The HLA class I and II phenotypes of the three population groups in the Cape Province of South Africa were determined. The HLA-A,B, and C antigens were tested in 1027 South African Negroes (Xhosa), 3716 Cape Coloureds and 1059 South African Caucasoids. This is the first study which has also included the class II antigens in the Southern African Negroes (Xhosa). The numbers tested for the DR and DQ antigens were smaller, as only typings done after the 8th Histocompatibility Workshop were included. A comparison was made between the frequencies in the Xhosa, the Cape Coloureds and the South African Caucasoids as well as the Nigerians, another group who also belong to the Bantu-speaking division of African Negroes and who were recently studied. The antigen, gene and haplotype frequencies were estimated in all three groups, and the genetic distances calculated. Striking differences in gene and haplotype frequencies between the various populations were seen. For example, Bw42 had a phenotype frequency of 0.062 in the Cape Coloureds, 0.213 in the Xhosa and 0.004 in the South African Caucasoids. The Xhosa showed marked differences in HLA distribution compared to the other Negro group (Nigerians), which can be attributed to a Khoisan admixture, e.g. HLA-DR4 had a phenotype frequency of 0.134 in the Xhosa and only 0.010 in the Nigerians. The haplotype B8,DR3, seen in association with many autoimmune diseases, had a significant delta value in all three populations.

No abstract

No abstract

some sample protocols are presented.An object-oriented framework for the design of distributed virtual memory consistency protocols is presented. It is shown that custom designed protocols for different applications are easy to construct and use with this framework. Consistency protocols are shown to be useful in implementing atomic update, and in controlling assignment of pages to processes. Finally, experimental results are presented.

One of the areas that is of primary importance in distributed applications is that of the name server and directory service. This area is one that the Service Location Protocol (SLP) addresses. The requirements for a name server differ in performance from the high speed needs of a transaction processing system to the more reasonable needs of a video-conferencing system. It is in this later area that this paper concentrates. For some years UCT has been involved in developing Java based network educational distributed systems including teleteaching delivery systems, which have required high speed delivery but reliable slow speed access to a naming server [Azbel97], [Azbel98]. During the implementation of these systems the requirement was found for a fully scalable directory service to permit users to find and connect to the available services with a degree of authentication and securit),. This paper describes an implementation of SLP in Java, which is designed to be used in this type of application area. The implementation issues, the problems faced and the advantages of scalability are discussed.