提高蛇形机器人的三维运动控制能力是提高蛇形机器人环境适应能力的关键之一.虽然联结中枢模式生成器(Connectionist central pattern generator,CCPG)模型具有复杂度小、适合硬件实现等优点,但是目前的CCPG模型难以生成相位协调的多自...提高蛇形机器人的三维运动控制能力是提高蛇形机器人环境适应能力的关键之一.虽然联结中枢模式生成器(Connectionist central pattern generator,CCPG)模型具有复杂度小、适合硬件实现等优点,但是目前的CCPG模型难以生成相位协调的多自由度运动的控制信号,从而限制了它的三维步态控制能力.本文根据生物CPG机制的分层结构和运动神经元的功能,提出一个有层次化结构的CCPG(Hierarchical CCPG,HCCPG)模型.HCCPG模型由基本节律信号生成层、模式形成层、运动信号调整层这三个部分组成.运动信号调整层的运动神经元能够独立地对模式形成层的输出信号的幅值、相位等进行调整,从而较好地解决了CCPG模型难以生成相位协调的多自由度运动控制信号的问题.HCCPG模型具有步态控制能力强、复杂度小、有良好的扩展性等优点,从而适合用于控制三维步态.在HCCPG模型的基础上提出一个三维步态控制方法.仿真验证了这个控制方法的有效性.展开更多
MicroRNAs play important roles in the devel- opment and progression of various cancers, including tongue squamous cell carcinoma （TSCC）. miR-29b and miR-195 have been reported to be tumor suppressors in TSCC. Here, ...MicroRNAs play important roles in the devel- opment and progression of various cancers, including tongue squamous cell carcinoma （TSCC）. miR-29b and miR-195 have been reported to be tumor suppressors in TSCC. Here, we investigated the expression of miR-29b and miR- 195 and their relationship in TSCC. Our data showed that miR-29b and miR-195 were significantly downregulated in TSCC com- pared with their matched nonmalignant tissues in 60 paired samples. The level of miR-29b was positively correlated with that of miR-195 in TSCC and the matched nonmalignant tissues. Moreover, miR-29b overexpression induced the demethylation of CpG islands upstream of miR-195 via targeting DNMT3B, leading to the upregulation of miR-195 in TSCC cell lines. Following DNMT3B silencing, the expression of miR-195 was increased and the methylation of CpG islands upstream of miR-195 was reduced. Although overexpression of miR-29b alone significantly increased miR- 195 expression, co-transfection of miR-29b with DNMT3B resulted in no change in miR-195 expression. Taken together, our results demonstrated that miR-29b could upregulate miR- 195 by directly targeting DNMT3B in TSCC. The interaction between miR-29b and miR-195 might provide new insights in developing novel therapeutic approaches of TSCC.展开更多
文摘提高蛇形机器人的三维运动控制能力是提高蛇形机器人环境适应能力的关键之一.虽然联结中枢模式生成器(Connectionist central pattern generator,CCPG)模型具有复杂度小、适合硬件实现等优点,但是目前的CCPG模型难以生成相位协调的多自由度运动的控制信号,从而限制了它的三维步态控制能力.本文根据生物CPG机制的分层结构和运动神经元的功能,提出一个有层次化结构的CCPG(Hierarchical CCPG,HCCPG)模型.HCCPG模型由基本节律信号生成层、模式形成层、运动信号调整层这三个部分组成.运动信号调整层的运动神经元能够独立地对模式形成层的输出信号的幅值、相位等进行调整,从而较好地解决了CCPG模型难以生成相位协调的多自由度运动控制信号的问题.HCCPG模型具有步态控制能力强、复杂度小、有良好的扩展性等优点,从而适合用于控制三维步态.在HCCPG模型的基础上提出一个三维步态控制方法.仿真验证了这个控制方法的有效性.
基金the National Natural Science Foundation of China (81402235)Foundation of Peking University School and Hospital of Stomatology (PKUSS20140104)
文摘MicroRNAs play important roles in the devel- opment and progression of various cancers, including tongue squamous cell carcinoma （TSCC）. miR-29b and miR-195 have been reported to be tumor suppressors in TSCC. Here, we investigated the expression of miR-29b and miR- 195 and their relationship in TSCC. Our data showed that miR-29b and miR-195 were significantly downregulated in TSCC com- pared with their matched nonmalignant tissues in 60 paired samples. The level of miR-29b was positively correlated with that of miR-195 in TSCC and the matched nonmalignant tissues. Moreover, miR-29b overexpression induced the demethylation of CpG islands upstream of miR-195 via targeting DNMT3B, leading to the upregulation of miR-195 in TSCC cell lines. Following DNMT3B silencing, the expression of miR-195 was increased and the methylation of CpG islands upstream of miR-195 was reduced. Although overexpression of miR-29b alone significantly increased miR- 195 expression, co-transfection of miR-29b with DNMT3B resulted in no change in miR-195 expression. Taken together, our results demonstrated that miR-29b could upregulate miR- 195 by directly targeting DNMT3B in TSCC. The interaction between miR-29b and miR-195 might provide new insights in developing novel therapeutic approaches of TSCC.
