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Ultraluminous X-ray bursts (ULXBs) are ultraluminous X-ray flares with a fast rise (∼1 minute) and a slow decay (∼1 hour), which are commonly observed in extragalactic globular clusters. Most ULXBs are observational one-off bursts, whereas five flares from the same source in NGC 5128 were discovered by Irwin et al. In this article, we propose a neutron star (NS)â€"white dwarf (WD) binary model with super-Eddington accretion rates to explain the repeating behavior of the ULXB source in NGC 5128. With an eccentric orbit, the mass transfer occurs at the periastron where the WD fills its Roche lobe. The ultraluminous X-ray flares can be produced by the accretion column around the NS magnetic poles. On the other hand, some repeating fast radio bursts (FRBs) were also found in extragalactic globular clusters. Repeating ULXBs and repeating FRBs are the most violent bursts in the X-ray and radio bands, respectively. We propose a possible association between the repeating ULXBs and the repeating FRBs. Such an association is worth further investigation by follow-up observations on nearby extragalactic globular clusters. [ABSTRACT FROM AUTHOR]

Outflows are inevitably driven from the disk if the vertical component of the black hole (BH) gravity cannot resist the radiation force. We derive the mass-loss rate in the outflows by solving a dynamical equation for the vertical gas motion in the disk. The structure of a supercritical accretion disk is calculated with the radial energy advection included. We find that most inflowing gas is driven into outflows if the disk is accreting at a moderate Eddington-scaled rate (up to ∼100) at its outer edge, i.e., only a small fraction of gas is accreted by the BH, which is radiating at several Eddington luminosities, while it reaches around ten for extremely high accretion rate cases ( m ̇ ≡ M ̇ / M ̇ Edd ∼ 1000). Compared with a normal slim disk, the disk luminosity is substantially suppressed due to the mass loss in the outflows. We apply the model to the light curves of the tidal disruption events (TDEs) and find that the disk luminosity declines very slowly with time even if a typical accretion rate m ̇ ∝ t âˆ' 5 / 3 is assumed at the outer edge of the disk, which is qualitatively consistent with the observed light curves in some TDEs and helps us to understand the energy deficient phenomenon observed in the TDEs. Strong outflows from supercritical accretion disks surrounding supermassive BHs may play crucial roles in their host galaxies, which can be taken as an ingredient in the mechanical feedback models. The implications of the results on the growth of supermassive BHs are also discussed. [ABSTRACT FROM AUTHOR]

We report a single-lined white dwarfâ€"main-sequence binary system, LAMOST J172900.17+652952.8, which is discovered by the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST)’s medium-resolution time-domain surveys. The radial-velocity semi-amplitude and orbital period of the optical visible star are measured by using follow-up observations with the Palomar 200 inch telescope and light curves from the Transiting Exoplanet Survey Satellite (TESS). Thus the mass function of the invisible candidate white dwarf is derived, f (M 2) = 0.120 ± 0.003 M ⊙. The mass of the visible star is measured based on a spectral energy distribution fitting, M 1 = 0.81 âˆ' 0.06 + 0.07 M ⊙ . Hence, the mass of its invisible companion is M 2 ≳ 0.63 M ⊙. The companion ought to be a compact object rather than a main-sequence star owing to the mass ratio q = M 2/ M 1 ≳ 0.78 and the single-lined spectra. The compact object is likely to be a white dwarf if the inclination angle is not small, i ≳ 40°. By using the Galaxy Evolution Explorer (GALEX) near-UV flux, the effective temperature of the white dwarf candidate is constrained as T eff WD ≲ 12,000â€"13,500 K. It is difficult to detect white dwarfs which are outshone by their bright companions via single-epoch optical spectroscopic surveys. Therefore, optical time-domain surveys can play an important role in unveiling invisible white dwarfs and other compact objects in binaries. [ABSTRACT FROM AUTHOR]

• The non-vacuum deposited PEDOT film without external oxidant. • The dense and smooth PEDOT film using BEDOT as monomer. • The PEDOT film with high electrical conductivity and hole mobility. • The PEDOT-based PSC with enhanced performance and stability. Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is a well-known hole transport material, and widely used in inverted perovskite solar cells (PSCs). However, its high acidity and hydrophilicity from PSS can corrode the adjacent electrode and perovskite layer, seriously reducing the device performance and durability. Herein, a PEDOT film is fabricated by reactive vapor deposition method, where 5-bromo-2,3-dihydro-thieno[3,4-b][1,4]dioxine as monomer is evaporated and self-polymerized on a substrate at ambient pressure and low temperatures without external oxidants. The resulting PEDOT film is uniform and smooth with high conductivity, and the corresponding inverted CH 3 NH 3 PbI 3 (MAPbI 3) PSC exhibits superior device performance with a PCE of 21.34 %, which is one of the best efficiencies reported for the inverted PSCs with PEDOT:PSS as HTMs. Moreover, a general issue related to the acidic nature of PSS is successfully resolved, and the target device without encapsulation retained more than 80 % of the initial efficiency after 1000 h at ∼ 30 °C and 50 % RH, and kept about 80 % of the initial efficiency after 100 h in N 2 atmosphere at 80 °C. This report may provide a facile and effective method for the PEDOT fabrication applied for perovskite solar cells and other optoelectronic devices with high performance and stability. [ABSTRACT FROM AUTHOR]

