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Evidence for particle acceleration approaching PeV energies in the W51 complex

Science Bulletin 2024年第18期69卷 2833-2841页

作者： Cao, Zhen Aharonian, F. Axikegu bai, y.x. Bao, y.W. Bastieri, D. Bi, x.J. Bi, y.J. Bian, W. Bukevich, A.V. Cao, Q. Cao, W.y. Cao, Zhe Chang, J. Chang, J.F. Chen, A.M. Chen, E.S. Chen, H.x. Chen, Liang Chen, Lin Chen, Long Chen, M.J. Chen, M.L. Chen, Q.H. Chen, S. Chen, S.H. Chen, S.Z. Chen, T.L. Chen, y. Cheng, N. Cheng, y.D. Cui, M.y. Cui, S.W. Cui, x.H. Cui, y.D. Dai, B.Z. Dai, H.L. Dai, Z.G. Danzengluobu Dong, x.Q. Duan, K.K. Fan, J.H. Fan, y.Z. Fang, J. Fang, J.H. Fang, K. Feng, C.F. Feng, H. Feng, L. Feng, S.H. Feng, x.T. Feng, y. Feng, y.L. Gabici, S. Gao, B. Gao, C.D. Gao, Q. Gao, W. Gao, W.K. Ge, M.M. Geng, L.S. Giacinti, G. Gong, G.H. Gou, Q.B. Gu, M.H. Guo, F.L. Guo, x.L. Guo, y.Q. Guo, y.y. Han, y.A. Hasan, M. He, H.H. He, H.N. He, J.y. He, y. Hor, y.K. Hou, B.W. Hou, C. Hou, x. Hu, H.B. Hu, Q. Hu, S.C. Huang, D.H. Huang, T.Q. Huang, W.J. Huang, x.T. Huang, x.y. Huang, y. Ji, x.L. Jia, H.y. Jia, K. Jiang, K. Jiang, x.W. Jiang, Z.J. Jin, M. Kang, M.M. Karpikov, I. Kuleshov, D. Kurinov, K. Li, B.B. Li, C.M. Li, Cheng Li, Cong Li, D. Li, F. Li, H.B. Li, H.C. Li, Jian Li, Jie Li, K. Li, S.D. Li, W.L. Li, x.R. Li, xin Li, y.Z. Li, Zhe Li, Zhuo Liang, E.W. Liang, y.F. Lin, S.J. Liu, B. Liu, C. Liu, D. Liu, D.B. Liu, H. Liu, H.D. Liu, J. Liu, J.L. Liu, M.y. Liu, R.y. Liu, S.M. Liu, W. Liu, y. Liu, y.N. Luo, Q. Luo, y. Lv, H.K. Ma, B.Q. Ma, L.L. Ma, x.H. Mao, J.R. Min, Z. Mitthumsiri, W. Mu, H.J. Nan, y.C. Neronov, A. Ou, L.J. Pattarakijwanich, P. Pei, Z.y. Qi, J.C. Qi, M.y. Qiao, B.Q. Qin, J.J. Raza, A. Ruffolo, D. Sáiz, A. Saeed, M. Semikoz, D. Shao, L. Shchegolev, O. Sheng, x.D. Shu, F.W. Song, H.C. Stenkin, yu.V. Stepanov, V. Su, y. Sun, D.x. Sun, Q.N. Sun, x.N. Sun, Z.B. Takata, J. Tam, P.H.T. Key Laboratory of Particle Astrophysics & Experimental Physics Division & Computing Center Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China University of Chinese Academy of Sciences Beijing 100049 China TIANFU Cosmic Ray Research Center Chengdu China Dublin Institute for Advanced Studies 31 Fitzwilliam Place 2 Dublin Ireland Max-Planck-Institut for Nuclear Physics P.O. Box 103980 Heidelberg 69029 Germany School of Physical Science and Technology & School of Information Science and Technology Southwest Jiaotong University Chengdu 610031 China School of Astronomy and Space Science Nanjing University Nanjing 210023 China Center for Astrophysics Guangzhou University Guangzhou 510006 China Tsung-Dao Lee Institute & School of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240 China Institute for Nuclear Research of Russian Academy of Sciences Moscow 117312 Russia Hebei Normal University Shijiazhuang 050024 China University of Science and Technology of China Hefei 230026 China State Key Laboratory of Particle Detection and Electronics China Key Laboratory of Dark Matter and Space Astronomy & Key Laboratory of Radio Astronomy Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210023 China Research Center for Astronomical Computing Zhejiang Laboratory Hangzhou 311121 China Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China School of Physics and Astronomy Yunnan University Kunming 650091 China Key Laboratory of Cosmic Rays (Tibet University) Ministry of Education Lhasa 850000 China National Astronomical Observatories Chinese Academy of Sciences Beijing 100101 China School of Physics and Astronomy (Zhuhai) & School of Physics (Guangzhou) & Sino-French Institute of Nuclear Engineering and Technology (Zhuhai) Sun Yat-sen University Zhuhai 519000 & Guangzhou 510275 Guangdong China Institute of Frontier and

