Physics

" The scanning tunneling microscope is proving to be a remarkably useful and flexible tool for probing the structure of matter at atomic scales. Work using it appears regularly in “Articles Alert” columns. For the uninitiated, a recent article will be a good introduction.

H.K. Wickramasinghe, “Scanned-probe microscopes,” Scientific American, 261,98-105, October 1989. (IBM Watson Research Center,Yorktown Heights, N.Y.)

" Some beautiful images of DNA molecules are an example of the striking results flowing from scanning tunneling microscope techniques. A. Cricenti, S. Selci, A.C. Felici, R. Generosi, et al., “Molecular structure of DNA by scanning tunneling micros- copy,”Science, 245, 1226-7, 15 September1989. (Consiglio Nazionale delle Richerche, Frascati, Italy; Universita’ di Roma, et al.)

" The lensing of distant quasars by intervening galaxies and galaxy clusters is a dramatic consequence of...