When the matter from a companion star is accreted towards the central compact accretor, i.e. a black hole (BH) or a neutron star (NS), an accretion disc and a jet outflow will form, providing bight X-ray and radio emission, which is known as X-ray binaries (XRBs). In the low/hard state, there exist disc–jet couplings in XRBs, but it remains uncertain whether the jet power comes from the disc or the central accretor. Moreover, black hole X-ray binaries (BHXRBs) have different properties compared with neutron star X-ray binaries (NSXRBs): quiescent BHXRBs are typically two to three orders of magnitude less luminous than NSXRBs in X-ray, whereas BHXRBs are more radio loud than NSXRBs. In observations, an empirical correlation has been established between radio and X-ray luminosity, |$L_{\rm R} \propto L_{\rm X}^b$|⁠ , where b ∼ 0.7 for BHXRBs and b ∼ 1.4 for non-pulsating NSXRBs. However, there are some outliers of BHXRBs showing unusually steep correlation as NSXRBs at higher luminosities. In this work, under the assumption that the origin of jet power is related to the internal energy of the inner disc, we apply our magnetized, radiatively efficient thin disc model and the well-known radiatively inefficient accretion flow model to NSXRBs and BHXRBs. We find that the observed radio/X-ray correlations in XRBs can be well understood by the disc–jet couplings. [ABSTRACT FROM AUTHOR]

The occurrence rates of bright X-ray flares in z  < 1 gamma-ray bursts (GRBs) with or without observed supernovae (SNe) association were compared. Our Sample I: the z  < 1 long GRBs (LGRBs) with SNe association (SN-GRBs) and with early Swift /X-Ray Telescope (XRT) observations, consists of 18 GRBs, among which only two GRBs have bright X-ray flares. Our Sample II: for comparison, all the z  < 1 LGRBs without observed SNe association and with early Swift /XRT observations, consists of 45 GRBs, among which 16 GRBs present bright X-ray flares. Thus, the study indicates a lower occurrence rate of bright X-ray flares in Sample I (11.1 per cent) than in Sample II (35.6 per cent). In addition, if dim X-ray fluctuations are included as flares, then 16.7 per cent of Sample I and 55.6 per cent of Sample II are found to have flares, again showing the discrepancy between these two samples. We examined the physical origin of these bright X-ray flares and found that most of them are probably related to the central engine reactivity. To understand the discrepancy, we propose that such a lower occurrence rate of flares in the SN-GRB sample may hint at an energy partition among the GRB, SNe, and X-ray flares under a saturated energy budget of massive star explosion. [ABSTRACT FROM AUTHOR]

• A single-crystal complex FA 4 Pb 3 I 6 Ac 4 is synthesized. • FAPbI 3 perovskite film has been fabricated from FA 4 Pb 3 I 6 Ac 4 via anion-exchange. • The FAPbI 3 film is dense and uniform with low trap-state density. • The PSC shows a PCE of 23.65% with enhanced stability. PbI 2 as precursor has been extensively employed for the fabrication of organic–inorganic hybrid perovskite films for high-efficiency perovskite solar cells (PSCs) by using two-step solution deposition method. However, the resultant perovskite film suffers from the incomplete reaction of PbI 2 and the volumetric expansion of the film, affecting both the performance and stability of the PSCs. Here, a single-crystal complex FA 4 Pb 3 I 6 Ac 4 (Ac−: CH 3 COO−) is synthesized, and utilized to replace PbI 2 for the fabrication of FAPbI 3 -based perovskite film in ambient conditions. The solution-processed crystal complex has good film-forming ability, and can be directly converted into stable black-phase FAPbI 3 perovskite at room temperature through anion exchange reaction between Ac− and I− upon coating with iodide salt solution. By the strategy, a dense and uniform perovskite film is obtained with reduced trap-state density and prolonged charge lifetime. The champion device delivers a power conversion efficiency (PCE) of 23.65% with high reproductivity. Importantly, the unencapsulated device exhibits a dramatically improved operational stability under temperature and humidity conditions. [ABSTRACT FROM AUTHOR]

• Multifunctional interlayer for highly stable and efficient P3HT-based PSCs. • Simultaneously passivating the defects of perovskite and improving the interface contaction and charge extraction. • Inducing the oriented self-assembly of P3HT and promoting efficient charge transfer. • Enhancing the thermal and moisture resistance of the perovskite film. Poly (3-hexylthiophene) (P3HT) has been recognized to be a potential hole-transport material (HTM) for stable and efficient perovskite solar cells (PSCs) due to its low cost, high hole mobility, and solution processability. However, the uncontrolled configuration of the polymer chains and the poor contact on the perovskite film restrain the charge extraction and transport in the devices. Here, we demonstrate a simple and versatile strategy for the fabrication of stable and efficient P3HT-based PSCs, using 1-hexyl-2,5-dimethyl-1H-pyrrole-3-carboxylic acid (HPCA) as interlayer between perovskite and P3HT layers. The carboxyl group in HPCA can effectively suppress anion-vacancy defects at the grain boundaries and surface of the perovskite film, reducing the trap state density and improving the carrier lifetimes. Moreover, the peripheral hexyl-pyrrole in HPCA can improve the interface contact between the perovskite and P3HT, and regulate P3HT orientation and improve charge extraction and transport in the device. As a result, the PSC using the dopant-free P3HT HTM yields a power conversion efficiency (PCE) of 20.8%, along with superior stability at a relative humidity of 60%, heat at 80 °C, or under continuous light illumination. [ABSTRACT FROM AUTHOR]

