9,986 research outputs found

    Analysis of the Chinese provincial air transportation network

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    The air transportation system is of a great impact on the economy and globalization of a country. In this paper, we analyze the Chinese air transportation network (ATN) from a provincial perspective via the complex network framework, where all airports located in one province are abstracted as a single node and flights between two provinces are denoted by a link. The results show that the network exhibits small-world property, homogeneous structure and disassortative mixing. The variation of the flight flow within 24 h is investigated and an obvious tide phenomenon is found in the dynamics of Chinese provincial ATN for high output level of tertiary industry. Our work will offer a novel approach for understanding the characteristic of the Chinese air transportation network.Peer ReviewedPostprint (author's final draft

    Topological Band Theory for Non-Hermitian Hamiltonians

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    We develop the topological band theory for systems described by non-Hermitian Hamiltonians, whose energy spectra are generally complex. After generalizing the notion of gapped band structures to the non-Hermitian case, we classify "gapped" bands in one and two dimensions by explicitly finding their topological invariants. We find nontrivial generalizations of the Chern number in two dimensions, and a new classification in one dimension, whose topology is determined by the energy dispersion rather than the energy eigenstates. We then study the bulk-edge correspondence and the topological phase transition in two dimensions. Different from the Hermitian case, the transition generically involves an extended intermediate phase with complex-energy band degeneracies at isolated "exceptional points" in momentum space. We also systematically classify all types of band degeneracies.Comment: 6 pages, 3 figures + 6 pages of supplemental materia

    Low Transmission to Elimination: Rural Development as a Key Determinant of the End-Game Dynamics of Schistosoma japonicum in China.

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    Rural development has been a critical component of China's economic miracle since the start of economic reform in the early 1980s, both benefiting from and contributing to the nation's rapid economic growth. This development has yielded substantial improvements of public health relevance, including contributing to major reductions in schistosomiasis prevalence. The history of schistosomiasis elimination in Japan suggests that development played a dominant causal role in that nation. We argue that it is highly probable that a similar story is playing out in at least some large regions of China. In particular, we summarize evidence from Sichuan Province which supports the case that economic development has led to improvements in rural irrigation and water supply which, together with changes in crop selection and agricultural mechanization, have all contributed to sustainable reductions in the prevalence of Schistosoma japonicum. The two major factors that have experienced major reductions are the area of snail habitat and the degree of human exposure, both through a variety of mechanisms which differ by region and economic circumstance. However, hotspots of transmission remain. Overall, however, economic development in traditionally endemic areas has provided the resources to carry out projects that have had major beneficial impacts on disease transmission that are likely to be sustainable

    Z_3 Symmetry and Neutrino Mixing in Type II Seesaw

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    Neutrino mixing matrix satisfying the current experimental data can be well described by the HPS tri-bimaximal mixing matrix. We propose that its origin can be understood within the seesaw framework by a hidden condition on the mass matrix of heavy right-handed neutrinos under the transformation of the Abelian finite group Z_3 on the flavor basis. Ignoring CP phases, we show that it can lead to the generic form of the effective light neutrino mass matrix from which the HPS mixing matrix appears naturally, as well as an expeimentally allowed non-zero \sin\theta_{13}. We show that the model based on our proposal is in good agreement with the current experimental data.Comment: 9 page

    Identifying vital edges in Chinese air route network via memetic algorithm

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    Due to its rapid development in the past decade, air transportation system has attracted considerable research attention from diverse communities. While most of the previous studies focused on airline networks, here we systematically explore the robustness of the Chinese air route network, and identify the vital edges which form the backbone of Chinese air transportation system. Specifically, we employ a memetic algorithm to minimize the network robustness after removing certain edges hence the solution of this model is the set of vital edges. Counterintuitively, our results show that the most vital edges are not necessarily the edges of highest topological importance, for which we provide an extensive explanation from the microscope of view. Our findings also offer new insights to understanding and optimizing other real-world network systems
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