A
bstract
Recently, a codimension two holography called wedge holography is proposed as a generalization of AdS/CFT. It is conjectured that a gravitational theory in
d
+ 1 dimensional wedge spacetime ...is dual to a
d −
1 dimensional CFT on the corner of the wedge. In this paper, we give an exact construction of the gravitational solutions for wedge holography from the ones in AdS/CFT. By applying this construction, we prove the equivalence between wedge holography and AdS/CFT for vacuum Einstein gravity, by showing that the classical gravitational action and thus the CFT partition function in large N limit are the same for the two theories. The equivalence to AdS/CFT can be regarded as a “proof” of wedge holography in a certain sense. As an application of this powerful equivalence, we derive easily the holographic Weyl anomaly, holographic Entanglement/Rényi entropy and correlation functions for wedge holography. Besides, we discuss the general solutions of wedge holography and argue that they correspond to the AdS/CFT with suitable matter fields. Interestingly, we notice that the intrinsic Ricci scalar on the brane is always a constant, which depends on the tension. Finally, we generalize the discussions to dS/CFT and flat space holography. Remarkably, we find that AdS/CFT, dS/CFT and flat space holography can be unified in the framework of codimension two holography in asymptotically AdS. Different dualities are distinguished by different types of spacetimes on the brane.
A
bstract
Entanglement islands play an essential role in the recent breakthrough in resolving the black hole information paradox. However, whether entanglement islands can exist in massless gravity ...theories is controversial. It is found that entanglement islands disappear in the initial model of wedge holography with massless gravity on the brane. As a result, the entanglement entropy of Hawking radiation becomes a time-independent constant, and there is no Page curve. In this paper, we recover massless entanglement islands in wedge holography with suitable DGP gravity or higher derivative gravity on the branes. We study two typical cases. In the first case, we consider a black hole on the strong-gravity brane and a bath on the weak-gravity brane. It is similar to the usual double holography with non-gravitational baths. In the second case, we discuss two black holes on the two branes with the same gravitational strength. We recover massless entanglement islands and non-trivial Page curves in both cases. We also argue that the entanglement island is consistent with massless gravity. Our results strongly support that entanglement islands can exist in long-range theories of gravity.
Biological soil crusts across the desert regions play a key role in regional ecological security and ecological health. They are vital biotic components of desert ecosystems that maintain soil ...stability, fix carbon and nitrogen, influence the establishment of vascular plants, and serve as habitats for a large number of arthropods and microorganisms, as well as influencing soil hydrological processes. Changes in temperature and precipitation are expected to influence the functioning of desert ecosystems by altering biotic components such as the species composition of biological soil crusts. However, it remains unclear how these important components will respond to the prolonged warming and reduced precipitation that is predicted to occur with climate change. To evaluate how the hydrological properties of these biological soil crusts respond to these alterations, we used open‐top chambers over a 10‐year period to simulate warming and reduced precipitation. Infiltration, dew entrapment, and evaporation were measured as surrogates of the hydrological functioning of biological soil crusts. It was found that the ongoing warming coupled with reduced precipitation will more strongly affect moss in crustal communities than lichens and cyanobacteria, which will lead to a direct alteration of the hydrological performance of biological soil crusts. Reductions in moss abundance, surface cover, and biomass resulted in a change in structure and function of crustal communities, decreased dew entrapment, and increased infiltration and evaporation of biological soil crusts in desert ecosystems, which further impacted on the desert soil water balance.
Warming coupled with reduced precipitation will more strongly affect moss in crustal communities than lichens and cyanobacteria. Reductions in moss abundance, surface cover, and biomass resulted in a change in structure and function of crustal communities, which will lead to a direct alteration of the hydrological performance of biological soil crusts.
We propose a novel codimension- n holography, called cone holography, between a gravitational theory in (d + 1)-dimensional conical spacetime and a conformal field theory (CFT) on the (d + 1 − n) ...-dimensional defects. Similar to wedge holography, the cone holography can be obtained by taking the zero-volume limit of holographic defect CFT. Remarkably, it can be regarded as a holographic dual of the edge modes on the defects. For one class of solutions, we prove that the cone holography is equivalent to AdS / CFT , by showing that the classical gravitational action and thus the CFT partition function in large N limit are the same for the two theories. In general, cone holography and AdS / CFT are different due to the infinite towers of massive Kaluza-Klein modes on the branes. We test cone holography by studying Weyl anomaly, entanglement/Rényi entropy, and correlation functions and find good agreement between the holographic and the CFT results. In particular, the c -theorem is obeyed by cone holography. These are strong supports for our proposal. We discuss two kinds of boundary conditions, the mixed boundary condition and Neumann boundary condition, and find that they both define a consistent theory of cone holography. We also analyze the mass spectrum on the brane and find that the larger the tension is, the more continuous the mass spectrum is. The cone holography can be regarded as a generalization of the wedge holography, and it is closely related to the defect CFT, entanglement/Rényi entropy, and AdS/BCFT(dCFT). Here BCFT(dCFT) means a conformal field theory defined in a manifold with a boundary (defect). Thus, it is expected to have a wide range of applications.
