Tim Wilkinson

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If sensitive information is to be included in a shared web, access controls will be required. However, the complex software needed to provide a web service is prone to failure. To provide access control without relying on such software, encryption can be used. Bob is a prototype system that supports complex access control expressions through the transparent(More)
The appearance of 64-bit processors allows a new approach t o microkernel desagn From our experience with a message passang microkernel MESHIX, we discovered that a multi-address space, POSIX architecture is unsvttable for general parallel applications development Angel was therefore deszgned to provide a more flexible envtronmeni. Central to these arms is(More)
In the mid eighties, the System Architecture Research Centre at City University developed a message-passing, UNIX compliant micro kernel (Meshix) for our own scalable distributed memory architecture (Topsy). Over the last two years we have been engaged in a research programme aimed at learning from this experience, and developing a new operating system(More)
This paper describes the current position of work on City University's Topsy project. Topsy is a new message passing multicomputer architecture. It comprises a fully Unix compatible distributed kernel, called Meshix, on top of a message based software system which in turn relies on new, high speed, communications hardware, Meshnet. A overview of the machine(More)
BACKGROUND In standard setting techniques involving panels of judges, the attributes of judges may affect the cut-scores. This simulation study modelled the effect of the number of judges and test items, as well as the impact of judges' attributes such as accuracy, stringency and influence on others on the precision of the cut-scores. METHODS Forty nine(More)