304 research outputs found

    The deflection of charged massive particles by a 4-Dimensional charged Einstein-Gauss-Bonnet black hole

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    Based on the Jacobi metric method, this paper studies the deflection of a charged massive particle by a novel 4-dimensional charged Einstein-Gauss-Bonnet black hole. We focus on the weak-filed approximation and consider the deflection angle with finite-distance effects, i.e. the source and observer at finite distances from the black hole. To this end, we use a geometric and topological method, which is to apply the Gauss-Bonnet theorem to the Jacobi-metric surface to calculate the deflection angle. We find that the deflection angle contains a pure gravitational contribution δg\delta_g, a pure electrostatic one δc\delta_c and a gravitational-electrostatic coupling term δgc\delta_{gc}. We also show that the electrostatic contribution δc\delta_c can also be computed by the Jacobi-metric method using the GB theorem to a charge in a Minkowski flat spacetime background. We find that the deflection angle increases(decreases) if the Gauss-Bonnet coupling constant α\alpha is negative(positive). Furthermore, the effects of the BH charge, the particle charge-to-mass ratio and the particle velocity on the deflection angle are analyzed.Comment: 11 pages, 5 Figures; conclusion part improved and reference adde

    Deflection and gravitational lensing with finite distance effect in the strong deflection limit in stationary and axisymmetric spacetimes

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    We study the deflection and gravitational lensing (GL) of both timelike and null signals in the equatorial plane of arbitrary stationary and axisymmetric spacetimes in the strong deflection limit. Our approach employs a perturbative method to show that both the deflection angle and the total travel time take quasi-series forms n=0[Cnln(1bc/b)+Dn](1bc/b)n\displaystyle \sum_{n=0}\left[ C_n\ln (1-b_c/b)+D_n\right] (1-b_c/b)^n, with the coefficients CnC_n and DnD_n incorporating the signal velocity and finite distance effect of the source and detector. This new deflection angle allows us to establish an accurate GL equation from which the apparent angles of the relativistic images and their time delays are found. These results are applied to the Kerr and the rotating Kalb-Ramond (KR) spacetimes to investigate the effect of the spacetime spin in both spacetimes, and the effective charge parameter and a transition parameter in the rotating KR spacetime on various observables. Moreover, using our approach, the effect of the signal velocity and the source angular position on these variables is also studied.Comment: 15 pages, 10 figures; updated to publish versio

    The Reconstruction of China's Regional Economic Pattern under the Background of "The Belt and Road" Strategy

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    The excessive development structure between China regions is generated in the process of industrialization and urbanization, and it is concentrated in an unequal spatial structure. The strategic concept of "The Belt and Road" provides an opportunity for the coordinated development of China's regional economy. On the one hand, it helps to promote economic transformation and upgrading in eastern China. On the other hand, it is helpful to realize the rising of central China and the opening of the western border zone, and optimize the regional development pattern. In this study, we propose that the regional coordination should be established by using "The Belt and Road" strategy. First of all, building a multi-center urban network to stimulate the economic development in the central and western regions; secondly, balancing the interests of different regions with a multi-level regional coordination mechanism and finally, forming a new pattern of coordinated regional development with institutionalized regional ecosystems. Keywords: The Belt and Road, regional imbalance, multi-center, regional coordination mechanism, institutio

    Testing the cosmic curvature at high redshifts: the combination of LSST strong lensing systems and quasars as new standard candles

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    The cosmic curvature, a fundamental parameter for cosmology could hold deep clues to inflation and cosmic origins. We propose an improved model-independent method to constrain the cosmic curvature by combining the constructed Hubble diagram of high-redshift quasars with galactic-scale strong lensing systems expected to be seen by the forthcoming LSST survey. More specifically, the most recent quasar data are used as a new type of standard candles in the range 0.036<z<5.1000.036<z<5.100, whose luminosity distances can be directly derived from the non-linear relation between X-ray and UV luminosities. Compared with other methods, the proposed one involving the quasar data achieves constraints with higher precision (ΔΩk102\Delta \Omega_k\sim 10^{-2}) at high redshifts (z5.0z\sim 5.0). We also investigate the influence of lens mass distribution in the framework of three types of lens models extensively used in strong lensing studies (SIS model, power-law spherical model, and extended power-law lens model), finding the strong correlation between the cosmic curvature and the lens model parameters. When the power-law mass density profile is assumed, the most stringent constraint on the cosmic curvature Ωk\Omega_k can be obtained. Therefore, the issue of mass density profile in the early-type galaxies is still a critical one that needs to be investigated further.Comment: 7 figures, 11 pages, accepted for publication in MNRA

