针对现有门式起重机主梁挠度测量方法存在操作复杂、不够安全、停机检测时间长和精度不稳定等问题,文章提出一种基于双目摄影测量的主梁挠度快速、安全与精准测量方法。相机标定是双目摄影测量精度的最重要影响之一,在传统灰狼算法(grey...针对现有门式起重机主梁挠度测量方法存在操作复杂、不够安全、停机检测时间长和精度不稳定等问题,文章提出一种基于双目摄影测量的主梁挠度快速、安全与精准测量方法。相机标定是双目摄影测量精度的最重要影响之一,在传统灰狼算法(grey wolf optimizer,GWO)中引入余弦函数收敛因子以提升算法的全局和局部搜索能力,并使用基于欧式距离的比例权重策略加快算法收敛速度,获得改进灰狼算法(improved grey wolf optimizer,IGWO)。将改进算法应用于双目相机的标定参数寻优中,获得最优标定值。通过仿真与现场试验进行验证,结果表明:该方法标定精确且快速,挠度检测误差在1%以内,满足门式起重机挠度的工程测量要求。展开更多
目的通过收集确诊及排除的新型冠状病毒肺炎(COVID-19)患者病历资料,分析其病例特点并拟定可疑患者急诊发热门诊筛查流程。方法回顾性收集2020年1月19日至1月26日于北京协和医院发热门诊筛查的有流行病学史及呼吸系统症状或有发热症状...目的通过收集确诊及排除的新型冠状病毒肺炎(COVID-19)患者病历资料,分析其病例特点并拟定可疑患者急诊发热门诊筛查流程。方法回顾性收集2020年1月19日至1月26日于北京协和医院发热门诊筛查的有流行病学史及呼吸系统症状或有发热症状的患者临床资料,根据鼻咽拭子新型冠状病毒核酸检测(实时逆转录聚合酶链反应方法,real time RT-PCR)结果确诊或除外新型冠状病毒感染,收集并分析患者的流行病学特征、临床表现、实验室检查及影像学特征。结果共筛查46例患者,其中9例为新型冠状病毒感染患者,37例为排除新型冠状病毒感染患者。新型冠状病毒感染患者于发病前2周内有武汉旅居史的比例较高(P<0.05),但两组在年龄、性别、其他流行病学特征及合并症方面差异无统计学意义(P>0.05)。新型冠状病毒感染患者最常见的临床表现是发热(100%),但该症状在两组间差异无统计学意义(P>0.05),其他症状如咳嗽、咳痰、咽痛等两组间差异亦无统计学意义(P>0.05)。新型冠状病毒感染患者白细胞计数低于非新型冠状病毒感染患者(P<0.05),且胸部CT均有肺炎表现。胸部CT正常者中均未检测到新型冠状病毒核酸阳性。结论新型冠状病毒感染无特异性临床症状,但胸部CT阴性对新型冠状病毒感染具有很高的阴性预测价值。推荐急诊与发热门诊采取基于流行病学史、胸部CT阳性再结合新型冠状病毒核酸检测的筛查流程以降低漏诊率并提高筛查效率。展开更多
OBJECTIVE: To better understand the working mechanism of acupuncture, we investigated the skin electrical impedance distribution around acupoints, and the impedance changes at 12 original acupoints bilaterally after b...OBJECTIVE: To better understand the working mechanism of acupuncture, we investigated the skin electrical impedance distribution around acupoints, and the impedance changes at 12 original acupoints bilaterally after bending the limbs.METHODS: We measured the skin electrical impedance in three study subjects in the frequency range of 40 to 10 k Hz using the four-electrode method with a sharp probe and a large reference electrode.A measurement matrix of 7 mm × 7 mm with spacing of 2.0(or 3.0) mm was measured to obtain 2 D impedance mapping of acupoints. The impedance spectra of 12 original acupoints were measured at the 0° position and the 90° position.RESULTS: The electrical impedance of some acupoints, such as Yangchi(TE 4), was 16 times lower than that of the surrounding area, showing a recognizable small central area of low impedance with a diameter of less than 4 mm. In contrast, other acupoints, such as Laogong(PC 8), had an electrical impedance that was not significantly different from that of the surrounding