Stan程序是一种用于估计统计模型的概率编程语言,Stan有命令行Shell的Cmdstan接口、Python的Pystan接口、R的Rstan接口、Matlab的Matlabstan接口,这些接口可以在Windows、MacOSX和Linux上运行,并且是开源许可的。R软件中Rstan软件包主...Stan程序是一种用于估计统计模型的概率编程语言,Stan有命令行Shell的Cmdstan接口、Python的Pystan接口、R的Rstan接口、Matlab的Matlabstan接口,这些接口可以在Windows、MacOSX和Linux上运行,并且是开源许可的。R软件中Rstan软件包主要采用MCMC(Markov chain Monte Carlo)算法,并用来估计四参数Logistic模型(4PLM)。Rstan的实现主要2种MCMC算法:HMC算法和The No-U-Turn采样器算法,计算效率要优于Gibbs抽样和Metropolis算法,不仅如此,这2种算法适用于任何先验分布。首先,介绍了四参数Logistic模型的定义(即在三参数Logistic模型的基础上增加一条小于1的上渐进线,称为失误参数);其次,介绍了Rstan实现的2种计算效率更高的MCMC算法,还介绍了如何使用Rstan包判断估计参数收敛的方法;最后,通过模拟试验验证了Rstan包在四参数Logistic模型参数估计的有效性及可行性。展开更多
There are several major technology standards, including audio video coding (AVS), automotive electronics, third generation(3G) mobile phones, mobile television, wireless networks and digital terrestrial television bro...There are several major technology standards, including audio video coding (AVS), automotive electronics, third generation(3G) mobile phones, mobile television, wireless networks and digital terrestrial television broadcasting, that have been released or are currently under development in China. This article offers a detailed analysis of each standard and studies their impact on China's high-technology industry.展开更多
Stan是一个新的用于估计指定统计模型的概率编程语言,它使用了强大而高效的汉密尔顿蒙特卡罗(Hamiltonian Monte Carlo,HMC)抽样算法,相比较传统的Gibbs抽样和Metropolis算法具有显著的效率提升.R软件包“rstan”链接了R与Stan 2个软件...Stan是一个新的用于估计指定统计模型的概率编程语言,它使用了强大而高效的汉密尔顿蒙特卡罗(Hamiltonian Monte Carlo,HMC)抽样算法,相比较传统的Gibbs抽样和Metropolis算法具有显著的效率提升.R软件包“rstan”链接了R与Stan 2个软件,使得Stan可以借助R的计算环境运行.首先,该文通过3参数Logistic(3PL)模型代码介绍了Stan的程序语言;其次,该文使用Stan计算2个评估模型-数据拟合的全新指标WAIC和LOO,为应用Stan进行IRT模型相关研究提供了有效的参考工具;最后,该文还采用了2个真实数据分别考察了Stan在单维IRT模型和多维IRT模型参数估计中的运行表现.研究结果表明:采用一个新的贝叶斯统计软件Stan,通过2个实证研究验证了该方法的有效性与可行性,为国内学者应用Stan进行IRT模型相关研究提供了有效的参考资料.展开更多
目的鉴于国内研究者熟悉的贝叶斯统计软件WinBUGS已停止更新,OpenBUGS已见介绍,本文介绍国外新近出现的贝叶斯统计软件Stan的基本原理与实际使用。方法由于Stan安装具有其自身特点且较为复杂,本文首先介绍Windows平台下Stan安装与使用方...目的鉴于国内研究者熟悉的贝叶斯统计软件WinBUGS已停止更新,OpenBUGS已见介绍,本文介绍国外新近出现的贝叶斯统计软件Stan的基本原理与实际使用。方法由于Stan安装具有其自身特点且较为复杂,本文首先介绍Windows平台下Stan安装与使用方法,接着介绍Stan语言及运行步骤,最后以线性-正态层次模型为例介绍Stan的应用。结果 Stan作为一种新型贝叶斯统计软件,使用了全新的汉密尔顿蒙托卡罗(Hamiltonian Monte Carlo,HMC)抽样方法,可以处理GIBBS抽样难以收敛的复杂多元层次模型。Stan使用的概率模型定义语言,相比较BUGS,逻辑清晰,程序更易理解。结论 Stan功能强大,应用方便,是贝叶斯分析的有力工具。展开更多
Objective:To highlight the nephroprotective activity of ethyl acetate extract of dried flowers of Tecomu stans for its protective effects on genlamicin-induced nephrotoxicity in albino rats. Methods:For studying acute...Objective:To highlight the nephroprotective activity of ethyl acetate extract of dried flowers of Tecomu stans for its protective effects on genlamicin-induced nephrotoxicity in albino rats. Methods:For studying acute toxicity study,single oral dose of 5（KM） mg ethyl acetate floral extract/kg hodv weight was administered to albino rats（five females,five males）.Nephrotoxicity was induced in albino rats by intraperitoneal administration of gentamicin 80 mg/kg/day for eight days.Effect of concurrent administration of ethyl acetate floral extract of Tecoma stans at a dose of 100.200 and 300 mg/kg/day given by oral mute was determined using serum creatinine,serum uric acid,blood urea nitrogen and serum urea as indicators of kidney damage.The study groups contained six rats in each group.As nephrotoxicity of gentamicin is known to involve induction of oxidative stress,in vitro antioxidant aclivity and free radical-scavenging activity of this extract was also evaluated.Results:For acute toxicity testing both female and male rats administered with the extract at a dose of 5 000 mg/kg.The results showed no toxicity in terms of general behavior change,mortality,or change in gross appearance of internal organs(LD<sub>50</sub>】5 000 mg/kg). It was observed that the ethyl acetate floral extract of Tecoma stans significantly protected rat kidneys from gentamicin-induced histopathological changes.Gentamicin-induced glomerular congestion,peritubular and blood vessel congestion,epithelial desquamation,accumulation ol inflamnialoiy cells and necrosis of the kidney cells were found to be reduced in the groups receiving the ethyl acetate floral extract of Tecoma starts along with gentamicin in a dose dependent manner.The floral extract also reduced the gentamicin-induced increase in serum creatinine,serum uric acid,blood urea nitrogen and serum urea levels（P】0.01）.Conclusions: The present study indicates a verv important role of reactive oxygen species（BOS） and the relation to renal dysfunction and point to the therapeutic potential of Tecoma stans in gentamicin induced nephrotoxicity.展开更多
