Papers by Douglas Rutledge
Talanta, 2015
Discriminant analysis (DA) methods, such as linear discriminant analysis (LDA) or factorial discr... more Discriminant analysis (DA) methods, such as linear discriminant analysis (LDA) or factorial discriminant analysis (FDA), are well-known chemometric approaches for solving classification problems in chemistry. In most applications, principle components analysis (PCA) is used as the first step to generate orthogonal eigenvectors and the corresponding sample scores are utilized to generate discriminant features for the discrimination.
Magnetic Resonance in Food Science, 2003
Magnetic Resonance in Food Science, 2003
Journal of pharmaceutical and biomedical analysis, 2014
Independent component analysis (ICA) was used as a blind source separation method on a Raman imag... more Independent component analysis (ICA) was used as a blind source separation method on a Raman image of a pharmaceutical tablet. Calculations were performed without a priori knowledge concerning the formulation. The aim was to extract the pure signals from the initial data set in order to examine the distribution of actives and major excipients within the tablet. As a method based on the decomposition of a matrix of mixtures of several components, the number of independent component to choose is a critical step of the analysis. The ICA_by_blocks method, based on the calculation of several models using an increasing number of independent components on initial matrix blocks, was used. The calculated ICA signals were compared with the pure spectra of the formulation compounds. High correlations between the two active principal ingredient spectra and their corresponding calculated signals were observed giving a good overview of the distributions of these compounds within the tablet. Infor...
Magnetic Resonance in Food Science, 2003
Magnetic Resonance in Food Science, 2003
Outer-product analysis (OPA) is a method which makes it possible to emphasise co-evolutions of sp... more Outer-product analysis (OPA) is a method which makes it possible to emphasise co-evolutions of spectral regions in signals acquired in two different domains or even for the same domain. The calculation of the outer-product (OP) matrix linking the two domains corresponds to a mutual weighting of the two signals.
A new approach to perform Principal Component Analysis (PCA) on very wide matrices is proposed in... more A new approach to perform Principal Component Analysis (PCA) on very wide matrices is proposed in this work. The procedure is based on an extension of the Principal Component Transform (PCT) concept-the PCT being applied to non-superimposed segments of the data matrix. It is shown that this method uses less memory than the classical global PCA since the decomposition is done on much smaller matrices, which has an important impact on the memory requirements. It is also shown that the Segmented PCT-PCA (SegPCT-PCA) yields the same results as the decomposition performed by a global PCA. This approach will allow the study of very wide data sets (e.g. 2D-NMR), which were difficult to do using the global PCA approach. The implementation of SegPCT-PCA is straightforward. An advantage of the method is that it is not necessary to read the complete matrix into the main memory, which could be an advantage for parallel calculations and for cross-validation purposes. D
Magnetic Resonance in Food Science, 2003
Applied Spectroscopy, 1997
... The result of the analysis of variance on the unfolded NIRMIR (l, n 3 m) matrix is folded bac... more ... The result of the analysis of variance on the unfolded NIRMIR (l, n 3 m) matrix is folded back to give an F matrix (n, m), where the F values indicate the signi®-cance levels of the simultaneous variation of intensity at each frequency in the MIR and NIR, resulting from the variation ...
Analusis, 1998
This article describes how Analysis of Variance may be used to select those regions of the curves... more This article describes how Analysis of Variance may be used to select those regions of the curves generated by a gas sensor ar ray which contain the most discriminant information for a particular application. The Analysis of Variance is performed on each point of the signals generated by the sensor array for a particular set of samples. The Group Variances and the Residual Variances are plotted as functions of their position in the signal. Regions of the signals that vary systematically from one group of samples to another will have high Group Variance values and low and randomly distributed Residual Variance values. This method has shown for a particular set of products for cats analysed with a thirty two polymer sensor array, that the most discriminant information is located at the end of the curves. It has also shown an absence of discrimination between standard and tainted pig fat samples with this sensor array. The ad vantage of this method is that it can be used on almost any sort of raw signal as a pre-analysis step in order to know whether it is worthwhile going on to more fastidious and time consuming signal analysis procedures.
International Journal of Pharmaceutics, 2013
This work focused on developing a new evaluation criterion of percutaneous penetration, in comple... more This work focused on developing a new evaluation criterion of percutaneous penetration, in complement to Log Pow and MW and based on high spatial resolution Fourier transformed infrared (FTIR) microspectroscopy with a synchrotron source (SR-FTIR). Classic Franz cell experiments were run and after 22 h molecule distribution in skin was determined either by HPLC or by SR-FTIR. HPLC data served as reference. HPLC and SR-FTIR results were compared and a new predictive criterion based from SR-FTIR results, named S(index), was determined using a multi-block data analysis technique (ComDim). A predictive cartography of the distribution of molecules in the skin was built and compared to OECD predictive cartography. This new criterion S(index) and the cartography using SR-FTIR/HPLC results provides relevant information for risk analysis regarding prediction of percutaneous penetration and could be used to build a new mathematical model.
ABSTRACT The processes involved in the growing, processing, distribution, and eating of food arou... more ABSTRACT The processes involved in the growing, processing, distribution, and eating of food around the world are both complex and diverse. Factors such as local customs and climates, culinary heritage and traditions, interest in nutrition and health, affordability, and availability of storage and distribution networks are all variable, and affect the relative importance of food-related questions and how they are addressed. A simplified supply chain provides a convenient framework for discussing the wide range of issues related to food. This framework also serves to categorise the diverse range of applications that NMR techniques currently address, as well as the potential for further exploitation of this most versatile and incisive analytical methodology. This overview will follow the various stages of the food supply chain as shown below, exemplifying some of the ways in which NMR techniques can be applied.
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Papers by Douglas Rutledge