10 research outputs found

    Mining Biclusters of Similar Values with Triadic Concept Analysis

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    Biclustering numerical data became a popular data-mining task in the beginning of 2000's, especially for analysing gene expression data. A bicluster reflects a strong association between a subset of objects and a subset of attributes in a numerical object/attribute data-table. So called biclusters of similar values can be thought as maximal sub-tables with close values. Only few methods address a complete, correct and non redundant enumeration of such patterns, which is a well-known intractable problem, while no formal framework exists. In this paper, we introduce important links between biclustering and formal concept analysis. More specifically, we originally show that Triadic Concept Analysis (TCA), provides a nice mathematical framework for biclustering. Interestingly, existing algorithms of TCA, that usually apply on binary data, can be used (directly or with slight modifications) after a preprocessing step for extracting maximal biclusters of similar values.Comment: Concept Lattices and their Applications (CLA) (2011

    Cavity Ring Down and Vacuum UV Spectroscopy - Applications for radical absolute density measurements in plasma

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    Survey of several experimental techniques applied for absolute density measurements of atoms and radicals in plasma is presented. It includes the Vacuum Ultraviolet Absorption Spectroscopy, Actinometry and Emission Spectroscopy, Laser Absorption Spectroscopy and highly sensitive Cavity Ring-Down Spectroscopy. Performances and operation procedures of these techniques are illustrated.SCOPUS: cp.pinfo:eu-repo/semantics/publishe

    Biclustering meets triadic concept analysis

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    International audienceBiclustering numerical data became a popular data-mining task at the be-ginning of 2000's, especially for gene expression data analysis and recommender sys-tems. A bicluster reflects a strong association between a subset of objects and a subset of attributes in a numerical object/attribute data-table. So-called biclusters of similar values can be thought as maximal sub-tables with close values. Only few methods address a complete, correct and non-redundant enumeration of such patterns, a well-known intractable problem, while no formal framework exists. We introduce impor-tant links between biclustering and Formal Concept Analysis (FCA). Indeed, FCA is known to be, among others, a methodology for biclustering binary data. Handling numerical data is not direct, and we argue that Triadic Concept Analysis (TCA), the extension of FCA to ternary relations, provides a powerful mathematical and algorithmic framework for biclustering numerical data. We discuss hence both theo-retical and computational aspects on biclustering numerical data with triadic concept analysis. These results also scale to n-dimensional numerical datasets

    State selective study of H 3

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    Rate coefficients for nuclear spin state-specific recombination of H3+ ions with thermal electrons were measured using FALP and SA techniques at temperatures 77–300 K. For this purpose H2 gas with both thermal and enriched population of the para nuclear spin configuration was used. Measurements have shown that at 77 K para-H3+ exhibits five times higher binary recombination rate coefficient than ortho-H3+: (1.5 ± 0.4) × 10−7 vs. (3 ± 2) × 10−8 cm3s−1
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