Data analysis techniques

An additional feature of ELECTRAS is a module which provides an introduction to various data analysis techniques One part of this module provides a typical work flow for data analysis. It explains the important steps when conducting a data analysis and describes the output of the data analysis methods. The second part gives a description of the methods offered. This modvJe can be used both as a guideline for novice users and as a reference for experts. 

Modern instruments capable of obtaining excitation-emission matrices (EEMs) allow use of new data-analysis techniques to resolve overlapped spectra. Resolution techniques such as the ratio method (28) and others (29,30) may provide further differentiation of the components present in the phases separated by solvent extraction. 

Cyclodextrin-modified solvent extraction has been used to extract several PAHs from ether to an aqueous phase. Data evaluation shows that the degree of extraction is related to the size of the potential guest molecule and that the method successfully separates simple binary mixtures in which one component does not complex strongly with CDx. The most useful application of cyclodextrin-modified solvent extraction is for the simplification of complex mixtures. The combined use of CDx modifier and data-analysis techniques may simplify the qualitative analysis of PAH mixtures. 

Data Interpretation extends data analysis techniques to label assignment and considers both integrated approaches to feature extraction and feature mapping and approaches with explicit and separable extraction and mapping steps. The approaches in this section focus on those that form numeric-symbolic interpreters to map from numeric data to specific labels of interest. 

Jones, J. J. Stump, M. J. Fleming, R. C. Lay, J. O. Wilkins, C. L. Strategies and data analysis techniques for lipid and phospholipid chemistry elucidation by intact cell MALDI-FTMS. /. Am. Soc. Mass Spectrom. 2004,15,1665-1674. 

A general comment that affects all statistical multivariate data analysis techniques, namely that each of the variables should be given equal chance to influence the outcome of the analysis. This can be achieved by scaling the variables in appropriative way. One popular method for scaling variables is autoscaling, whereby the variance of each variable is adjusted to 1. 

The objective of this research was to examine the effect of crystallinity, additives and data analysis technique on isothermally pyrolyzed cellulose. The Ea, activation enthalpy (AH+) and activation entropy (AS+) were determined from the mass loss rates. This data was used to develop an understanding of how cellulose pyrolysis is affected by crystallinity and additives and how the results obtained are dependent on the data analysis technique. 

The rotational relaxation of DNA from 1 to 150 ns is due mainly to Brownian torsional (twisting) deformations of the elastic filament. Partial relaxation of the FPA on a 30-ns time scale was observed and qualitatively attributed to torsional deformations already in 1970.(15) However, our quantitative understanding of DNA motions in the 0- to 150-ns time range has come from more accurate time-resolved measurements of the FPA in conjunction with new theory and has developed entirely since 1979. In that year, the first theoretical treatments of FPA relaxation by spontaneous torsional deformations appeared. 16 171 and the first commercial synch-pump dye laser systems were delivered. Experimental confirmation of the predicted FPA decay function and determination of the torsional rigidity of DNA were first reported in 1980.(18) Other labs 19 21" subsequently reported similar results, although their anisotropy formulas were not entirely correct, and they did not so rigorously test the predicted decay function or attempt to fit likely alternatives. The development of new instrumentation, new data analysis techniques, and new theory and their application to different DNAs in various circumstances have continued to advance this field up to the present time. 

Since a larger sample volume is presumed to be probed, the use of transmission mode has led to simpler, more accurate models requiring fewer calibration samples [50]. Scientists at AstraZeneca found that with a transmission Raman approach as few as three calibration samples were required to obtain prediction errors nearly equivalent to their full model [42]. For a fixed 10-s acquisition time, the transmission system had prediction errors as much as 30% less than the WAI system, though both approaches had low errors. It is hoped that this approach in combination with advanced data analysis techniques, such as band target entropy minimization (BTEM) [51], might help improve Raman s quantitative sensitivity further. 

NIR spectroscopy is probably the most successful technique for the development of qualitative and quantitative methods in the pharmaceutical industry. NIR spectra contain both chemical and physical information from samples (solid and liquid). Spectra can be acquired off-line in three different modes transmittance, reflectance and transflectance. In all cases, the spectra are obtained in a few seconds without or minimum sample pretreatment. Multivariate data analysis techniques are usually needed for the development of the... 

To be effective the investigation must apply an approach which is based on basic incident causation theories and use tested data analysis techniques. Investigating incidents to determine root causes and make recommendations can be as much an art as a science. Within the industry, best practices in incident investigation have evolved substantially in the last 20 years. This chapter provides a brief overview of some of the more relevant causation theories. 

Although the measurement uncertainties limit the conclusions which can be drawn from these results, the data set proved useful for the determination of general Influences on rainwater composition In the Seattle area and for the demonstration of the application of these exploratory data analysis techniques. Current efforts to collect and analyze aerosol and rainwater samples over meteorologically appropriate time scales with precise analytical techniques are expected to provide better resolution of the factors controlling the composition of rainwater. 

Neustadter, H. E., Fordyce, J. S. and King, R. B. (1976). "Elemental Composition of Airborne Particulates and Source Identification Data Analysis Techniques," Journal of the Air Pollution Control Association, 26, 1079. 

Figure 5 shows the results of the authors study on the ability of NIR to monitor the scale-up from the laboratory Carver Press to the Fitzpatrick roller compactor. Because the NIR signal is influenced by changes in the physical and mechanical properties, multivariate data analysis techniques were used to identify and separate these contributions in the overall NIR signal. A flat-faced rectangular die and punch set, 40 x 15 mm in size, was fitted on the laboratory Carver Press to prepare tablets similar in shape and size to the roller compacted samples. 

The wide latitude available to the practitioner and its relative ease of implementation have made discriminant analysis and, especially, LDA a useful data analysis technique for spectroscopic data. Initial reports document carefully the steps and caveats in implementation [107] and substantial acceptance of the methodology exists in the spectroscopy community due to these early... 

Inspection of Figure 7.8(a) also reveals one of the major difficulties in determining A /hfs to a few ppm, namely that the natural line width is large, approximately 6200 ppm, and extremely fine line splitting must be accomplished. This topic, and related systematics, were discussed in detail by Rich (1981), who noted that the accord between the two groups, who used different data analysis techniques, is important confirmation of the reported accuracy. 

The following section contains a more detailed treatment of the theory behind the nonresonant spectroscopy of liquids. This will be followed by a description of the experimental implementation and data analysis techniques for a common OKE scheme, optical-heterodyne-detected Raman-induced Kerr-effect spectroscopy (22). We will then discuss the application of this technique to the study of the temperature-dependent dynamics of simple liquids composed of symmetric-top molecules. 

We have analyzed the rainwater chemical data with multivariate data analysis techniques to identify sources influencing the area covered by our sampling network. Two events were included in the principal component analysis (PCA) the February 15 storm presented here and another storm collected during smelter operation on March 20, 1985... 

Hauschild, K., and Picker, K. M. (2003), The 3D model Comparison with other data analysis techniques for tableting, AAPS PharmSci, 5(S1), W4304. 

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