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Repeating fast radio bursts: Coherent circular polarization by bunches

Science China(Physics,Mechanics & Astronomy) 2022年第8期65卷 148-157页

作者： Wei-Yang Wang jin-chen jiang Jiguang Lu Heng Xu jiangwei Xu Kejia Lee Jifeng Liu Renxin Xu School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking UniversityBeijing100871China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing100871China CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing100101China Guizhou Radio Astronomy Observatory Chinese Academy of SciencesGuiyang550025China Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing100101China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing100049China

Fast radio bursts(FRBs) are millisecond-duration signals that are highly dispersed at distant galaxies. However, the physical origin of FRBs is still unknown. Coherent curvature emission by bunches, e.g., powered by starquakes, has already been proposed for repeating FRBs. It has the nature of understanding narrowband radiation exhibiting time-frequency drifting. Recently, a highly active FRB source, i.e., FRB 20201124A, was reported to enter a newly active episode and emit at least some highly circular-polarized bursts. In this study, we revisit the polarized FRB emission, particularly investigating the production mechanisms of a highly circular polarization(CP) by deriving the intrinsic mechanism and propagative effect. The intrinsic mechanisms of invoking charged bunches are approached with radiative coherence. Consequently, a highly CP could naturally be explained by the coherent summation of outcome waves, generated or scattered by bunches, with different phases and electric vectors. Different kinds of evolutionary trajectories are found on the Poincaré sphere for the bunch-coherent polarization, and this behavior could be tested through future observations. Cyclotron resonance can result in the absorption of R-mode photons at a low altitude region of the magnetosphere, and an FRB should then be emitted from a high-altitude region if the waves have strong linear polarization. Circularly polarized components could be produced from Faraday conversion exhibiting a λ-oscillation, but the average CP fraction depends only on the income wave, indicating a possibility of a highly circular-polarized income wave. The analysis could be welcome if extremely high(e.g., almost 100%) CP from repeating FRBs is detected in the future. Finally, the production of a bulk of energetic bunches in the pulsar-like magnetosphere is discussed, which is relevant to the nature of the FRB central engine.

关键词： fast radio burst radiation mechanism neutron stars

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FRB 171019:an event of binary neutron star merger?

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Research in Astronomy and Astrophysics 2020年第4期20卷 107-114页

作者： jin-chen jiang Wei-Yang Wang Rui Luo Shuang Du Xuelei chen Ke-Jia Lee Ren-Xin Xu State Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China Key Laboratory of Computational Astrophysics National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China CSIRO Astronomy and Space Science ATNFBox 76 EppingNSW 1710Australia Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China

The fast radio burst,FRB 171019,was relatively bright when discovered first by ASKAP but was identified as a repeater with three faint bursts detected later by GBT and *** observations lead to the discussion of whether the first bright burst shares the same mechanism with the following repeating bursts.A model of binary neutron star merger is proposed for FRB 171019,in which the first bright burst occurred during the merger event,while the subsequent repeating bursts are starquake-induced,and generally fainter,as the energy release rate for the starquakes can hardly exceed that of the catastrophic merger *** scenario is consistent with the observation that no later burst detected is as bright as the first one.

关键词： pulsars:general stars:neutron dense matter gravitational waves

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FAST Observations of an Extremely Active Episode of FRB 20201124A.Ⅱ.Energy Distribution

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Research in Astronomy and Astrophysics 2022年第12期22卷 70-80页

作者： Yong-Kun Zhang Pei Wang Yi Feng Bing Zhang Di Li Chao-Wei Tsai chen-Hui Niu Rui Luo Ju-Mei Yao Wei-Wei Zhu jin-Lin Han Ke-Jia Lee De-jiang Zhou Jia-Rui Niu jin-chen jiang Wei-Yang Wang Chun-Feng Zhang Heng Xu Bo-Jun Wang jiang-Wei Xu National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Research Center for Intelligent Computing Platforms Zhejiang LaboratoryHangzhou 311100China Department of Physics and Astronomy University of NevadaLas VegasNV 89154USA Nevada Center for Astrophysics University of NevadaLas VegasNV 89154USA NAOC-UKZN Computational Astrophysics Centre University of KwaZulu-NatalDurban 4000South Africa CSIRO Space and Astronomy PO Box 76EppingNSW 1710Australia Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China Department of Astronomy Peking UniversityBeijing 100871China

