Optical Monitoring of the Seyfert Galaxy NGC 4151 and Possible Periodicities in the Historical Light Curve

We report B, V, and R band CCD photometry of the Seyfert galaxy NGC 4151 obtained with the 1.0-m telescope at Weihai Observatory of Shandong University and the 1.56-m telescope at Shanghai Astronomical Observatory from 2005 December to 2013 February. Combining all available data from literature, we have constructed a historical light curve from 1910 to 2013 to study the periodicity of the source using three different methods (the Jurkevich method, the Lomb-Scargle periodogram method and the Discrete Correlation Function method). We find possible periods of P_1=4\pm0.1, P_2=7.5\pm0.3 and P_3=15.9\pm0.3 yr.Comment: 8 pages, 5 figures, Accepted by Research in Astronomy and Astrophysic

Kuaipedia: a Large-scale Multi-modal Short-video Encyclopedia

Online encyclopedias, such as Wikipedia, have been well-developed and researched in the last two decades. One can find any attributes or other information of a wiki item on a wiki page edited by a community of volunteers. However, the traditional text, images and tables can hardly express some aspects of an wiki item. For example, when we talk about ``Shiba Inu'', one may care more about ``How to feed it'' or ``How to train it not to protect its food''. Currently, short-video platforms have become a hallmark in the online world. Whether you're on TikTok, Instagram, Kuaishou, or YouTube Shorts, short-video apps have changed how we consume and create content today. Except for producing short videos for entertainment, we can find more and more authors sharing insightful knowledge widely across all walks of life. These short videos, which we call knowledge videos, can easily express any aspects (e.g. hair or how-to-feed) consumers want to know about an item (e.g. Shiba Inu), and they can be systematically analyzed and organized like an online encyclopedia. In this paper, we propose Kuaipedia, a large-scale multi-modal encyclopedia consisting of items, aspects, and short videos lined to them, which was extracted from billions of videos of Kuaishou (Kwai), a well-known short-video platform in China. We first collected items from multiple sources and mined user-centered aspects from millions of users' queries to build an item-aspect tree. Then we propose a new task called ``multi-modal item-aspect linking'' as an expansion of ``entity linking'' to link short videos into item-aspect pairs and build the whole short-video encyclopedia. Intrinsic evaluations show that our encyclopedia is of large scale and highly accurate. We also conduct sufficient extrinsic experiments to show how Kuaipedia can help fundamental applications such as entity typing and entity linking

Ethyl 3-(2,4-difluoro­phen­oxy)-2-(4-methoxy­phen­yl)acrylate

In the title mol­ecule, C18H16F2O4, the two benzene rings form a dihedral angle of 55.2 (2)°. In the crystal structure, weak inter­molecular C—H⋯O hydrogen bonds link the mol­ecules into chains propagating along the c axis

Mechanical Properties of MJ-Class Toroidal Magnet Wound by Composite HTS Conductor

An MJ-class superconducting magnetic energy storage (SMES) system has a wide range of potential applications in electric power systems. The composite high-temperature superconducting HTS conductor, which has the advantages of carrying large critical currents and withstanding high magnetic fields, is suitable for winding an MJ-class magnet coil. However, the Lorentz force of an HTS wire is so large that its induced mechanical stresses should be examined to ensure that the magnet is in good condition. By means of the equivalent material properties method and the sequential coupling method, this paper studies the mechanical properties of a three MJ toroidal SMES magnet wound by a composite HTS conductor. Based on the electromagnetic-structural coupling analysis, the Von-Mises stress, the radial stress, and the hoop stress of a magnet coil are calculated and employed to validate the stability of the MJ-class toroidal SMES magnet

Review on respiratory infectious disease transmission mechanism: effects of human movement and facemask use

Respiratory infectious diseases can cause public health emergencies, threatening human well-being, social operation, and economic development. Clarifying the transmission mechanism of respiratory infectious diseases is essential for control measures. We review the main research findings on the transmission mechanism of respiratory infectious diseases in recent decades. The source characteristics of respiratory infectious diseases, the airborne transmission mechanism, the exposure of susceptible persons, and the infection risk assessment methods are discussed. Given that the dynamic scenario of respiratory infectious disease transmission has attracted wide attention in recent years, we summarize the effects of human movement on indoor airflow, pathogen diffusion, and human exposure. Considering the everyday use of facemasks, the effects of facemasks on source characteristics and infection risk are also discussed. Finally, future research prospects are proposed. The transmission mechanism of infectious diseases can be comprehensively explored by delving into patients' pathological characteristics and personnel protection measures. This exploration can be facilitated by establishing a multi-pose manikin database, enabling personalized and refined evaluations. Interdisciplinary cooperation will play a pivotal role in fostering a holistic understanding. Furthermore, it is crucial to account for the impact of individuals' activity patterns on disease transmission dynamics. This review is expected to reference public health emergency management