The Wide-Lane(WL)and Narrow-Lane(NL)Uncalibrated Phase Delays(UPDs)are the prerequisites in the traditional Precise Point Positioning(PPP)Ambiguity Resolution(AR).As the generation mechanism of various biases becomes ...The Wide-Lane(WL)and Narrow-Lane(NL)Uncalibrated Phase Delays(UPDs)are the prerequisites in the traditional Precise Point Positioning(PPP)Ambiguity Resolution(AR).As the generation mechanism of various biases becomes more complex,we systematically studied the impact factors of four satellite systems WL and NL UPDs from the perspective of parameter estimation.Approximately 100 stations in a global network are used to generate the UPDs.The results of different satellite systems show that the estimation method,update frequency,and solution mode need to be treated differently.Two regional networks with different receiver types,JAVAD,and Trimble,are also adopted.The results indicate that the receiver-dependent bias has an influence on UPD estimation.Also,the hardware delays can inhibit the satellite-side UPDs if these receiver-specific errors are not fully deployed or even misused.Furthermore,the temporal stability and residual distribution of NL UPDs are significantly enhanced by utilizing a regional network,with the improvements by over 68%and 40%,respectively.It demonstrates that different network scales exhibit the different implication of unmodeled errors,and the unmodeled errors cannot be ignored and must be handled in UPD estimation.展开更多
Discrete choice model acts as one of the most important tools for studies involving mode split in the context of transport demand forecast. As different types of discrete choice models display their merits and restric...Discrete choice model acts as one of the most important tools for studies involving mode split in the context of transport demand forecast. As different types of discrete choice models display their merits and restrictions diversely, how to properly select the specific type among discrete choice models for realistic application still remains to be a tough problem. In this article, five typical discrete choice models for transport mode split are, respectively, discussed, which includes multinomial logit model, nested logit model （NL）, heteroscedastic extreme value model, multinominal probit model and mixed multinomial logit model （MMNL）. The theoretical basis and application attributes of these five models are especially analysed with great attention, and they are also applied to a realistic intercity case of mode split forecast, which results indi- cating that NL model does well in accommodating similarity and heterogeneity across alternatives, while MMNL model serves as the most effective method for mode choice prediction since it shows the highest reliability with the least significant prediction errors and even outperforms the other four models in solving the heterogeneity and similarity problems. This study indicates that conclusions derived from a single discrete choice model are not reliable, and it is better to choose the proper model based on its characteristics.展开更多
In sexual organisms, division of the zygote initiates a new life cycle. Although several genes involved in zygote division are known in plants, how the zygote is activated to start embryogenesis has remained elusive. ...In sexual organisms, division of the zygote initiates a new life cycle. Although several genes involved in zygote division are known in plants, how the zygote is activated to start embryogenesis has remained elusive. Here, we showed that a mutation in ZYGOTE-ARREST 3 （ZYG3） in Arabidopsis led to a tight zygote-lethal phenotype. Map-based cloning revealed that ZYG3 encodes the transfer RNA （tRNA） ligase AtRNL, which is a single-copy gene in the Arabidopsis genome. Expression analyses showed that