We report the properties of more than 800 bursts detected from the repeating fast radio burst(FRB)source FRB20201124A with the Five-hundred-meter Aperture Spherical radio Telescope(FAST)during an extremely active episode on UTC 2021 September 25–28 in a series of four *** this second paper of the series,we study the energy distribution of 881 bursts(defined as significant signals separated by dips down to the noise level)detected in the first four days of our 19 hr observational campaign spanning 17 *** event rate initially increased exponentially but the source activity stopped within 24 hr after the 4th *** detection of 542 bursts in one hour during the fourth day marked the highest event rate detected from one single FRB source so *** bursts have complex structures in the time-frequency *** find a double-peak distribution of the waiting time,which can be modeled with two log-normal functions peaking at 51.22 ms and 10.05 s,*** with the emission from a previous active episode of the source detected with FAST,the second distribution peak time is smaller,suggesting that this peak is defined by the activity level of the *** calculate the isotropic energy of the bursts using both a partial bandwidth and a full bandwidth and find that the energy distribution is not significantly *** find that an exponentially connected broken-power law function can fit the cumulative burst energy distribution well,with the lower and higher-energy indices being-1.22±0.01 and-4.27±0.23,*** a radio radiative efficiency ofη_(r)=10^(-4),the total isotropic energy of the bursts released during the four days when the source was active is already 3.9×10^(46)erg,exceeding~23%of the available magnetar dipolar magnetic *** challenges the magnetar models which invoke an inefficient radio emission(e.g.,synchrotron maser models).

关键词： (stars:)pulsars:general stars:individual(FRB 20201124A) methods:data analysis

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Study on Quality Improvement Effect and Separate Character of Soybean Male Sterile (MS1) Recurrent Selection Population

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Agricultural Sciences in China 2007年第5期6卷 545-551页

作者： ZHAO Shuang-jin ZHANG Meng-chen jiang Chun-zhi YANG Chun-yan LIU Bing-qiang CUI Jue Institute of Food and Oil Crops Hebei Academy of Agricultural and Forestry Sciences~National Soybean Improvement Center ShijiazhuangSub-Center Shijiazhuang 050031 P.R.China

To solve the problem that soybean has narrow genetic base, we constructed a series of male sterile recurrent selection populations, and studied the effects of quality improvement and practical value. An LD-base population, which fits to our ecology type was constructed by 6 years＇ gene enrichment through the introduction of new genes from 23 local varieties and recurrent selection. The LD-base populations were then improved by making crosses with high protein and high oil genotypes. As a result we obtained a high protein sub-population （db） and a high oil sub-population （gy）, For the db sub-population, the protein content is 1.18% higher than the base population, 22.38% of the individuals contain 45% or more of protein, which is 10.99% higher than the base population. For the gy sub-population, oil content is 0.24% higher than the base population. Individuals with oil content of 20% or more are 11.05% higher than the base population. The quantitative characters such as flowering date, mature date, pod habit, and hilum color, etc., all showed wide range of separation, and the segregation ratio approached balance. The c.v. of branch number of ms1 recurrent population （72.8%） is higher than general cross-population （57.3%）, and the c.v. of 100 seed weight of ms1 （18.1%） is higher than general cross population （16.5%）, the coefficient of variation of plant height, pods per plant, and seeds per pod were not significantly different. It was demonstrated in this paper that the quality character of ms 1 male sterile recurrent selection population was improved by adding new genes. And the segregation of other characters widened, making the populations suitable for the objective of soybean breeding. In this paper, we also discussed the breeding method, key technology, and selection effect of soybean ms 1 population.

