The 'double' Michaelis-Menten equation: estimation of parameters

When the concentration dependence of an enzymic reaction or a transport process can be described by the sum of two Michaelis-Menten terms, reliable data that relate reaction rate and substrate concentration can be obtained even when as much as 70 per cent of substrate was consumed during the assay. Each data pair consists of the average reaction rate during an assay and the concentration where the instantaneous reaction rate was equal to the average rate. Although that concentration cannot be computed exactly (as it depends on the four kinetic parameters), it may be computed in a good approximation as if the reaction followed the simple Michaelis-Menten relationship. The relative error in the approximated concentration for 1 less than or equal to K2/K1 less than or equal to 10(5) and 10(-2) less than or equal to V2/V1 less than or equal to 10(2) did not exceed 5 per cent up to 50 per cent of substrate consumption, and did not exceed 10 per cent up to 70 per cent of substrate consumption.     

Determination of the point position for brachytherapy from the shift-projection method using the least squares method and geometrical solutions

We have derived formulas by the least squares method and six sets of geometrical solutions for calculating the position for brachytherapy from shift-projection images on one or two films. There are four types of expression for each coordinate in both methods, the shift-film technique with double exposures on a film and the stereo-shift technique with two films. Some geometrical solutions for the shift-film technique are equal to well-known conventional formulas. In the case of the stereo-shift technique, each conventional formula for the two coordinates is equal to the mean of the two geometrical solutions of each coordinate, and the one for the other coordinate is equal to one of the geometrical solutions. Formulas for the shift-film technique can be easily reduced to those for the stereo-shift technique. The error of the position calculated by the least squares method was the smallest among all the formulas for the shift-film technique in simulation.     

Appropriate method for the least squares analysis of categorical data.

Attempts to clarify some issues that have stemmed from J. E. Overall and D. K. Spiegel's (see record 1970-01534-001) article on least squares analysis, as well as from a number of subsequent articles. C. E. Werts and R. L. Linn (1971) provided a logical basis for selecting Method 3 from the Overall and Spiegel article. The present article outlines statistical as well as substantive arguments for the choice of Method 3. A variation of Method 3 is also suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

一种基于最小二乘支持向量机法的常见废弃塑料分类方法

将最小二乘支持向量机法(LS_SVM)应用于中红外光谱分析,建立一种新的对常见废弃塑料进行分类的方法.依据不同类别的塑料在红外波段具有不同的特征吸收峰,采用LS_SVM方法对塑料的中红外光谱数据进行处理,并与全局相关法、系统比较法进行比较.实验结果表明,LS_SVM进行分类的正确率为0.92.与全局相关法和系统比较法相比,LS_SVM分类正确率较高,其解决小样本问题效果显著,可应用于常见废弃塑料的分类.     

基于偏最小二乘回归模型的带钢热镀锌质量监控方法

提出了基于偏最小二乘回归模型的带钢热镀锌质量监控方法.以带钢热镀锌生产中带钢力学性能和锌层质量的质量监控为研究对象,用偏最小二乘方法建立了生产过程参数与质量结果之间的回归模型,对生产过程控制能力进行了分析,并给出了产品质量的预测方法.用鞍钢股份有限公司带钢热镀锌的实际生产数据进行验证.结果表明,偏最小二乘法比传统的多元线性回归方法具有更好的预测精度,基于偏最小二乘回归的锌层质量预测模型,其相对预测误差可达到5.93%.     

Quantitative analysis of gel electrophoretograms by image analysis and least squares modeling

A computer-aided quantitative method for a complex analysis of gel electrophoretograms is presented. The analysis consists of several steps: (i) determination of the background image by methods of mathematical morphology and its subtraction from the gel image, (ii) selection of an appropriate part of the gel lane including curved lanes and lanes with a nonuniform width, (iii) computation of the lane densitogram by averaging several lane-parallel scans, (iv) decomposition of the lane densitogram into component bands using a data selecting algorithm and Marquardt's minimizer. Several different functions for component bands are utilized. It is shown that the densitogram can be decomposed into component bands with reasonable accuracy only if an appropriate model function is chosen. The algorithms are tested on several different gel electrophoretograms which show typical features as a nonuniform background, curved lanes, an asymmetrical band shape and a superposition of small bands on the shoulders of big ones. It is shown that overlapped bands are best approximated by an asymmetrical Gausian curve and an asymmetrical Gauss-Cauchy function. Linear response to the serial dilution of the protein sample is tested.     

