Locked segments are recognized as a critical role that controls the stability of rock slopes but remain an unclear and challenging problem with respect to their role incorporated into the failure mechanism.In order to...Locked segments are recognized as a critical role that controls the stability of rock slopes but remain an unclear and challenging problem with respect to their role incorporated into the failure mechanism.In order to study the effect of the locked segments on the initial failure process of rockslides,thirty-six groups of locked segment specimens with three different lithologies were prepared,direct shear tests were carried out to obtain the accelerations caused by brittle failure of the locked segment specimens.Experiment results showed that the maximum accelerations caused by the brittle failure of locked segment specimens was 2.91 g in the horizontal direction,and 3.18 g in the vertical direction.We took the Wangjiayan rockslide in 2008 Wenchuan earthquake as an example,the critical balance condition of the sliding mass under combined effect of gravity and accelerations induced by brittle failure of locked segment was analyzed,which indicated that the initial failure process of the Wangjiayan rockslides was notably influenced by the existence of the locked segment.The departure acceleration and direction of the Wangjiayan rockslide were proposed.The study results can provide a new insight into the understanding of the initial failure mechanism of rockslides with locked segments.展开更多
Most heart failure （HF） related mortality is due to sudden cardiac death （SCD） and worsening HF, particularly in the case of reduced ejection fraction. Predicting and preventing SCD is an important goal but most w...Most heart failure （HF） related mortality is due to sudden cardiac death （SCD） and worsening HF, particularly in the case of reduced ejection fraction. Predicting and preventing SCD is an important goal but most works include no or few patients with advanced age, and the prevention of SCD in elderly patients with HF is still controversial. A recent reduction in the annual rate of SCD has been recently described but it is not clear if this is also true in advanced age patients. Age is associated with SCD, although physicians frequently have the perception that elderly patients with HF die mainly of pump failure, underestimating the importance of SCD. Other clinical variables that have been associated to SCD are symptoms, New York Heart Association functional class, ischemic cause, and comorbidities （chronic obstructive pulmonary disease, renal dysfunction and diabetes）. Some test results that should also be considered are left ventricular ejection fraction and diameters, natriuretic peptides, non-sustained ventricular tachycardias and autonomic abnormalities. The combination of all these markers is probably the best option to predict SCD. Different risk scores have been described and, although there are no specific ones for elderly populations, most include age as a risk predictor and some were developed in populations with mean age 〉 65 years. Finally, it is important to stress that these scores should be able to predict any type of SCD as, although most are due to tachyarrhythmias, bradyarrhythmias also play a role, particularly in the case of the elderly.展开更多
Sudden cardiac death (SCD) is one of the most debilitating and life-threatening complications of heart failure (HF) which has challenged medical care for long. Current guidelines suggest the use of Implantable Cardiov...Sudden cardiac death (SCD) is one of the most debilitating and life-threatening complications of heart failure (HF) which has challenged medical care for long. Current guidelines suggest the use of Implantable Cardioverter Defibrillator (ICD) in primary prevention of SCD in both New York Heart Association (NYHA) class II and class III heart failure. This paper critically evaluated the evidence underlying the guideline recommendation. In contrast to recent guidelines, the majority of the intervention trials conducted on the topic till date found a promising role of ICD only in the prevention of SCD in NYHA class II HF. One of the trials which found a significant role of ICD in type III heart failure was underpowered. Thus, further trials are needed to validate the use of ICD in the prevention of SCD in type III HF.展开更多
目的探究24 h动态心电图微伏级T波电交替(AECGs-MTWA)技术对慢性心力衰竭(CHF)患者心源性猝死(SCD)的预测价值。方法选取2019年4月至2021年7月期间成都市第六人民医院收治的96例CHF患者为研究对象,所有患者均行动态心电图(AECGs)检查,...目的探究24 h动态心电图微伏级T波电交替(AECGs-MTWA)技术对慢性心力衰竭(CHF)患者心源性猝死(SCD)的预测价值。方法选取2019年4月至2021年7月期间成都市第六人民医院收治的96例CHF患者为研究对象,所有患者均行动态心电图(AECGs)检查,并借助时域分析法移动平均修正技术分析24 h AECGs-MTWA,测量V1导联及V5导联中的MTWAmax及8∶00amMTWA;随访1年,主要终点为SCD,次要终点为CHF死亡,根据患者结局将其分为存活组、SCD组、非SCD组,比较3组基线资料、V1导联及V5导联MTWA最大值及8∶00amMTWA,采用受试者工作特征(ROC)曲线分析对CHF患者SCD的预测效能。结果3组基线资料比较,差异均无统计学意义;3组V1导联及V5导联中的MTWAmax及8∶00amMTWA比较,差异均有统计学意义(P<0.05);SCD组V1导联及V5导联中的MTWAmax及8∶00amMTWA均低于存活组,差异均有统计学意义(P<0.05),但存活组、非SCD组上述指标比较,差异均无统计学意义(P>0.05)。ROC曲线结果分析,V1导联MTWAmax预测SCD的曲线下面积、敏感度、特异度分别为0.865、76.00%、88.50%;V5导联MTWAmax预测SCD的曲线下面积、敏感度、特异度分别为0.851、72.00%、92.30%;V1导联8∶00amMTWA预测SCD的曲线下面积、敏感度、特异度分别为0.846、80.00%、88.50%;V5导联8∶00amMTWA预测SCD的曲线下面积、敏感度、特异度分别为0.861、80.00%、90.04%。结论AECGs-MTWA技术对CHF患者发生SCD具有一定的预测价值,可为临床诊疗提供科学依据。展开更多