A
bstract
Neumann boundary condition plays an important role in the initial proposal of holographic dual of boundary conformal field theory, which has yield many interesting results and passed ...several non-trivial tests. In this paper, we show that Dirichlet boundary condition works as well as Neumann boundary condition. For instance, it includes AdS solution and obeys the g-theorem. Furthermore, it can produce the correct expression of one point function, the boundary Weyl anomaly and the universal relations between them. We also study the relative boundary condition for gauge fields, which is the counterpart of Dirichlet boundary condition for gravitational fields. Interestingly, the four-dimensional Reissner-Nordström black hole with magnetic charge is an exact solution to relative boundary condition under some conditions. This holographic model predicts that a constant magnetic field in the bulk can induce a constant current on the boundary in three dimensions. We suggest to measure this interesting boundary current in materials such as the graphene.
Entanglement islands play an essential role in the recent breakthrough in addressing the black hole information paradox. Inspired by double holography, it is conjectured that the entanglement islands ...can exist only in massive gravity. There are many pieces of evidence but also debates for this conjecture. This paper recovers the massless entanglement island in wedge holography with negative DGP gravity on the brane. However, the spectrum of negative DGP gravity includes a massive ghost, implying the model is unstable. Our work supports the view that there is no entanglement island in a well-defined braneworld model of massless gravity if one divides the radiation and black hole regions by minimizing entanglement entropy. However, such a partition results in a zero radiation region containing no information. Whether there are other physical non-trivial partitions of the radiation region is an open question and deserves further study.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Tumor‐associated neutrophils (TANs) play a crucial role in tumor development and progression in the cancer microenvironment. Despite increased understanding of TAN contributions to hepatocellular ...carcinoma (HCC) progression and prognosis, the direct interaction between TANs and HCC cells is not fully understood. In this study, we tested the effect of TANs on HCC cells in vitro and in vivo and investigated the mechanism of interaction between them. Our results showed that TANs secreted bone morphogenetic protein 2 and transforming growth factor beta 2 and triggered microRNA 301b‐3p (miR‐301‐3p) expression in HCC cells, subsequently suppressed gene expression of limbic system–associated membrane protein (LSAMP) and CYLD lysine 63 deubiquitinase (CYLD), and increased stem cell characteristics in HCC cells. These TAN‐induced HCC stem‐like cells were hyperactive in nuclear factor kappa B signaling, secreted higher levels of chemokine (C‐X‐C motif) ligand 5 (CXCL5), and recruited more TAN infiltration, suggesting a positive feedback loop. In clinical HCC samples, increased TANs correlated with elevated miR‐301b‐3p, decreased LSAMP and CYLD expression, and increased nuclear p65 accumulation and CXCL5 expression, all of which predicted patient outcome. Conclusion: Our work identified a positive feedback loop governing cancer stem‐like cells and TANs in HCC that controls tumor progression and patient outcome.
A novel printed log-periodic dipole array (PLPDA) antenna with bow-tie parasitic cell for the gain enhancement is presented for 5G mobile and wireless communication. The antenna is fed by the ...substrate integrated waveguide. The gain of the antenna is enhanced using parasitic cell-several bow-tie directors and bow-tie parasitic patches. The adding of bow-tie directors are based on the principle of the quasi-Yagi and the bow-tie antenna. Moreover, the parasitic patches are used to enhance the antenna gain by expanding the transverse radiation aperture of the antenna according to the principle of the antenna array. The proposed antenna has been designed, fabricated, and tested. It can be observed that the PLPDA antenna gain with the parasitic cell is increased about 1-dBi compared with the antenna with the single-sided rectangle directors. And the S11 of the proposed antenna is less than -12 dB, the cross-polarization level is better than -15 dB, and the gain of the presented antenna is 7.3-12.5 dBi over the whole operating frequency range of 40-50 GHz.
A
bstract
This paper investigates the Casimir effect of a wedge and its holographic dual. We prove that the displacement operator universally determines the wedge Casimir effect in the smooth limit. ...Besides, we argue that the wedge Casimir energy increases with the opening angle and test it with several examples. Furthermore, we construct the holographic dual of wedges in AdS/BCFT in general dimensions. We verify that our proposal can produce the expected Casimir effect within smooth and singular limits. We observe that the Casimir energy density of a wedge increases with the brane tension. Next, we discuss the wedge contribution to holographic entanglement entropy and find it increases with the opening angle, similar to the wedge Casimir energy. Finally, we briefly discuss the holographic polygon in AdS
3
/BCFT
2
and its generalization to higher dimensions.
A
bstract
According to Witten 1, the conformal boundary condition of gravity, which specifies the conformal geometry of the boundary and the trace of the extrinsic curvature, is elliptic and leads to ...well-defined perturbation theory of gravity about any classical solution. The conformal boundary condition was previously considered in 2, 3 in the context of AdS/BCFT, wherein the equation of motion of the end-of-the-world was derived and emphasized. In this paper, we investigate further other consequences of the conformal boundary condition in AdS/BCFT. We derive the boundary central charges of the holographic Weyl anomaly and show that they are exactly the same for conformal boundary condition and Dirichlet boundary condition. We analysis the metric perturbation with conformal boundary condition (CBC), Dirichlet boundary condition (DBC) and Neumann boundary condition (NBC) imposed on the end-of-the-world brane and show that they admit an interpretation as the fluctuation of the extrinsic curvature (case of CBC and DBC) and the induced metric (case of NBC) of
Q
respectively. In all cases, the fluctuation modes are massive, which are closely relevant to the massive island formation in the literature. Our results reveal that there are non-trivial gravitational dynamics from extrinsic curvatures on the conformal and Dirichlet branes, which may have interesting applications to the island. We also discuss, in passing, the localization of gravitons in brane world theory. We find that, contrary to NBC, the graviton for CBC/DBC is located on the brane with non-positive tension instead of non-negative tension.
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