• In-Situ Polymerization of conducting polymer PEDOT in Perovskite Thin Films. • Simultaneously passivating the defects and improving carrier extraction efficiency. • Enhancing the thermal and moisture resistance of the perovskite film. • The PSCs with 22.58% PCE with enhanced stability. Solution-processed polycrystalline perovskite films have detrimental defects in the bulk and surfaces/grain boundaries, especially the uncoordinated lead ions (Pb2+) with low formation energy, limiting both the performance and stability of the photovoltaic devices. In this work, a conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is incorporated into a bulk perovskite film by a facile in-situ polymerization method, where 5-bromo-2,3-dihydro-thieno[3,4-b][1,4]dioxine (BEDOT) as monomer is directly added to a perovskite precursor solution and then in-situ polymerized within the perovskite film during the film formation. The PEDOT is chemically anchored at the surface and grain boundaries of the perovskite film via interaction of sulfur and oxygen atoms in PEDOT with uncoordinated lead ions in the perovskite, passivating the surface and bulk defects and also improving the charge extraction efficiency in the solar cell. Moreover, robust and hydrophobic properties of PEDOT can enhance the thermal and moisture resistance of the perovskite film. As a result, a champion power conversion efficiency (PCE) of 22.58% is achieved, along with significantly enhanced environmental, thermal, and light-soaking stability. [ABSTRACT FROM AUTHOR]

Rapid temporal variability has been widely observed in the light curves of gamma-ray bursts (GRBs). One possible mechanism for such variability is related to the relativistic eddies in the jet. In this paper, we include the contribution of the inter-eddy medium together with the eddies to the gamma-ray emission. We show that the gamma-ray emission can either lead or lag behind the observed synchrotron emission, where the latter originates in the inter-eddy medium and provides most of the seed photons for producing gamma-ray emission through inverse Compton scattering. As a consequence, we argue that the lead/lag found in non-stationary short-lived light curves may not reveal the intrinsic lead/lag of different emission components. In addition, our results may explain the lead of gamma-ray emission with respect to optical emission observed in GRB 080319B. [ABSTRACT FROM AUTHOR]

The variability of active galactic nuclei (AGNs) has long been servicing as an essential avenue of exploring the accretion physics of a black hole (BH). There are two commonly used methods for analyzing AGN variability. First, the AGN variability, characterized by the structure function (SF) of a single band, can be well described by a damped random walk (DRW) process on timescales longer than ∼weeks, shorter than which departures have been reported. Second, the color variation (CV) between two bands behaves timescale dependent, raising challenges to the widely accepted reprocessing scenario. However, both the departure from the DRW process and the timescale-dependent CV are hitherto limited to AGNs, mainly quasars, at the supermassive scale. Here, utilizing the high-cadence multiwavelength monitoring on NGC 4395 harboring an intermediate-mass BH, we unveil at the intermediate-mass scale for the first time, prominent departures from the DRW process at timescales shorter than ∼hours in all three nights and bands, and plausible timescale-dependent CVs in the two longest nights of observation. Furthermore, comparing SFs of NGC 4395 to four AGNs at the supermassive scale, we suggest a new scaling relation between the timescale (τ ; across nearly 3 orders of magnitude) and the BH mass (M BH): τ ∝ M BH γ where the exponent γ is likely ≃0.6–0.8. This exponent differs from most previous measurements, but confirms a few, and is consistent with a recent theoretical prediction, suggesting a similar accretion process in AGNs across different mass scales. [ABSTRACT FROM AUTHOR]

ABSTRACT In accretion systems, outflows may have significant influence on luminosity fluctuations. In this paper, following Lyubarskii's general scheme, we revisit the power spectral density of luminosity fluctuations by taking into account the role of outflows. Our analysis is based on the assumption that the coupling between the local outflow and inflow is weak for accretion-rate fluctuations. We find that, for inflow mass accretion rate , the power spectrum of the flicker-noise component will present a power-law distribution p( f) ∝ f−(1 + 4 s/3) for advection-dominated flows. We also obtain descriptions of p( f) for both standard thin discs and neutrino-cooled discs, which show that the power-law index of a neutrino-cooled disc is generally larger than that of a photon-cooled disc. Furthermore, the relationship obtained between p( f) and s indicates the possibility of evaluating the strength of outflows through the power spectrum in X-ray binaries and gamma-ray bursts. In addition, we discuss the possible influence of outflow-inflow coupling on our results. [ABSTRACT FROM AUTHOR]