关键词： soybean recurrent selection population ms 1 gene quality improvement segregating characteristics

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FAST Observations of an Extremely Active Episode of FRB 20201124A.Ⅳ.Spin Period Search

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Research in Astronomy and Astrophysics 2022年第12期22卷 99-122页

作者： Jia-Rui Niu Wei-Wei Zhu Bing Zhang Mao Yuan De-jiang Zhou Yong-Kun Zhang jin-chen jiang J.L.Han Di Li Ke-Jia Lee Pei Wang Yi Feng Dong-Zi Li Rui Luo Fa-Yin Wang Zi-Gao Dai chen-chen Miao chen-Hui Niu Heng Xu Chun-Feng Zhang Wei-Yang Wang Bo-Jun Wang jiang-Wei Xu National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Institute for Frontier in Astronomy and Astrophysics Beijing Normal UniversityBeijing 102206China Department of Physics and Astronomy University of NevadaLas VegasNV 89154USA Department of Astronomy Peking UniversityBeijing 100871China NAOC-UKZN Computational Astrophysics Centre University of KwaZulu-NatalDurban 4000South Africa Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China Research Center for Intelligent Computing Platforms Zhejiang LaboratoryHangzhou 311100China Cahill Center for Astronomy and Astrophysics MC 249-17 California Institute of TechnologyPasadena CA 91125USA CSIRO Space and Astronomy PO Box 76EppingNSW 1710Australia School of Astronomy and Space Science Nanjing UniversityNanjing 210093China Key Laboratory of Modern Astronomy and Astrophysics Nanjing UniversityMinistry of EducationNanjing 210093China Department of Astronomy University of Science and Technology of ChinaHefei 230026China

关键词： pulsars:general methods:observational radio continuum:general

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FAST Observations of an Extremely Active Episode of FRB 20201124A.Ⅲ.Polarimetry

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Research in Astronomy and Astrophysics 2022年第12期22卷 81-98页

作者： jin-chen jiang Wei-Yang Wang Heng Xu jiang-Wei Xu Chun-Feng Zhang Bo-Jun Wang De-jiang Zhou Yong-Kun Zhang Jia-Rui Niu Ke-Jia Lee Bing Zhang jin-Lin Han Di Li Wei-Wei Zhu Zi-Gao Dai Yi Feng Wei-Cong jing Dong-Zi Li Rui Luo chen-chen Miao chen-Hui Niu Chao-Wei Tsai Fa-Yin Wang Pei Wang Ren-Xin Xu Yuan-Pei Yang Zong-Lin Yang Ju-Mei Yao Mao Yuan Department of Astronomy Peking UniversityBeijing 100871China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China School of Astronomy University of Chinese Academy of SciencesBeijing 100049China Department of Physics and Astronomy University of NevadaLas VegasNV 89154USA CAS Key Laboratory of FAST NAOCChinese Academy of SciencesBeijing 100101China Research Center for Intelligent Computing Platforms Zhejiang LaboratoryHangzhou 311100China NAOC-UKZN Computational Astrophysics Centre University of KwaZulu-NatalDurban 4000South Africa Department of Astronomy University of Science and Technology of ChinaHefei 230026China Cahill Center for Astronomy and Astrophysics MC 249-17California Institute of TechnologyPasadenaCA 91125USA CSIRO Space and Astronomy P.O.Box 76EppingNSW 1710Australia School of Astronomy and Space Science Nanjing UniversityNanjing 210093China Key Laboratory of Modern Astronomy and Astrophysics(Nanjing University) Ministry of EducationChina South-Western Institute For Astronomy Research Yunnan UniversityYunnan 650504China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China

As the third paper in the multiple-part series,we report the statistical properties of radio bursts detected from the repeating fast radio burst(FRB)source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio Telescope during an extremely active episode between the 25th and 28th of September 2021(UT).We focus on the polarization properties of536 bright bursts with S/N>*** found that the Faraday rotation measures(RMs)monotonically dropped from-579to-605 rad m^(-2)in the 4 day *** RM values were compatible with the values(-300 to-900 rad m^(-2))reported 4 months ***,the RM evolution rate in the current observation window was at least an order of magnitude smaller than the one(~500 rad m^(-2)day^(-1))previously reported during the rapid RM-variation phase,but is still higher than the one(≤1 rad m^(-2)day^(-1))during the later RM no-evolution *** bursts of FRB 20201124A were highly polarized with the total degree of polarization(circular plus linear)greater than 90%for more than 90%of all *** distribution of linear polarization position angles(PAs),degree of linear polarization(L/I)and degree of circular polarization(V/I)can be characterized with unimodal distribution *** the observation window,the distributions became wider with time,i.e.,with larger scatter,but the centroids of the distribution functions remained nearly *** individual bursts,significant PA variations(confidence level 5σ)were observed in 33%of all *** polarization of single pulses seems to follow certain complex trajectories on the Poincarésphere,which may shed light on the radiation mechanism at the source or the plasma properties along the path of FRB propagation.