The γ-ray emission from the W51 complex is widely acknowledged to be attributed to the interaction between the cosmic rays (CRs) accelerated by the shock of supernova remnant (SNR) W51C and the dense molecular clouds in the adjacent star-forming region, W51B. However, the maximum acceleration capability of W51C for CRs remains elusive. Based on observations conducted with the Large High Altitude Air Shower Observatory (LHAASO), we report a significant detection of γ rays emanating from the W51 complex, with energies from 2 to 200 TeV. The LHAASO measurements, for the first time, extend the γ-ray emission from the W51 complex beyond 100 TeV and reveal a significant spectrum bending at tens of TeV. By combining the "π0-decay bump" featured data from Fermi-LAT, the broadband γ-ray spectrum of the W51 region can be well-characterized by a simple pp-collision model. The observed spectral bending feature suggests an exponential cutoff at ∼400 TeV or a power-law break at ∼200 TeV in the CR proton spectrum, most likely providing the first evidence of SNRs serving as CR accelerators approaching the PeV regime. Additionally, two young star clusters within W51B could also be theoretically viable to produce the most energetic γ rays observed by LHAASO. Our findings strongly support the presence of extreme CR accelerators within the W51 complex and provide new insights into the origin of Galactic CRs. © 2024 Science China Press

关键词： Cosmic rays

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Distinct Electrical and Mechanical Responses of a Cu-10Fe Composite Prepared by Hot-Pressed Sintering and Post Treatment

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Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 255-265页

作者： x.y.yue S.y.Peng x.Zhang C.N.He y.Z.Tian Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang110819China School of Materials Science and Engineering and Tianjin Key Laboratory of Composite and Functional Materials Tianjin UniversityTianjin300350China Research Centre for Metallic Wires Northeastern UniversityShenyang110819China

A Cu-10wt%Fe composite was prepared through hot-pressed sintering,and the material was subsequently solution *** hot-pressed sintered and solution treated materials were rolled and *** precipitation behavior and performance changes were systematically studied by using scanning electron microscopy and transmission electron *** contrast to the hot-pressed sintered specimen,the solution treatment significantly affects the thermal stability and properties of the Cu-10wt%Fe *** Cu-10wt%Fe composite was prepared after solid solution,cold rolling and aging at 773 K for 1 h,and it obtained excellent tensile strength of 494 MPa,uniform elongation of 16.3%,electrical conductivity of 51.1%IACS and softening temperature of 838 *** for the distinct difference in thermal stability and properties between hot-pressed sintered and solution treated specimens were *** findings provide a theoretical basis for designing high-performance Cu-based in-situ composites by post treatment.