ABSTRACT The stress evolution process is taken into account in the linear stability analysis of standard thin accretion discs. We find that the growth rate of thermally unstable modes can decrease significantly owing to the stress delay, which may help to understand the quasi-periodic variability of GRS 1915+105. We also discuss the possible application of stress evolution to the stability of the Shapiro-Lightman-Eardley disc. [ABSTRACT FROM AUTHOR]

We present LAMOST J041920.07+072545.4 (hereafter J0419), a close binary consisting of a bloated, extremely low mass pre-white dwarf (pre-ELM WD) and a compact object with an orbital period of 0.607189 days. The large-amplitude ellipsoidal variations and the evident Balmer and He i emission lines suggest a filled Roche lobe and ongoing mass transfer. No outburst events were detected in the 15 years of monitoring of J0419, indicating a very low mass transfer rate. The temperature of the pre-ELM, T eff = 5793 âˆ' 133 + 124 K , makes it cooler than the known ELMs, but hotter than most cataclysmic variable donors. Combining the mean density within the Roche lobe and the radius constrained from our spectral energy distribution fitting, we obtain the mass of the pre-ELM, M 1 = 0.176 ± 0.014 M ⊙. The joint fitting of light and radial velocity curves yields an inclination angle of i = 66.5 âˆ' 1.7 + 1.4 degrees, corresponding to a mass of the compact object of M 2 = 1.09 ± 0.05 M ⊙. The very bloated pre-ELM has a smaller surface gravity ( log g = 3.9 ± 0.01 , R 1 = 0.78 ± 0.02 R ⊙) than the known ELMs or pre-ELMs. The temperature and the luminosity ( L bol = 0.62 âˆ' 0.10 + 0.11 L ⊙ ) of J0419 are close to those of the main sequence, which makes the selection of such systems through the H-R diagram inefficient. Based on the evolutionary model, the relatively long period and small log g indicate that J0419 could be close to the “bifurcation period” in the orbital evolution, which makes J0419 a unique source to connect ELM/pre-ELM WD systems, wide binaries, and cataclysmic variables. [ABSTRACT FROM AUTHOR]

We revisit the eccentric neutron star (NS)â€"white dwarf (WD) binary model for the periodic activity of fast radio burst (FRB) sources, by including the effects of gravitational-wave (GW) radiation. In this model, the WD fills its Roche lobe at the periastron and mass transfer occurs from the WD to the NS. The accreted materials can be fragmented and arrive at the NS episodically, resulting in multiple bursts through curvature radiation. Consequently, the WD may be kicked away owing to the conservation of angular momentum. To initiate the next mass transfer, the WD has to refill its Roche lobe through GW radiation. In this scenario, whether the periodic activity can show up relies on three timescales, i.e., the orbital period P orb, the timescale T GW for the Roche lobe to be refilled, and the time span T frag for all the episodic events corresponding to each mass-transfer process. Only when the two conditions T GW ≲ P orb and T frag < P orb are both satisfied, the periodic activity will manifest itself and the period should be equal to P orb. In this spirit, the periodic activity is more likely to show up for relatively long periods (P orb ≳ several days). Thus, it is reasonable that FRBs 180916 and 121102, the only two sources having been claimed to manifest periodic activity, both correspond to relatively long periods. [ABSTRACT FROM AUTHOR]

We investigate the vertical structure of neutrino-dominated accretion flows in spherical coordinates. In our calculation, the empty funnel along the rotation axis can naturally explain the neutrino annihilable ejection. The outflow is possible due to the positive Bernoulli function, and the luminosity of neutrino annihilation is enhanced by one or two orders of magnitude. [ABSTRACT FROM AUTHOR]

GRB 170817A, detected by Fermi Gamma-ray Burst Monitor 1.7 s after the merger of a neutron star (NS) binary, provides the first direct evidence for a link between such a merger and a short-duration gamma-ray burst. The X-ray observations after GRB 170817A indicate a possible X-ray flare with a peak luminosity |$L_{\rm peak} \sim 2\times 10^{39}\, {\rm erg\, s}^{-1}$| near day 156. Here we show that this X-ray flare may be understood based on a slim disc around a compact object. On the one hand, there exists the maximal accretion rate |$\dot{M}_{\rm max}$| for the slim disc, above which an optically thick outflow is significant and radiation from the disc is obscured. Based on the energy balance analysis, we find that |$\dot{M}_{\rm max}$| is in the range of |${\sim } 4\dot{M}_{\rm Edd}$| and |${\sim } 21\dot{M}_{\rm Edd}$| when the angular velocity of the slim disc is between |$\rm (1/5)^{1/2}\Omega _K$| and |$\rm \Omega _K$| (where |$\dot{M}_{\rm Edd}$| is the Eddington accretion rate and ΩK is the Keplerian angular velocity). With |$\dot{M}_{\rm max}$|⁠, the slim disc can provide a luminosity ∼ L peak for a compact object of |$2.5 \, \mathrm{M}_{\odot }$|⁠. On the other hand, if the merger of two NSs forms a typical neutrino-dominated accretion disc whose accretion rate |$\dot{M}$| follows a power-law decline with an index −1.8, then the system must pass through the outflow regime and enter the slim disc in ∼11–355 d. These results imply that a post-merger slim accretion disc could account for the observed late-time L peak. [ABSTRACT FROM AUTHOR]

