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| 1 | Long-term variations of X-ray pulse profiles for the Crab pulsar:data analysis and modeling显示文摘The pulse profiles of the Crab pulsar(as well as some other pulsars)vary with time.They can lead to a major source of intrinsic timing noise,which lacks a detailed physical model.The phase separation?between the first left peak(P1)and the second right peak(P2)is a key parameter that shows the variations of pulse profiles for the Crab pulsar.It was found that the evolution of?has a tendency with increasing rates of 0.82?±0.25?,0.80?±0.54?,and 0.77?±0.28?per century for the 2-6,6-15,and15-60 ke V bands,respectively.Furthermore,the flux ratios(P2/P1)of X-ray pulse profiles in the three bands were calculated,and the derived flux ratios were consistent with the radio and X-ray measurements of the Insight-HXMT.In addition to discovering the physical origin of the pulse changes,the high-SNR X-ray pulse profiles were simulated in the annular gap model,and two model parameters(e.g.,the maximum emission heights of the two peaks)were observed to slightly affect the variations of peak separation.We fitted the long-term variations of emission heights of the two peaks and discovered that the emission heights showed increasing tendencies with time.Variations of these emission heights induced a characteristic period derivative,and a complete formula for both the magnetic dipole radiation and wind-particle-induced variations of the moment of inertia was used for the pulsar’s spin-down to obtain the variation rate˙αof the magnetic inclination angle,which was-1.60?per century.Intrinsic timing noise is observed to be mainly induced by the variations of pulse profiles,which might correlate with a characteristic spin period derivative arising from the fluctuations of the emission regions.This work will lay a foundation for understanding the origin of intrinsic timing noise and making high-precision timing models in the future. | LunHua Shang YuanJie Du XiangQun Cui ShiJun Dang JiGuang Lu JunTao Bai QiJun Zhi YouLi Tuo LinLi Yan LiangWei Huang XinYuan Zhang XiaoMin Bei QingQing Lin GuoJun Qiao Hua Shen RiHong Zhu | 2020 | Science China(Physics,Mechanics & Astronomy)2020，63，10： | 2 |
| 2 | Reinforcement learning based UAV formation control in GPS-denied environment显示文摘Highly accurate positioning is a crucial prerequisite of multi Unmanned Aerial Vehicle close-formation flight for target tracking,formation keeping,and collision avoidance.Although the position of a UAV can be obtained through the Global Positioning System(GPS),it is difficult for a UAV to obtain highly accurate positioning data in a GPS-denied environment(e.g.,a GPS jamming area,suburb,urban canyon,or mountain area);this may cause it to miss a tracking target or collide with another UAV.In particular,UAV close-formation control in GPS-denied environments faces difficulties owing to the low-accuracy position,close distance between vehicles,and nonholonomic dynamics of a UAV.In this paper,on the one hand,we develop an innovative UAV formation localization method to address the formation localization issues in GPS-denied environments;on the other hand,we design a novel reinforcement learning based algorithm to achieve the high-efficiency and robust performance of the controller.First,a novel Lidar-based localization algorithm is developed to measure the localization of each aircraft in the formation flight.In our solution,each UAV is equipped with Lidar as the position measurement sensor instead of the GPS module.The k-means algorithm is implemented to calculate the center point position of UAV.A novel formation position vector matching method is proposed to match center points with UAVs in the formation and estimate their position information.Second,a reinforcement learning based UAV formation control algorithm is developed by selecting the optimal policy to control UAV swarm to start and keep flying in a close formation of a specific geometry.Third,the innovative collision risk evaluation module is proposed to address the collision-free issues in the formation group.Finally,a novel experience replay method is also provided in this paper to enhance the learning efficiency.Experimental results validate the accuracy,effectiveness,and robustness of the proposed scheme. | Bodi MA Zhenbao LIU Feihong JIANG Wen ZHAO Qingqing DANG Xiao WANG Junhong ZHANG Lina WANG | 2023 | Chinese Journal of Aeronautics2023，36，11： | 0 |
| 3 | Genome assembly of wild loquat (Eriobotrya japonica) and resequencing provide new insights into the genomic evolution and fruit domestication in loquat显示文摘Wild loquats(Eriobotrya japonica Lindl.)provide remarkable genetic resources for studying domestication and breeding improved varieties.Herein,we generate the first high-quality chromosome-level genome assembly of wild loquat,with 45791 predicted proteincoding genes.Analysis of comparative genomics indicated that loquat shares a common ancestor with apple and pear,and a recent whole-genome duplication event occurred in loquat prior to its divergence.Genome resequencing showed that the loquat germplasms can be distinctly classified into wild and cultivated groups,and the commercial cultivars have experienced allelic admixture.Compared with cultivated loquats,the wild loquat genome showed very few selected genomic regions and had higher levels of genetic diversity.However,whole-genome scans of selective sweeps were mainly related to fruit quality,size,and f lesh color during the domestication process.Large-scale transcriptome and metabolome analyses were further performed to identify differentially expressed genes(DEGs)and differentially accumulated metabolites(DAMs)in wild and cultivated loquats at various fruit development stages.Unlike those in wild loquat,the key DEGs and DAMs involved in carbohydrate metabolism,plant hormone signal transduction,f lavonoid biosynthesis,and carotenoid biosynthesis were significantly regulated in cultivated loquats during fruit development.These high-quality reference genome,resequencing,and large-scale transcriptome/metabolome data provide valuable resources for elucidating fruit domestication and molecular breeding in loquat. | Danlong Jing Xinya Liu Qiao He Jiangbo Dang Ruoqian Hu Yan Xia Di Wu Shuming Wang Yin Zhang Qingqing Xia Chi Zhang Yuanhui Yu Qigao Guo Guolu Liang | 2023 | Horticulture Research2023，10，2： | 0 |
| 4 | Phytoestrogen-derived multifunctional ligands for targeted therapy of breast cancer显示文摘Nano-targeted delivery systems have been widely used for breast tumor drug delivery.Estrogen receptors are considered to be significant drug delivery target receptors due to their overexpression in a variety of tumor cells.However,targeted ligands have a significant impact on the safety and effectiveness of active delivery systems,limiting the clinical transformation of nanoparticles.Phytoestrogens have shown good biosafety characteristics and some affinity with the estrogen receptor.In the present study,molecular docking was used to select tanshinone IIA(Tan IIA)among phytoestrogens as a target ligand to be used in nanodelivery systems with somemodifications.Modified Tan IIA(Tan-NH2)showed a good biosafety profile and demonstrated tumor-targeting,anti-tumor and anti-tumor metastasis effects.Moreover,the ligand was utilized with the anti-tumor drug Dox-loaded mesoporous silica nanoparticles via chemical modification to generate a nanocomposite Tan-Dox-MSN.Tan-Dox-MSN had a uniform particle size,good dispersibility and high drug loading capacity.Validation experiments in vivo and in vitro showed that it also had a better targeting ability,anti-tumor effect and lower toxicity in normal organs.These results supported the idea that phytoestrogens with high affinity for the estrogen receptor could improve the therapeutic efficacy of nano-targeted delivery systems in breast tumors. | Ying Zhang Hao Pan Changxiang Yu Rui Liu Bin Xing Bei Jia Jiachen He Xintao Jia Xiaojiao Feng Qingqing Zhang Wenli Dang Zheming Hu Xiuping Deng Pan Guo Zhidong Liu Weisan Pan | 2023 | Asian Journal of Pharmaceutical Sciences2023，18，4： | 0 |
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