关键词： Cu-Fe composite Hot-pressed sintering Thermal stability Strength Electrical conductivity

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Identity-based searchable attribute signcryption in lattice for a blockchain-based medical system

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Frontiers of Information Technology & Electronic Engineering 2024年第3期25卷 461-471页

作者： Huifang yU xiaoping bai School of Cyberspace Security Xi'an University of Posts&TelecommunicationsXi'an 710121China School of Information Engineering Qinghai Communications Technical CollegeXining 810003China

Electronic healthcare systems can offer convenience but face the risk of data forgery and information *** solve these issues,we propose an identity-based searchable attribute signcryption in lattice for a blockchain-based medical system(BCMS-LIDSASC).BCMS-LIDSASC achieves decentralization and anti-quantum security in the blockchain environment,and provides fine-grained access control and ***,smart contracts are used to replace traditional trusted third parties,and the interplanetary file system(IPFS)is used for ciphertext storage to alleviate storage pressure on the *** to other schemes,BCMS-LIDSASC requires smaller key size and less storage,and has lower computation *** contributes to secure and efficient management of medical data and can protect patient privacy and ensure the integrity of electronic healthcare systems.

关键词： Blockchain Identity-based searchable attribute signcryption Distributed storage NTRU lattice

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A novel efficient energy absorber with free inversion of a metal foam-filled circular tube

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Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 1-14页

作者： Jianxun ZHANG Jinwen bai State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace EngineeringXi'an Jiaotong UniversityXi'an 710049China

In this paper, a novel efficient energy absorber with free inversion of a metal foam-filled circular tube(MFFCT) is designed, and the axial compressive behavior of the MFFCT under free inversion is studied analytically and numerically. The theoretical analysis reveals that the energy is mainly dissipated through the radial bending of the metal circular tube, the circumferential expansion of the metal circular tube, and the metal filled-foam compression. The principle of energy conservation is used to derive the theoretical formula for the minimum compressive force of the MFFCT over free inversion under axial loading. Furthermore, the free inversion deformation characteristics of the MFFCT are analyzed numerically. The theoretical steady values are found to be in good agreement with the results of the finite element(FE) analysis. The effects of the average diameter of the metal tube, the wall thickness of the metal tube, and the filled-foam strength on the free inversion deformation of the MFFCT are considered. It is observed that in the steady deformation stage, the load-carrying and energy-absorbing capacities of the MFFCT increase with the increase in the average diameter of the metal tube, the wall thickness of the metal tube, or the filled-foam strength. The specific energy absorption(SEA) of free inversion of the MFFCT is significantly higher than that of the metal tube alone.

关键词： metal foam-filled circular tube(MFFCT) free inversion load-carrying capacity energy absorption

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Use of induced pluripotent stem cell-derived brain cells,organoids,assembloids,and blood-brain barrier models in understanding alcohol and anesthetic-induced brain injuries:an emerging perspective

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Neural Regeneration Research 2024年第5期19卷 953-954页

作者： xiaowen bai Department of Cell Biology Neurobiology&AnatomyMedical College of WisconsinMilwaukeeWIUSA

Neurological disorders,including developmental disorders,Alzheimer’s disease(AD),and psychiatric conditions,have significant social and economic impacts *** extensive research into the underlying mechanisms of these disorders,effective treatments remain elusive,partly due to the complexity of the brain,the limited availability of human brain tissue,and the blood-brain barrier(BBB)’s impermeability to certain *** perspective article discusses the potential of human induced pluripotent stem cell(iPSC)-based models of brain cells,organoids,assembloids,and BBB to advance our understanding of the etiology,progression,and mechanisms of brain injuries induced by alcohol consumption and general *** models could also be used to develop protective and therapeutic approaches.

关键词： injuries protective drugs

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Fast efficient photon deceleration in plasmas by using two laser pulses at different frequencies

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Matter and Radiation at Extremes 2024年第3期9卷 11-18页

作者： y.x.Wang x.L.Zhu S.M.Weng P.Li x.F.Li H.Ai H.R.Pan Z.M.Sheng Key Laboratory for Laser Plasmas(moe) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghai 200240China Research Center of Laser Fusion of China Academy of Engineering Physics MianyangSichuan 621900China State key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Tsung-dao Lee Institute Shanghai Jiao Tong UniversityShanghai 200240China

The generation of ultrashort high-power light sources in the mid-infrared(mid-IR)to terahertz(THz)range is of interest for applications in a number of fields,from fundamental research to biology and *** conventional laser technology,photon deceleration in plasma wakes provides an alternative approach to the generation of ultrashort mid-IR or THz ***,we present a photon deceleration scheme for the efficient generation of ultrashort mid-IR or THz pulses by using an intense driver laser pulse with a relatively short wavelength and a signal laser pulse with a relatively long *** signal pulse trails the driver pulse with an appropriate time delay such that it sits at the front of the second wake bubble that is driven by the driver *** to its relatively long wavelength,the signal pulse will be subjected to a large gradient of the refractive index in the plasma wake ***,the photon deceleration in the plasma wake becomes faster and more efficient for signal pulses with longer *** greatly enhances the capacity and efficiency of photon deceleration in the generation of ultrashort high-power light sources in the long-wavelength IR and THz spectral ranges.