We propose the thick-disc model of Gu et al. to interpret the transition between soft ultraluminous state (SUL) and supersoft ultraluminous (SSUL) state in NGC 247. As accretion rate increases, the inner disc will puff up and act as shield to block the innermost X-ray emission regions and absorb both soft and hard X-ray photons. The absorbed X-ray emission will be re-radiated as a much softer blackbody X-ray spectrum. Hence NGC 247 shows flux dips in the hard X-ray band and transits from the SUL state to the SSUL state. The ∼200 s transition time-scale can be explained by the viscous time-scale. According to our model, the inner disc in the supersoft state is thicker and has smaller viscous time-scale than in the soft state. X-ray flux variability, which is assumed to be driven by accretion rate fluctuations, might be viscous time-scale invariant. Therefore, in the SSUL state, NGC 247 is more variable. The bolometric luminosity is saturated in the thick disc; the observed radius–temperature relation can therefore be naturally explained. [ABSTRACT FROM AUTHOR]

By taking into account photon absorption, we investigate the vertical structure of accretion flows with comparable radiation and gas pressures. We consider two separate energy equations for matter and radiation in the diffusion limit. In order to solve the set of radiation hydrodynamic equations in steady state and axisymmetric configuration, we employ self-similar technique in the radial direction. We need the reflection symmetry about the mid-plane to find gas density at the equator. For a typical solution, we assume that the gas pressure has 10–50 per cent portion of the total pressure. In this paper, since the radiation energy is involved directly, we are able to estimate how much energy of viscous heating is transported in the radial direction and advected towards the central object. Our results show that although the mass accretion rate does not approach the Eddington limit, the energy advection is rather high. Moreover, in a disc with greater accretion rate and less portion of gas pressure at the total pressure, more energy is advected to its centre. In addition, as we expect the accretion flow becomes thicker with greater values of gas pressure. Based on Solberg–Høiland conditions, we notice that the flow is convectively stable in all parts of such a disc. [ABSTRACT FROM AUTHOR]

We present a deep optical imaging campaign on the starburst galaxy NGC 4631 with CFHT/MegaCam. By supplementing the HST/ACS and Chandra/ACIS archival data, we search for the optical counterpart candidates of the five brightest X-ray sources in this galaxy, four of which are identified as ultraluminous X-ray sources (ULXs). The stellar environments of the X-ray sources are analyzed using the extinction-corrected color–magnitude diagrams and the isochrone models. We discover a highly asymmetric bubble nebula around X4 that exhibits different morphology in the H α and [O iii ] images. The [O iii ]/H α ratio map shows that the H α -bright bubble may be formed mainly via the shock ionization by the one-sided jet/outflow, while the more compact [O iii ] structure is photoionized by the ULX. We constrain the bubble expansion velocity and interstellar medium density with the MAPPINGS V code and hence estimate the mechanical power injected into the bubble as P w ∼ 5 × 1040 erg s−1 and the corresponding bubble age as ∼7 × 105 yr. Relativistic jets are needed to provide such a level of mechanical power with a mass-loss rate of ∼10−7 M ⊙ yr−1. Besides the accretion, the black hole spin is likely an additional energy source for the super-Eddington jet power. [ABSTRACT FROM AUTHOR]

We investigate the thermal stability of optically thin, two-temperature, radiative cooling-dominated accretion disks. Our linear analysis shows that the disk is thermally unstable without magnetic fields, which agrees with previous stability analysis on the Shapiro-Lightman-Eardley disk. By taking into account the effects of magnetic fields, however, we find that the disk can be, or partly be, thermally stable. Our results may be helpful to understand the outflows in optically thin flows. Moreover, such radiative cooling-dominated disks may provide a new explanation of the different behaviors between black hole and neutron star X-ray binaries on the radio/X-ray correlation. [ABSTRACT FROM AUTHOR]

The Eastern Staging System, which was specially developed for patients undergoing surgical resection for hepatocellular carcinoma (HCC), has been proposed for more than ten years. To prospectively validate the predictive accuracy of the Eastern staging on long-term survival after HCC resection. Patients who underwent hepatectomy for HCC from 2011 to 2020 at 10 Chinese hospitals were identified from a prospectively collected database. The survival predictive accuracy was evaluated and compared between the Eastern Staging with six other staging systems, including the JIS, BCLC, Okuda, CLIP, 8th AJCC TNM, and HKLC staging. Among 2365 patients, the 1-, 3-, and 5-year overall survival rates were 84.2%, 64.5%, and 52.6%, respectively. Among these seven staging systems, the Eastern staging was associated with the best monotonicity of gradients (linear trend χ2: 408.5) and homogeneity (likelihood ratio χ2: 447.3), and the highest discriminatory ability (the areas under curves for 1-, 3-, and 5-year mortality: 0.776, 0.787, and 0.768, respectively). In addition, the Eastern staging was the most informative staging system in predicting survival (Akaike information criterion: 2982.33). Using a large multicenter prospectively collected database, the Eastern Staging was found to show the best predictive accuracy on long-term overall survival in patients with resectable HCC than the other 6 commonly-used staging systems. [Display omitted] [ABSTRACT FROM AUTHOR]

