Validation of Soft Classification Models using Partial Class Memberships: An Extended Concept of Sensitivity & Co. applied to the Grading of Astrocytoma Tissues

We use partial class memberships in soft classification to model uncertain labelling and mixtures of classes. Partial class memberships are not restricted to predictions, but may also occur in reference labels (ground truth, gold standard diagnosis) for training and validation data. Classifier performance is usually expressed as fractions of the confusion matrix, such as sensitivity, specificity, negative and positive predictive values. We extend this concept to soft classification and discuss the bias and variance properties of the extended performance measures. Ambiguity in reference labels translates to differences between best-case, expected and worst-case performance. We show a second set of measures comparing expected and ideal performance which is closely related to regression performance, namely the root mean squared error RMSE and the mean absolute error MAE. All calculations apply to classical crisp classification as well as to soft classification (partial class memberships and/or one-class classifiers). The proposed performance measures allow to test classifiers with actual borderline cases. In addition, hardening of e.g. posterior probabilities into class labels is not necessary, avoiding the corresponding information loss and increase in variance. We implement the proposed performance measures in the R package "softclassval", which is available from CRAN and at http://softclassval.r-forge.r-project.org. Our reasoning as well as the importance of partial memberships for chemometric classification is illustrated by a real-word application: astrocytoma brain tumor tissue grading (80 patients, 37000 spectra) for finding surgical excision borders. As borderline cases are the actual target of the analytical technique, samples which are diagnosed to be borderline cases must be included in the validation.Comment: The manuscript is accepted for publication in Chemometrics and Intelligent Laboratory Systems. Supplementary figures and tables are at the end of the pd

Biosensors based on SPR Imaging

Surface plasmon resonance (SPR) belongs to the most sensitive detection methods and has been used for more than 20 years to study a variety of chemical and biochemical sensor developments. Now, with the recent introduction of biochips, SPR as a label-free technology for monitoring biomolecular interactions is a promising technique for rapid and parallel detection. SPR imaging using fast optical array detectors permits simultaneous measurements across an array of immobilized molecules. SPR imaging provides excellent spatial resolution at the same sensitivity as classical SPR. These features make SPR imaging a promising detection technology for biochips

Employment and Careers of European Chemists (ESEC2)

Employment conditions and career opportunities are in the focus of the new Employment Survey for European Chemists (ESEC2). Conditions and opportunities are individually analysed for all countries with a statistically significant number of responses. The results provide important clues for careers in these countries and in Europe as a whole. The importance of employer sectors varies very much between European countries. A chapter of this report is devoted to career planning of students and new graduates. This is the first general evaluation of the survey. It provides many details about the chemistry workforce in Europe and its development.Publisher PDFPeer reviewe

Employment and Careers of European Chemists (ESEC2)

Employment conditions and career opportunities are in the focus of the new Employment Survey for European Chemists (ESEC2). Conditions and opportunities are individually analysed for all countries with a statistically significant number of responses. The results provide important clues for careers in these countries and in Europe as a whole. The importance of employer sectors varies very much between European countries. A chapter of this report is devoted to career planning of students and new graduates. This is the first general evaluation of the survey. It provides many details about the chemistry workforce in Europe and its development.Publisher PDFPeer reviewe

Biomedical Imaging: Principles and Applications

This book presents and describes imaging technologies that can be used to study chemical processes and structural interactions in dynamic systems, principally in biomedical systems. The imaging technologies, largely biomedical imaging technologies such as MRT, Fluorescence mapping, raman mapping, nanoESCA, and CARS microscopy, have been selected according to their application range and to the chemical information content of their data. These technologies allow for the analysis and evaluation of delicate biological samples, which must not be disturbed during the profess. Ultimately, this may m

Linked Curriculum – Chemistry: Different from a Virtual University Vernetztes Studium – Chemie: anders als eine virtuelle Universität

Since 1999 the German Federal Ministry of Education and Research has been supporting the lead project 'Vernetztes Studium – Chemie' ('Network for Education – Chemistry'). Sixteen professors and their co-workers from Germany, Switzerland, and the United Kingdom are involved. During a period of five years a novel internet-based modular system will be developed connecting theory and practice of the chemistry basic studies. This new approach will provide the basic chemical knowledge via the use of multimedia methods in the form of browser-based learning modules which are compiled within an integrated educational concept. The students are able to choose different learning levels depending on their knowledge. Potential users are students and lecturers of chemistry and of other branches of study as well as laboratory assistants, pupils and interested people undertaking further studies in chemistry

Important Figures of Analytical Chemistry from Germany in Brief BiographiesFrom the Middle Ages to the Twentieth Century /

VII, 132 p. 70 illus., 3 illus. in color.online r