关键词： laser ultrashort photon

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Knowledge-Driven Possibilistic Clustering with Automatic Cluster Elimination

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Computers, Materials and Continua 2024年第3期80卷 4917-4945页

作者： Hu x. Tang y. Pedrycz W. Jiang J. Jiang y. The School of Computer Science and Engineering Southeast University Nanjing 211189 China The School of Computer and Information Hefei University of Technology Hefei 230601 China The Department of Electrical and Computer Engineering University of Alberta Edmonton T6R 2V4 AB Canada The Systems Research Institute Polish Academy of Sciences Warsaw 00-901 Poland The School of Information Engineering Nanjing University of Finance and Economics Nanjing 210023 China

Traditional Fuzzy C-Means (FCM) and Possibilistic C-Means (PCM) clustering algorithms are data-driven, and their objective function minimization process is based on the available numeric data. Recently, knowledge hints have been introduced to form knowledge-driven clustering algorithms, which reveal a data structure that considers not only the relationships between data but also the compatibility with knowledge hints. However, these algorithms cannot produce the optimal number of clusters by the clustering algorithm itself; they require the assistance of evaluation indices. Moreover, knowledge hints are usually used as part of the data structure (directly replacing some clustering centers), which severely limits the flexibility of the algorithm and can lead to knowledge misguidance. To solve this problem, this study designs a new knowledge-driven clustering algorithm called the PCM clustering with High-density Points (HP-PCM), in which domain knowledge is represented in the form of so-called high-density points. First, a new data density calculation function is proposed. The Density Knowledge Points Extraction (DKPE) method is established to filter out high-density points from the dataset to form knowledge hints. Then, these hints are incorporated into the PCM objective function so that the clustering algorithm is guided by high-density points to discover the natural data structure. Finally, the initial number of clusters is set to be greater than the true one based on the number of knowledge hints. Then, the HP-PCM algorithm automatically determines the final number of clusters during the clustering process by considering the cluster elimination mechanism. Through experimental studies, including some comparative analyses, the results highlight the effectiveness of the proposed algorithm, such as the increased success rate in clustering, the ability to determine the optimal cluster number, and the faster convergence speed. Copyright © 2024 The Authors. Published by

关键词： Fuzzy C-Means (FCM) fuzzy logic knowledge-driven machine learning optimal number of clusters possibilistic clustering

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Magnetic and electrical transport study of the intrinsic magnetic topological insulator MnBi_(2)Te_(4)with Ge doping

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Frontiers of physics 2024年第3期19卷 51-59页

作者： Qingwang bai Mingxiang xu School of Physics Southeast UniversityNanjing 211189China

As an intrinsic magnetic topological insulator with magnetic order and non-trivial topological structure,MnBi_(2)Te_(4)is an ideal material for studying exotic topological states such as quantum anomalous Hall effect and topological axion insulating ***,we carry out magnetic and electrical transport measurements on(Mn1–xGex)Bi_(2)Te_(4)(x=0,0.15,0.30,0.45,0.60,and 0.75)single *** is found that with increasing x,the dilution of magnetic moments gradually weakens the antiferromagnetic exchange ***,Ge doping reduces the critical field of ferromagnetic ordering,which may provide a possible way to implement the quantum anomalous Hall effect at lower magnetic *** transport measurements suggest that electrons are the dominant charge carriers,and the carrier density increases with the Ge doping ***,the Kondo effect is observed in the samples with x=0.45,0.60,and *** results suggest that doping germanium is a viable way to tune the magnetic and electrical transport properties of MnBi_(2)Te_(4),opening up the possibility of future applications in magnetic topological insulators.

