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991.
Jani Anttila 《Physics letters. A》2011,375(43):3755-3761
A course of a game is formulated as a physical process that will consume free energy in the least time. Accordingly, the rate of entropy increase is the payoff function that will subsume all forms of free energy that motivate diverse decisions. Also other concepts of game theory are related to their profound physical counterparts. When the physical portrayal of behavior is mathematically analyzed, the course of a game is found to be inherently unpredictable because each move affects motives in the future. Despite the non-holonomic character of the natural process, the objective of consuming free energy in the least time will direct an extensive-form game toward a Lyapunov-stable point that satisfies the minimax theorem. 相似文献
992.
Yan H Han BX Wu QY Jiang MZ Gui ZZ 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(1):179-184
We have investigated surface-enhanced Raman spectroscopy (SERS) spectrum of Omethoate (O,O-dimethyl-S-methylcarbamoylmethylthiophosphate). It is found significant signals in the ordinary Raman spectrum for solid-state Omethoate as well as strong vibrational signals absorbed on the silver sol surface which is prepared by γ-irradiation technique at a very low concentration. Effects of pH and anions (Cl-, Br-, I-) on the adsorption orientation are investigated as well. Two different adsorption mechanisms are deduced, depending on the experimental conditions. The sulfur atom or the sulfur and two oxygen atoms are adsorbed onto the silver sol surface. Among halide ions, Br- and I- are more strongly adsorbed onto the silver sol surface. As a result, the adsorption of Omethoate is less effective due to their steric hindrance. 相似文献
993.
Pietro Franceschi Domenico Masuero Urska Vrhovsek Fulvio Mattivi Ron Wehrens 《Journal of Chemometrics》2012,26(1-2):16-24
The development and the validation of innovative approaches for biomarker selection are of paramount importance in many ‐omics technologies. Unfortunately, the actual testing of new methods on real data is difficult, because in real data sets, one can never be sure about the “true” biomarkers. In this paper, we present a publicly available metabolomic ultra performance liquid chromatography–mass spectrometry spike‐in data set for apples. The data set consists of 10 control samples and three spiked sets of the same size, where naturally occurring compounds are added in different concentrations. In this sense, the data set can serve as a test bed to assess the performance of new algorithms and compare them with previously published results. We illustrate some of the possibilities provided by this spike‐in data set by comparing the performance of two popular biomarker‐selection methods, the univariate t‐test and the multivariate variable importance in projection. To promote a widespread use of the data, raw data files as well as preprocessed peak lists are made available. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
994.
Christopher R. Anderton Bita Vaezian Kaiyan Lou Jessica F. Frisz Mary L. Kraft 《Surface and interface analysis : SIA》2012,44(3):322-333
Principal component analysis (PCA) of time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) data enables differentiating structurally similar molecules according to linear combinations of multiple peaks in their spectra. However, in order to use PCA to correctly identify variations in lipid composition between samples, the discrimination achieved must be based on chemical differences that are related to the lipid species, and not sample‐associated contamination. Here, we identify the positive‐ion TOF‐SIMS peaks that are related to phosphatidylcholine lipid headgroups and tail groups by PCA of spectra acquired from lipid isotopologs. We demonstrate that restricting PCA to a contaminant‐free lipid‐related peak set reduces the variability in the spectra acquired from lipid samples that is due to contaminants, which enhanced differentiating different lipid standards, but adversely affected the contrast in PC scores images of phase‐separated lipid membranes. We also show that PCA of a restricted data set consisting of the peaks related to lipids and amino acids increases the likelihood that the discrimination of TOF‐SIMS data acquired from intact cells is based on differences in the lipids and proteins on the cell surface, and not sample‐specific contamination without compromising sample discrimination. We expect that the lipid‐related peak database established herein will facilitate interpreting the TOF‐SIMS data and PCA results from studies of both model and cellular membranes, and enhance identifying the origins of the peaks that contribute to discriminating different types of cells. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
995.
