Presents a method based on a constrained optimization technique that determines the time of removal of scientific periodicals from the shelf of a library. A geometrical interpretation of the theoretical result is given, and a numerical example illustrates how the technique is applicable to real bibliographic data. (FM)

Data for the raw frequency of use of 138 physics journals in the science library at MIT are re-examined and converted to densities of use-per-metre of shelf. There is no evidence for synchronous obsolescence in the 1955 to 1968 volumes, and some evidence of greater density of use with greater age. (Author/LS)

Describes a study that examined the median citation ages of 9,850 references from 37 journals in music education, music theory, and musicology. Synchronous and diachronous obsolescence are explained, median citation age and half life are discussed, and results are compared with those of an earlier study. (29 references) (LRW)

A study comparing citations received by patents in given year to number received in subsequent years found that, even though influential patents remain influential, both highly and infrequently cited patents age at same rate. Distribution of patents by number of citations received is stable over time. (17 references) (EJS)

The scientific information diffusion theory is used to explain the increased citation frequency of recently published articles in respect to the normal exponential decay of older articles. Appendices illustrate this approach. (Author/FM)

Discusses obsolescence as a criterion for libraries to use when selecting journals and suggests topicality of the research theme that has been cited in subsequent years as a better variable. Describes the use of the Rasch model as a measuring instrument and compares rank order using the two methods. (LRW)

Examines the distribution of use of items in a large information store and suggests that a simple exponential model describes the process of obsolescence more precisely. Three tables, four figures, and a 17-item reference list are included. (Author/JL)

Examines relationship between journal productivity (number of references to particular journal) and journal obsolescence (median age of references to particular journal) for database of references dealing with desalination. Citation age by Bradford zones, continuous measurement of productivity and citation age, and underlying structure of observed…

Examines the problem of aging of books in university libraries and presents a mathematical model of the aging process. Indexes for the aging time limit, over-age book rate, and aging rate are suggested; use of the mean unit price is considered; and countermeasures for control of the aging process are proposed. (four references) (MES)

Describes the authors' research behind the Historic Cancellation of Fact method, a solution to the information explosion crisis. Each existing paper is evaluated in the light of new papers published the day before, and any "old" paper which has suffered obsolescence is immediately pulled and republished in its entirety in SCRUB (Science Culling…