AtRNL is expressed throughout zygotic embryogenesis, and in meristematic tissues. Using pAtRNL：：cAtRNL-sYFP- complemented zyg3/zyg3 plants, we showed that AtRNL is localized exclusively in the cytoplasm, suggesting that tRNA splicing occurs primarily in the cytoplasm. Analyses using partially rescued embryos showed that mutation in AtRNL compromised splicing of intron-containing tRNA. Mutations of two tRNA endonuclease genes, SEN1 and SEN2, also led to a zygote-lethal phenotype. These results together suggest that tRNA splicing is critical for initiating zygote division in Arabidopsis.展开更多
To make use of the prior knowledge of the image more effectively and restore more details of the edges and structures, a novel sparse coding objective function is proposed by applying the principle of the non-local si...To make use of the prior knowledge of the image more effectively and restore more details of the edges and structures, a novel sparse coding objective function is proposed by applying the principle of the non-local similarity and manifold learning on the basis of super-resolution algorithm via sparse representation. Firstly, the non-local similarity regularization term is constructed by using the similar image patches to preserve the edge information. Then, the manifold learning regularization term is constructed by utilizing the locally linear embedding approach to enhance the structural information. The experimental results validate that the proposed algorithm has a significant improvement compared with several super-resolution algorithms in terms of the subjective visual effect and objective evaluation indices.展开更多
The neck linker （NL） docking to the motor domain is the key force generation process of a kinesin motor. In the initiation step of NL docking the first three residues （LYS325, THR326 and ILE327 in 2KIN） of the NL ...The neck linker （NL） docking to the motor domain is the key force generation process of a kinesin motor. In the initiation step of NL docking the first three residues （LYS325, THR326 and ILE327 in 2KIN） of the NL must form an ＇extra turn＇, thus the other parts of the NL could dock to the motor domain. How the extra turn is formed remains elusive. We investigate the extra turn formation mechanism using structure-based mechanical analysis via molecular dynamics simulation. We find that the motor head rotation induced by ATP binding first drives ILE327 to move towards a hydrophobic pocket on the motor domain. The driving force, together with the hydrophobic interaction of ILE327 with the hydrophobic pocket, then causes a clockwise rotation of THR326, breaks the locking of LYS325, and finally drives the extra turn formation. This extra turn formation mechanism provides a clear pathway from ATP binding to NL docking of kinesin.展开更多
Rate coefficients for energy-pooling （EP） collisions Rb（5PJ）＋ Cs（6P3/2） →Rb（5S1/2）＋ Cs（nlJ^1） have been measured. Atoms were excited to Rb（5PJ） and Cs（6P3/2） states using two single-mode diode lasers....Rate coefficients for energy-pooling （EP） collisions Rb（5PJ）＋ Cs（6P3/2） →Rb（5S1/2）＋ Cs（nlJ^1） have been measured. Atoms were excited to Rb（5PJ） and Cs（6P3/2） states using two single-mode diode lasers. To isolate the heteronuclear contribution in the fluorescence spectrum, a double-modulation technique has been adopted. The excited-atom density and spatial distribution are mapped by monitoring the absorption of a counterpropagating single-mode diode laser beam, tuned to Rb（5PJ→7S1/2） and Cs（6P3/2→8S1/2） transitions respectively, which could be translated parallelly to the pump beams. The excited atom densities are combined with the measured fluorescence ratios to determine cross sections for the EP processes. It was found that Rb（5P1/2）＋Cs（6Pa/2） collisions are more efficient than Rb（5Pa/2）＋Cs（6P3/2） collisions for populating Cs（4F5/2）, while the opposite is true for populating Cs（4F7/2）.展开更多
