title: Non-negative matrix analysis for effective feature extraction in X-ray spectromicroscopy.
abstract: X-Ray absorption spectromicroscopy provides rich information on the chemical organization of materials down to the nanoscale. However, interpretation of this information in studies of "natural" materials such as biological or environmental science specimens can be complicated by the complex mixtures of spectroscopically complicated materials present. We describe here the shortcomings that sometimes arise in previously-employed approaches such as cluster analysis, and we present a new approach based on non-negative matrix approximation (NNMA) analysis with both sparseness and cluster-similarity regularizations. In a preliminary study of the large-scale biochemical organization of human spermatozoa, NNMA analysis delivers results that nicely show the major features of spermatozoa with no physically erroneous negative weightings or thicknesses in the calculated image.
authors.affiliation: Department of Physics & Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA. rachel.mak@u.northwestern.edu.
authors.forename: Rachel
authors.initials: R
authors.lastname: Mak
authors.forename: Mirna
authors.initials: M
authors.lastname: Lerotic
authors.forename: Holger
authors.initials: H
authors.lastname: Fleckenstein
authors.forename: Stefan
authors.initials: S
authors.lastname: Vogt
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Wild
authors.forename: Sven
authors.initials: S
authors.lastname: Leyffer
authors.forename: Yefim
authors.initials: Y
authors.lastname: Sheynkin
authors.forename: Chris
authors.initials: C
authors.lastname: Jacobsen
mesh_terms: D016000:Cluster Analysis; D006801:Humans; D008297:Male; D008853:Microscopy; D013057:Spectrum Analysis / Q000379:methods*; D013094:Spermatozoa / Q000737:chemistry*; D014965:X-Rays