目的本研究旨在构建一个基于临床和影像学特征的极端梯度提升(extreme gradient boosting,XGBoost)模型,以鉴别乳腺非肿块病变的良恶性。材料与方法收集2018年1月至2024年7月2个机构,2种乳腺X线设备检查的有病理结果的首诊乳腺非肿块病...目的本研究旨在构建一个基于临床和影像学特征的极端梯度提升(extreme gradient boosting,XGBoost)模型,以鉴别乳腺非肿块病变的良恶性。材料与方法收集2018年1月至2024年7月2个机构,2种乳腺X线设备检查的有病理结果的首诊乳腺非肿块病变480个。患者被分为建模组[n=310,数字乳腺X线摄影(digital mammography,DM)检查]、内部验证组(n=108,DM检查),和外部验证组[n=62,数字乳腺体层合成摄影(digital breast tomosynthesis,DBT)检查]。记录患者术前乳腺X线(DM或DBT),MRI以及临床特征。采用XGBoost算法和多因素逻辑回归分析,分别构建XGBoost模型和逻辑回归(logistic regression,LR)模型。使用受试者工作特征(receiver operating characteristic,ROC)曲线评估模型的诊断效能。结果在建模组中,患者以7∶3随机分为训练集(n=217)和测试集(n=93)。训练集、测试集、训练集的内部验证组及训练集的外部验证组中,恶性非肿块病灶分别为159(73%)、58(62%)、73(68%)和43(69%)。XGBoost模型的诊断效能明显优于LR模型,在独立的训练集、测试集、训练集的内部验证组及训练集的外部验证组中均表现出良好的诊断效能,曲线下面积(area under the curve,AUC)在0.884~0.913之间。XGBoost模型在四个队列中也表现出良好的校准能力和临床净获益。结论XGBoost模型能够准确鉴别乳腺非肿块病变的良恶性,具有推广应用的潜力。展开更多
Heat stress hinders the growth and productivity of sweetpotato plants,predominantly through oxidative damage to cellular membranes.Therefore,the development of efficient approaches for mitigating heat-related impairme...Heat stress hinders the growth and productivity of sweetpotato plants,predominantly through oxidative damage to cellular membranes.Therefore,the development of efficient approaches for mitigating heat-related impairments is essential for the long-term production of sweetpotatoes.Melatonin has been recognised for its capacity to assist plants in dealing with abiotic stress conditions.This research aimed to investigate how different doses of exogenous melatonin influence heat damage in sweetpotato plants.Heat stress drastically affected shoot and root fresh weight by 31.8 and 44.5%,respectively.This reduction resulted in oxidative stress characterised by increased formation of hydrogen peroxide(H_(2)O_(2))by 804.4%,superoxide ion(O_(2)^(·-))by 211.5%and malondialdehyde(MDA)by 234.2%.Heat stress also reduced chlorophyll concentration,photosystemⅡefficiency(F_v/F_m)by 15.3%and gaseous exchange.However,pre-treatment with 100μmol L^(-1)melatonin increased growth and reduced oxidative damage to sweetpotato plants under heat stress.In particular,melatonin decreased H_(2)O_(2),O_(2)^(·-)and MDA by 64.8%,42.7%and 38.2%,respectively.Melatonin also mitigated the decline in chlorophyll levels and improved stomatal traits,gaseous exchange and F_(v)/F_(m)(13%).Results suggested that the favorable outcomes of melatonin treatment can be associated with elevated antioxidant enzyme activity and an increase in non-enzymatic antioxidants and osmo-protectants.Overall,these findings indicate that exogenous melatonin can improve heat stress tolerance in sweetpotatoes.This stu dy will assist re searchers in further investigating how melatonin makes sweetpotatoes more resistant to heat stress.展开更多
为了解决传统变换器电压增益低的问题,将Boost变换器与Cuk变换器进行并联集成,并利用耦合电感倍压技术提高变换器的电压增益。设计而成的高增益耦合电感组合Boost-Cuk变换器保留了Cuk变换器输出电流的连续性,新型结构中使用无源钳位来...为了解决传统变换器电压增益低的问题,将Boost变换器与Cuk变换器进行并联集成,并利用耦合电感倍压技术提高变换器的电压增益。设计而成的高增益耦合电感组合Boost-Cuk变换器保留了Cuk变换器输出电流的连续性,新型结构中使用无源钳位来吸收漏感能量,对寄生电容与漏感谐振引起的电压尖峰起到约束作用,降低了开关管的电压应力。描述了变换器电感电流连续模式(Continuous current mode,CCM)下的运行特点,并进行了该变换器的参数设计。最后,通过搭建一台100 W的试验样机来求证理论的正确性。展开更多
