北京地区珍稀鸟类的保护对维护当地生物多样性具有重要意义。随着人工智能技术的发展,利用深度学习技术自动识别鸟类成为鸟类调查保护的重要手段。实际鸟类图像存在背景复杂以及相近科属鸟类具有外观相似等特点,导致模型识别精度不佳。...北京地区珍稀鸟类的保护对维护当地生物多样性具有重要意义。随着人工智能技术的发展,利用深度学习技术自动识别鸟类成为鸟类调查保护的重要手段。实际鸟类图像存在背景复杂以及相近科属鸟类具有外观相似等特点,导致模型识别精度不佳。针对以上问题,本文提出一种基于TC-YOLO模型的鸟类识别方法。首先,为解决鸟类识别中复杂背景导致的漏检问题,本文方法结合CARAFE(content-aware reassembly of features)机制,自适应生成不同特征点所对应的上采样核,在更大的感受野内聚合上下文语义信息,有效聚焦鸟类前景区域。其次,为解决鸟类识别中相似外观导致的误检问题,本文方法引入TSCODE(task-specificcontextdecoupling)解耦定位和分类任务,通过获取多层级特征图的信息以回归目标边界,并利用包含底层纹理和高层语义的特征进行物种分类,进而提高模型的鸟类识别精度。最后,本文开展对比实验以验证模型的性能。实验结果表明,TC-YOLO模型的平均精度均值在包含北京地区28种国家一级保护鸟类的自建数据集Beijing-28和鸟类公开数据集CUB200-2011上分别达到78.7%和75.3%,均优于已有方法,而且在公开数据集MS COCO上验证了TC-YOLO模型拥有较强的泛化性。本文提出的TC-YOLO模型对背景复杂或外观相似的鸟类图像都能有效识别,漏检率和误检率较低,能够为鸟类保护提供重要技术支撑。展开更多
A nonlocal Euler beam model with second-order gradient of stress taken into consideration is used to study the thermal vibration of nanobeams with elastic boundary. An analytical solution is proposed to investigate th...A nonlocal Euler beam model with second-order gradient of stress taken into consideration is used to study the thermal vibration of nanobeams with elastic boundary. An analytical solution is proposed to investigate the free vibration of nonlocal Euler beams subjected to axial thermal stress. The effects of the nonlocal parameter, thermal stress and stiffness of boundary constraint on the vibration behaviors of nanobeams are revealed. The results show that natural frequencies including the thermal stress are lower than those without the thermal stress when temperature rises. The boundary-constrained springs have significant effects on the vibration of nanobeams. In addition, numerical simulations also indicate the importance of small-scale effect on the vibration of nanobeams.展开更多
背景与目的免疫治疗的应用大大改善了肺癌患者的临床结局。很大一部分肺癌患者能从程序性死亡受体1(programmed cell death 1,PD-1)/程序性死亡配体1(programmed cell death ligand 1,PD-L1)单抗治疗中获益,然而,仍有一部分耐药患者疗...背景与目的免疫治疗的应用大大改善了肺癌患者的临床结局。很大一部分肺癌患者能从程序性死亡受体1(programmed cell death 1,PD-1)/程序性死亡配体1(programmed cell death ligand 1,PD-L1)单抗治疗中获益,然而,仍有一部分耐药患者疗效不佳,临床上迫切需要能早期、便捷识别获益人群的生物标志物。在此,本研究回顾性分析了PD-1抗体治疗对局部晚期无法手术或转移性肺癌患者的疗效,并初步探索了外周血免疫指标与患者临床反应的相关性。方法该单中心研究共纳入2020年3月至2021年12月接受PD-1/PD-L1抗体治疗的ⅢA-Ⅳ期肺癌患者61例,收集PD-1/PD-L1抗体一线或后线治疗的病历数据。检测并分析患者外周血血清中多重Th1和Th2细胞因子水平以及外周血T细胞表型,探索细胞因子水平、T细胞表型等和患者临床反应之间的关系。结果入组患者均完成至少2个周期PD-1/PD-L1单抗治疗。其中,42例(68.9%)患者获得部分缓解(partial response,PR),7例(11.5%)患者疾病稳定(stable disease,SD),12例(19.7%)患者疾病进展(progressive disease,PD)。治疗前,疾病控制(disease control rate,DCR)组(有效组)患者外周血干扰素γ(interferon gamma,IFN-γ)(P=0.023)、肿瘤坏死因子α(tumor necrosis factorα,TNF-α)(P=0.007)和白介素5(interleukin 5,IL-5)(P=0.002)水平高于PD组(无效组)患者。此外,PD-1/PD-L1抗体治疗后外周血淋巴细胞绝对计数的减少与疾病进展有关联(P=0.023)。治疗后血清中IL-5(P=0.0027)和IL-10(P=0.0208)水平较治疗前明显升高。结论肺癌患者外周血血清IFN-γ、TNF-α和IL-5水平在预测抗PD-1阻断治疗临床疗效方面有一定的作用,肺癌患者外周血淋巴细胞绝对计数的减少与疾病进展有一定相关性,还需要大型前瞻性研究进一步阐明这些生物标志物的价值。展开更多
Due to their unique properties and appealing applications,low dimensional sp^(3)carbon nanostructures have attracted increasing attention recently.Based on the beam theory and atomistic studies,this work carries out a...Due to their unique properties and appealing applications,low dimensional sp^(3)carbon nanostructures have attracted increasing attention recently.Based on the beam theory and atomistic studies,this work carries out a comprehensive investigation on the vibrational properties of the ultrathin carbon nanothreads(NTH).Size effect is observed in transverse free vibrations of NTHs.To quantify such effects,the modified couple stress theory(MCST)is utilized to modify the Timoshenko beam theory.According to the first four order frequencies of NTHs from atomistic simulations,the critical length scale parameter of MCST is calibrated as 0.1 nm.It is shown that MCST has minor effect on the first four order modal shapes,except for the clamped boundary.MCST makes the modal shapes at the clamped boundary closer to those observed in atomistic simulations.This study suggests that to some extent the MCST-based Timoshenko beam theory can well describe the transverse vibration characteristics of the ultrafine NTHs,which are helpful for designing and fabricating the NTH-based nanoscale mechanical resonators.展开更多
