Brønsted acids of anionic chiral CoIII complexes act as bifunctional phase‐transfer catalysts to shuttle the substrates across the solvent interface and control stereoselectivity. The diastereomeric ...chiral CoIII‐templated Brønsted acids, with the same chiral ligands, enabled a switch in the enantioselective bromoaminocyclization of olefins to afford the two enantiomers of 2‐substituted pyrrolidines with high enantioselectivities (up to 99:1 e.r.).
Flip of the switch: Brønsted acids of anionic chiral CoIII complexes act as bifunctional phase‐transfer catalysts to shuttle the substrates across the solvent interface and control stereoselectivity. The diastereomeric chiral CoIII‐templated Brønsted acids, with the same chiral ligands, enabled a switch in the enantioselective bromoaminocyclization of olefins to afford the two enantiomers of the 2‐substituted pyrrolidines with high stereoselectivities.
Let
H(𝔹n) be the set of all holomorphic functions on the open unit ball
𝔹n in
ℂn, φ a holomorphic self‐map of
𝔹n,
u∈H(𝔹n), and ℜm the mth iterated radial derivative operator on
H(𝔹n). We ...characterize the metrical boundedness and metrical compactness of the weighted iterated radial composition operator
ℜu,φm from the weighted Bergman–Orlicz space to the weighted‐type space.
In this paper, we focus on the weak cosmic censorship conjecture (WCCC) in the Einstein–Maxwell gravity sourced by a conformally coupled scalar field, where the black hole solution can carry a scalar ...hair apart from the conserved charges of the electromagnetic field. Motivated by the new version of the gedanken experiments proposed by Sorce and Wald, we derive the first two order perturbation inequalities in the scalar-hair Reissner–Nordström (shRN) black holes based on the Iyer–Wald formalism under the stability consumption. In the collision process, we assume that the scalar hair can also be changed. As a result, we find that the nearly extremal shRN black holes cannot be destroyed by the above collision process under the second-order approximation after the two perturbation inequalities are considered. Our result at some level implies that the WCCC can also be restored in the black holes with some scalar hairs.
•The feature aggregation module is designed for the features fusion.•The change information extraction module is designed to obtain robust features.•The correlation between subtasks is considered ...during the decoding phase.
In recent years, change detection has been one of the hot research topics within the field of remote sensing. Previous studies have concentrated on binary change detection (BCD), but it doesn’t meet the current needs. Therefore, semantic change detection (SCD) is also gradually developing, which focuses on determining the specific changed type while obtaining changed areas. In the paper, we propose a multi-task learning method (MTSCD-Net) for SCD task. The SCD task is decoupled into two related subtasks, semantic segmentation (SS) and BCD, then unifies them under the same framework. Multi-scale features are extracted using the Siamese semantic-aware encoder based on Swin Transformer, and the aggregation module is designed to combine features. Then, the change information extraction module is designed to enhance the capacity to express features by fully integrating the two-level difference features that are generated from fused features. Moreover, in the decoder stage, the spatial attention weight map is obtained using the features of the BCD subtask, which provides location prior information for the features of the SS subtask. It helps fully explore the correlation between the two subtasks. The two loss functions of subtasks are weighted to train MTSCD-Net. The comparative experiments results on two typical SCD datasets confirm the advantage of MTSCD-Net for SCD task. For the SeK index, MTSCD-Net achieves 3.96% and 20.57% on HRSCD and SECOND datasets, respectively. This outperforms other comparative methods such as Bi-SRNet (which achieves 4.86% and 1.47% higher on two datasets, respectively). The same is true for the Score metric. Moreover, the ablation experiment results confirm the effectiveness of key modules.
Changes in global land monsoon (GLM) precipitation determine the local water resource, affecting two thirds of global population. The future changes in GLM summer precipitation and the sources of ...projection uncertainty under four scenarios are investigated using the Coupled Model Intercomparison Project Phase 6 (CMIP6) models. The GLM summer precipitation is projected to increase by 1.76 ± 1.57% (2.54 ± 2.22%), 1.33 ± 1.97% (3.52 ± 3.05%), 0.96 ± 2.04% (3.51 ± 4.97%), and 1.71 ± 2.38% (5.75 ± 5.92%) in the near (long) term under Shared Socioeconomic Pathway (SSP) 1–2.6, SSP2–4.5, SSP3–7.0, and SSP5–8.5, respectively. The enhancement is caused by thermodynamic responses due to increased moisture, which is partly offset by dynamic responses due to weakened circulation. The uncertainty in GLM precipitation projection is the largest in SSP5–8.5 long‐term projection. The uncertainty of submonsoon precipitation projections is larger than that in GLM precipitation. The uncertainty of monsoon precipitation projection arises from the circulation changes, which can be partly explained by model‐dependent response to uniform sea surface temperature warming.