Biomarker selection through the metabolomics approach involves the acquisition of nontargeted metabolic profiles. In this study, some critical factors that may affect this process were investigated using urine test samples and a UPLC‐TOF system. Repeated injections of a single sample demonstrated that the percentage of undetected and poorly repeatable measurements (intensity RSD > 15%) decreased from 22.5 to 5.8% and from 32.9 to 14.7%, respectively, as the scan time was increased up to 0.6 s (approximately 11 data points per peak). An additional critical factor was identified in the presence of broad concentration differences between the samples; the application of a dilution scheme that minimized these differences reduced the number of missing values in the final datasets by 36%. The impact of missing values was further investigated in the study of two groups of samples produced by using a spike as artificial marker. Missing values weakened the models used for the interpretation of the metabolic profiles, and greatly hindered the identification of possible markers. Finally, a simple strategy for an effective analysis of urine samples was outlined; it proved to limit the need for the post‐acquisition elaboration of the data. The same strategy can easily be adapted to other matrices. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
996.
《Analytical letters》2012,45(9):661-672
Abstract A first step towards developing a calculation method, predicting the analytical method suitable to solve a distinct analytical problem, is described. With pattern recognition, a binary decision maker is calculated, deciding the analytical method from two alternatives, w-vie spectrometry and atomic absorption spectrometry. This procedure yielded a 85% predicting accuracy. 相似文献
997.
《Analytical letters》2012,45(6):1187-1202
ABSTRACT A multicomponent spectrophotometric methodology for the simultaneous determination of Co2+, Cu2+, Mn2+, Ni2+ and Zn2+ in aqueous solution is reported, using (4-(pyridil-2-azo) resorcinol), a diode array spectrophotometer and multivariate calibration by partial least-squares and principal component regerssions. Spectra are recorded in the UV region. The 225 – 320 nm range is selected as optimal, through a criterion based on tederivatives of the differences between individual spectra, which compares favorably with a genetic algorithm. The methodology is applied to the simultaneous determination of the five than 1.5 mgL?1. The best result are obtanied at pH 9.0, with average absolute errors of prediction lower than 0.09 mgL?1 相似文献
998.
Fernanda Vera Cruz de Vasconcelos Paulo Fernandes Barbosa de Souza Jr. Maria Fernanda Pimentel Márcio José Coelho Pontes Claudete Fernandes Pereira 《Analytica chimica acta》2012
This work evaluates the use of near-infrared (NIR) overtone regions to determine biodiesel content, as well potential adulteration with vegetable oil, in diesel/biodiesel blends. For this purpose, NIR spectra (12,000–6300 cm−1) were obtained using three different optical path lengths: 10 mm, 20 mm and 50 mm. Two strategies of regression with variable selection were evaluated: partial least squares (PLS) with significant regression coefficients selected by Jack-Knife algorithm (PLS/JK) and multiple linear regression (MLR) with wavenumber selection by successive projections algorithm (MLR/SPA). For comparison, the results obtained by using PLS full-spectrum models are also presented. In addition, the performance of models using NIR (1.0 mm optical path length, 9000–4000 cm−1) and MIR (UATR – universal attenuated total reflectance, 4000–650 cm−1) spectral regions was also investigated. The results demonstrated the potential of overtone regions with MLR/SPA regression strategy to determine biodiesel content in diesel/biodiesel blends, considering the possible presence of raw oil as a contaminant. This strategy is simple, fast and uses a fewer number of spectral variables. Considering this, the overtone regions can be useful to develop low cost instruments for quality control of diesel/biodiesel blends, considering the lower cost of optical components for this spectral region. 相似文献
999.
1000.
为实现山楂叶产地的快速判别,提出一种基于稀疏主成分分析特征选择(SPCAFS)与支持向量机(SVM)建模的定性分析方法。采用近红外积分球漫反射光谱法采集6个产地共41批山楂叶123份样品的近红外光谱图,经数据预处理后,通过SPCAFS对代表性特征波段进行选择,并采用SVM建立山楂叶近红外产地判别模型。模型与连续投影(SPA),正则化自表示(RSR)和稀疏子空间聚类(SSC)3种特征选择算法进行对比,以准确率、精确度和灵敏度作为评价标准,评估所提模型的预测性能。结果显示,SPCAFS的特征波段数相比于全波长建模从1 500减少到21,预测结果的准确率和精确度分别从78%、76%提升至97%、100%。同时,相比于SPA、RSR、SSC算法,准确率分别提升了6%、3%、3%,精确度分别提升了13%、10%、5%,模型的预测能力得到显著提升,基于SPCAFS的SVM判别模型可实现山楂叶南北产地的快速判别。 相似文献