    Integrating Stock Features and Global Information via Large Language Models for Enhanced Stock Return Prediction

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    The remarkable achievements and rapid advancements of Large Language Models (LLMs) such as ChatGPT and GPT-4 have showcased their immense potential in quantitative investment. Traders can effectively leverage these LLMs to analyze financial news and predict stock returns accurately. However, integrating LLMs into existing quantitative models presents two primary challenges: the insufficient utilization of semantic information embedded within LLMs and the difficulties in aligning the latent information within LLMs with pre-existing quantitative stock features. We propose a novel framework consisting of two components to surmount these challenges. The first component, the Local-Global (LG) model, introduces three distinct strategies for modeling global information. These approaches are grounded respectively on stock features, the capabilities of LLMs, and a hybrid method combining the two paradigms. The second component, Self-Correlated Reinforcement Learning (SCRL), focuses on aligning the embeddings of financial news generated by LLMs with stock features within the same semantic space. By implementing our framework, we have demonstrated superior performance in Rank Information Coefficient and returns, particularly compared to models relying only on stock features in the China A-share market.Comment: 8 pages, International Joint Conferences on Artificial Intelligenc

    ReAct: Temporal Action Detection with Relational Queries

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    This work aims at advancing temporal action detection (TAD) using an encoder-decoder framework with action queries, similar to DETR, which has shown great success in object detection. However, the framework suffers from several problems if directly applied to TAD: the insufficient exploration of inter-query relation in the decoder, the inadequate classification training due to a limited number of training samples, and the unreliable classification scores at inference. To this end, we first propose a relational attention mechanism in the decoder, which guides the attention among queries based on their relations. Moreover, we propose two losses to facilitate and stabilize the training of action classification. Lastly, we propose to predict the localization quality of each action query at inference in order to distinguish high-quality queries. The proposed method, named ReAct, achieves the state-of-the-art performance on THUMOS14, with much lower computational costs than previous methods. Besides, extensive ablation studies are conducted to verify the effectiveness of each proposed component. The code is available at https://github.com/sssste/React.Comment: ECCV202

    New ages for the Upper Palaeolithic site of Xibaimaying in the Nihewan Basin, northern China: implications for small-tool and microblade industries in north-east Asia during Marine Isotope Stages 2 and 3

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    It has been suggested that the \u27small-tool\u27 and microblade Upper Palaeolithic industries coexisted in the Nihewan Basin of northern China for about 8-14 000 years during Marine Isotope Stage (MIS) 2. This inference was based on uranium-series ages of around 15 and 18 ka for bovid teeth recovered from the \u27latest\u27 small-tool site of Xibaimaying - the youngest occurrence of such tools in the region - and optically stimulated luminescence (OSL) dating of the earliest typical microblade site (Youfang: ∼26-29 ka). In this study, we re-dated the Xibaimaying site using single-grain OSL methods and the resulting ages indicate that the cultural layer was deposited 46 ± 3 ka ago, during MIS 3 - more than 20 millennia earlier than previously thought and older also than the so-called earliest \u27primitive\u27 and typical microblade tools found at Zhiyu (∼31-39 ka cal BP) and Youfang. These new ages for human occupation of Xibaimaying remove support for the parallel development of the small-tool and microblade industries in the Nihewan Basin during the Upper Palaeolithic, but reliable age estimates from additional sites are needed to confidently infer the nature of the chronological relationship between these two Upper Palaeolithic industries and the associated toolmakers
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