Rstan包在四参数Logistic模型参数估计中的应用

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。

Emme和Stan在温州港集疏运项目规划决策中的联合应用

为从综合交通运输网络的整体和定量分析角度对港口集疏运系统进行研究,运用Emme和Stan相结合的方法,通过分析温州港集疏运系统、建造疏港铁路专线的经济和系统效益等问题,以区域综合运输系统优化为指导,建立基于广义费用的多货种、多方式的港口集疏运网络平衡优化模型,对温州状元岙港区集疏运网络系统进行优化.结果表明,该方法具有优越的适用性,可为政府的规划决策提供重要依据.

应用胎儿心电图STAN诊断产时胎儿缺氧

胎儿心电图 (fetalelectrocrdiogram ,FECG)的ST段分析 (STanalysis ,STAN)是利用计算机软件对FECG的T波抬高、ST段改变 (分Ⅰ、Ⅱ、Ⅲ级 )、T/QRS (T波和QRS波群高度之比 )进行自动分析。指导临床时需与胎心宫缩图 (cardiotocography ,CTG)联合应用 ,对于正常CTG无需进行STAN ;中间或异常CTG如STAN无异常应继续观察 ,如STAN异常 ,提示胎儿宫内缺氧 ,需临床干预 ;如终末期CTG ,不管STAN有无异常均应尽快结束分娩。联合应用CTG和STAN可降低胎儿酸中毒的发生率 。

紫色马铃薯花青素StAN1基因的克隆及功能分析

MYB是植物花青素合成代谢途径中最主要的转录因子。该研究以紫色马铃薯B-5为试验材料,通过同源克隆技术,克隆了马铃薯花青素StAN1基因,并对StAN1基因的表达、遗传转化及其转基因烟草的花青素含量进行分析。结果表明:(1)StAN1基因全长774bp,编码了258个氨基酸;系统进化树分析发现,StAN1与辣椒、茄子、芦竹的亲缘关系最近,与矮牵牛、苹果等的亲缘关系最远。(2)荧光定量PCR分析显示,StAN1基因在马铃薯不同组织均有表达,其表达量从小到大依次为:根<叶<茎<匍匐茎<薯皮<薯肉。(3)成功构建了表达载体pJAM1502-AN1,并经农杆菌(Gv3101)转化获得根、茎、叶片及叶脉均为紫红色的转StAN1基因烟草,PCR鉴定表明目的基因StAN1已成功转入烟草中。(4)花青素含量分析表明,野生型烟草叶片中花青素含量为2mg/g,叶片颜色为绿色,而转StAN1基因烟草叶片花青素含量达20mg/g,叶片颜色变成了紫红色。

China's High-technology Standards Development

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.

转彩色马铃薯StAN1基因的烟草幼苗耐旱性分析

该研究以转彩色马铃薯StAN1基因烟草为材料、野生型烟草(WT)为对照,测定分析转StAN1基因烟草在种子萌发期、幼苗期和苗期对干旱(甘露醇)处理的耐受情况,并对苗期旱热共同胁迫的耐受情况进行测定分析,以探讨彩色马铃薯StAN1基因的功能,为耐旱彩色马铃薯育种提供新路径。结果显示:(1)转StAN1基因烟草鉴定显示,阳性率为82.6%,且转基因烟草的叶片明显变紫,花青素含量极显著高于野生型烟草。(2)在培养基甘露醇浓度为150 mmol/L时,点播在培养基上的转基因烟草种子第5天时的萌发率达到了7%,是野生型烟草萌发率的2.3倍。(3)在甘露醇浓度为0和100 mmol/L的培养基上竖直培养时,转基因烟草的根长分别是野生型烟草的1.46和1.30倍,根长比野生型烟草显著增长。(4)在干旱胁迫下,转基因烟草幼苗叶片中的脯氨酸含量以及超氧化物歧化酶活性均显著高于野生型烟草,丙二醛含量均显著低于野生型烟草。(5)转基因烟草LEA基因和ERF基因在干旱和旱热处理中的相对表达量均高于野生型烟草。研究表明,StAN1基因在提高植物花青素含量的同时也提高了植物的耐旱性。

应用Stan软件包实现IRT模型的贝叶斯参数估计

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.

贝叶斯统计分析的新工具— Stan

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。

Floral extract of Tecoma stans:A potent inhibitor of gentamicin-induced nephrotoxicity in vivo

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(LD50】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.

