Aim: To compare their prediction performance of BP neural network model and Cox proportion hazard model in survival analysis and to explore the superiority of BP neural network model in survival analysis. Methods: Monte Carlo was used to generate the data sets under the condition of different sample size,different degree of censoring,number of variable and interactions,non-linear effect,distinct distribution of covariate and proportional vs non-proportional hazard.Then BP neural network model and Cox model were built,and their prediction performance was compared using concord-ance index C. Results: In the research on simulation data sets,when the sample size of 100,proportion of censoring of60%,80%,and sample size of 300,proportion of censoring of 80%,BP neural network model performed superior to Cox model( P 0. 05). And when the covariates don' t meet PH assumption and had three-way interaction,non-linear effect,BP neural network performed superior to Cox model( P 0. 05). In the real data,BP neural network model's concordance index was 0. 835,which performed superior to Cox model( tpaired= 4. 311,P 0. 001). Conclusion: For the small sample size,high and the covariates don't meet PH assumption and has three-way interaction,non-linear effect data sets,BP neural network has better advantage than Cox model. It is worth to popularize further in survival analysis.
The research on lab continuous caster system is little currently. A three-dimensional model constructions and motion simulations are carried out for crystallizer,secondary cooling area and transimission mechanism of lab continuous caster system by SolidWorks software and its pluggable unit COSMOSmotion respectively. The model diagram,relevant blast diagram of crystallizer assembly and secondary cooling area assembly are obtained. The curves of force,angle displacement and moment changed with time during the motion simulation of gear transimission mechanism assembly,and the curves of barycenter acceleration,force and level move momentum changed with time during the motion simulation of cam transimission mechanism assembly are also obtained. The finite element analysis is carried out for slip shaft part by the simulation pluggable unit of SolidWorks software. The stress and displacement of slip shaft part are obtained. The research provides important references for the design and use of lab continuous caster system.
Poly-( N-vinyl-2-pyrrolidone)( PVP)-protected Pt /Ni /Fe trimetallic nanoparticles( TNPs) were prepared using a chemical co-reduction method. The obtained TNPs were characterized by transmission electron microscopy( TEM). The effects of metal compositions on the hydrolysis reaction of the alkaline NaBH4 solution were studied. The results indicated that the prepared Pt /Ni /Fe TNPs had an average size of 2 nm.The activities of TNPs were much higher than that of Fe,Ni and Pt monometallic nanoparticles( MNPs) and Ni /Fe,Pt /Fe and Pt /Ni bimetallic nanoparticles( BNPs). Among all the synthesized MNPs,BNPs and TNPs,Pt /Ni /Fe TNPs with molar ratio of 10∶ 78. 75∶ 11. 25 displayed the highest catalytic activity,showing a high hydrogen release rate of 63. 920 × 103molH2/(molPt·h) at 30 ℃. The corresponding apparent activation energy for the hydrolysis reaction of the alkaine NaBH4 solution over the Pt10Ni87. 75Fe1 1. 25 TNP is about 52 kJ /mol. In addition,the prepared Pt /Ni /Fe TNPs had a good catalytic stability,which kept a high activity even after 10-run catalytic evaluation.
Objective To investigate the effect of sepsis bundles in the management of septic shock through clinical pathway.Methods Fifty patients with septic shock admitted into ICU from emergency room during February 1,2009 to February 28,2010 were enrolled as the clinical pathway group,which were treated by 6-hour and 24-hour bundle treatment.47 patients with matched disease history admitted from January 1,2008 to January 31,2009 were enrolled as the control group.Results ① In 6-hour bundle treatment,statistically significant difference was found in diagnosis time,serum lactate measured,blood culture,antibiotics administration within 1 hour,central catheter inserted within 2 hours,vasopressors received and EGDT achieved within 6 hours between the two groups.② In 24-hour bundle treatment,statistically significant differences was found in low-dose steroids received,blood glucose control and lung-prtective ventilation strategy administered between the two groups.③ No statistically significant difference was found in the ventilation time and the days in ICU between the two groups(P0.05).As compared with the control group,a 22% absolute mortality reduction was found in the clinical pathway group(22% vs 44%,P=0.030).Conclusion Implementation of sepsis bundles through clinical pathway not only improves the compliance of SSC guidelines,but also reduce the mortality of patients with septic shock.
There are many problems in current endowment service system confronting unique population aging trend.Based on the experience of developed countries,the social endowment service system construction in the future should be highlighting the responsibility of individuals,society and government in the responsibility level;meanwhile it should attach importance to the legislative authority,completeness and scientific in the legislative level;furthermore,it should also establish service types,service items and service mode as one of the multilayer composite system in the content level.
Briefly introduces the basic principles for AT post differential current protection of traction power supply system in Shijiazhuang-Taiyuan passenger dedicated lines.Explains in details the normal load current,exciting surge current,short circuit current distribution and degrees of influence when the contact switches of AT post for up and down lines are in closed loop or open loop status.Analyzes the miss operation status of AT post differential current protection,puts forward the causes of differential current protection miss operation.By means of theoretical analysis and real test,introduces the setting principles,setting method and calculation formula that shall be taken for AT post differential current protection,and re-illustrates the reliability of the new setting values.Thus puts forward the suggestions on perfection of AT post differential current protection wiring and adding associated relay protection.
Objective To preliminarily analyze the histologic changes and mechanical characters after reconstruction of posterior cruciate ligament (PCL) using bone-1/3 patellar tenden-bone (B-PT-B) and bone-Achilles tendon allografts. Methods Twenty-five adult sheep were divided into three groups, ie, Group A (five sheep, materials harvesting group), Group B and Group C (10 sheep respectively, both as experimental groups). PCL reconstruction using fresh frozen B-PT-B and bone-Achilles tendon allografts was carried out in both Groups B and C. Histologic changes and mechanical characters were primarily assessed one and six months after PCL reconstruction by means of morphology and biomechanics. Results Routine histologic staining showed that the reconstructed PCL six months later was similar to the normal PCL in aspects of the structure and the mechanical characters. The biomechanical test proved that the tension of PCL reconstructed by bone-Achilles tendon allograft obtained similar mechanical characters and was stronger than that by B-PT-B allograft. Conclusion Bone-Achilles tendon allograft is more applicable clinically than B-PT-B allograft in PCL reconstruction.
T To counter with the existing phenomenon of differential relay miss operation of main transformer after putting into operation of Beijing-Zhengzhou electrified railway, it analyzes both in theory and test the causes of differential relay miss operation when LCD-14 type relay is under the over-zone tripping and circuit switching operation and the causes of non-tripping of main circuit breaker when differential relay is under the miss operation status, it raises the resolution plan for protection of differential relay miss operation of substation.