关键词： MnBi_(2)Te_(4) intrinsic magnetic topological insulator transition points Kondo effect

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Evaluating CMIP6 models in simulating the North Pacific decadal variability in sea surface salinity

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Science China Earth Sciences 2024年第8期67卷 2661-2680页

作者： Jian CHEN Hailong LIU Pengfei LIN Wenrong bai Chengzu bai Lu WANG Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China State Key Laboratory of Geo-Information Engineering Xi’an 710054China Beijing Municipal Climate Center Beijing Meteorological BureauBeijing 100089China Space System Department Equipment Department Beijing 100096China

The North Pacific sea surface salinity(SSS)decadal variability(NPSDV)and its potential forcing were evaluated from 25 coupled models of the Coupled Model Intercomparison Project phase 6(CMIP6)considering the prospects for decadal climate *** results indicated that the CMIP6 models generally reproduced the spatial patterns of *** large standard deviation of the SSS anomaly over the strong current regions,such as the Kuroshio-Oyashio Extension(KOE),North Pacific Current(NPC),California Current System(CCS),and Alaskan Coastal Current(ACC),is reflected in the two leading modes of NPSDV:a dipole with out-of-phase loadings in the KOE-NPC versus CCS-ACC and a monopole with positive loading over the *** order of modes is sensitive to individual models that exhibit discrepancies,especially in temporal phases and power *** autoregressive model of order-1 was used to reconstruct the NPSDV with several forcing *** generally weaker influence of forcings in an autoregressive model of order-1 is partly related to the overestimated response time of NPSDV relative to *** NPSDV variances originate from the persistence of SSS anomalies,but the dominant forcing factors are diverse among *** model diversity for the NPSDV simulation mainly arises from the influence of the tropical El Ni?o-Southern Oscillation through teleconnection on the North Pacific Oscillation or Aleutian Low with timescale ***,models that can reproduce the NPSDV well are not dependent on those with larger impacts from the North Pacific oceanic processes.

关键词： North Pacific Sea surface salinity Decadal variability CMIP6 Leading mode

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Microphysical Insights into a Tornadic Supercell from Dual-Polarization Radar Observations in Jiangsu, China on 14 May 2021

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Journal of Meteorological Research 2024年第2期38卷 303-320页

作者： Chao yUAN yang bai Pengfei SUN Hua bai Lu xIA China Meteorological Administration Tornado Key Laboratory Foshan 528315 Institute of Atmospheric Environment China Meteorological AdministrationShenyang 110166 Panjin National Climate Observatory Panjin 124010 yangzhou Meteorological Bureau of Jiangsu Province Yangzhou 225100 yichun Meteorological Bureau of Heilongjiang Province Yichun 153000

Tornadoes are incredibly powerful and destructive natural events,yet the microphysical characteristics of the parent storm and its effects on tornadogenesis remain *** study analyzed polarization radar data of a tornadic supercell that occurred in Jiangsu Province of China on 14 May 2021,in comparison with another tornadic supercell and two non-tornadic supercells that occurred in the same region in *** two tornadic supercells exhibited lower differential reflectivity(ZDR)in the hook echo region compared with the non-tornadic supercells,indicating smaller median drop sizes.A distinct increase in ZDR from the melting of frozen hydrometeors,observed between2.5-and 4.0-km altitude in the non-tornadic storms,was absent in the tornadic *** non-tornadic supercells also displayed substantially higher specific differential phase(KDP)below the melting level,likely aroused from enhanced melting and *** findings suggest fundamental microphysical contrasts between tornadic and nontornadic ***,tornadic supercells have smaller droplets and may reduce melting in hook ***,greater separation between the ZDR arc and the KDP foot was observed during *** vertical gradient of KDP related to the cooling pool strength of the hook echo,regulating rear-flank downdraft *** the limited number of cases investigated,the findings of this study indicate that monitoring ZDR,KDP,and drop size distribution trends could assist with tornado prediction and warnings.

关键词： tornado polarimetric radar supercell hook echo drop size distribution

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