Objective: The purpose of this study was to monitor the introduction of the STAN-methodology(Noventa Medical, Moelndal, Sweden). Study design: This was a prospective observational study covering the total population o...Objective: The purpose of this study was to monitor the introduction of the STAN-methodology(Noventa Medical, Moelndal, Sweden). Study design: This was a prospective observational study covering the total population of deliveries at term during 2 years. Four thousand eight hundred and thirty out of 14,687 term pregnancies were monitored using the STAN S 21 fetal heart monitor and the associated clinical guidelines. Cord artery metabolic acidosis, neonatal outcome, and rates of operative deliveries for fetal distress were assessed. Results: The annual rate of STAN usage increased from 28.1%to 37.7%and was associated with a significant reduction in metabolic acidosis rate in the total population from 0.76%to 0.44%(P < .05). The compliance with the clinical guidelines increased in cases requiring intervention. The rates for moderate/severe hypoxic neonatal encephalopathy were consistently low, 0.55 and 0.68 per 1000 deliveries, respectively, and corresponding to previous findings. The rate of operative delivery did not change during the 2 years in the total population. Conclusion: Increasing STAN usage provided consistent improvements in fetal outcome equalling those noted in the Swedish randomized controlled trial(RCT) without increasing operative interventions for fetal distress.展开更多
Anthocyanins are a class of products of plant secondary metabolism and are responsible for tubers color in potato. The biosynthesis of anthocyanins is a complex biological process, in which multiple genes are involved...Anthocyanins are a class of products of plant secondary metabolism and are responsible for tubers color in potato. The biosynthesis of anthocyanins is a complex biological process, in which multiple genes are involved including structural genes and regulatory genes. In this study, StAN11, a WD4o-repeat gene, was cloned from potato cultivar Chieftain （Solanum tuberosum L.）. StAN11 （HQ5995o6） contained no intron and its open reading frame （ORF） was 1,o29 bp long, encoding a putative protein of 342 amino acids. In order to verify its role in anthocyanin biosynthesis, StAN11 was inserted behind the CaMV-35S promoter of pCMBIA1304 and the recombination vector was introduced into the potato cultivar Desiree plants by Agrobacterium-mediated transfor- mation. The color of transgenic tuber skin was significantly deepened, compared to the wild-type control, which was highly consistent with the accumulation of anthocyanin and expression of StAN11 in transgenic lines tuber skin. Further analysis on the expression of Flavonone-3-hydroxylase （F3H）,Dihydroflavonol reductase （DFR）, Anthocyanidin synthase （ANS）, and F1avonoid 3-O-glucosyl transferase （3GT） in transgenic plants revealed that only DFR was upregulated. This result suggested that StAN11 regulated anthocyanin biosynthesis in potato by controlling DFR expression and accumulation of anthocyanin could be increased through overexpression of .StAN11 in the tubers with the genetic background of anthocyanin biosynthesis.展开更多
Certificateless public key cryptography elimi- nates inherent key escrow problem in identity-based cryptog- raphy, and does not yet requires certificates as in the tradi- tional public key infrastructure. In this pape...Certificateless public key cryptography elimi- nates inherent key escrow problem in identity-based cryptog- raphy, and does not yet requires certificates as in the tradi- tional public key infrastructure. In this paper, we give crypt- analysis to Hwang et al.＇s certificateless encryption scheme which is the first concrete certificateless encryption scheme that can be proved to be secure against ＂malicious-but- passive＂ key generation center （KGC） attack in the stan- dard model. Their scheme is proved to be insecure even in a weaker security model called ＂honest-but-curious＂ KGC at- tack model. We then propose an improved scheme which is really secure against ＂malicious-but-passive＂ KGC attack in the standard model.展开更多
