In the previous work, it was shown that the degrees of freedom on the horizon of BTZ black hole can be described by two chiral massless scalar fields with opposite chirality. In this paper, we ...continuous this research. It is found that the scalar field is actually a compact boson field on a circle. The compactness results in the quantization of the black hole radius. Then we quantize the two boson fields and get two abelian Kac-Moody algebras. From the boson field, one can construct the full W1+∞ algebra which was used to classify the BTZ black holes.
Optical coherence tomography (OCT) shows an important role in the diagnosis of cardiovascular diseases and the detection and intervention of vulnerable plaques. Clinical diagnosis of vulnerable ...plaques in cardiovascular system based on optical coherence tomography mainly relies on the manual analysis of vulnerable plaques in images by cardiovascular physicians. This analysis process is prone to subjective misjudgments and heavy workload. Studying the recognition technology of cardiovascular vulnerable plaque image will greatly improve the accuracy of diagnosis and reduce the workload of cardiovascular physicians, which is an effective way to achieve efficient diagnosis and treatment. In view of the recognition of cardiovascular vulnerable plaque medical images, a model based on convolution neural network (CNN) recognition is constructed. The CNN is used to learn the features of different levels from the original input OCT images. At the same time, several decision-making levels are designed. These decision-making levels can classify OCT images according to different feature maps, and finally make final recognition decisions according to the classification results. The experimental results on the clinical data set labeled by doctors show that the classification and recognition model of cardiovascular vulnerable plaque OCT image based on CNN has a high recognition rate. Making full use of the multilevel features of convolutional neural networks can effectively classify and recognize the OCT images of vulnerable cardiovascular plaques, provide support for the clinical diagnosis of cardiovascular diseases, and have great significance for the early intervention and prevention of cardiovascular diseases.
Hawking radiation is an essential property of the quantum black hole. It results in the information loss paradox and provides an important clue with regard to the unification of quantum mechanics and ...general relativity. In previous work, the boundary scalar fields on the horizon of black holes were used to determine the microstates of BTZ black holes and Kerr black holes. They account for Bekenstein–Hawking entropy. In this paper, we show that the Hawking radiation can also be derived from those scalar fields. Hawking radiation is a mixture of the thermal radiation of right- and left-moving sectors at different temperatures. Based on this result, for static BTZ black holes and Schwarzschild black holes, we propose a simple solution for the information loss paradox; i.e., the Hawking radiation is pure due to its entanglement between the left-moving sector and the right-moving sector. This entanglement may be detected in an analogue black hole in the near future.
Most existing methods of semantic segmentation still suffer from two aspects of challenges: intra-class inconsistency and inter-class indistinction. To tackle these two problems, we propose a ...Discriminative Feature Network (DFN), which contains two sub-networks: Smooth Network and Border Network. Specifically, to handle the intra-class inconsistency problem, we specially design a Smooth Network with Channel Attention Block and global average pooling to select the more discriminative features. Furthermore, we propose a Border Network to make the bilateral features of boundary distinguishable with deep semantic boundary supervision. Based on our proposed DFN, we achieve state-of-the-art performance 86.2% mean IOU on PASCAL VOC 2012 and 80.3% mean IOU on Cityscapes dataset.
In this research, heterostructured g-C3N4 quantum dots (CNQDs)/Bi3.64Mo0.36O6.55 nanospheres have been fabricated trough an in situ precipitation process. Compared to the pure Bi3.64Mo0.36O6.55, the ...as-fabricated CNQDs/Bi3.64Mo0.36O6.55 nanocomposites exhibited significantly improved photocatalytic performance for the photodegradation of rhodamine B (Rh B) and bisphenol A (BPA). In addition, 5 wt% CNQDs/Bi3.64Mo0.36O6.55 sample showed the highest photocatalytic efficiency under visible-light irradiation (λ > 420 nm). The effective separation and transmission of photogenerated electron-hole pairs caused by CNQD loading as well as the improved BET surface area are associated with the enhancement of the photocatalytic activity of the CNQDs/Bi3.64Mo0.36O6.55 photocatalyst.
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•A novel CNQDs/Bi3.64Mo0.36O6.55 composite photocatalyst have been fabricated via a facile in situ precipitation method.•The composite photocatalyst included CNQDs assembling on the surface of Bi3.64Mo0.36O6.55 nanospheres.•The CNQDs/Bi3.64Mo0.36O6.55 nanospheres exhibited enhanced photocatalytic activity.
Graphitic carbon nitride (g-C3N4) is a promising metal-free photocatalyst for solar photocatalytic hydrogen gas (H2) generation from water. In particularly, high-crystalline g-C3N4 (GCN-HC) material ...with fewer structural defects possesses the fast photoexcited electron-hole pair's separation efficiency as comparison with bulk g-C3N4 (GCN-B) powders, leading to the drastic improvement of photocatalytic activity. However, the fabrication of such GCN-HC photocatalyst by a simple and economical synthesis approach still remains a challenge. Herein, we firstly develop a one-step rapid polymerization strategy for synthesizing the GCN-HC, that is direct calcination of melamine at 550 °C not only without the early heating process, but also without the assistance of any additive or salt intercalation. As a result, the GCN-HC exhibits an obviously boosting visible-light-induced photocatalytic H2-generation performance, which is over 2.06-folds much greater than that of GCN-B. Our work provides an available one-step synthetic strategy for the large-scale preparation of high performance GCN-HC towards sustainable solar-to-chemical energy conversion.
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•The GCN-HC was firstly prepared by a one-step rapid polymerization strategy.•The GCN-HC shows an enhanced photocatalytic activity for H2 evolution.•The GCN-HC presents the fast charge transfer efficiency as compared with GCN-B.•The GCN-HC can be as a promising photocatalyst for solar-to-H2 conversion.
Photonics is a promising platform for implementing universal quantum information processing. Its main challenges include precise control of massive circuits of linear optical components and effective ...implementation of entangling operations on photons. By using large-scale silicon photonic circuits to implement an extension of the linear combination of quantum operators scheme, we realize a fully programmable two-qubit quantum processor, enabling universal two-qubit quantum information processing in optics. The quantum processor is fabricated with mature CMOS-compatible processing and comprises more than 200 photonic components. We programmed the device to implement 98 different two-qubit unitary operations (with an average quantum process fidelity of 93.2 ± 4.5%), a two-qubit quantum approximate optimization algorithm, and efficient simulation of Szegedy directed quantum walks. This fosters further use of the linear-combination architecture with silicon photonics for future photonic quantum processors.
The random walk formalism is used across a wide range of applications, from modelling share prices to predicting population genetics. Likewise, quantum walks have shown much potential as a framework ...for developing new quantum algorithms. Here we present explicit efficient quantum circuits for implementing continuous-time quantum walks on the circulant class of graphs. These circuits allow us to sample from the output probability distributions of quantum walks on circulant graphs efficiently. We also show that solving the same sampling problem for arbitrary circulant quantum circuits is intractable for a classical computer, assuming conjectures from computational complexity theory. This is a new link between continuous-time quantum walks and computational complexity theory and it indicates a family of tasks that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor.
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