1,655 research outputs found
Violations of the weak cosmic censorship conjecture in the higher dimensional black holes with pressure
We adopt the energy momentum relation of charged particles to study the
thermodynamics laws and weak cosmic censorship conjecture of -dimensional
AdS black holes in different phase spaces by considering charged
particle absorption. In the normal phase space, it turns out that the laws of
thermodynamic and the weak cosmic censorship conjecture are valid. In the
extended phase space, though the first law of thermodynamics is valid, the
second law of thermodynamics is invalid. More interestingly, the weak cosmic
censorship conjecture is shown to be violated only in higher-dimensional
near-extremal AdS black holes. In addition, the magnitudes of the
violations for both the second law and weak cosmic censorship conjecture are
dependent on the charge , constant scalar curvature , AdS radius
, dimension parameters , and their variations.Comment: Accepted by Eur. Phys. J.
Holographic Einstein rings of Non-commutative black holes
With the help of the AdS/CFT correspondence, we easily derive the desired
response function of QFT on the boundary. Using the virtual optical system with
a convex lens, we are able to obtain the image of the black hole from the
response function and further study the Einstein ring of the non-commutative
black holes. All the results show that there are some common features and
different features compared to the previous study of other background black
holes. The common features include that the holographic ring always appears
with the concentric stripe surrounded when the observer located at the north
pole, and an extremely bright ring when the observer is at the position of the
photon sphere of the black hole. And with the change of the observation
position, this ring will change into a luminosity-deformed ring, or light
points. In addition to these similarities, there are some different features
which are due to the singularity of the event horizon temperature. Explicitly,
the relation between temperature and the event horizon has two branches
when the non-commutative parameter is fixed. These in turn have an effect
on the behavior of the response function and the Einstein ring. For example,
the amplitude of the response function increases with the
decrease of the non-commutative strength parameter for both two branches of
relation. However, the amplitude of increases with
the decrease of the temperature for the left branch of relation,
while the amplitude of decreases with the decrease of the
temperature for the right branch. These differences are also reflected in
the Einstein ring. Therefore, these differences can be used to distinguish
different black hole backgrounds. Furthermore, we show that the non-commutative
parameter has an effect on the brightness and the position of Einstein ring.Comment: revised version. arXiv admin note: text overlap with
arXiv:2307.01973; text overlap with arXiv:1811.12617, arXiv:1906.09113 by
other author
Holographic Einstein Rings of an AdS Black Hole in Massive Gravity
In the context of holography, the Einstein ring of an AdS black hole (BH) in
massive gravity (MG) is depicted. An oscillating Gaussian source on one side of
the AdS boundary propagates in bulk, and we impose a response function to
explain it. Using a wave optics imaging system, we obtain the optical
appearance of the Einstein ring. Our research reveals that the ring can change
into a luminosity-deformed ring or light spots depending on the variation of
parameters and observational positions. When observers are positioned at the
north pole, the holographic profiles always appear as a ring with concentric
stripe surroundings, and a bright ring appears at the location of the photon
sphere of the BH. These findings are consistent with the radius of the photon
sphere of the BH, which is calculated in geometrical optics. Our study
contributes to a better understanding of the analytical studies of holographic
theory, which can be used to evaluate different types of BHs for a fixed wave
source and optical system.Comment: 15 pages, 14 figure
A new Agkistrodon halys venom-purified protein C activator prevents myocardial fibrosis in diabetic rats
Aim To assess the effects of protein C activator (PCA) from
Agkistrodon halys snake venom on cardiac fibrosis in streptozotocin
(STZ) induced diabetic rat model, and investigate
the mechanisms of its action.
Methods PCA was identified by one-dimensional reversed
phase liquid chromatography – mass spectrometry/mass
spectrometry. Male Sprague-Dawley rats (120-140 g) were
randomly assigned to negative control (NC) and diabetic
group. Diabetes was induced by STZ in high-fat diet fed
rats. Diabetic group was subdivided into three groups: diabetic
group (DM), diabetic group treated with PCA (0.5, 2,
and 8 mg/kg), and diabetic group treated with metformin
(5 mg/kg, positive control). NC and DM groups received
the same volume of distilled water. Left ventricular mass
index (LVWI) and collagen volume fraction were measured
by hematoxylin and eosin and Masson staining. Transforming
growth factor beta-1 (TGF-β1) and interleukin 1 beta
(IL-1β) levels were determined by enzyme-linked immunosorbent
assay.
Results The diabetic rat model was successfully established
by STZ induction and high-fat diet. Glucose level,
LVWI, TGF-β1 and IL-1β level, and collagen volume fraction
were significantly reduced in diabetic rats treated by PCA
in a dose-dependent manner (P < 0.050), especially in the
high dose (8 mg/kg) group (P < 0.010), compared to diabetes
group. The high dose PCA had the same effect as
metformin positive control in reducing the level of fasting
blood glucose. PCA decreased the expression of MMP-2
and reduced that of TIMP-2.
Conclusion Our results indicate that PCA has anti-fibrotic
effects and that it may be used to treat myocardial fibrosis
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