First, we extend the Burns-Krantz rigidity for the unit disk to domains with corners. Then, we prove the Burns-Krantz type rigidity for some fibered domains over these one-dimensional domains with ...corners.
We concentrate on the Fano effect in the Andreev reflection spectra of a two-arm three-terminal normal/superconducting (NS) heterojunction, in which one normal metallic lead is coupled to two s-wave ...superconducting leads via respective quantum dots. It is found that if an arm of this system provides the reference channel for the Andreev reflection, Fano antiresonance is allowed to appear in the differential conductance spectrum. Superconducting phase difference between the superconducting leads plays its nontrivial role in modulating the Fano lineshapes in the conductance spectra. However in the linear conductance spectra, Fano lineshapes are relatively weak and not related to any antiresonance point, though they can be reversed by adjusting the dot level of the reference channel. It can be believed that the results of this work will help to understand the Fano interference in the Andreev reflection driven by two respective superconducting leads.
There has been suggestive evidence of intermediate-mass black holes (IMBHs; 103−5 M ) existing in some globular clusters (GCs) and dwarf galaxies, but IMBHs as a population remain elusive. As a ...main-sequence star passes too close by an IMBH it might be tidally captured and disrupted. We study the long-term accretion and observational consequence of such tidal disruption events. The disruption radius is hundreds to thousands of the BH's Schwarzschild radius, so the circularization of the falling-back debris stream is very inefficient due to weak general relativity effects. Due to this and a high mass fallback rate, the bound debris initially goes through a ∼10 yr long super-Eddington accretion phase. The photospheric emission of the outflow ejected during this phase dominates the observable radiation and peaks in the UV/optical bands with a luminosity of . After the accretion rate drops below the Eddington rate, the bolometric luminosity follows the conventional t−5/3 power-law decay, and X-rays from the inner accretion disk start to be seen. Modeling the newly reported IMBH tidal disruption event candidate 3XMM J2150-0551, we find a general consistency between the data and predictions. The search for these luminous, long-term events in GCs and nearby dwarf galaxies could unveil the IMBH population.
Abstract An expanding X-ray halo or rings appear when short pulses of X-ray radiation from a background source are scattered by clouds of dust in the Milky Way. We study the X-ray rings of the ...brightest gamma-ray burst (GRB) 221009A, detected by the Swift X-Ray Telescope. The rings center on the GRB position, and their angular radii increase with time. We identify five major expanding rings, and our modeling of their expansion history suggests that they are scattered off from five dusty clouds at distances of 0.4–13 kpc from the observer. Given an assumed prompt X-ray fluence of this GRB, the fluxes of those rings suggest that these clouds have dust grain column densities of 10 7∼8 cm −2 . More interestingly, our time-dependent spectral analysis of these rings shows that they all experience spectral softening, i.e., getting softer as they expand, with spectral indices ranging from 2.2 to 5, consistent with what the dust-scattering model predicts.
Pulsar–black hole (BH) close binary systems, which have not been found yet, are unique laboratories for testing theories of gravity and understanding the formation channels of gravitational-wave ...sources. We study the self-gravitational lensing effect in a pulsar–BH system on the pulsar’s emission. Because this effect occurs once per orbital period for almost edge-on binaries, we find that it could generate apparently ultralong period (minutes to hours) radio signals when the intrinsic pulsar signal is too weak to detect. Each of such lensed signals, or “pulse,” is composed of a number of amplified intrinsic pulsar pulses. We estimate that a radio telescope with a sensitivity of 10 mJy could detect a few systems that emit such signals in our Galaxy. The model is applied to three recently found puzzling long-period radio sources: GLEAM-X J1627, PSR J0901-4046, and GPM J1839-10. To explain their observed signal durations and periods, the masses of their lensing components are estimated as ∼104M⊙, ∼4 M⊙, and 103−6M⊙, respectively, with their binary coalescence times ranging from a few tens to thousands of years. However, the implied merger rates (as high as ∼103−4 Myr−1 per galaxy) and the large period decay rates (>10−8 s s−1) tend to disfavor this self-lensing scenario for these three sources. Despite this, our work still provides observational characteristics for self-lensed pulsar–BH binaries, which could help the detection of related sources in the future. Finally, for a binary containing a millisecond pulsar and a stellar-mass BH, the Shapiro delay effect would cause a ≥10% variation of the profile width for the subpulses in such lensed signals.
