345 research outputs found
Gray-body factor and absorption of the Dirac field in ESTGB gravity
The gray-body factor and the absorption cross section of the 4D ESTGB gravity
with a mode of nonlinear electrodynamics for the massless Dirac field are
studied in this paper. The magnetic charge value varies between
and as well as the ADM mass is set to , which
corresponds to a non-extreme black hole. The gray-body factor is obtained using
the semi-analytic WKB method after solving the massless Dirac equation. When
the absolute value of magnetic charge is increasing, the gray-body factor
is decreasing. In addition, the partial absorption cross
section and the total absorption cross section are calculated by using the
partial wave method. We find that the maximum value of partial absorption cross
section decreases as increases. And the existence of magnetic charge
causes the diminishing of the total absorption cross section. Finally, we find
that the absorption cross section of the Dirac field is more sensitive to
electric charge than magnetic charge by comparing the absorption cross section
of the Reissner-Nordstrm and ESTGB-NLED black holes.Comment: 11 pages, 7 figure
Shadow, absorption and Hawking radiation of a Schwarzschild black hole surrounded by a cloud of strings in Rastall gravity
This paper studies the black hole shadow, absorption cross section, and
Hawking radiation of a massless scalar field in the background of a static
spherically symmetric black hole spacetime that is surrounded by a cloud of
strings in Rastall gravity. Specifically, the effects of the parameters and
on the photon sphere and shadow radii are investigated. The results
show that as the negative parameter decreases, the photon sphere and
shadow radii change in an N-shape. In addition, the absorption cross section
obtained after solving the massless Klein-Gordon equation is calculated using
the sinc approximation and the partial waves method. We compare the absorption
cross section obtained by the sinc approximation and the partial waves method,
and find it to be exceptionally consistent in the mid-to-high frequency region.
Furthermore, the effects of parameters and on absorption are
examined in detail. Finally, we study in detail the effects of the parameters
, and on the Hawking radiation power emission spectrum of the
considered black hole. It turns out that the string parameter always
suppresses the power emission spectrum, indicating that such black holes live
longer when the string parameter is increased while other parameters are
fixed.Comment: 27 pages, 10 figures, 1 Tabl
RIDCP: Revitalizing Real Image Dehazing via High-Quality Codebook Priors
Existing dehazing approaches struggle to process real-world hazy images owing
to the lack of paired real data and robust priors. In this work, we present a
new paradigm for real image dehazing from the perspectives of synthesizing more
realistic hazy data and introducing more robust priors into the network.
Specifically, (1) instead of adopting the de facto physical scattering model,
we rethink the degradation of real hazy images and propose a phenomenological
pipeline considering diverse degradation types. (2) We propose a Real Image
Dehazing network via high-quality Codebook Priors (RIDCP). Firstly, a VQGAN is
pre-trained on a large-scale high-quality dataset to obtain the discrete
codebook, encapsulating high-quality priors (HQPs). After replacing the
negative effects brought by haze with HQPs, the decoder equipped with a novel
normalized feature alignment module can effectively utilize high-quality
features and produce clean results. However, although our degradation pipeline
drastically mitigates the domain gap between synthetic and real data, it is
still intractable to avoid it, which challenges HQPs matching in the wild.
Thus, we re-calculate the distance when matching the features to the HQPs by a
controllable matching operation, which facilitates finding better counterparts.
We provide a recommendation to control the matching based on an explainable
solution. Users can also flexibly adjust the enhancement degree as per their
preference. Extensive experiments verify the effectiveness of our data
synthesis pipeline and the superior performance of RIDCP in real image
dehazing.Comment: Acceptted by CVPR 202
Experimental observation of Dirac-like surface states and topological phase transition in PbSnTe(111) films
The surface of a topological crystalline insulator (TCI) carries an even
number of Dirac cones protected by crystalline symmetry. We epitaxially grew
high quality PbSnTe(111) films and investigated the TCI phase by
in-situ angle-resolved photoemission spectroscopy. PbSnTe(111)
films undergo a topological phase transition from trivial insulator to TCI via
increasing the Sn/Pb ratio, accompanied by a crossover from n-type to p-type
doping. In addition, a hybridization gap is opened in the surface states when
the thickness of film is reduced to the two-dimensional limit. The work
demonstrates an approach to manipulating the topological properties of TCI,
which is of importance for future fundamental research and applications based
on TCI
Stark tuning of telecom single-photon emitters based on a single Er
The implementation of scalable quantum networks requires photons at the
telecom band and long-lived spin coherence. The single Er in solid-state
hosts is an important candidate that fulfills these critical requirements
simultaneously. However, to entangle distant Er ions through photonic
connections, the emission frequency of individual Er in solid-state
matrix must be the same, which is challenging because the emission frequency of
Er depends on its local environment. In this study, we propose and
experimentally demonstrate the Stark tuning of the emission frequency of a
single Er in a YSiO crystal by employing electrodes interfaced
with a silicon photonic crystal cavity. We obtain a Stark shift of 182.9
0.8 MHz which is approximately 27 times of the optical emission linewidth,
demonstrating the promising applications in tuning the emission frequency of
independent Er into the same spectral channels. Our results provide a
useful solution for the construction of scalable quantum networks based on
single Er and a universal tool for tuning the emission of individual
rare-earth ions
Preparation of bufalin-loaded pluronic polyetherimide nanoparticles, cellular uptake, distribution, and effect on colorectal cancer [Corrigendum]
Preparation of bufalin-loaded pluronic polyetherimide nanoparticles, cellular uptake, distribution, and effect on colorectal cancer
Human Bocavirus Infection, People’s Republic of China
A newly identified parvovirus, human bocavirus (HBoV), was found in 21 (8.3%) of 252 nasopharyngeal aspirates from hospitalized children with lower respiratory tract infection in Hunan Province, People’s Republic of China. Viral loads were 104 to 1010 copies/mL. Phylogenetic analysis of the VP1 gene showed a single genetic lineage of HBoV worldwide
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