4,244 research outputs found
Kernel-based distance metric learning for microarray data classification
BACKGROUND: The most fundamental task using gene expression data in clinical oncology is to classify tissue samples according to their gene expression levels. Compared with traditional pattern classifications, gene expression-based data classification is typically characterized by high dimensionality and small sample size, which make the task quite challenging. RESULTS: In this paper, we present a modified K-nearest-neighbor (KNN) scheme, which is based on learning an adaptive distance metric in the data space, for cancer classification using microarray data. The distance metric, derived from the procedure of a data-dependent kernel optimization, can substantially increase the class separability of the data and, consequently, lead to a significant improvement in the performance of the KNN classifier. Intensive experiments show that the performance of the proposed kernel-based KNN scheme is competitive to those of some sophisticated classifiers such as support vector machines (SVMs) and the uncorrelated linear discriminant analysis (ULDA) in classifying the gene expression data. CONCLUSION: A novel distance metric is developed and incorporated into the KNN scheme for cancer classification. This metric can substantially increase the class separability of the data in the feature space and, hence, lead to a significant improvement in the performance of the KNN classifier
Optically-Nonactive Assorted Helices Array with Interchangeable Magnetic/Electric Resonance
We report here the designing of optically-nonactive metamaterial by
assembling metallic helices with different chirality. With linearly polarized
incident light, pure electric or magnetic resonance can be selectively
realized, which leads to negative permittivity or negative permeability
accordingly. Further, we show that pure electric or magnetic resonance can be
interchanged at the same frequency band by merely changing the polarization of
incident light for 90 degrees. This design demonstrates a unique approach to
construct metamaterial.Comment: 15 pages, 4 figure
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