We study the fluctuations of standard thin accretion disks by linear analysis of the time-dependent energy equation together with the vertical hydrostatic equilibrium and the equation of state. We show that some of the simulation results in Hirose et al., such as the time delay, the relationship of power spectra, and the correlation between magnetic energy and radiation energy, can be understood well by our analytic results. [ABSTRACT FROM AUTHOR]

By taking into account the local energy balance per unit volume between the viscous heating and the advective cooling plus the radiative cooling, we investigate the vertical structure of radiation pressure-supported accretion disks in spherical coordinates. Our solutions show that the photosphere of the disk is close to the polar axis and therefore the disk seems to be extremely thick. However, the density profile implies that most of the accreted matter exists in a moderate range around the equatorial plane. We show that the well-known polytropic relation between the pressure and the density is unsuitable for describing the vertical structure of radiation pressure-supported disks. More importantly, we find that the energy advection is significant even for slightly sub-Eddington accretion disks. We argue that the non-negligible advection may help us understand why the standard thin disk model is likely to be inaccurate above ∼0.3 Eddington luminosity, which was found by some works on black hole spin measurement. Furthermore, the solutions satisfy the Solberg-Høiland conditions, which indicate the disk to be convectively stable. In addition, we discuss the possible link between our disk model and ultraluminous X-ray sources. [ABSTRACT FROM AUTHOR]

The optical light curves of quiescent black hole low-mass X-ray binaries often exhibit significant nonellipsoidal variabilities, showing the photospheric radiation of the companion star is veiled by other sources of optical emission. Assessing this “veiling” effect is critical to the black hole mass measurement. Here in this work, we carry out a strictly simultaneous spectroscopic and photometric campaign on the prototype of black hole low-mass X-ray binary A0620-00. We find that for each observation epoch, the extra optical flux beyond a pure ellipsoidal modulation is positively correlated with the fraction of veiling emission, indicating the accretion disk contributes most of the nonellipsoidal variations. Meanwhile, we also obtain a K2V spectral classification of the companion, as well as the measurements of the companion’s rotational velocity v sin i = 83.8 ± 1.9 km sâˆ'1 and the mass ratio between the companion and the black hole q = 0.063 ± 0.004. [ABSTRACT FROM AUTHOR]

The existence of intermediate-mass black holes (IMBHs) in globular clusters (GCs) remains a crucial problem. Searching for IMBHs in GCs reveals a discrepancy between radio observations and dynamical modelings: the upper mass limits constrained by radio observations are systematically lower than that of dynamical modelings. One possibility for such a discrepancy is that, as we suggest in this work, there exist outflows in accretion flows. Our results indicate that, for most sources, current radio observations cannot rule out the possibility that IMBHs may exist in GCs. In addition, we adopt an relation to revisit this issue, which confirms the results obtained by the fundamental plane relation. [ABSTRACT FROM AUTHOR]

Background and aims: Although adjuvant transcatheter arterial chemoembolization (TACE) for resected hepatocellular carcinoma (HCC) may improve survival for some patients, identifying which patients can benefit remains challenging. The present study aimed to construct a survival prediction calculator for individualized estimating the net survival benefit of adjuvant TACE for patients with resected HCC. Methods: From a multicenter database, consecutive patients undergoing curative resection for HCC were enrolled and divided into the developing and validation cohorts. Using the independent survival predictors in the developing cohort, two nomogram models were constructed for patients with and without adjuvant TACE, respectively, which predictive performance was validated internally and externally by measuring concordance index (C-index) and calibration. The difference between two estimates of the prediction models was the expected survival benefit of adjuvant TACE. Results: A total of 2514 patients met the inclusion criteria for the study. The nomogram prediction models for patients with and without adjuvant TACE were, respectively, built by incorporating the same eight independent survival predictors, including portal hypertension, Child–Pugh score, alpha-fetoprotein level, tumor size and number, macrovascular and microvascular invasion, and resection margin. These two prediction models demonstrated good calibration and discrimination, with all the C-indexes of greater than 0.75 in the developing and validation cohorts. A browser-based calculator was generated for individualized estimating the net survival benefit of adjuvant TACE. Conclusions: Based on large-scale real-world data, an easy-to-use online calculator can be adopted as a decision aid to predict which patients with resected HCC can benefit from adjuvant TACE. [ABSTRACT FROM AUTHOR]