Plain Language Summary
The changes of monsoon rainfall under a warmer climate receive much attention. Here we revealed the future changes of summer precipitation over global and submonsoon regions in different periods under four new scenarios designed by the Coupled Model Intercomparison Project Phase 6 (CMIP6). In 2021–2040 (2080–2099), the monsoon summer rainfall will increase by about 1.76 ± 1.57% (2.54 ± 2.22%), 1.33 ± 1.97% (3.52 ± 3.05%), 0.96 ± 2.04% (3.51 ± 4.97%), and 1.71 ± 2.38% (5.75 ± 5.92%) under the low, medium, and two high emission scenarios, respectively. At the end of the 21st century, the monsoon rainfall will increase largest in the highest emission scenario with largest spread. Moreover, the spread over each submonsoon region is much larger than that of global land monsoon. The increase of rainfall is associated with the increase of water vapor but offset by the weakened circulation. The spread of rainfall changes is caused by the spread of circulation projection, which is partly caused by the model‐dependent responses of circulation to uniform sea surface temperature warming.
Key Points
Global land monsoon precipitation increase is due to moisture increases, while the uncertainty is due to uncertainty of circulation changes
The uncertainty of circulation mainly comes from model spread in midterm and long‐term projections but from internal variability in near term
Model‐dependent response to uniform sea surface temperature warming is one of the uncertainty sources in land monsoon circulation projection
We explore how the internal structure of a test particle affects its equatorial stable circular orbits around the Kerr black hole with or without a cosmological constant. To this end, we first ...explicitly write equations of motion for a test particle in the pole-dipole-quadrupole approximation specifying the quadrupole momentum tensor to a spin-induced model. Then we calculate characteristic quantities – radius, angular momentum, energy, angular velocity, and impact parameter – for the particles on the stable circular orbits. Once the pole-dipole-quadrupole approximation is taken, we find that for a particle on an innermost stable circular orbit, all characteristic quantities, except the angular velocity, become greater relative to the pole-dipole case. In contrast, for a particle on an outermost stable circular orbit, which only exists in the case of the spacetime background being asymptotically de Sitter, it is the radius that becomes smaller while all other quantities become greater.
We investigate whether the Strong Cosmic Censorship (SCC) Conjecture can be reinstated at the classical level in Reissner–Nordström–de Sitter (RNdS) black holes by introducing non-minimal couplings ...between the electromagnetic and scalar fields in Einstein–Maxwell-scalar (EMS) theory. By conducting numerical calculations, we find that the SCC can be restored within a specific range of the coupling constant. Notably, for a given value of the cosmological constant, there exists a critical coupling constant above which the EMS theory satisfies the SCC. These findings suggest that the non-minimal couplings between the electromagnetic and scalar fields may play a crucial role in the restoration of the SCC in RNdS spacetime. Additionally, under negative coupling constants, the low-lying modes of nearly extremal black holes exhibit
β
>
1
,
enabling
C
2
extensions beyond the Cauchy horizon and intensifying the violation of the SCC.
Viewing the negative cosmological constant as a dynamical quantity derived from the matter field, we study the weak cosmic censorship conjecture for the higher-dimensional asymptotically AdS ...Reissner–Nordström black hole. To this end, using the stability assumption of the matter field perturbation and the null energy condition of the matter field, we first derive the first-order and second-order perturbation inequalities containing the variable cosmological constant and its conjugate quantity for the black hole. We prove that the higher-dimensional RN-AdS black hole cannot be destroyed under a second-order approximation of the matter field perturbation process.
Recently, Fernandes discovered an analytic solution for rotating black holes in semiclassical gravity induced by the trace anomaly. These solutions exhibit some distinctive characteristics, including ...a non-spherically symmetric event horizon, the absence of circularity conditions, and violations of the Kerr bound. As a crucial assumption to uphold causality in spacetime, we investigate the validity of the weak cosmic censorship conjecture (WCCC) within this class of solutions with type-A trace anomaly by introducing a test particle on the equatorial plane. Our study reveals three distinct mechanisms that can potentially destroy the event horizon, leading to a violation of the WCCC. Our findings indicate that, with the exception of extremal Kerr, static extremal, and static singular black holes, the WCCC may be violated under the first-order perturbation of the test particle. These results suggest the need for further exploration of modifications to the behavior of the test particle under quantum effects in order to address the violation of the WCCC in this system.
Let Mu be the multiplication operator with symbol u which is a holomorphic function on the open unit ball
𝔹 in
ℂn,Cφ the composition operator with symbol φ which is a holomorphic self‐map of
𝔹, and
...ℜm,m∈ℕ, the mth iterated radial derivative operator. The boundedness and compactness of the weighted iterated radial composition operator
ℜu,φm:=MuCφℜm from logarithmic Bloch spaces to weighted‐type spaces are characterized.
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