关键词： (stars:)pulsars:general stars:magnetars radio continuum:general polarization

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Chinese Medical Journal 2013年第19期126卷 3782-3783页

作者： chen Wen-qing ZHANG Ying jiang Hong LI Heng LI Xia-yu YANG Xian FENG Shi WANG Yu-chen LIN Chuan SHEN Xiu-jing ZHOU Qin jin Juan chen jiang-hua Kidney Disease Center the First Affiliated Hospital Zhejiang University College of Medicine Kidney Disease Immunology Laboratory The Third Grade Laboratory State Administration of Traditional Chinese Medicine of China Key Laboratory of Multiple Organ Transplantation Ministry of Health of China Key Laboratory of Nephropathy Zhejiang Province Hangzhou Zhejiang 310003 China

Membranous nephropathy （MN） is the most common cause of nephrotic syndrome in *** renal biopsy is the gold standard for the disease diagnosis,but is invasive.M-type phospholipase A2 receptor （PLA2R） on human podocytes could serve as the target for podocytopathic antibodies （anti-PLA2R）.1 Patients with iMN （70%-80%） were found the circulating antibodies against PLA2R.1 And the podocyte-secreted angiopoietinlike-4 （Angptl4） could be another key role in nephrotic syndrome3.

关键词： PLA2R Angptl4 membranous nephropathy podocyte

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Toward understanding the role of genomic repeat elements in neurodegenerative diseases

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Neural Regeneration Research 2025年第3期20卷 646-659页

作者： Zhengyu An Aidi jiang jingqi chen Institute of Science and Technology for Brain-Inspired Intelligence Fudan UniversityShanghaiChina MOE Frontiers Center for Brain Science Fudan UniversityShanghaiChina MOE Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence Fudan UniversityShanghaiChina Zhangjiang Fudan International Innovation Center ShanghaiChina

Neurodegenerative diseases cause great medical and economic burdens for both patients and society;however, the complex molecular mechanisms thereof are not yet well understood. With the development of high-coverage sequencing technology, researchers have started to notice that genomic repeat regions, previously neglected in search of disease culprits, are active contributors to multiple neurodegenerative diseases. In this review, we describe the association between repeat element variants and multiple degenerative diseases through genome-wide association studies and targeted sequencing. We discuss the identification of disease-relevant repeat element variants, further powered by the advancement of long-read sequencing technologies and their related tools, and summarize recent findings in the molecular mechanisms of repeat element variants in brain degeneration, such as those causing transcriptional silencing or RNA-mediated gain of toxic function. Furthermore, we describe how in silico predictions using innovative computational models, such as deep learning language models, could enhance and accelerate our understanding of the functional impact of repeat element variants. Finally, we discuss future directions to advance current findings for a better understanding of neurodegenerative diseases and the clinical applications of genomic repeat elements.

关键词： Alzheimer's disease ataxia deep learning long-read sequencing neurodegeneration neurodegenerative diseases Parkinson's disease repeat element structural variant

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The FAST Galactic Plane Pulsar Snapshot survey:*** design and pulsar discoveries

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Research in Astronomy and Astrophysics 2021年第5期21卷 5-42页

