91 research outputs found

    Graph Learning of Multifaceted Motivations for Online Engagement Prediction in Counter-party Social Networks

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    Social media has emerged as an essential venue to invigorate online political engagement. However, political engagement is multifaceted and impacted by both individuals\u27 self-motivation and social influence from peers and remains challenging to model in a counter-party network. Therefore, we propose a counter-party graph representation learning model to study individuals\u27 intrinsic and extrinsic motivations for online political engagement. Firstly, we capture users\u27 intrinsic political interests providing self-motivation from a user-topic network. Then, we encode how users cast influence on others from the inner-/counter-party through a user-user network. With the learned embedding of intrinsic and extrinsic motivations, we model the interactions between these two facets and utilize the dependency by deep sequential model decoding. Finally, extensive experiments using Twitter data related to the 2020 U.S. presidential election and the 2019 HK protests validate the model\u27s predictive power. This study has implications for online political engagement, political participation, and political polarization

    Unconventional Flatband Line States in Photonic Lieb Lattices

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    Flatband systems typically host "compact localized states"(CLS) due to destructive interference and macroscopic degeneracy of Bloch wave functions associated with a dispersionless energy band. Using a photonic Lieb lattice(LL), we show that conventional localized flatband states are inherently incomplete, with the missing modes manifested as extended line states which form non-contractible loops winding around the entire lattice. Experimentally, we develop a continuous-wave laser writing technique to establish a finite-sized photonic LL with specially-tailored boundaries, thereby directly observe the unusually extended flatband line states.Such unconventional line states cannot be expressed as a linear combination of the previously observed CLS but rather arise from the nontrivial real-space topology.The robustness of the line states to imperfect excitation conditions is discussed, and their potential applications are illustrated

    Wearable grain silo working environment sensing and safety alarm system

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    A set of wearable granary working environment sensing and security alarm system is developed to ensure the safety of granary staff. The gas sensor, piezoelectric ceramic chip, infrared transmitting and receiving tube and photosensitive resistance are used as the core components of each circuit module to collect the gas concentration signal, human respiration intensity signal, pulse intensity signal and light signal in the granary. AD0809 module chip is used to convert analog data into digital data and send it to MCU for information processing to make alarm judgment. At the same time, PTR2000 module is used to transmit the sensor data to the upper computer. The upper computer determines whether to alarm through data comparison, and transmits the alarm signal to the mobile phone through Wi-Fi in real time. Each module cooperates with each other, information real-time transmission to complete the detection of granary environment and danger alarm. The test results show that the system can meet the safety operation requirements of large and medium-sized state-owned grain depot

    Robust mode-locking in a hybrid ultrafast laser based on nonlinear multimodal interference

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    We experimentally demonstrate the realization of a half-polarization-maintaining (half-PM) fiber laser, in which mode-locking is provided by a reflective multimode-interference saturable absorber (SA). In the specially designed SA, linearly polarized light is coupled into a 15-cm-long graded-index multimode fiber (GIMF) through the PM fiber, and then reflected back to the PM structure through a mirror pigtailed with a single-mode fiber (SMF). The modulation depth and saturation peak power are measured to be 1.5% and 0.6 W, respectively. The proposed SA device is incorporated into a novel half-PM erbium-doped fiber oscillator, which generates soliton pulses with 409 fs temporal duration at a 33.3 MHz repetition rate. The proposed fiber laser is compared with a conventional non-PM fiber laser mode-locked by nonlinear polarization evolution (NPE) in terms of optical properties such as spectral bandwidth, pulse duration, and stability performance. Short- and long-time stability tests and superior noise performance corroborate robust mode-locking in this setup.Comment: to be published in Optics and Laser Technolog

    Ecological vulnerability assessment based on remote sensing ecological index (RSEI): A case of Zhongxian County, Chongqing

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    The ecological vulnerability evaluation index was established through Normalized Difference Vegetation Index (NDVI), Wetness (WET), Normalized Difference Build-up and Soil Index (NDBSI) and Land Surface Temperature (LST) indicators, comprehensively evaluate the ecological vulnerability of Zhongxian County of Chongqing in 2002, 2009, and 2016 by Principal Components Analysis (PCA), and analyze its spatio-temporal evolution. The vulnerability areas of five levels were calculated respectively, and the overall index of ecological vulnerability was also calculated. The index of remote sensing ecological index (RSEI) and Normalized Difference Vegetation Index decreased first and then increased; the Wetness index showed an upward trend; the Normalized Difference Build-up and Soil Index index increased first and then decreased; and the Land Surface Temperature index decreased. The ecological vulnerability body index (EVBI) shows a downward trend, and the incremental changes are mainly concentrated in the negligible vulnerability areas and light vulnerability area, while the medium vulnerability, strong vulnerability and extreme vulnerability area generally show a downward trend. Furthermore, the new increment of ecological vulnerability grade area concentrates on negligible vulnerability area and light vulnerability area from 2002 to 2016. In general, the ecological vulnerability gradually shifts to low vulnerability, and the ecological environment tends to develop healthily

    Universal momentum-to-real-space mapping of topological singularities

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    Topological properties of materials, as manifested in the intriguing phenomena of quantum Hall effect and topological insulators, have attracted overwhelming transdisciplinary interest in recent years. Topological edge states, for instance, have been realized in versatile systems including electromagnetic-waves. Typically, topological properties are revealed in momentum space, using concepts such as Chern number and Berry phase. Here, we demonstrate a universal mapping of the topology of Dirac-like cones from momentum space to real space. We evince the mapping by exciting the cones in photonic honeycomb (pseudospin-1/2) and Lieb (pseudospin-1) lattices with vortex beams of topological charge l, optimally aligned for a chosen pseudospin state s, leading to direct observation of topological charge conversion that follows the rule of l to l+2s. The mapping is theoretically accounted for all initial excitation conditions with the pseudospin-orbit interaction and nontrivial Berry phases. Surprisingly, such a mapping exists even in a deformed lattice where the total angular momentum is not conserved, unveiling its topological origin. The universality of the mapping extends beyond the photonic platform and 2D lattices: equivalent topological conversion occurs for 3D Dirac-Weyl synthetic magnetic monopoles, which could be realized in ultracold atomic gases and responsible for mechanism behind the vortex creation in electron beams traversing a magnetic monopole field
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