The timescales of the variabilities in changing look (CL) active galactic nuclei (AGNs) are usually on the order of years to tens of years (some of them are even shorter than one year), which is much shorter than the viscous timescale of a standard thin accretion disk. This implies that the variabilities of CL AGNs cannot be reproduced by varying the mass accretion rate of the thin disk. In this work, we employ a magnetic accretion disk-outflow model to calculate the inflow time of the disk predominantly driven by magnetic outflows. In this model, most angular momentum of the gas in the disk is carried away by the outflows, and therefore its radial velocity can be substantially higher than that of a conventional viscous disk. Our calculations show that the inflow time of such a disk with outflows can be around several years to tens of years. The calculated spectra of the disk with outflows can fit the observed spectra of a CL AGN Mrk 1018 quite well both in the low and high states. The derived inflow time of such a disk with outflows is around 5 yr in the high state, while it becomes ∼20 yr in the low state, which is roughly consistent with the observations of the variabilities in Mrk 1018. [ABSTRACT FROM AUTHOR]

Aging of the population and prolonged life expectancy have significantly increased the number of elderly patients undergoing hepatectomy for hepatocellular carcinoma (HCC). However, potential benefits, especially long-term oncologic outcomes of hepatectomy for elderly patients with HCC remain unclear. Patients treated with curative-intent hepatectomy for HCC in 8 Chinese hospitals were enrolled. Patients were divided into the elderly (≥70 years old) and younger (<70 years old) groups. Overall survival (OS), cancer-specific survival (CSS), and time-to-recurrence (TTR) were compared. Risk factors of CSS and TTR were evaluated by univariable and multivariable competing-risk regression analyses. Of 2134 patients, 259 (12.1%) and 1875 (87.9%) were elderly and younger aged, respectively. Postoperative 30-day and 90-day mortality was comparable among elderly and younger patients. Compared with younger patients, the elderly had a worse 5-year OS (49.4% vs. 55.3%, P = 0.032), yet a better 5-year CCS (74.5% vs. 61.0%, P = 0.005) and a lower 5-year TTR (33.7% vs. 44.9%, P < 0.001), respectively. Multivariable analyses identified that elder age was independently associated with more favorable CSS (HR 0.74, 95%CI 0.58–0.90, P = 0.011) and TTR (0.69, 0.53–0.88, P < 0.001) but was not associated with OS (P = 0.136). Age by itself is not a contraindication to surgery, and selected elderly patients with HCC can benefit from hepatectomy. Compared with younger patients, elderly patients have noninferior oncologic outcomes following hepatectomy for HCC. [ABSTRACT FROM AUTHOR]

A clear definition of "early recurrence" after hepatocellular carcinoma (HCC) resection is still lacking. This study aimed to determine the optimal cutoff between early and late HCC recurrence, and develop nomograms for pre- and postoperative prediction of early recurrence. Patients undergoing HCC resection were identified from a multi-institutional Chinese database. Minimum P -value approach was adopted to calculate optimal cut-off to define early recurrence. Pre- and postoperative risk factors for early recurrence were identified and further used for nomogram construction. The results were externally validated by a Western cohort. Among 1501 patients identified, 539 (35.9%) were recurrence-free. The optimal length to distinguish between early (n = 340, 35.3%) and late recurrence (n = 622, 64.7%) was 8 months. Multivariable logistic regression analyses identified 5 preoperative and 8 postoperative factors for early recurrence, which were further incorporated into preoperative and postoperative nomograms (C-index: 0.785 and 0.834). The calibration plots for the probability of early recurrence fitted well. The nomogram performance was maintained using the validation dataset (C-index: 0.777 for preoperative prediction and 0.842 for postoperative prediction). An interval of 8 months was the optimal threshold for defining early HCC recurrence. The two web-based nomograms have been published to allow accurate pre- and postoperative prediction of early recurrence. These may offer useful guidance for individual treatment or follow up for patients with resectable HCC. [ABSTRACT FROM AUTHOR]

The resection margin (RM) status and microscopic vascular invasion (MVI) are known prognostic factors for hepatocellular carcinoma (HCC). An enhanced understanding of their impact on long-term prognosis is required to improve oncological outcomes. Using multi-institutional data, the different impact of the RM status (narrow, <1 cm, or wide, ≥1 cm) and MVI (positive or negative) on overall survival (OS) and recurrence-free survival (RFS) after curative liver resection of solitary HCC without macrovascular invasion was analyzed. In 801 patients, 306 (38%) had a narrow RM and 352 (44%) had positive MVI. The median OS and RFS were 109.8 and 74.8 months in patients with wide RM & negative MVI, 93.5 and 53.1 months with wide RM & positive MVI, 79.2 and 41.6 months with narrow RM & negative MVI, and 69.2 and 37.5 months with narrow RM & positive MVI (both P < 0.01). On multivariable analyses, narrow RM & positive MVI had the highest hazard ratio with reduced OS and RFS (HR 2.96, 95% CI 2.11–4.17, and HR 3.15, 95% CI, 2.09–4.67, respectively). Concomitant having narrow RM and positive MVI increases the risks of postoperative death and recurrence by about 2-fold in patients with solitary HCC. [ABSTRACT FROM AUTHOR]