文摘Stan程序是一种用于估计统计模型的概率编程语言,Stan有命令行Shell的Cmdstan接口、Python的Pystan接口、R的Rstan接口、Matlab的Matlabstan接口,这些接口可以在Windows、MacOSX和Linux上运行,并且是开源许可的。R软件中Rstan软件包主要采用MCMC(Markov chain Monte Carlo)算法,并用来估计四参数Logistic模型(4PLM)。Rstan的实现主要2种MCMC算法:HMC算法和The No-U-Turn采样器算法,计算效率要优于Gibbs抽样和Metropolis算法,不仅如此,这2种算法适用于任何先验分布。首先,介绍了四参数Logistic模型的定义(即在三参数Logistic模型的基础上增加一条小于1的上渐进线,称为失误参数);其次,介绍了Rstan实现的2种计算效率更高的MCMC算法,还介绍了如何使用Rstan包判断估计参数收敛的方法;最后,通过模拟试验验证了Rstan包在四参数Logistic模型参数估计的有效性及可行性。
文摘There are several major technology standards, including audio video coding (AVS), automotive electronics, third generation(3G) mobile phones, mobile television, wireless networks and digital terrestrial television broadcasting, that have been released or are currently under development in China. This article offers a detailed analysis of each standard and studies their impact on China's high-technology industry.
文摘Stan是一个新的用于估计指定统计模型的概率编程语言,它使用了强大而高效的汉密尔顿蒙特卡罗(Hamiltonian Monte Carlo,HMC)抽样算法,相比较传统的Gibbs抽样和Metropolis算法具有显著的效率提升.R软件包“rstan”链接了R与Stan 2个软件,使得Stan可以借助R的计算环境运行.首先,该文通过3参数Logistic(3PL)模型代码介绍了Stan的程序语言;其次,该文使用Stan计算2个评估模型-数据拟合的全新指标WAIC和LOO,为应用Stan进行IRT模型相关研究提供了有效的参考工具;最后,该文还采用了2个真实数据分别考察了Stan在单维IRT模型和多维IRT模型参数估计中的运行表现.研究结果表明:采用一个新的贝叶斯统计软件Stan,通过2个实证研究验证了该方法的有效性与可行性,为国内学者应用Stan进行IRT模型相关研究提供了有效的参考资料.
文摘目的鉴于国内研究者熟悉的贝叶斯统计软件WinBUGS已停止更新,OpenBUGS已见介绍,本文介绍国外新近出现的贝叶斯统计软件Stan的基本原理与实际使用。方法由于Stan安装具有其自身特点且较为复杂,本文首先介绍Windows平台下Stan安装与使用方法,接着介绍Stan语言及运行步骤,最后以线性-正态层次模型为例介绍Stan的应用。结果 Stan作为一种新型贝叶斯统计软件,使用了全新的汉密尔顿蒙托卡罗(Hamiltonian Monte Carlo,HMC)抽样方法,可以处理GIBBS抽样难以收敛的复杂多元层次模型。Stan使用的概率模型定义语言,相比较BUGS,逻辑清晰,程序更易理解。结论 Stan功能强大,应用方便,是贝叶斯分析的有力工具。
基金supported by Chairman,Mother Mary education Society,Vikas nagar,Hyderabad,Andhra Pradesh,India
文摘Objective:To highlight the nephroprotective activity of ethyl acetate extract of dried flowers of Tecomu stans for its protective effects on genlamicin-induced nephrotoxicity in albino rats. Methods:For studying acute toxicity study,single oral dose of 5（KM） mg ethyl acetate floral extract/kg hodv weight was administered to albino rats（five females,five males）.Nephrotoxicity was induced in albino rats by intraperitoneal administration of gentamicin 80 mg/kg/day for eight days.Effect of concurrent administration of ethyl acetate floral extract of Tecoma stans at a dose of 100.200 and 300 mg/kg/day given by oral mute was determined using serum creatinine,serum uric acid,blood urea nitrogen and serum urea as indicators of kidney damage.The study groups contained six rats in each group.As nephrotoxicity of gentamicin is known to involve induction of oxidative stress,in vitro antioxidant aclivity and free radical-scavenging activity of this extract was also evaluated.Results:For acute toxicity testing both female and male rats administered with the extract at a dose of 5 000 mg/kg.The results showed no toxicity in terms of general behavior change,mortality,or change in gross appearance of internal organs(LD<sub>50</sub>】5 000 mg/kg). It was observed that the ethyl acetate floral extract of Tecoma stans significantly protected rat kidneys from gentamicin-induced histopathological changes.Gentamicin-induced glomerular congestion,peritubular and blood vessel congestion,epithelial desquamation,accumulation ol inflamnialoiy cells and necrosis of the kidney cells were found to be reduced in the groups receiving the ethyl acetate floral extract of Tecoma starts along with gentamicin in a dose dependent manner.The floral extract also reduced the gentamicin-induced increase in serum creatinine,serum uric acid,blood urea nitrogen and serum urea levels（P】0.01）.Conclusions: The present study indicates a verv important role of reactive oxygen species（BOS） and the relation to renal dysfunction and point to the therapeutic potential of Tecoma stans in gentamicin induced nephrotoxicity.
