Optimization of the HDLC I-Frame Structure and IIASA Data Communication Network

This memorandum presents a solution to one of the most basic optimization problems which arose from the adoption of the HDLC (High level Data Link Control) procedure in the IIASA data communication network data link control protocol. Strictly, the problem discussed here is finding out the optimal HDLC Information-frame structure in order to maximize the throughput, so that the solution states the optimal length of the information part of the Information-frame is 5, 16, 57, 190, 610 and 1800 bytes corresponding to the line quality of 10^(-2), 10^(-3), 10^(-4), 10^(-5), 10^(-6), and 10^(-7) in bit error probability, where the HDLC half duplex normal response mode and the case of file-transfer are assumed. Some other related results and remarks are also given in this memorandum

The Local Computer Network in Tohoku District, Japan

This Working Paper gives an outline of the local computer network in the Tohoku district of Japan, in which the design and implementation I participated in during 1974 at the Research Institute of Electrical Communication, Tohoku University, Japan. At present IIASA is planning its own inter-European computer network, which will be able to interconnect with many existing computer networks, including EIN and those existing in Eastern Europe. This program has already commenced with the interconnection of three computer centres, IIASA, Bratislava (Czechoslovakia) and Budapest (Hungary) using a European public switched telephone line. It is planned to use: a line switching technique to interconnect two computer centres; packets as a unit of information transmission on telephone lines; an asynchronous serial data transmission technique; a half duplex communication facility; and 1200 baud communication speed. I should mention here that the above techniques, computer centre facilities and the topological location of the computer centres are very similar to the computer network in the Tohoku district, and this is the reason why I am writing this paper. I will describe briefly the design of this computer network, which consists of the following five sections

Optimal HDLC I-Frame Structure in a Two-Way File Transfer and IIASA Data Communication Network

This memorandum discusses the optimization problem that arises from adopting the HDLC procedure as the link protocol for the IIASA data communication network. In particular, the problem of identifying the optimal length of the information part of a HDLC information frame (I-frame) is solved by using a "two-way" file transfer in the network. The results show that the optimal length of the information part of a HDLC I-frame is 5, 13, 47, 160, 500 and 1,460 bytes, corresponding to the communication line error probabilities of 10^(-2), 10^(-3), 10^(-4), 10^(-5), 10^(-6), and 10^(-7) in one bit, respectively, so that the throughput is maximized, where the modem polarity switching time is set at 250 ms. The author suggests that the results of the two-way file transfer be compared with those of a "one-way" file transfer presented in [6]; the optimal length in a two-way file transfer is about 20% less than that in a one-way file transfer. It is suggested that the network designer choose the length of the information part that lies between two values corresponding to the line quality. This is because the two-way and one-way file transfers cover two extreme cases where the load (i.e. files to be transmitted) is equally distributed among network stations, and the one-way file transfer represents the case where the load is only partially distributed. The author also discusses the effects of the change in the modem polarity switching time on the optimal length of the information part. When the switching time is changed. from 250 to 100 ms, the optimal length is about 13% less

Comparison of physicochemical properties of soils under contrasting land use systems in Southwestern Nigeria

Soil physicochemical properties were determined for soils under cropland and forest at the headquarters of the International Institute of Tropical Agriculture in Ibadan, Southwestern Nigeria to examine the 30-year effects of different land use on the fertility of five soil series toposequences underlain by a Basement Complex. The cropland had been under cultivation for 30 years, during which mainly maize and yams had been cultivated in rotation with application of chemical fertilizer and intermittent fallow, while the forest had secondary vegetation that had been regenerated during a 30-year period under protection. The findings for cropland indicated an accumulation of available phosphorus and exchangeable potassium, soil compaction and slight depletion of topsoil organic carbon content; and the findings for forest indicated soil acidification and accumulation of exchangeable Ca at the surface soil horizon. These findings suggest the possibility of maintaining soil fertility with a long-term intensive and continuous crop farming system in kaolinitic Alfisol soil over the inland valley toposequences of tropical Africa

H3S28P Antibody Staining of Okinawan Oikopleura dioica Suggests the Presence of Three Chromosomes [version 2; peer review: 2 approved]

Oikopleura dioica is a ubiquitous marine zooplankton of biological interest owing to features that include dioecious reproduction, a short life cycle, conserved chordate body plan, and a compact genome. It is an important tunicate model for evolutionary and developmental research, as well as investigations into marine ecosystems. The genome of north Atlantic O. dioica comprises three chromosomes. However, comparisons with the genomes of O. dioica sampled from mainland and southern Japan revealed extensive sequence differences. Moreover, historical studies have reported widely varying chromosome counts. We recently initiated a project to study the genomes of O. dioica individuals collected from the coastline of the Ryukyu (Okinawa) Islands in southern Japan. Given the potentially large extent of genomic diversity, we employed karyological techniques to count individual animals’ chromosomes in situ using centromere-specific antibodies directed against H3S28P, a prophase-metaphase cell cycle-specific marker of histone H3. Epifluorescence and confocal images were obtained of embryos and oocytes stained with two commercial anti-H3S28P antibodies (Abcam ab10543 and Thermo Fisher 07-145). The data lead us to conclude that diploid cells from Okinawan O. dioica contain three pairs of chromosomes, in line with the north Atlantic populations. The finding facilitates the telomere-to-telomere assembly of Okinawan O. dioica genome sequences and gives insight into the genomic diversity of O. dioica from different geographical locations. The data deposited in the EBI BioImage Archive provide representative images of the antibodies’ staining properties for use in epifluorescent and confocal based fluorescent microscopy