suggesting an increasing X-ray emitting region, possibly due to an expanding corona. By jointly fitting the lag-energy spectra in a number of broad frequency ranges with the reverberation model reltrans, we find the increase in reverberation lag is best described by an increase in the X-ray coronal height. This result, along with the finding that the corona contracts in the hard state, suggests a close relationship between spatial extent of the X-ray corona and the radio jet. We find the corona expansion (as probed by reverberation) precedes a radio flare by ~5 days, which may suggest that the hard-to-soft transition is marked by the corona expanding vertically and launching a jet knot that propagates along the jet stream at relativistic velocities

National Trends and Outcomes in Isolated Tricuspid Valve Surgery.

BACKGROUND: Severe isolated disease of the tricuspid valve (TV) is increasing and results in intractable right heart failure. However, isolated TV surgery is rarely performed, and there are little data describing surgical outcomes. OBJECTIVES: The purpose of this study was to evaluate contemporary utilization trends and in-hospital outcomes for isolated TV surgery in the United States. METHODS: Patients age \u3e18 years who underwent TV repair or replacement from 2004 to 2013 were identified using the National Inpatient Sample. Patients with congenital heart disease, with endocarditis, and undergoing concomitant cardiac operations except for coronary bypass surgery were excluded. RESULTS: Over a 10-year period, a total of 5,005 isolated TV operations were performed nationally. Operations per year increased from 290 in 2004 to 780 in 2013 (p \u3c 0.001 for trend). In-hospital mortality was 8.8% and did not vary across the study period. Adjusted in-hospital mortality for TV replacement was significantly higher than TV repair (odds ratio: 1.91; 95% confidence interval: 1.18 to 3.09; p = 0.009). CONCLUSIONS: Isolated TV surgery is rarely performed, although utilization has increased over time. However, despite an increase in surgical volume, operative mortality has not changed. Mortality is greatest in patients undergoing valve replacement. Given the increasing prevalence of isolated TV disease in the population, research into optimal surgical timing and patient selection is critical