The vibration caused by blasting excavation of rock mass frequently poses a threat to the stability of adjacent tunnels.Previous research is limited by the simplification of a rock mass as a homogeneous elastic medium...The vibration caused by blasting excavation of rock mass frequently poses a threat to the stability of adjacent tunnels.Previous research is limited by the simplification of a rock mass as a homogeneous elastic medium,without considering the wave attenuation caused by viscoelasticity and wave separation induced by rock discontinuities,as well as plane waves while neglecting geometric attenuation of near-field nonplane blast waves.This paper establishes a theoretical model of cylindrical P-wave propagation across a fault to an adjacent existing tunnel.Based on the time-domain recursive method,vibration equations and peak particle velocity on the adjacent existing tunnel wall caused by a cylindrical wave passing through a fault are derived.The rock mass and fault are assumed to satisfy Kelvin viscoelastic bodies,and contact interfaces between fault and rock mass follow a nonlinear hyperbolic deformation model in the normal direction and a linear model in the tangential direction.The results show that tunnel vibration caused by the blast cylindrical P-wave is primarily induced by transmitted P-waves.With the increase of the fault dip angle,vibration on the upper side of the adjacent existing tunnel gradually decreases,while vibration on the lower side increases.The closer the vibration to the upper and lower sides,the stronger the shear effect on the tunnel wall,and the closer the vibration to the middle,the stronger the pressure effect on the tunnel wall.Larger fault thickness and higher initial blast wave frequency result in weaker vibration of the adjacent tunnel.The deeper the burial depth,the stronger the vibration of the adjacent tunnel wall.Findings of this study provide insight into the dynamic response of rock construction and safety evaluation in engineering service.展开更多
Severe acute pancreatitis(SAP)can induce acute respiratory distress syndrome(ARDS)and abdominal compartment syndrome(ACS).Although prone position ventilation(PPV)can improve outcomes in patients with ARDS,there is sig...Severe acute pancreatitis(SAP)can induce acute respiratory distress syndrome(ARDS)and abdominal compartment syndrome(ACS).Although prone position ventilation(PPV)can improve outcomes in patients with ARDS,there is significant controversy regarding its concurrent use with ACS owing to concerns of increased risk of intra-abdominal pressure(IAP).[1]We present a case of successful PPV application without adverse eff ects.展开更多
Streptococcus pneumoniae is a known notorious cause of invasive pneumococcal diseases as well as asymptomatic host carriage. Efforts have been made to curb this infectious organism through various vaccine strategies. ...Streptococcus pneumoniae is a known notorious cause of invasive pneumococcal diseases as well as asymptomatic host carriage. Efforts have been made to curb this infectious organism through various vaccine strategies. However, its several strains and serotypes have necessitated various vaccine schedules and updates in the USA and globally. The evolution in pneumococcal vaccine schedules is not without challenges, such as cost, vaccine hesitancy, uptake and global disparities. This narrative review synopsizes the history of the Pneumococcal Vaccine and changes in its schedules in the last two decades based on published data. We focused on the impact of pneumococcal vaccination on invasive pneumococcal diseases, historical limitations, current challenges and future directions. Despite advancements in vaccination against S. pneumoniae infections, some pertinent issues exist that need to be swiftly fixed, to reduce national and thus global burden of pneumococcal diseases.展开更多
基金Natural Science Basic Research Program of Shaanxi Province,Grant/Award Number:2023-YBGY-085National Natural Science Foundation of China,Grant/Award Numbers:41902277,42172302Fundamental Research Funds for the Central Universities,Grant/Award Number:CHD.300102282201。
文摘The vibration caused by blasting excavation of rock mass frequently poses a threat to the stability of adjacent tunnels.Previous research is limited by the simplification of a rock mass as a homogeneous elastic medium,without considering the wave attenuation caused by viscoelasticity and wave separation induced by rock discontinuities,as well as plane waves while neglecting geometric attenuation of near-field nonplane blast waves.This paper establishes a theoretical model of cylindrical P-wave propagation across a fault to an adjacent existing tunnel.Based on the time-domain recursive method,vibration equations and peak particle velocity on the adjacent existing tunnel wall caused by a cylindrical wave passing through a fault are derived.The rock mass and fault are assumed to satisfy Kelvin viscoelastic bodies,and contact interfaces between fault and rock mass follow a nonlinear hyperbolic deformation model in the normal direction and a linear model in the tangential direction.The results show that tunnel vibration caused by the blast cylindrical P-wave is primarily induced by transmitted P-waves.With the increase of the fault dip angle,vibration on the upper side of the adjacent existing tunnel gradually decreases,while vibration on the lower side increases.The closer the vibration to the upper and lower sides,the stronger the shear effect on the tunnel wall,and the closer the vibration to the middle,the stronger the pressure effect on the tunnel wall.Larger fault thickness and higher initial blast wave frequency result in weaker vibration of the adjacent tunnel.The deeper the burial depth,the stronger the vibration of the adjacent tunnel wall.Findings of this study provide insight into the dynamic response of rock construction and safety evaluation in engineering service.
文摘Severe acute pancreatitis(SAP)can induce acute respiratory distress syndrome(ARDS)and abdominal compartment syndrome(ACS).Although prone position ventilation(PPV)can improve outcomes in patients with ARDS,there is significant controversy regarding its concurrent use with ACS owing to concerns of increased risk of intra-abdominal pressure(IAP).[1]We present a case of successful PPV application without adverse eff ects.
文摘Streptococcus pneumoniae is a known notorious cause of invasive pneumococcal diseases as well as asymptomatic host carriage. Efforts have been made to curb this infectious organism through various vaccine strategies. However, its several strains and serotypes have necessitated various vaccine schedules and updates in the USA and globally. The evolution in pneumococcal vaccine schedules is not without challenges, such as cost, vaccine hesitancy, uptake and global disparities. This narrative review synopsizes the history of the Pneumococcal Vaccine and changes in its schedules in the last two decades based on published data. We focused on the impact of pneumococcal vaccination on invasive pneumococcal diseases, historical limitations, current challenges and future directions. Despite advancements in vaccination against S. pneumoniae infections, some pertinent issues exist that need to be swiftly fixed, to reduce national and thus global burden of pneumococcal diseases.
