On the validity of the definition of angular momentum in general relativity

We exam the validity of the definition of the ADM angular momentum without the parity assumption. Explicit examples of asymptotically flat hypersurfaces in the Minkowski spacetime with zero ADM energy-momentum vector and finite non-zero angular momentum vector are presented. We also discuss the Beig-\'O Murchadha-Regge-Teitelboim center of mass and study analogous examples in the Schwarzschild spacetime.Comment: References are updated, and typos and computational errors are corrected. Accepted by Ann. Henri Poincar

The evaluation of English listening courses at Taiwanese universities : an exploratory study

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Towards 4D Human Video Stylization

We present a first step towards 4D (3D and time) human video stylization, which addresses style transfer, novel view synthesis and human animation within a unified framework. While numerous video stylization methods have been developed, they are often restricted to rendering images in specific viewpoints of the input video, lacking the capability to generalize to novel views and novel poses in dynamic scenes. To overcome these limitations, we leverage Neural Radiance Fields (NeRFs) to represent videos, conducting stylization in the rendered feature space. Our innovative approach involves the simultaneous representation of both the human subject and the surrounding scene using two NeRFs. This dual representation facilitates the animation of human subjects across various poses and novel viewpoints. Specifically, we introduce a novel geometry-guided tri-plane representation, significantly enhancing feature representation robustness compared to direct tri-plane optimization. Following the video reconstruction, stylization is performed within the NeRFs' rendered feature space. Extensive experiments demonstrate that the proposed method strikes a superior balance between stylized textures and temporal coherence, surpassing existing approaches. Furthermore, our framework uniquely extends its capabilities to accommodate novel poses and viewpoints, making it a versatile tool for creative human video stylization.Comment: Under Revie

Coarse-Grain Model for Lipid Bilayer Self-Assembly and Dynamics: Multiparticle Collision Description of the Solvent

A mesoscopic coarse-grain model for computationally-efficient simulations of biomembranes is presented. It combines molecular dynamics simulations for the lipids, modeled as elastic chains of beads, with multiparticle collision dynamics for the solvent. Self-assembly of a membrane from a uniform mixture of lipids is observed. Simulations at different temperatures demonstrate that it reproduces the gel and liquid phases of lipid bilayers. Investigations of lipid diffusion in different phases reveals a crossover from subdiffusion to normal diffusion at long times. Macroscopic membrane properties, such as stretching and bending elastic moduli, are determined directly from the mesoscopic simulations. Velocity correlation functions for membrane flows are determined and analyzed

Research Performance, Collaboration, and Movement of Researchers in the Field of Business and Management: A Comparison between International and Domestic Migrants in East Asia

This study examines differences in research performance, international collaboration, and migration moves between two types of migrant researchers: international and domestic migrant researchers. The investigation focuses on 929 researchers in the field of business and management in four East Asian countries—China, Japan, South Korea, and Taiwan—and explores their scientific output and movements across types of institutions. The study uses bibliographic data from the Web of Science and Scopus author ID to disambiguate information across databases. The findings reveal that both international and domestic migrants demonstrate comparable productivity. Concerning publication quality, international migrants exhibit a higher citation impact, and researchers from Taiwan demonstrate the highest average number of citations per paper among the four countries. For international collaboration, international migrants report a higher rate of international collaboration than domestic migrants. The United States serves as the primary collaborative partner for migrant researchers from Taiwan, Japan, and South Korea, whereas China has a closer partnership with Hong Kong. Finally, international migrants demonstrate a higher frequency of migration, with an average of two moves per capita. This study provides empirical evidence for the value of scientific migration from the perspectives of international and domestic migrants in East Asian countries