文摘Objective: The purpose of this study was to monitor the introduction of the STAN-methodology(Noventa Medical, Moelndal, Sweden). Study design: This was a prospective observational study covering the total population of deliveries at term during 2 years. Four thousand eight hundred and thirty out of 14,687 term pregnancies were monitored using the STAN S 21 fetal heart monitor and the associated clinical guidelines. Cord artery metabolic acidosis, neonatal outcome, and rates of operative deliveries for fetal distress were assessed. Results: The annual rate of STAN usage increased from 28.1%to 37.7%and was associated with a significant reduction in metabolic acidosis rate in the total population from 0.76%to 0.44%(P < .05). The compliance with the clinical guidelines increased in cases requiring intervention. The rates for moderate/severe hypoxic neonatal encephalopathy were consistently low, 0.55 and 0.68 per 1000 deliveries, respectively, and corresponding to previous findings. The rate of operative delivery did not change during the 2 years in the total population. Conclusion: Increasing STAN usage provided consistent improvements in fetal outcome equalling those noted in the Swedish randomized controlled trial(RCT) without increasing operative interventions for fetal distress.
基金supported financially by grants from the Jiangsu Agricultural Science and Technology Innovation Fund (cx (11)1020)National Natural Science Foundation of China (11171155)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions: Modern horticultural science (PAPD)
文摘Anthocyanins are a class of products of plant secondary metabolism and are responsible for tubers color in potato. The biosynthesis of anthocyanins is a complex biological process, in which multiple genes are involved including structural genes and regulatory genes. In this study, StAN11, a WD4o-repeat gene, was cloned from potato cultivar Chieftain （Solanum tuberosum L.）. StAN11 （HQ5995o6） contained no intron and its open reading frame （ORF） was 1,o29 bp long, encoding a putative protein of 342 amino acids. In order to verify its role in anthocyanin biosynthesis, StAN11 was inserted behind the CaMV-35S promoter of pCMBIA1304 and the recombination vector was introduced into the potato cultivar Desiree plants by Agrobacterium-mediated transfor- mation. The color of transgenic tuber skin was significantly deepened, compared to the wild-type control, which was highly consistent with the accumulation of anthocyanin and expression of StAN11 in transgenic lines tuber skin. Further analysis on the expression of Flavonone-3-hydroxylase （F3H）,Dihydroflavonol reductase （DFR）, Anthocyanidin synthase （ANS）, and F1avonoid 3-O-glucosyl transferase （3GT） in transgenic plants revealed that only DFR was upregulated. This result suggested that StAN11 regulated anthocyanin biosynthesis in potato by controlling DFR expression and accumulation of anthocyanin could be increased through overexpression of .StAN11 in the tubers with the genetic background of anthocyanin biosynthesis.
文摘Certificateless public key cryptography elimi- nates inherent key escrow problem in identity-based cryptog- raphy, and does not yet requires certificates as in the tradi- tional public key infrastructure. In this paper, we give crypt- analysis to Hwang et al.＇s certificateless encryption scheme which is the first concrete certificateless encryption scheme that can be proved to be secure against ＂malicious-but- passive＂ key generation center （KGC） attack in the stan- dard model. Their scheme is proved to be insecure even in a weaker security model called ＂honest-but-curious＂ KGC at- tack model. We then propose an improved scheme which is really secure against ＂malicious-but-passive＂ KGC attack in the standard model.