Due to the massive bed materials in its typical main loop,a circulating fluidized bed(CFB)boiler may face greater trouble in operation and restart-up if an unplanned sudden power failure happens in the power plant.Thi...Due to the massive bed materials in its typical main loop,a circulating fluidized bed(CFB)boiler may face greater trouble in operation and restart-up if an unplanned sudden power failure happens in the power plant.This study aims to explore the restart-up performance of a 170 t/h natural circulation CFB boiler after a sudden power failure and evaluate whether the hot restart-up can be realized.The heat transfer process after the restoration of the primary air is modeled.Validating the isothermal property of the bed after the restoration of the power and air supply,the correlation among the accident duration time,bed temperature after the power restores,inlet air temperature,air supply time,and air velocity is proposed.The predicted results indicate that the major influencing factor of the bed temperature during this process is primary air velocity.To provide guidelines for judgment on whether the hot restart-up can be realized,the maximum values of the air supply time and accident duration time for hot restart-up for different types of coals are given.The results show both of them have a rapid decrease as the coal ignition temperature in a CFB boiler increases from 450°C to 650°C,which also means that the coal ignition temperature plays a very important role in the restart-up process.Based on the simulation results of bed temperature during the accident,it is also estimated that the drum level drops by 77.7 mm after 8 hours but still stays in the permissible range.展开更多
3日龄健康足月顺产女婴,Apgar评分:1 min 10分、5 min 10分,生后第3天凌晨母婴同床时突发心跳、呼吸停止,经积极抢救恢复自主呼吸及心跳,复苏时间持续约10 min,复苏后患儿反应差并出现抽搐,血气分析提示代谢性酸中毒,振幅整合脑电图提...3日龄健康足月顺产女婴,Apgar评分:1 min 10分、5 min 10分,生后第3天凌晨母婴同床时突发心跳、呼吸停止,经积极抢救恢复自主呼吸及心跳,复苏时间持续约10 min,复苏后患儿反应差并出现抽搐,血气分析提示代谢性酸中毒,振幅整合脑电图提示爆发-抑制图形,诊断为新生儿生后突发意外衰竭。该患儿经亚低温及对症支持治疗,病情好转。该文首次报道国内1例新生儿生后突发意外衰竭,并对其危险因素、病理生理机制、预防和治疗措施进行总结。展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 41672295)
文摘Locked segments are recognized as a critical role that controls the stability of rock slopes but remain an unclear and challenging problem with respect to their role incorporated into the failure mechanism.In order to study the effect of the locked segments on the initial failure process of rockslides,thirty-six groups of locked segment specimens with three different lithologies were prepared,direct shear tests were carried out to obtain the accelerations caused by brittle failure of the locked segment specimens.Experiment results showed that the maximum accelerations caused by the brittle failure of locked segment specimens was 2.91 g in the horizontal direction,and 3.18 g in the vertical direction.We took the Wangjiayan rockslide in 2008 Wenchuan earthquake as an example,the critical balance condition of the sliding mass under combined effect of gravity and accelerations induced by brittle failure of locked segment was analyzed,which indicated that the initial failure process of the Wangjiayan rockslides was notably influenced by the existence of the locked segment.The departure acceleration and direction of the Wangjiayan rockslide were proposed.The study results can provide a new insight into the understanding of the initial failure mechanism of rockslides with locked segments.
文摘Most heart failure （HF） related mortality is due to sudden cardiac death （SCD） and worsening HF, particularly in the case of reduced ejection fraction. Predicting and preventing SCD is an important goal but most works include no or few patients with advanced age, and the prevention of SCD in elderly patients with HF is still controversial. A recent reduction in the annual rate of SCD has been recently described but it is not clear if this is also true in advanced age patients. Age is associated with SCD, although physicians frequently have the perception that elderly patients with HF die mainly of pump failure, underestimating the importance of SCD. Other clinical variables that have been associated to SCD are symptoms, New York Heart Association functional class, ischemic cause, and comorbidities （chronic obstructive pulmonary disease, renal dysfunction and diabetes）. Some test results that should also be considered are left ventricular ejection fraction and diameters, natriuretic peptides, non-sustained ventricular tachycardias and autonomic abnormalities. The combination of all these markers is probably the best option to predict SCD. Different risk scores have been described and, although there are no specific ones for elderly populations, most include age as a risk predictor and some were developed in populations with mean age 〉 65 years. Finally, it is important to stress that these scores should be able to predict any type of SCD as, although most are due to tachyarrhythmias, bradyarrhythmias also play a role, particularly in the case of the elderly.