Abstract
Short-duration gamma-ray bursts (sGRBs) are commonly attributed to the mergers of double neutron stars (NSs) or the mergers of a neutron star with a black hole (BH). While the former ...scenario was confirmed by the event GW170817, the latter remains elusive. Here, we consider the latter scenario in which an NS is tidally disrupted by a fast-spinning low-mass BH and the accretion onto the BH launches a relativistic jet and hence produces an sGRB. The merging binary’s orbit is likely misaligned with the BH’s spin. Hence, the Lense–Thirring precession around the BH may cause a hyperaccreting thick disk to precess in a solid-body manner. We propose that a jet, initially aligned with the BH spin, is deflected and collimated by the wind from the disk, therefore being forced to precess along with the disk. This would result in a quasiperiodic oscillation or modulation in the gamma-ray light curve of the sGRB, with a quasi-period of ∼0.01–0.1 s. The appearance of the modulation may be delayed respective to the triggering of the light curve. This feature, unique to the BH–NS merger, may have already revealed itself in a few observed sGRBs (such as GRB 130310A), and it carries the spin–orbit orientation information of the merging system. Identification of this feature would be a new approach to reveal spin–orbit misaligned merging BH–NS systems, which are likely missed by the current gravitational-wave searching strategy that is principally targeting aligned systems.
•ED nurses exposed to COVID-19 could be psychologically and mentally exhausted.•Prevalence of depression among 1,103 ED nurses was 43.61% (95% CI=40.68%–46.54%).•A heightened awareness of and timely ...treatment for depression for frontline ED nurses should be provided.
Frontline medical staff exposed to the novel coronavirus disease (COVID-19) could be psychologically and mentally exhausted. This study examined the prevalence of depressive symptoms (depression hereafter) and their correlates and the association between depression and quality of life (QOL) in Emergency Department (ED) nurses during the COVID-19 pandemic in China.
This national, cross-sectional online survey was conducted between March 15 and March 20, 2020 in China. Depression and QOL were measured using the 9-item Patient Health Questionnaire, and the World Health Organization Quality of Life Questionnaire-Brief Version, respectively.
The overall prevalence of depression in 1103 ED nurses was 43.61% (95% CI=40.68–46.54%). Multiple logistic regression analysis revealed that working in tertiary hospitals (OR=1.647, P=0.009), direct patient care of COVID-19 patients (OR=1.421, P=0.018), and current smokers (OR=3.843, P<0.001) were significantly associated with depression. After controlling for covariates, nurses with depression had an overall lower QOL compared to those without (F(1,1103)=423.83, P<0.001).
Depression was common among ED nurses during the COVID-19 pandemic. Considering the negative impact of depression on quality of patient care and nurses’ QOL, a heightened awareness of, and early treatment for depression for frontline ED nurses should be provided.
In this paper, we study the quantum transport properties in a double-quantum-dot circuit with two laterally-coupled superconductors. It is clearly found that with the adjustment of the phase ...difference between the superconductors, the electron tunneling and the local and crossed Andreev reflections display different characteristics. This phenomenon can be observed in the linear and nonlinear regimes, even in the presence of Coulomb interaction terms. Moreover, appropriate superconducting phase differences can efficiently enhance the crossed Andreev reflection, accompanied by the suppression of the local Andreev reflection and electron tunneling processes. Therefore, this setup can be used to be a promising device to realize the Cooper-pair splitting.
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