20,335 research outputs found

    Chaos in two black holes with next-to-leading order spin-spin interactions

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    We take into account the dynamics of a complete third post-Newtonian conservative Hamiltonian of two spinning black holes, where the orbital part arrives at the third post-Newtonian precision level and the spin-spin part with the spin-orbit part includes the leading-order and next-to-leading-order contributions. It is shown through numerical simulations that the next-to-leading order spin-spin couplings play an important role in chaos. A dynamical sensitivity to the variation of single parameter is also investigated. In particular, there are a number of \textit{observable} orbits whose initial radii are large enough and which become chaotic before coalescence

    Monitoring the Quality of After-school Services: Theoretical Logic, System Construction and Implementation Mechanisms

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    With the introduction of the “double reduction” policy in 2021, China’s after-school services have begun the historical process of germination, exploration, development and deepening. With the full coverage of after-school services, it is urgent to monitor the quality of after-school services, which is also in line with the requirements of the report of the 20th National Congress that “we should adhere to the people-centred development of education, accelerate the construction of high-quality education, accelerate the construction of a high-quality education system, develop quality education and promote educational equity”. Monitoring the quality of after-school services is a systematic, process-oriented and cyclical practice. The construction of a monitoring system should systematically integrate elements such as government, headmasters, teachers and parents, and should establish a collaborative mechanism of multiple subjects with clear responsibilities, an innovative mechanism of testing tools driven by big data, and a comprehensive mechanism for the long-term operation of the testing system
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