作者： J.L.Han chen Wang P.F.Wang Tao Wang D.J.Zhou jing-Hai Sun Yi Yan Wei-Qi Su Wei-Cong jing Xue chen X.Y.Gao Li-Gang Hou Jun Xu K.J.Lee Na Wang Peng jiang Ren-Xin Xu Jun Yan Heng-Qian Gan Xin Guan Wen-Jun Huang jin-chen jiang Hui Li Yun-Peng Men Chun Sun Bo-Jun Wang H.G.Wang Shuang-Qiang Wang jin-Tao Xie Heng Xu Rui Yao Xiao-Peng You D.J.Yu Jian-Ping Yuan Rai Yuen Chun-Feng Zhang Yan Zhu National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China CAS Key Laboratory of FAST NAOCChinese Academy of SciencesBeijing 100101China School of Astronomy University of Chinese Academy of SciencesBeijing 100049China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China Department of Astronomy Peking UniversityBeijing 100871China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China Key Laboratory of Radio Astronomy Chinese Academy of SciencesNanjing 210008China Department of Astronomy Guangzhou UniversityGuangzhou 510006China School of Physical Science and Technology Southwest UniversityChongqing 400715China

Discovery of pulsars is one of the main goals for large radio *** Five-hundredmeter Aperture Spherical radio Telescope(FAST),that incorporates an L-band 19-beam receiver with a system temperature of about 20 K,is the most sensitive radio telescope utilized for discovering *** designed the snapshot observation mode for a FAST key science project,the Galactic Plane Pulsar Snapshot(GPPS)survey,in which every four nearby pointings can observe a cover of a sky patch of 0.1575 square degrees through beam-switching of the L-band 19-beam *** integration time for each pointing is 300 seconds so that the GPPS observations for a cover can be made in 21 *** goal of the GPPS survey is to discover pulsars within the Galactic latitude of±10∘from the Galactic plane,and the highest priority is given to the inner Galaxy within±5∘.Up to now,the GPPS survey has discovered 201 pulsars,including currently the faintest pulsars which cannot be detected by other telescopes,pulsars with extremely high dispersion measures(DMs)which challenge the currently widely used models for the Galactic electron density distribution,pulsars coincident with supernova remnants,40 millisecond pulsars,16 binary pulsars,some nulling and mode-changing pulsars and rotating radio transients(RRATs).The follow-up observations for confirmation of new pulsars have polarization-signals recorded for polarization profiles of the ***-detection of previously known pulsars in the survey data also leads to significant improvements in parameters for 64 *** GPPS survey discoveries are published and will be updated at http://***/GPPS/.

关键词： pulsars:general

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CaH2-promoted activity of Ni-carbonate interface for CO2 methanation

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Journal of Energy Chemistry 2025年第1期100卷 522-532页

作者： jin-Peng Wang Guo-Cui Mao Hui-Lin jiang Bao-Xia Dong Yun-Lei Teng School of Chemistry and Chemical Engineering Yangzhou University

Transition metal-carbonate interfaces often act as active sites in heterogeneous catalytic *** interface between transition metal and metal carbonate exhibits a dynamic equilibrium during the CO2hydrogenation reaction,involving surface carbonate hydrogenation and ***,there have been few reports on engineering the activity of the interface between transition metal and alkaline earth metal carbonate for catalytic *** work demonstrated that the incorporation of CaH2in Ni/CaCO3enhances the CO2methanation activity of the *** CO2conversion for Ni/CaH2-CaCO3reached 68.5%at 400°C,which was much higher than that of the Ni/CaCO3（31.6%） and Ni/CaH2-CaO （42.4%） ***,the Ni/CaH2-CaCO3catalysts remained stable during the stability test for 24 h at 400°C and 8 *** research revealed that CaH2played a crucial role in promoting the activity of the Ni-carbonate interface for ***2could modify the electronic structure of Ni and tune the structural properties of CaCO3to generate medium basic sites （OH groups）,which are favorable for the activation of H2and ***-situ Fourier transform infrared spectroscopy （FTIR） analysis combined with density functional theory calculations demonstrated that CO2activation occurs at the hydroxyl group （OH） on the CaH2-modified Ni-carbonate surface,leading to the formation of CO3H****,our study has confirmed that CO2methanation over the Ni/CaH2-CaCO3catalysts proceeds via the formate pathway.

关键词： Metal hydride Ni catalysts Carbonate Metal-carbonate interface

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