文摘目的本研究旨在构建一个基于临床和影像学特征的极端梯度提升(extreme gradient boosting,XGBoost)模型,以鉴别乳腺非肿块病变的良恶性。材料与方法收集2018年1月至2024年7月2个机构,2种乳腺X线设备检查的有病理结果的首诊乳腺非肿块病变480个。患者被分为建模组[n=310,数字乳腺X线摄影(digital mammography,DM)检查]、内部验证组(n=108,DM检查),和外部验证组[n=62,数字乳腺体层合成摄影(digital breast tomosynthesis,DBT)检查]。记录患者术前乳腺X线(DM或DBT),MRI以及临床特征。采用XGBoost算法和多因素逻辑回归分析,分别构建XGBoost模型和逻辑回归(logistic regression,LR)模型。使用受试者工作特征(receiver operating characteristic,ROC)曲线评估模型的诊断效能。结果在建模组中,患者以7∶3随机分为训练集(n=217)和测试集(n=93)。训练集、测试集、训练集的内部验证组及训练集的外部验证组中,恶性非肿块病灶分别为159(73%)、58(62%)、73(68%)和43(69%)。XGBoost模型的诊断效能明显优于LR模型,在独立的训练集、测试集、训练集的内部验证组及训练集的外部验证组中均表现出良好的诊断效能,曲线下面积(area under the curve,AUC)在0.884~0.913之间。XGBoost模型在四个队列中也表现出良好的校准能力和临床净获益。结论XGBoost模型能够准确鉴别乳腺非肿块病变的良恶性,具有推广应用的潜力。
基金supported jointly by the earmarked fund for CARS-10-GW2the key research and development program of Hainan Province(Grant No.ZDYF2020226)+1 种基金Collaborative innovation center of Nanfan and high-efficiency tropical agriculture,Hainan University(Grant No.XTCX2022NYC21)funding of Hainan University[Grant No.KYQD(ZR)22123]。
文摘Heat stress hinders the growth and productivity of sweetpotato plants,predominantly through oxidative damage to cellular membranes.Therefore,the development of efficient approaches for mitigating heat-related impairments is essential for the long-term production of sweetpotatoes.Melatonin has been recognised for its capacity to assist plants in dealing with abiotic stress conditions.This research aimed to investigate how different doses of exogenous melatonin influence heat damage in sweetpotato plants.Heat stress drastically affected shoot and root fresh weight by 31.8 and 44.5%,respectively.This reduction resulted in oxidative stress characterised by increased formation of hydrogen peroxide(H_(2)O_(2))by 804.4%,superoxide ion(O_(2)^(·-))by 211.5%and malondialdehyde(MDA)by 234.2%.Heat stress also reduced chlorophyll concentration,photosystemⅡefficiency(F_v/F_m)by 15.3%and gaseous exchange.However,pre-treatment with 100μmol L^(-1)melatonin increased growth and reduced oxidative damage to sweetpotato plants under heat stress.In particular,melatonin decreased H_(2)O_(2),O_(2)^(·-)and MDA by 64.8%,42.7%and 38.2%,respectively.Melatonin also mitigated the decline in chlorophyll levels and improved stomatal traits,gaseous exchange and F_(v)/F_(m)(13%).Results suggested that the favorable outcomes of melatonin treatment can be associated with elevated antioxidant enzyme activity and an increase in non-enzymatic antioxidants and osmo-protectants.Overall,these findings indicate that exogenous melatonin can improve heat stress tolerance in sweetpotatoes.This stu dy will assist re searchers in further investigating how melatonin makes sweetpotatoes more resistant to heat stress.
文摘为了解决传统变换器电压增益低的问题,将Boost变换器与Cuk变换器进行并联集成,并利用耦合电感倍压技术提高变换器的电压增益。设计而成的高增益耦合电感组合Boost-Cuk变换器保留了Cuk变换器输出电流的连续性,新型结构中使用无源钳位来吸收漏感能量,对寄生电容与漏感谐振引起的电压尖峰起到约束作用,降低了开关管的电压应力。描述了变换器电感电流连续模式(Continuous current mode,CCM)下的运行特点,并进行了该变换器的参数设计。最后,通过搭建一台100 W的试验样机来求证理论的正确性。
