A Relational Model for the Search and Classification of Biomedical Literature: TREC-2005 Genomics Track

A double-beam spectrophotometer comprising a light source, a monochromator, optical means for causing the monochromatic light beam from the monochromator to alternately advance along a pair of optical paths, the axes of which intersect generally perpendicularly to each other, a pair of cells each disposed in one of the two optical paths, and a photoelectric detector disposed at or adjacent the point of intersection of the pair of optical paths.