area. When the limb was bent from a straight position(0o) to a vertical position(90o), the electrical impedance of the 12 original acupoints showed varied trends, either increasing or decreasing by a factor of up to ten times, or remaining at the same level.CONCLUSION: Not all acupoints tested show the property of low impedance, which might be related to the varied depth of the openings of superficial collaterals. The unexpected dependence of acupoint impedance on limb angle is a novel discovery, which implies that the channel paths are located in interstitial structures in the limbs. It might be possible to determine an optimized limb position for each particular acupuncture treatment in clinical practice.展开更多
文摘针对现有门式起重机主梁挠度测量方法存在操作复杂、不够安全、停机检测时间长和精度不稳定等问题,文章提出一种基于双目摄影测量的主梁挠度快速、安全与精准测量方法。相机标定是双目摄影测量精度的最重要影响之一,在传统灰狼算法(grey wolf optimizer,GWO)中引入余弦函数收敛因子以提升算法的全局和局部搜索能力,并使用基于欧式距离的比例权重策略加快算法收敛速度,获得改进灰狼算法(improved grey wolf optimizer,IGWO)。将改进算法应用于双目相机的标定参数寻优中,获得最优标定值。通过仿真与现场试验进行验证,结果表明:该方法标定精确且快速,挠度检测误差在1%以内,满足门式起重机挠度的工程测量要求。
文摘目的通过收集确诊及排除的新型冠状病毒肺炎(COVID-19)患者病历资料,分析其病例特点并拟定可疑患者急诊发热门诊筛查流程。方法回顾性收集2020年1月19日至1月26日于北京协和医院发热门诊筛查的有流行病学史及呼吸系统症状或有发热症状的患者临床资料,根据鼻咽拭子新型冠状病毒核酸检测(实时逆转录聚合酶链反应方法,real time RT-PCR)结果确诊或除外新型冠状病毒感染,收集并分析患者的流行病学特征、临床表现、实验室检查及影像学特征。结果共筛查46例患者,其中9例为新型冠状病毒感染患者,37例为排除新型冠状病毒感染患者。新型冠状病毒感染患者于发病前2周内有武汉旅居史的比例较高(P<0.05),但两组在年龄、性别、其他流行病学特征及合并症方面差异无统计学意义(P>0.05)。新型冠状病毒感染患者最常见的临床表现是发热(100%),但该症状在两组间差异无统计学意义(P>0.05),其他症状如咳嗽、咳痰、咽痛等两组间差异亦无统计学意义(P>0.05)。新型冠状病毒感染患者白细胞计数低于非新型冠状病毒感染患者(P<0.05),且胸部CT均有肺炎表现。胸部CT正常者中均未检测到新型冠状病毒核酸阳性。结论新型冠状病毒感染无特异性临床症状,但胸部CT阴性对新型冠状病毒感染具有很高的阴性预测价值。推荐急诊与发热门诊采取基于流行病学史、胸部CT阳性再结合新型冠状病毒核酸检测的筛查流程以降低漏诊率并提高筛查效率。
文摘目的分析急诊气管插管(endotracheal intubation,ETI)后患者平均动脉压(mean arterial pressure,MAP)及呼气末二氧化碳(end tidal CO_(2),ETCO_(2))的变化特点,探讨急诊ETI后监测MAP和ETCO_(2)对早期预测严重循环崩溃(cardiovascular collapse,CVC)的价值。方法前瞻性顺序收集2015年3月至2020年5月北京协和医院急诊科行急诊ETI成人患者的临床资料。观察并记录患者ETI后5、10、30、60和120 min MAP和ETCO_(2)的数值。根据患者急诊ETI后是否发生严重CVC分为严重CVC组和无严重CVC组。对两组MAP和ETCO_(2)的数值进行组间相同时间点和组内相邻时间点的比较,并将ETI后MAP与ETCO_(2)的数值进行相关性分析。采用ROC曲线分析急诊ETI后5 min和10 min MAP及ETCO_(2)对严重CVC的预测能力。结果共纳入研究患者116例,其中75(64.7%)例患者ETI后发生严重CVC,严重CVC组中以男性和高龄患者居多。严重CVC组急诊ETI后5、10、30、60、120 min MAP和ETCO_(2)的数值明显低于无严重CVC组。两组MAP和ETCO_(2)在急诊ETI后5~30 min表现为同步下降,在ETI后30 min达最低值,其后至ETI后120 min表现为同步回升。ETI后MAP和ETCO_(2)两者的变化具有相关性(rs=0.653,P<0.01)。ETI后5 min MAP可准确预测严重CVC(AUC=0.86,P<0.01),最佳截断值为MAP≤72 mmHg(灵敏度为78.7%,特异度为87.8%)。