该文提出一种基于结构相似性指数(SSIM)的非局部均值(Non Local means,NL-means)滤波的合成孔径雷达(SAR)图像相干斑噪声抑制新方法。该方法用SSIM改进NL-means算法中小块相似性的度量,能利用结构信息来进行相干斑抑制。通过在真实SAR...该文提出一种基于结构相似性指数(SSIM)的非局部均值(Non Local means,NL-means)滤波的合成孔径雷达(SAR)图像相干斑噪声抑制新方法。该方法用SSIM改进NL-means算法中小块相似性的度量,能利用结构信息来进行相干斑抑制。通过在真实SAR图像上的实验表明,与GammaMAP滤波、CHMT算法、BLS-GSM算法、NL-means滤波相比,此方法在有效去除相干斑噪声的同时能更好地保持边缘结构信息。展开更多
文摘目的:探讨健脾化瘀解毒方通过抑制细胞焦亡防治胃癌前病变的作用机制。方法:构建胃癌前病变小鼠模型和细胞焦亡模型,将小鼠随机分为空白组,模型组,健脾化瘀解毒方高剂量组(15 g/kg)、低剂量组(7.5 g/kg)和维酶素组(0.2 g/kg),每组10只。分别进行干预后,观察小鼠胃黏膜组织病理变化及焦亡相关分子表达情况。细胞分为空白组、模型组和中药组,空白组与模型组给予空白血清,中药组给予含药血清干预后,除空白组外先后予以LPS、ATP处理。观察焦亡相关分子表达情况。结果:与空白组比较,模型组小鼠胃黏膜NLRP3、GSDMD、HMGB1表达显著升高(P<0.01),健脾化瘀解毒方高、低剂量组可显著降低其表达(P<0.01)。与空白组比较,模型组细胞焦亡关键分子NLRP3、GSDMD、Caspase-1 mRNA和蛋白表达水平升高(P<0.01,P<0.05),I L-1β、I L-18 m R NA表达水平显著升高(P<0.01),中药组可显著降低其表达水平(P<0.01,P<0.05)。结论:健脾化瘀解毒方可通过抑制细胞焦亡防治胃癌前病变。
基金This study is sponsored by the National Natural Science Foundation of China(U20B2056,42004014,41974001)the Natural Science Foundation of Jiangsu Province(BK20200530).
文摘The Wide-Lane(WL)and Narrow-Lane(NL)Uncalibrated Phase Delays(UPDs)are the prerequisites in the traditional Precise Point Positioning(PPP)Ambiguity Resolution(AR).As the generation mechanism of various biases becomes more complex,we systematically studied the impact factors of four satellite systems WL and NL UPDs from the perspective of parameter estimation.Approximately 100 stations in a global network are used to generate the UPDs.The results of different satellite systems show that the estimation method,update frequency,and solution mode need to be treated differently.Two regional networks with different receiver types,JAVAD,and Trimble,are also adopted.The results indicate that the receiver-dependent bias has an influence on UPD estimation.Also,the hardware delays can inhibit the satellite-side UPDs if these receiver-specific errors are not fully deployed or even misused.Furthermore,the temporal stability and residual distribution of NL UPDs are significantly enhanced by utilizing a regional network,with the improvements by over 68%and 40%,respectively.It demonstrates that different network scales exhibit the different implication of unmodeled errors,and the unmodeled errors cannot be ignored and must be handled in UPD estimation.
基金supported by the Science&Technology pillar project(No.0556)of Guangzhou
文摘Discrete choice model acts as one of the most important tools for studies involving mode split in the context of transport demand forecast. As different types of discrete choice models display their merits and restrictions diversely, how to properly select the specific type among discrete choice models for realistic application still remains to be a tough problem. In this article, five typical discrete choice models for transport mode split are, respectively, discussed, which includes multinomial logit model, nested logit model （NL）, heteroscedastic extreme value model, multinominal probit model and mixed multinomial logit model （MMNL）. The theoretical basis and application attributes of these five models are especially analysed with great attention, and they are also applied to a realistic intercity case of mode split forecast, which results indi- cating that NL model does well in accommodating similarity and heterogeneity across alternatives, while MMNL model serves as the most effective method for mode choice prediction since it shows the highest reliability with the least significant prediction errors and even outperforms the other four models in solving the heterogeneity and similarity problems. This study indicates that conclusions derived from a single discrete choice model are not reliable, and it is better to choose the proper model based on its characteristics.
