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How to choose an optimal threshold is a key problemin the generalized Pareto distribution (GPD) model.This paper attains the exactthreshold by testing for GPD,and shows that GPD model allows the actuary to easily estimate high quantiles and the probable maximum loss from the medical insurance claims data. 相似文献
113.
The monolayer behavior of long-chain fatty acids at the air/water interface on a poly(ethyleneimine) containing subphase was investigated. The interaction of the polymeric gegenions in the subphase leads to expanded states and permits the visualization of the aggregation behavior of different long-chain fatty acids via fluorescence microscopy. The monolayer morphologies and their variability were intensively studied by fluorescence microscopy. In addition, the transfer of the complexed fatty acid monolayers to solid substrates has been investigated. 相似文献
114.
Dong-Zhao Yang Zhen-Zhen Chen Mei Chi Ying-Ying Dong Shou-Zhi Pu Qi Sun 《Molecules (Basel, Switzerland)》2022,27(3)
5-Hydroxymethyl-2′-deoxycytidine (5hmdC) phosphoramidite and triphosphate are important building blocks in 5hmdC-containing DNA synthesis for epigenetic studies. However, efficient and practical methods for the synthesis of these compounds are still limited. The current research provides an intensively improved synthetic method that enables the preparation of commercially available cyanoethyl-protected 5hmdC phosphoramidite with an overall yield of 39% on 5 g scale. On the basis of facile and efficient accesses to cyanoethyl protected-5hmdU and 5hmdC intermediates, two efficient synthetic routes for 5hmdC triphosphate were also developed. 相似文献
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116.
本文结合可见-近红外-中红外瞬态吸收光谱技术对离子交换法制备的少层MoS2中缺陷介导的载流子动力学进行了详细的解析. 在近红外瞬态吸收光谱中观察到的宽带漂白信号表明少层MoS2纳米片带隙中分布着大量的缺陷态. 实验结果明确揭示了载流子被缺陷态的快速捕获以及进一步的复合过程,证明带隙中的缺陷态对MoS2光生载流子动力学过程起着至关重要的作用. 在中红外瞬态吸收光谱中观察到的正信号到负信号的转变进一步证实了在导带下小于0.24 eV处存在被载流子占据的缺陷态. 这些在少层MoS2纳米片中存在的缺陷态可以作为有效的载流子捕获中心来辅助光生载流子在皮秒时间尺度内完成非辐射复合过程. 相似文献
117.
The Gerchberg–Saxton (G-S) algorithm is a phase retrieval algorithm that is widely used in beam shaping and optical information processing. However, the G-S algorithm has difficulty obtaining the exact solution after iterating, and an approximate solution is often obtained. In this paper, we propose a series of modified G-S algorithms based on the Fresnel transform domain, including the single-phase retrieval (SPR) algorithm, the double-phase retrieval (DPR) algorithm, and the multiple-phase retrieval (MPR) algorithm. The analysis results show that the convergence of the SPR algorithm is better than that of the G-S algorithm, but the exact solution is not obtained. The DPR and MPR algorithms have good convergence and can obtain exact solutions; that is, the information is recovered losslessly. We discuss the security advantages and verification reliability of the proposed algorithms in image encryption. A multiple-image encryption scheme is proposed, in which n plaintexts can be recovered from n ciphertexts, which greatly improves the efficiency of the system. Finally, the proposed algorithms are compared with the current phase retrieval algorithms, and future applications are discussed. We hope that our research can provide new ideas for the application of the G-S algorithm. 相似文献
118.
Teng Wang Chi Zhang LiangCai Xu JinHua Wang Shan Jiang ZengWei Zhu ZhaoSheng Wang JiaNan Chu JiaXin Feng LingLing Wang Wei Li Tao Hu XiaoSong Liu Gang Mu 《中国科学:物理学 力学 天文学(英文版)》2020,(2):124-129
Recently, 12442 system of Fe-based superconductors has attracted considerable attention owing to its unique double-Fe As-layer structure. A steep increase in the in-plane upper critical field with cooling has been observed near the superconducting transition temperature, Tc, in KCa2Fe4As4F2 single crystals. Herein, we report a high-field investigation on upper critical field of this material over a wide temperature range, and both out-of-plane(H∥c, Hc2c) and in-plane(H∥ab, Hc2ab ) directions have been measured.A sublinear temperature-dependent behavior is observed for the out-of-plane Hc2c , whereas strong convex curvature with cooling is observed for the in-plane Hc2ab . Such behaviors could not be described by the conventional Werthamer-Helfand-Hohenberg(WHH) model. The data analysis based on the WHH model by considering the spin aspects reveals a large Maki parameter α=9,indicating that the in-plane upper critical field is affected by a very strong Pauli paramagnetic effect. 相似文献
119.
Gitae Moon Intae Son Chunho Kim Chi Hyeong Cho Eunbi Lee Eun Hyoung Bae 《Molecular Crystals and Liquid Crystals》2019,687(1):60-67
AbstractTo enable recent 3D and moving picture applications, liquid crystal displays (LCD) must exhibit fast response and wide viewing angle characteristics. Pre-tilted vertical alignment layers for high-speed LCD were fabricated using bi-functional photoreactive monomers. The monomers can be confined to the polyimide layer and photo-polymerized by UV exposure under voltage. Response characteristics of photo-controlled alignment films according to the structure were investigated. Vertical alignment properties were evaluated using a polarizing optical microscope, and electro-optical characteristics were compared through the voltage-transmittance curve and response time measurement. Faster response speed could be obtained by using photoreactive monomers having a long alkyl chain. 相似文献
120.
Visible thermal person re-identification (VT Re-ID) is the task of matching pedestrian images collected by thermal and visible light cameras. The two main challenges presented by VT Re-ID are the intra-class variation between pedestrian images and the cross-modality difference between visible and thermal images. Existing works have principally focused on local representation through cross-modality feature distribution, but ignore the internal connection of the local features of pedestrian body parts. Therefore, this paper proposes a dual-path attention network model to establish the spatial dependency relationship between the local features of the pedestrian feature map and to effectively enhance the feature extraction. Meanwhile, we propose cross-modality dual-constraint loss, which adds the center and boundary constraints for each class distribution in the embedding space to promote compactness within the class and enhance the separability between classes. Our experimental results show that our proposed approach has advantages over the state-of-the-art methods on the two public datasets SYSU-MM01 and RegDB. The result for the SYSU-MM01 is Rank-1/mAP 57.74%/54.35%, and the result for the RegDB is Rank-1/mAP 76.07%/69.43%. 相似文献