运用最小二乘法,建立AOD炉工艺参数及合金成分对还原期增氮影响的数学模型

在AOD炉中冶炼铬锰氮奥氏体不锈钢,通过对不同的冶炼控制工艺参数和不同的合金成分在实际生产中对还原期增氮后影响氮含量的不同情况,运用最小二乘法来进行数理统计分析,建立起符合本企业AOD炉冶炼该钢种的增氮工艺参数控制的数学模型.     

Determination of kinetic parameters for both reversible and irreversible first-order reactions

The paper reviews the main recent publications concerning infrared (IR) spectroscopy as applied to the study of lipid-protein interactions in model and cell membranes, lipoproteins, and related systems (e.g. lung surfactant). The review focuses mainly on transmission IR. Based on the available data, a number of general conclusions are presented on the perturbations caused by proteins on either the hydrocarbon chains, the polar headgroups or the interface region. Lipid-protein interactions in native cell membranes do not reveal significant differences from what is observed in semisynthetic model systems.     

偶氮荧光桃红催化动力学光度法测定痕量钌

在磷酸介质中, 痕量钌能灵敏地催化溴酸钾氧化偶氮荧光桃红褪色, 据此建立了一种测定痕量钌的新方法。通过实验, 确定了该催化褪色反应的最佳反应条件及动力学参数。于波长528nm处, 钌的质量浓度在3~10μg/L范围与催化反应和非催化反应的吸光度差有良好的线性关系, 线性相关系数等于0.9954, 方法的检出限为7.96×10^-8g/L。测得反应速率常数为3.30×10^-3/s, 表观活化能为193.72kJ/mol。干扰实验表明, 其他离子的允许量均在钌量的10倍以上。将本测定方法与蒸馏分离法相结合成功地测定了矿石和冶金产品中钌, 测定结果的相对标准偏差小于1.9%(n=6), 加标回收率在98.6%~104.0%之间。     

基于互信息特征筛选偏最小二乘的激光诱导击穿光谱铁矿浆定量分析

目前检测矿浆品位相对准确的方法是传统化学分析,但周期长、有滞后性,无法实现在线检测。实验利用激光诱导击穿光谱(Laser induced breakdown spectroscopy,LIBS)在线、原位、快速等优点,分析了铁矿选矿过程尾矿浆中铁元素的品位值。由于LIBS采集到的光谱数据中存在大量对成分分析无用的冗余信息,进而增加了建模复杂程度,导致建立的模型精确度不够、泛化能力不强。因此,在偏最小二乘(PLS)模型基础上,提出了基于互信息特征筛选的偏最小二乘模型。实验结果表明,与传统的PLS模型相比,基于互信息特征筛选的偏最小二乘模型在分析精度上得到了明显改善,测试样品的决定系数R²从0.52提高到0.90,测试样本的平均绝对误差(MAEP)从2.87%下降到1.38%,总样本的平均绝对误差(MAE)从1.0%下降到0.60%。     

Error estimates for results of nonstationary noise analysis derived with linear least squares methods

Nonstationary noise analysis of electrophysiological data is applied to the estimation of the single-channel current, i, and the number of active channels, N(C), whenever they cannot be determined directly due to limited resolution. Using least squares methods, the accuracy of estimating i and N(C) chiefly depends on the statistical error of the ensemble variance. It is shown that if the correlation among the binned data points is taken into account correctly, the variability of i and N(C) can be remarkably reduced and exact confidence limits of the parameters can be calculated. Least-squares methods are introduced which consider the measured error-covariance matrix of the binned variance in a model-independent fashion. Employing Monte Carlo methods, it is demonstrated that both the error predictions and the confidence limits are correct. The method is used to investigate the performance of nonstationary noise analysis at low channel open-probabilities. The application of the approach to simulated data as well as to experimental, i.e. non-ideal, data is discussed.     