基金supported by the National Basic Research Program of China from MOST(2014CB943401)
文摘In sexual organisms, division of the zygote initiates a new life cycle. Although several genes involved in zygote division are known in plants, how the zygote is activated to start embryogenesis has remained elusive. Here, we showed that a mutation in ZYGOTE-ARREST 3 （ZYG3） in Arabidopsis led to a tight zygote-lethal phenotype. Map-based cloning revealed that ZYG3 encodes the transfer RNA （tRNA） ligase AtRNL, which is a single-copy gene in the Arabidopsis genome. Expression analyses showed that AtRNL is expressed throughout zygotic embryogenesis, and in meristematic tissues. Using pAtRNL：：cAtRNL-sYFP- complemented zyg3/zyg3 plants, we showed that AtRNL is localized exclusively in the cytoplasm, suggesting that tRNA splicing occurs primarily in the cytoplasm. Analyses using partially rescued embryos showed that mutation in AtRNL compromised splicing of intron-containing tRNA. Mutations of two tRNA endonuclease genes, SEN1 and SEN2, also led to a zygote-lethal phenotype. These results together suggest that tRNA splicing is critical for initiating zygote division in Arabidopsis.
基金supported by the National Natural Science Foundation of China(Nos.61672335 and 61602191)the Foundation of Fujian Education Department(No.JAT170053)
文摘To make use of the prior knowledge of the image more effectively and restore more details of the edges and structures, a novel sparse coding objective function is proposed by applying the principle of the non-local similarity and manifold learning on the basis of super-resolution algorithm via sparse representation. Firstly, the non-local similarity regularization term is constructed by using the similar image patches to preserve the edge information. Then, the manifold learning regularization term is constructed by utilizing the locally linear embedding approach to enhance the structural information. The experimental results validate that the proposed algorithm has a significant improvement compared with several super-resolution algorithms in terms of the subjective visual effect and objective evaluation indices.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11545014 and 11605038the Open Project Program of State Key Laboratory of Theoretical Physics of Institute of Theoretical Physics of Chinese Academy of Science under Grant No Y5KF211CJ1
文摘The neck linker （NL） docking to the motor domain is the key force generation process of a kinesin motor. In the initiation step of NL docking the first three residues （LYS325, THR326 and ILE327 in 2KIN） of the NL must form an ＇extra turn＇, thus the other parts of the NL could dock to the motor domain. How the extra turn is formed remains elusive. We investigate the extra turn formation mechanism using structure-based mechanical analysis via molecular dynamics simulation. We find that the motor head rotation induced by ATP binding first drives ILE327 to move towards a hydrophobic pocket on the motor domain. The driving force, together with the hydrophobic interaction of ILE327 with the hydrophobic pocket, then causes a clockwise rotation of THR326, breaks the locking of LYS325, and finally drives the extra turn formation. This extra turn formation mechanism provides a clear pathway from ATP binding to NL docking of kinesin.
基金This work was partially supported by the National Natural Science Foundation of China under Grant No.10264004.
文摘Rate coefficients for energy-pooling （EP） collisions Rb（5PJ）＋ Cs（6P3/2） →Rb（5S1/2）＋ Cs（nlJ^1） have been measured. Atoms were excited to Rb（5PJ） and Cs（6P3/2） states using two single-mode diode lasers. To isolate the heteronuclear contribution in the fluorescence spectrum, a double-modulation technique has been adopted. The excited-atom density and spatial distribution are mapped by monitoring the absorption of a counterpropagating single-mode diode laser beam, tuned to Rb（5PJ→7S1/2） and Cs（6P3/2→8S1/2） transitions respectively, which could be translated parallelly to the pump beams. The excited atom densities are combined with the measured fluorescence ratios to determine cross sections for the EP processes. It was found that Rb（5P1/2）＋Cs（6Pa/2） collisions are more efficient than Rb（5Pa/2）＋Cs（6P3/2） collisions for populating Cs（4F5/2）, while the opposite is true for populating Cs（4F7/2）.
文摘该文提出一种基于结构相似性指数(SSIM)的非局部均值(Non Local means,NL-means)滤波的合成孔径雷达(SAR)图像相干斑噪声抑制新方法。该方法用SSIM改进NL-means算法中小块相似性的度量,能利用结构信息来进行相干斑抑制。通过在真实SAR图像上的实验表明,与GammaMAP滤波、CHMT算法、BLS-GSM算法、NL-means滤波相比,此方法在有效去除相干斑噪声的同时能更好地保持边缘结构信息。
