324 research outputs found

    Development and Control of Soybean Aphid, Aphis glycines, in Heilongjiang Province

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    Originating text in Chinese.Citation: Wang, Chunrong, Chen, Jiguang, Guo, Yuren, Gong, Xiangyu, Xu, Zhaofei, Lin, Chao. (1998). Development and Control of Soybean Aphid, Aphis glycines, in Heilongjiang Province. Soybean Bulletin, 6, 15

    Decays of 1−+1^{-+} Charmoniumlike Hybrid

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    By extracting the transition amplitudes, we give the first lattice QCD prediction of the two-body decay partial widths of the 1−+1^{-+} charmoniumlike hybrid ηc1\eta_{c1}. Given the calculated mass value mηc1=4.329(36)m_{\eta_{c1}}=4.329(36) GeV, the ηc1\eta_{c1} decay is dominated by the open charm modes D1DˉD_1\bar{D}, D∗DˉD^*\bar{D} and D∗Dˉ∗D^*\bar{D}^* with partial widths of 258(133)258(133) MeV, 88(18)88(18) MeV and 150(118)150(118) MeV, respectively. The coupling of ηc1\eta_{c1} to χc1\chi_{c1} plus a flavor singlet pseudoscalar is not small, but χc1η\chi_{c1}\eta decay is suppressed by the small η−η′\eta-\eta' mixing angle. The partial width of ηc1→ηcη′\eta_{c1}\to \eta_c\eta' is estimated to be around 1 MeV. We suggest experiments to search for ηc1\eta_{c1} in the PP-wave D∗DˉD^*\bar{D} and D∗Dˉ∗D^*\bar{D}^* systems. Especially, the polarization of D∗Dˉ∗D^*\bar{D}^* can be used to distinguish the 1−+1^{-+} product (total spin S=1S=1) from 1−−1^{--} products (S=0S=0).Comment: 16 pages, 8 figure

    PolarNet: An Improved Grid Representation for Online LiDAR Point Clouds Semantic Segmentation

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    The need for fine-grained perception in autonomous driving systems has resulted in recently increased research on online semantic segmentation of single-scan LiDAR. Despite the emerging datasets and technological advancements, it remains challenging due to three reasons: (1) the need for near-real-time latency with limited hardware; (2) uneven or even long-tailed distribution of LiDAR points across space; and (3) an increasing number of extremely fine-grained semantic classes. In an attempt to jointly tackle all the aforementioned challenges, we propose a new LiDAR-specific, nearest-neighbor-free segmentation algorithm - PolarNet. Instead of using common spherical or bird's-eye-view projection, our polar bird's-eye-view representation balances the points across grid cells in a polar coordinate system, indirectly aligning a segmentation network's attention with the long-tailed distribution of the points along the radial axis. We find that our encoding scheme greatly increases the mIoU in three drastically different segmentation datasets of real urban LiDAR single scans while retaining near real-time throughput.Comment: Accepted by CVPR 2020; Code at https://github.com/edwardzhou130/PolarSe

    Meta-Transformer: A Unified Framework for Multimodal Learning

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    Multimodal learning aims to build models that can process and relate information from multiple modalities. Despite years of development in this field, it still remains challenging to design a unified network for processing various modalities (e.g.\textit{e.g.} natural language, 2D images, 3D point clouds, audio, video, time series, tabular data) due to the inherent gaps among them. In this work, we propose a framework, named Meta-Transformer, that leverages a frozen\textbf{frozen} encoder to perform multimodal perception without any paired multimodal training data. In Meta-Transformer, the raw input data from various modalities are mapped into a shared token space, allowing a subsequent encoder with frozen parameters to extract high-level semantic features of the input data. Composed of three main components: a unified data tokenizer, a modality-shared encoder, and task-specific heads for downstream tasks, Meta-Transformer is the first framework to perform unified learning across 12 modalities with unpaired data. Experiments on different benchmarks reveal that Meta-Transformer can handle a wide range of tasks including fundamental perception (text, image, point cloud, audio, video), practical application (X-Ray, infrared, hyperspectral, and IMU), and data mining (graph, tabular, and time-series). Meta-Transformer indicates a promising future for developing unified multimodal intelligence with transformers. Code will be available at https://github.com/invictus717/MetaTransformerComment: Project website: https://kxgong.github.io/meta_transformer

    1−+1^{-+} Hybrid in J/ψJ/\psi Radiative Decays from Lattice QCD

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    We present the first theoretical prediction of the production rate of 1−+1^{-+} light hybrid meson η1\eta_1 in J/ψJ/\psi radiative decays. In the Nf=2N_f=2 lattice QCD formalism with the pion mass mπ≈350m_\pi\approx 350 MeV, the related electromagnetic multipole form factors are extracted from the three-point functions that involve necessarily quark annihilation diagrams, which are calculated through the distillation method. The partial width of J/ψ→γη1J/\psi\to \gamma \eta_1 is determined to be 2.29(77) eV2.29(77)~\mathrm{eV} at the η1\eta_1 mass mη1=2.23(4)m_{\eta_1}=2.23(4) GeV. If η1\eta_1 corresponds to the recently observed η1(1855)\eta_1(1855) in the process J/ψ→γη1(1855)→γηη′J/\psi\to \gamma\eta_1(1855)\to \gamma \eta\eta' by BESIII, then the branching fraction Br(J/ψ→γη1(1855))\mathrm{Br}(J/\psi\to \gamma\eta_1(1855)) is estimated to be 6.2(2.2)×10−56.2(2.2)\times 10^{-5}, which implies Br(η1(1855)→ηη′)∼4.3%\mathrm{Br}(\eta_1(1855)\to \eta\eta')\sim 4.3\%

    The dilemma of public information disclosures

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    In this paper, we document a novel fact that disclosures of public information reshape social dynamics in China. Using the staggered roll-out of a quasi-natural experiment of air pollution information disclosure and a novel high-frequency data set of social and public events, we find socioeconomic cooperation and protests both significantly decrease after disclosure. The negative effects are larger when the disclosed pollution level is higher and when residents have higher environmental awareness and lower trust in local governments. Our results are rationalized in a theoretical model and suggest that information disclosure involves a tradeoff between economic efficiency and political stability and leads to a dilemma for policymakers

    Extreme high temperatures and adaptation by social dynamics: Theory and Evidence from China

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    Using a novel city-level high-frequency panel data set of social and public events in Chinese cities, we document that extreme high temperatures significantly reshape social dynamics. Extreme high temperatures lead to an increase in social cooperation, and the effects are more salient when productivity is lower and labor is more intensively used. This implies extreme high temperatures boost the relative returns of cooperation given lowered productivity. Our estimates and quantitative model suggest that the human race adapts to global warming by reshaping its social dynamics: adaptation via social dynamics offsets about one-third of the negative impacts of extreme high temperatures on the economy
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