文摘北京地区珍稀鸟类的保护对维护当地生物多样性具有重要意义。随着人工智能技术的发展,利用深度学习技术自动识别鸟类成为鸟类调查保护的重要手段。实际鸟类图像存在背景复杂以及相近科属鸟类具有外观相似等特点,导致模型识别精度不佳。针对以上问题,本文提出一种基于TC-YOLO模型的鸟类识别方法。首先,为解决鸟类识别中复杂背景导致的漏检问题,本文方法结合CARAFE(content-aware reassembly of features)机制,自适应生成不同特征点所对应的上采样核,在更大的感受野内聚合上下文语义信息,有效聚焦鸟类前景区域。其次,为解决鸟类识别中相似外观导致的误检问题,本文方法引入TSCODE(task-specificcontextdecoupling)解耦定位和分类任务,通过获取多层级特征图的信息以回归目标边界,并利用包含底层纹理和高层语义的特征进行物种分类,进而提高模型的鸟类识别精度。最后,本文开展对比实验以验证模型的性能。实验结果表明,TC-YOLO模型的平均精度均值在包含北京地区28种国家一级保护鸟类的自建数据集Beijing-28和鸟类公开数据集CUB200-2011上分别达到78.7%和75.3%,均优于已有方法,而且在公开数据集MS COCO上验证了TC-YOLO模型拥有较强的泛化性。本文提出的TC-YOLO模型对背景复杂或外观相似的鸟类图像都能有效识别,漏检率和误检率较低,能够为鸟类保护提供重要技术支撑。
基金supported by the National Science Fund for Distinguished Young Scholars (Grant No.11925205)the National Natural Science Foundation of China (Grant No.51921003).
基金supported in part by the National Natural Science Foundation of China (Nos.11522217,11632003)in part by The 333 Talent Program in Jiangsu Province (No.BRA2017374)+1 种基金Funding of Jiangsu Province Innovation Program for Graduate Education (KYLX15-0234)in part by the Fundamental Research Funds for the Central Universities of China (No.NE2012001)
文摘A nonlocal Euler beam model with second-order gradient of stress taken into consideration is used to study the thermal vibration of nanobeams with elastic boundary. An analytical solution is proposed to investigate the free vibration of nonlocal Euler beams subjected to axial thermal stress. The effects of the nonlocal parameter, thermal stress and stiffness of boundary constraint on the vibration behaviors of nanobeams are revealed. The results show that natural frequencies including the thermal stress are lower than those without the thermal stress when temperature rises. The boundary-constrained springs have significant effects on the vibration of nanobeams. In addition, numerical simulations also indicate the importance of small-scale effect on the vibration of nanobeams.
基金the National Natural Science Foundation of China(Grant No.12102176)the China Postdoctoral Science Foundation(Grant No.2022M711617)+1 种基金the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20210274)Partially supported by the High Performance Computing Platform of Nanjing University of Aeronautics and Astronautics。
文摘Due to their unique properties and appealing applications,low dimensional sp^(3)carbon nanostructures have attracted increasing attention recently.Based on the beam theory and atomistic studies,this work carries out a comprehensive investigation on the vibrational properties of the ultrathin carbon nanothreads(NTH).Size effect is observed in transverse free vibrations of NTHs.To quantify such effects,the modified couple stress theory(MCST)is utilized to modify the Timoshenko beam theory.According to the first four order frequencies of NTHs from atomistic simulations,the critical length scale parameter of MCST is calibrated as 0.1 nm.It is shown that MCST has minor effect on the first four order modal shapes,except for the clamped boundary.MCST makes the modal shapes at the clamped boundary closer to those observed in atomistic simulations.This study suggests that to some extent the MCST-based Timoshenko beam theory can well describe the transverse vibration characteristics of the ultrafine NTHs,which are helpful for designing and fabricating the NTH-based nanoscale mechanical resonators.
