Fluorescence data analysis

Maximum (maximized) likelihood is a statistical term that refers to the probability of randomly drawing a particular sample from a population, maximized over the possible values of the population parameters. Selected entries from Methods in Enzymology [vol, page(s)] Theory, 210, 203 testing by simulations, 210, 225 computer applications for, 210, 233 fitting of sums of exponentials to dwell-time distributions, 207, 772 fluorescence data analysis, 210,... 

In addition to its exquisite sensitivity, other key advantages of ZnO NR platforms include ease of array fabrication, mechanical and chemical robustness, no autofluoroescence, and direct correlation of observed signal to protein concentration. Unlike other commonly used biosupport materials, this unique proper of ZnO NRs exhibiting no spectral overlap with fluorophores can be conveniently used in fluorescence data analysis. Fluorescence signal in the ZnO NR-assisted assays... 

Fluorescence Data Analysis and Inner Filter Corrections. Figure 2 shows the fluorescence intensity for Fobs versus the concentration of the DOC in ppm for the four san )les. The Fobs that increasing DOC concentrations leads to a decrease... 

L. Eriksson, J. Trygg, E. Johansson, R. Bro, S. Wold, Orthogonal signal correction, wavelet analysis, and multivariate calibration of complicated process fluorescence data. Anal. Chim. Acta, 2000 420, 181-195. 

X-ray fluorescence (XRF) analysis is successfully used to determine chemical composition of various geological and ecological materials. It is known that XRF analysis has a high productivity, acceptable accuracy of results, developed theory and industrial analytical equipment sets. Therefore the complex methods of XRF analysis have to be constituent part of basis data used in ecological and geochemical investigations... 

The methodical elaboration is included for estimation of random and systematic errors by using of single factor dispersion analysis. For this aim the set of reference samples is used. X-ray analyses of reference samples are performed with followed calculation of mass parts of components and comparison of results with real chemical compositions. Metrological characteristics of x-ray fluorescence silicate analysis are established both for a-correction method and simplified fundamental parameter method. It is established, that systematic error of simplified FPM is less than a-correction method, if the correction of zero approximation for simplified FPM is used by preliminary established correlation between theoretical and experimental set data. 

C.N. Ho, G.D. Christian and E.R. Davidson, Application of the method of rank annihilation to quantitative analysis of multicomponent fluorescence data from the video fluorometer. Anal. Chem., 52 (1980) 1108-1113. 

To reduce intensity effects, the data were normalized by reducing the area under each spectrum to a value of 1 [42]. Principal component analysis (PCA) was applied to the normalized data. This method is well suited to optimize the description of the fluorescence data sets by extracting the most useful data and rejecting the redundant ones [43]. From a data set, PCA assesses principal components and their corresponding spectral pattern. The principal components are used to draw maps that describe the physical and chemical variations observed between the samples. Software for PCA has been written by D. Bertrand (INRA Nantes) and is described elsewhere [44]. 

Quantitative fluorescence imaging techniques and FLIM in particular are becoming increasingly important in biological and biomedical sciences. Knowledge of instrumentation and data analysis is required to avoid misinterpretation of the experimental results and to exploit the wealth of information provided by these techniques. 

The first FRET-based biosensors employing fluorescent proteins were developed over 10 years ago. These protease sensors consisted of a BFP donor fused to a GFP acceptor by a protease-sensitive linker [44, 119]. BFP and GFP have well separated emission spectra, resulting in little fluorescence bleed-through (Figs. 5.5A and 5.6A). This facilitates data analysis for FRET ratio imaging... 

It is interesting to note that when using two fluorophores (whose fluorescence decays are known to be single exponentials), one as a sample and the other as a reference, it is possible to determine the lifetimes of both the fluorophores without external reference this can be achieved in data analysis by varying the reference lifetime until a minimum value of x is reached. 

Fluorescence spectroscopy and its applications to the physical and life sciences have evolved rapidly during the past decade. The increased interest in fluorescence appears to be due to advances in time resolution, methods of data analysis and improved instrumentation. With these advances, it is now practical to perform time-resolved measurements with enough resolution to compare the results with the structural and dynamic features of macromolecules, to probe the structures of proteins, membranes, and nucleic acids, and to acquire two-dimensional microscopic images of chemical or protein distributions in cell cultures. Advances in laser and detector technology have also resulted in renewed interest in fluorescence for clinical and analytical chemistry. 

A major limitation of flow cytometric analysis is that it provides data from individual cells at a single point in time and the same cells are not available for further analysis once they have passed through the flow cell of the instrument. Therefore, it is not possible to monitor a given cell over time for changes in fluorescence intensity or distribution of fluorescence signal. Such studies require microinjection of the fluorochrome into individual cells and fluorescence microscopy analysis. 

The BioView sensor includes a software package (CAMO ASA, Norway) for data analysis and on-Une estimation of different bioprocess variables simultaneously. Thus, the instrument is able to predict the trends of the concentration courses of different variables during a cultivation and is used to give information about important process steps (e.g., feeding time, harvesting time, etc.). The instrument is able to monitor on-line several fluorophores in situ and non-invasively during cultivation processes and permits an estimation of different bioprocess variables simultaneously. The increasing of cell mass concentration and the product formation as well as the actual metabolic state of the cells is simultaneously detectable by this fluorescence technique. 

This problem is overcome by the Bio View sensor, which offers the possibility to monitor the whole spectral range simultaneously, and by using suitable data analysis and mathematical methods like chemometric regression models 11061. Real-time fluorescence measurement can be used more effectively comparing time-consuming off-line methods. Partial least squares (PLS) calibration models were developed for simultaneous on-line prediction of the cell dry mass concentration (Fig. 5), product concentration (Fig. 6), and metabolite concentrations (e. g., acetic acid, not shown) from 2D spectra. 

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