VIDAS~实现致病菌的全自动检测——访生物梅里埃公司行业科学事务总监Stan Bailey

据统计,我国每年发生的由致病菌引起的食物中毒事件占食物中毒事件总数的30%-90%,中毒人数占食物中毒总人数的60%-90%。因此,致病菌的检测应引起我们足够的重视。食物中致病菌的种类很多,如沙门氏菌、李斯特菌、志贺氏菌、大肠杆菌O157:H7、蜡样芽孢杆菌、金黄色葡萄球菌等。但由于中西方饮食习惯的差异,检测重点有所不同。如中国饮食以米饭、蔬菜为主,而这类食品适合蜡样芽孢杆菌和金黄色葡萄球菌的生长,因此检测也以这两类致病菌为主。

临床实践中的STAN:哥德堡市2年定期应用的结果

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.

老年Stanford A型主动脉夹层患者一站式杂交手术临床效果观察

回顾性分析老年Stanford A型主动脉夹层一站式杂交手术78例患者的临床资料,结果显示Stanford A型主动脉夹层一站式杂交手术避免了深低温停循环,达到了升主动脉置换、全弓置换、象鼻支架置入术的近期效果,手术时间短,手术创伤小,近期效果好。

Cloning and characterization of a potato StAN11 gene involved in anthocyanin biosynthesis regulation

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.

中美民用航空器水上救援体系建设现状分析与探讨

航空应急管理体系是民航发展的生命线,而航空器水上救援体系建设则是航空应急管理体系的重要内容。本文从中美民用航空器水上救援体系建设现状出发,客观分析我国民用航空器水上救援体系在标准建设、应急处置、救援装备、专业培训等方面存在的问题。认为可以通过完善民航水上救援标准体系、构建区域部门救援协调机制、加大专项救援设备研发力度、建立国家综合信息保障平台、合理布局水上救援培训基地等途径,进一步完善我国民用航空器水上救援体系的建设和发展。

Cryptanalysis and improvement of a certificateless encryption scheme in the standard model

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.

《电子档案单套管理一般要求》的主要内容述评及相关问题思考

《电子档案单套管理一般要求》是为满足我国电子政务和档案法规发展的需求而制定的。本文分析了该标准的制定背景、主要内容,并讨论了其主要特点、理论意义与实践价值,进一步提出了《电子档案单套管理一般要求》如何适应信息技术发展,以及在档案信息技术国产化方面进一步改进的建议。

成果导向的高职课程规范建设与研究

以《冷冲压模具设计》课程规范建设为例,运用成果导向课程开发理念,以学生掌握的成果为导向,制定了课程预期学习成果,策划了课程实施策略,建立了匹配的评价标准和评价方法,以期为职业院校课程规范建设提供借鉴,为课程教学改革提供参考,提升技能人才培养质量。

浅谈常用家用净水器滤芯及其评价标准

近年来随着健康饮水知识的不断普及,人们对日常饮水的安全卫生程度愈发关注,因此家用净水器受到很大的欢迎。而净水滤芯作为净水器的核心部件,对净水器的净水效果起着至关重要的作用。文章梳理了常见的家用净水滤芯类型和评价指标,为净水器滤芯的评价选型提供依据。

Stan Lee

"Stan Lee was as extraordinary as the characters he created.A super hero in his own right to Marvel fans around the world,Stan had the power to inspire,to entertain,and to connect.The scale of his imagination was only exceeded by the size of his heart,"said Bob Iger,Chairman and CEO,The Walt Disney Company.

菌酶协同处理对棕榈仁粕营养价值的影响

试验旨在研究菌酶协同处理棕榈仁粕最佳工艺条件及肉鸡营养价值,为开发肉鸡非粮饲料原料提供参考。采用单因素试验设计研究甘露聚糖酶、纤维素酶和α-半乳糖苷酶单独添加对菌酶协同处理棕榈仁粕的影响。利用正交试验得到甘露聚糖酶、纤维素酶和α-半乳糖苷酶混合添加处理棕榈仁粕的最佳比例,制得菌酶协同处理棕榈仁粕;通过肉鸡饲养试验测定菌酶协同处理棕榈仁粕表观代谢能和氨基酸标准回肠消化率。结果表明:与未处理棕榈仁粕相比,菌酶协同处理棕榈仁粕粗蛋白含量增加15.10%,粗纤维和中性洗涤剂纤维含量分别下降25.10%和21.96%。处理后的棕榈仁粕肉鸡表观代谢能增加33.81%;有16种(88.9%)氨基酸标准回肠消化率显著增加(P>0.05),增加幅度为5.48%~148.28%,赖氨酸和精氨酸的标准回肠消化率有增加的趋势,但差异不显著(P<0.05)。综上,菌酶协同处理显著增加了棕榈仁粕的营养价值,对提高棕榈仁粕利用率、扩大我国饲料原料来源有重要意义。