文摘Sudden cardiac death (SCD) is one of the most debilitating and life-threatening complications of heart failure (HF) which has challenged medical care for long. Current guidelines suggest the use of Implantable Cardioverter Defibrillator (ICD) in primary prevention of SCD in both New York Heart Association (NYHA) class II and class III heart failure. This paper critically evaluated the evidence underlying the guideline recommendation. In contrast to recent guidelines, the majority of the intervention trials conducted on the topic till date found a promising role of ICD only in the prevention of SCD in NYHA class II HF. One of the trials which found a significant role of ICD in type III heart failure was underpowered. Thus, further trials are needed to validate the use of ICD in the prevention of SCD in type III HF.
文摘目的探究24 h动态心电图微伏级T波电交替(AECGs-MTWA)技术对慢性心力衰竭(CHF)患者心源性猝死(SCD)的预测价值。方法选取2019年4月至2021年7月期间成都市第六人民医院收治的96例CHF患者为研究对象,所有患者均行动态心电图(AECGs)检查,并借助时域分析法移动平均修正技术分析24 h AECGs-MTWA,测量V1导联及V5导联中的MTWAmax及8∶00amMTWA;随访1年,主要终点为SCD,次要终点为CHF死亡,根据患者结局将其分为存活组、SCD组、非SCD组,比较3组基线资料、V1导联及V5导联MTWA最大值及8∶00amMTWA,采用受试者工作特征(ROC)曲线分析对CHF患者SCD的预测效能。结果3组基线资料比较,差异均无统计学意义;3组V1导联及V5导联中的MTWAmax及8∶00amMTWA比较,差异均有统计学意义(P<0.05);SCD组V1导联及V5导联中的MTWAmax及8∶00amMTWA均低于存活组,差异均有统计学意义(P<0.05),但存活组、非SCD组上述指标比较,差异均无统计学意义(P>0.05)。ROC曲线结果分析,V1导联MTWAmax预测SCD的曲线下面积、敏感度、特异度分别为0.865、76.00%、88.50%;V5导联MTWAmax预测SCD的曲线下面积、敏感度、特异度分别为0.851、72.00%、92.30%;V1导联8∶00amMTWA预测SCD的曲线下面积、敏感度、特异度分别为0.846、80.00%、88.50%;V5导联8∶00amMTWA预测SCD的曲线下面积、敏感度、特异度分别为0.861、80.00%、90.04%。结论AECGs-MTWA技术对CHF患者发生SCD具有一定的预测价值,可为临床诊疗提供科学依据。
基金supported by National Natural Science Foundation of China(U1710251)。
文摘Due to the massive bed materials in its typical main loop,a circulating fluidized bed(CFB)boiler may face greater trouble in operation and restart-up if an unplanned sudden power failure happens in the power plant.This study aims to explore the restart-up performance of a 170 t/h natural circulation CFB boiler after a sudden power failure and evaluate whether the hot restart-up can be realized.The heat transfer process after the restoration of the primary air is modeled.Validating the isothermal property of the bed after the restoration of the power and air supply,the correlation among the accident duration time,bed temperature after the power restores,inlet air temperature,air supply time,and air velocity is proposed.The predicted results indicate that the major influencing factor of the bed temperature during this process is primary air velocity.To provide guidelines for judgment on whether the hot restart-up can be realized,the maximum values of the air supply time and accident duration time for hot restart-up for different types of coals are given.The results show both of them have a rapid decrease as the coal ignition temperature in a CFB boiler increases from 450°C to 650°C,which also means that the coal ignition temperature plays a very important role in the restart-up process.Based on the simulation results of bed temperature during the accident,it is also estimated that the drum level drops by 77.7 mm after 8 hours but still stays in the permissible range.
文摘3日龄健康足月顺产女婴,Apgar评分:1 min 10分、5 min 10分,生后第3天凌晨母婴同床时突发心跳、呼吸停止,经积极抢救恢复自主呼吸及心跳,复苏时间持续约10 min,复苏后患儿反应差并出现抽搐,血气分析提示代谢性酸中毒,振幅整合脑电图提示爆发-抑制图形,诊断为新生儿生后突发意外衰竭。该患儿经亚低温及对症支持治疗,病情好转。该文首次报道国内1例新生儿生后突发意外衰竭,并对其危险因素、病理生理机制、预防和治疗措施进行总结。