基于DBN-LSSVM的热连轧带钢厚度预测

为提高热连轧带钢精轧厚度预测精度,建立了通过深度置信网络(deep belief network,简称DBN)提取特征的最小二乘支持向量机回归模型(DBN-LSSVM),并且利用粒子群优化算法(particle swarm optimization,简称PSO)优化最小二乘支持向量机(least squares support vector machine,简称LSSVM)相关超参数。通过采集某热连轧带钢生产线实时现场数据,对所提出厚度预测模型进行训练和离线仿真。结果表明,基于DBN-LSSVM的预测模型具有良好的学习能力和泛化性,DBN-LSSVM模型的预测精度较传统BP算法和DBN-BP算法有显著提高,该厚度预测模型在生产实践中具有很好的应用前景。     

偏最小二乘-神经网络光度法同时测定钢中钨和钼

在钨(钼)-2,4 二氯苯基荧光酮-CTMAB显色体系中,用偏最小二乘法(PLS)与神经网络(NN)联用辅助分光光度法,不经分离,同时测定合金钢中钨和钼。经比较,结果优于PLS法和BP神经网络法。     

Determination of kinetic parameters for devitrification of metallic glass — A theoretical approach

A new and useful theoretical approach has been proposed for calculating kinetic parameters like growth rate, diffusion constant and activation energy for crystallization of glassy alloy using classical homogeneous nucleation theory. This approach does not need any critical experiments.     

The least mean squares network with information coding: A model of cue learning.

Information coding, a method for coding variables in the least mean squares (LMSs) network, is proposed as an associative model of human cue learning. According to this model, participants in cue learning experiments assume the linear hypothesis and implement this hypothesis by updating their estimate of cue–target correlation on each trial. Because absence of a stimulus may give information about correlation, this model codes an absent stimulus as a nonzero value under some conditions. Thus, Information Coding differs from R. A. Rescorla and A. R. Wagner's (1972) model, a version of the LMSs network in which absence is always coded as 0. In 5 experiments, participants estimated the likelihood that a hypothetical patient had a disease given the patient's symptoms. The results support Information Coding, whereas the Rescorla-Wagner model, G. B. Chapman's (see record 1992-04135-001) variant of the Rescorla-Wagner model, and A. B. Markman's (see record 1990-09047-001) coding of the LMSs network all failed to account for at least one of these results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Determination of kinetic parameters using differential thermal analysis—Application to the decomposition of CaCO3

An analytical method has been developed to determine the kinetic parameters of a chemical reaction involving a substantial enthalpy change using differential thermal analysis (DTA). The theoretical treatment is based on fundamental equations considering the heat balance. The analytical derivation was simplified by carefully choosing the experimental conditions. The method was applied to the decomposition of CaCO₃ in argon gas. The activation energy of the decomposition of CaCO₃ evaluated using the present approach is in very good agreement with the result obtained from the thermogravimetric analyses (TGA) carried out simultaneously with the DTA measurements. The limitation of the technique includes maintaining the temperature rise of the sample small enough not to significantly affect temperature reading but large enough to ensure accurate measurement of the heat generation.     

阻抑动力学光度法测定痕量铜

研究了脂肪醇聚氧乙烯醚 (平平加 )存在下 ,铜阻抑Fe2 + 催化KIO3氧化罗丹明 4G褪色反应的新指示反应及测定条件 ,建立了动力学光度法测定痕量铜的新方法 ,此法检出限为 4.3× 10 - 1 0 gCu/mL ,线性范围 0～ 3.5 μgCu/2 5ml