A fast algorithm for computing distance spectrum of convolutionalcodes

A fast algorithm for searching a tree (FAST) is presented for computing the distance spectrum of convolutional codes. The distance profile of a code is used to limit substantially the error patterns that have to be searched. The algorithm can easily be modified to determine the number of nonzero information bits of an incorrect path as well as the length of an error event. For testing systematic codes, a faster version of the algorithm is given. FAST is much faster than the standard bidirectional search. On a microVAX, d_∞=27 was verified for a rate R=1/2, memory M=25 code in 37 s of CPU time. Extensive tables of rate R=1/2 encoders are given. Several of the listed encoders have distance spectra superior to those of any previously known codes of the same rate and memory. A conjecture than an R=1/2 systematic convolutional code of memory 2M will perform as well as a nonsystematic convolutional code of memory M is given strong support     

Patient-number-based computerized medical records in Crete. A tool for planning and assessment of primary health care.

Primary Health Care (PHC) in Crete is in a state of rapid development. The strategy for introducing PHC involves an orientation towards the population and the creation of possibilities for evaluation. A case records system, "Egino", was installed in the University of Heraklion and at the Health Centre in Spili in 1988, and was further developed according to local needs during 1989, when also a Greek version of the statistical system, "DoIt", was installed. The main reasons for establishing a computerized medical information system were (i) to assess the health needs in Crete, (ii) to monitor activities of the primary health care organizations, and (iii) to introduce epidemiological research into primary health care in Greece. The information system was based on specially assigned patient numbers containing several pieces of information about the individual; the system was developed at the Dalby Health Sciences Centre in Sweden. Each month, data were extracted in Spili Health Centre, and these data were regularly used to present incidence and prevalence indices. Some of the data extracted were reported to the health authorities in Greece. "EginO" and "DoIt" gave possibilities to evaluate health services by following the morbidity, while also making it possible to describe and analyse health needs in the population of Spili and other primary health care catchment areas in Greece.