Objective:To evaluate the efficacy and safety of the treatment of traumatic hemothorax by closed pleural drainage using a central venous catheter(CVC),compared with using a conventional chest tube.Methods:A prospectiv...Objective:To evaluate the efficacy and safety of the treatment of traumatic hemothorax by closed pleural drainage using a central venous catheter(CVC),compared with using a conventional chest tube.Methods:A prospective controlled study with the Ethics Committee approval was undertaken.A total of 407 patients with traumatic hemothorax were involved and they were randomly assigned to undergo closed pleural drainage with CVCs(n=214) or conventional chest tubes(n=193).The Seldinger technique was used for drainage by CVC,and the conventional technique for drainage by chest tube.If the residual volume of the hemothorax was less than 200 ml after the daily volume of drainage decreased to below 100 ml for two consecutive days,the treatment was considered successful.The correlative data of efficacy and safety between the two groups were analyzed using t or chi-squared tests with SPSS 13.0.A P value of less than 0.05 was taken as indicating statistical significance.Results:Compared with the chest tube group,the operation time,fraction of analgesic treatment,time of surgical wound healing,and infection rate of surgical wounds were significantly decreased(P<0.05) in the CVC group.There were no significant differences between the two groups in the success rate of treatment and the incidence of serious complications(P>0.05),or in the mean catheter/tube indwelling time and mean medical costs of patients treated successfully(P>0.05).Conclusions:Management of medium or large traumatic hemothoraxes by closed thoracic drainage using CVC is minimally invasive and as effective as using a conventional large-bore chest tube.Its complications can be prevented and it has the potential to replace the large-bore chest tube.展开更多
Numerical simulations of the flow in the draft tube of a Francis turbine are carried out in order to elucidate the effects of tangential velocity on flow stability.Influence of the location of the maximum tangential v...Numerical simulations of the flow in the draft tube of a Francis turbine are carried out in order to elucidate the effects of tangential velocity on flow stability.Influence of the location of the maximum tangential velocity is explored considering the equality of the total energy at the inlet of the draft tube.It is found that the amplitude of the pressure fluctuation decreases when the location of the maximum of the tangential velocity moves from the centre to the wall on the cross section.Thus,the stability of the flow in the draft tube increases with the moving of the location of the maximum tangential velocity.However,the relative hydraulic loss increases and the recovery coefficient of the draft tube decreases slightly.展开更多
An analytical model for the subthreshold current of a strained-Si metal-oxide-semiconductor field-effect transistor (MOSFET) is developed by solving the two-dimensional (2D) Poisson equation and the conventional drift...An analytical model for the subthreshold current of a strained-Si metal-oxide-semiconductor field-effect transistor (MOSFET) is developed by solving the two-dimensional (2D) Poisson equation and the conventional drift-diffusion theory. Model verification is carried out using the 2D device simulator ISE. Good agreement is obtained between the model's calculations and the simulated results. By analyzing the model, the dependence of current on the strained-Si layer strain, doping concentration, source/drain junction depths and substrate voltage is studied. This subthreshold current model provides valuable information for strained-Si MOSFET design.展开更多
文摘Objective:To evaluate the efficacy and safety of the treatment of traumatic hemothorax by closed pleural drainage using a central venous catheter(CVC),compared with using a conventional chest tube.Methods:A prospective controlled study with the Ethics Committee approval was undertaken.A total of 407 patients with traumatic hemothorax were involved and they were randomly assigned to undergo closed pleural drainage with CVCs(n=214) or conventional chest tubes(n=193).The Seldinger technique was used for drainage by CVC,and the conventional technique for drainage by chest tube.If the residual volume of the hemothorax was less than 200 ml after the daily volume of drainage decreased to below 100 ml for two consecutive days,the treatment was considered successful.The correlative data of efficacy and safety between the two groups were analyzed using t or chi-squared tests with SPSS 13.0.A P value of less than 0.05 was taken as indicating statistical significance.Results:Compared with the chest tube group,the operation time,fraction of analgesic treatment,time of surgical wound healing,and infection rate of surgical wounds were significantly decreased(P<0.05) in the CVC group.There were no significant differences between the two groups in the success rate of treatment and the incidence of serious complications(P>0.05),or in the mean catheter/tube indwelling time and mean medical costs of patients treated successfully(P>0.05).Conclusions:Management of medium or large traumatic hemothoraxes by closed thoracic drainage using CVC is minimally invasive and as effective as using a conventional large-bore chest tube.Its complications can be prevented and it has the potential to replace the large-bore chest tube.
基金supported by the open fund of State Key Laboratory of Hydroscience and Engineer of Tsinghua University(No.sklhse-2013-E-02)the Special Major Project of Science and Technology of Zhejiang province(No.2013C 01139)
文摘Numerical simulations of the flow in the draft tube of a Francis turbine are carried out in order to elucidate the effects of tangential velocity on flow stability.Influence of the location of the maximum tangential velocity is explored considering the equality of the total energy at the inlet of the draft tube.It is found that the amplitude of the pressure fluctuation decreases when the location of the maximum of the tangential velocity moves from the centre to the wall on the cross section.Thus,the stability of the flow in the draft tube increases with the moving of the location of the maximum tangential velocity.However,the relative hydraulic loss increases and the recovery coefficient of the draft tube decreases slightly.
基金supported by the National Ministries and Commissions (Grant Nos.51308040203 and 6139801)the Fundamental Research Funds for the Central Universities (Grant Nos.72105499 and 72104089)the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No.2010JQ8008)
文摘An analytical model for the subthreshold current of a strained-Si metal-oxide-semiconductor field-effect transistor (MOSFET) is developed by solving the two-dimensional (2D) Poisson equation and the conventional drift-diffusion theory. Model verification is carried out using the 2D device simulator ISE. Good agreement is obtained between the model's calculations and the simulated results. By analyzing the model, the dependence of current on the strained-Si layer strain, doping concentration, source/drain junction depths and substrate voltage is studied. This subthreshold current model provides valuable information for strained-Si MOSFET design.