Abstract Background Serum prealbumin is a sensitive and stable marker for nutritional status and liver function. Whether preoperative prealbumin level is associated with long-term prognosis in patients undergoing liver resection for hepatocellular carcinoma (HCC) is unclear. Methods Patients who underwent liver resection for HCC between 2001 and 2014 at six institutions were enrolled. These patients were divided into the low and normal prealbumin groups using a cut-off value of 170 mg/L for preoperative prealbumin level. The overall survival (OS) and recurrence-free survival (RFS) were compared between them. Results In 1483 patients, 437 (29%) had a low prealbumin level. The 3- and 5-year OS and RFS rates of patients in the low-prealbumin group were 57 and 31%, and 40 and 20%, respectively, which were significantly poorer than those in the normal-prealbumin group (76 and 43%, and 56 and 28%, respectively, both p < 0.001). Multivariable Cox-regression analyses revealed that preoperative prealbumin level was an independent predictor of OS (HR, 1.45, 95% CI: 1.24–1.70, p <0.001) and RFS (HR, 1.28, 95% CI: 1.10–1.48, p <0.001). Conclusions Preoperative prealbumin level could be used in predicting long-term prognosis for patients undergoing liver resection for HCC. [ABSTRACT FROM AUTHOR]

The standard thin disk model predicts that when the accretion rate is moderately high, the disk is radiation-pressure-dominated and thermally unstable. However, observations indicate the opposite, namely the disk is quite stable. We present an explanation in this work by taking into account the role of the magnetic field which was ignored in the previous analysis. [ABSTRACT FROM AUTHOR]

We present the effects of self-gravity on the vertical structure and neutrino luminosity of the neutrino-dominated accretion disks in cylindrical coordinates. It is found that significant changes of the structure appear in the outer region of the disk, especially for high accretion rates (e.g., ≳ 1 M☼ s–1), and thus cause the slight increase in the neutrino luminosity. Furthermore, the gravitational instability of the disk is reviewed by the vertical distribution of the Toomre parameter, which may account for the late-time flares in gamma-ray bursts and the extended emission in short-duration gamma-ray bursts. [ABSTRACT FROM AUTHOR]

The giant X-ray bump of GRB 121027A observed by Swift is different from the typical X-ray flares in gamma-ray bursts. The observed structural variability in the rise and decay phases of the bump has four components. Of these four components, only the data in the bump from about 5300 to about 6100 s is of good enough quality to be analysed using the stepwise filter correlation method. A $86^{+5.9}_{-9.4} \rm s$ periodic oscillation is postulated, which is confirmed by the Lomb–Scargle method. A jet precession model is proposed to account for this variability. [ABSTRACT FROM AUTHOR]

B Introduction: b The long-term prognosis after liver resection for multinodular (>= 3 nodules) hepatocellular carcinoma (HCC) is generally considered to be unfavorable. B Method: b From a multicenter database, consecutive patients who underwent curative-intent liver resection for HCC with 2 tumor nodules and without macrovascular invasion were retrospectively reviewed. B Conclusion: b Liver resection was safe and feasible in patients having HCC with 2 tumor nodules, with acceptable perioperative and long-term outcomes. [Extracted from the article]

Soft extended emission (EE) following initial hard spikes up to 100 s was observed with Swift/BAT for about half of known short-type gamma-ray bursts (SGRBs). This challenges the conversional central engine models of SGRBs, i.e., compact star merger models. In the framework of black-hole-neutron-star merger models, we study the roles of radial angular momentum transfer in the disk and the magnetic barrier around the black hole in the activity of SGRB central engines. We show that radial angular momentum transfer may significantly prolong the lifetime of the accretion process, which may be divided into multiple episodes by the magnetic barrier. Our numerical calculations based on models of neutrino-dominated accretion flows suggest that disk mass is critical for producing the observed EE. In the case of the mass being ∼0.8 M☼, our model can reproduce the observed timescale and luminosity of both the main and the EE episodes in a reasonable parameter set. The predicted luminosity of the EE component is lower than the observed EE within about one order of magnitude and the timescale is shorter than 20 s if the disk mass is ∼0.2 M☼. Swift/BAT-like instruments may be not sensitive enough to detect the EE component in this case. We argue that the EE component could be a probe for the merger process and disk formation for compact star mergers. [ABSTRACT FROM AUTHOR]

The physical nature of gamma-ray bursts (GRBs) is believed to involve an ultra-relativistic jet. The observed complex structure of light curves motivates the idea of jet precession. In this work, we study the gravitational waves of jet precession based on neutrino-dominated accretion disks around black holes, which may account for the central engine of GRBs. In our model, the jet and the inner part of the disk may precess along with the black hole, which is driven by the outer part of the disk. Gravitational waves are therefore expected to be significant from this black-hole-inner-disk precession system. By comparing our numerical results with the sensitivity of some detectors, we find that it is possible for DECIGO and BBO to detect such gravitational waves, particularly for GRBs in the Local Group. [ABSTRACT FROM AUTHOR]

B Introduction: b Surgical resection for hepatocellular carcinoma (HCC) is potentially curative, but long-term survival remains unsatisfactory. B Result: b Of the 377 patients in this study, 88 (23.3%) received preoperative TACE followed by surgical resection. B Conclusion: b Preoperative TACE did not increase peri-operative morbidity or mortality, yet was associated with an improve OS and RFS after liver resection of huge HCC (>= 10 cm). [Extracted from the article]