ETCO_(2)也可准确预测严重CVC(AUC=0.85,P<0.01),最佳截断值为ETCO_(2)≤35 mmHg(灵敏度为77.3%,特异度为85.4%)。ETI后10 min MAP可准确预测严重CVC(AUC=0.90,P<0.01),最佳截断值为MAP≤67 mmHg(灵敏度为89.3%,特异度为85.4%)。ETI后10 min ETCO_(2)也可准确预测严重CVC(AUC=0.87,P<0.01),最佳截断值为ETCO_(2)≤33 mmHg(灵敏度为81.3%,特异度为78.0%)。急诊ETI后5 min和10 min的MAP和ETCO_(2)中任意两个指标的预测能力差异无统计学意义(P>0.05)。结论急诊ETI后严重CVC患者早期即有MAP和ETCO_(2)下降表现,但识别滞后和干预不足可能与CVC的发生发展有关。ETI后早期MAP和ETCO_(2)对预测严重CVC均有较高效能。插管后5 min MAP≤72 mmHg、ETCO_(2)≤35 mmHg、插管后10 min MAP≤67 mmHg及ETCO_(2)≤33 mmHg均提示患者发生严重CVC的可能性大。
基金Supported by the National Natural Science Foundation of China(No.11374016,No.91221202)Medicineschool of electronics engineering and computer science Joint Seed Fund 2016,Peking University
文摘OBJECTIVE: To better understand the working mechanism of acupuncture, we investigated the skin electrical impedance distribution around acupoints, and the impedance changes at 12 original acupoints bilaterally after bending the limbs.METHODS: We measured the skin electrical impedance in three study subjects in the frequency range of 40 to 10 k Hz using the four-electrode method with a sharp probe and a large reference electrode.A measurement matrix of 7 mm × 7 mm with spacing of 2.0(or 3.0) mm was measured to obtain 2 D impedance mapping of acupoints. The impedance spectra of 12 original acupoints were measured at the 0° position and the 90° position.RESULTS: The electrical impedance of some acupoints, such as Yangchi(TE 4), was 16 times lower than that of the surrounding area, showing a recognizable small central area of low impedance with a diameter of less than 4 mm. In contrast, other acupoints, such as Laogong(PC 8), had an electrical impedance that was not significantly different from that of the surrounding area. When the limb was bent from a straight position(0o) to a vertical position(90o), the electrical impedance of the 12 original acupoints showed varied trends, either increasing or decreasing by a factor of up to ten times, or remaining at the same level.CONCLUSION: Not all acupoints tested show the property of low impedance, which might be related to the varied depth of the openings of superficial collaterals. The unexpected dependence of acupoint impedance on limb angle is a novel discovery, which implies that the channel paths are located in interstitial structures in the limbs. It might be possible to determine an optimized limb position for each particular acupuncture treatment in clinical practice.
