Simon Andrew Williamson

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Decentralised coordination in multi-agent systems is typically achieved using communication. However, in many cases, communication is expensive to utilise because there is limited bandwidth, it may be dangerous to communicate, or communication may simply be unavailable at times. In this context, we argue for a rational approach to communication — if it has(More)
Cyber security is increasingly important for defending computer systems from loss of privacy or unauthorised use. One important aspect is threat analysis — how does an attacker infiltrate a system and what do they want once they are inside. This paper considers the problem of Active Malware Analysis, where we learn about the human or software intruder by(More)
The use of busulphan and cyclophosphamide permitted engraftment in 44 of 49 children receiving 'displacement' bone marrow transplants. Three patients who received T-cell-depleted marrow cells from HLA-haploidentical donors failed to engraft and other graft failures were due to inadequate induction dosage. Our standard schedule comprises busulphan 80(More)
Matched sibling transplants enjoy over 95% survival of the grafting procedure, but are only available for 1:5 patients. A sibling sharing one genetic haplotype is today our next choice of donor (67% survival) faring better than other relatives (50% survival), providing total body irradiation (of the thymus) has been avoided. The latter, without increasing(More)
The endogenous opiate peptide, beta-endorphin, has two effects on human natural killing (NK). Preincubation of effector lymphocytes with between 10(-7) and 10(-11) M beta-endorphin increases NK. Preincubation with lower concentrations results in a reduction in NK. Endorphin peptides containing an unmodified N-terminal sequence, and which are known to bind(More)
Synthetic human beta endorphin shows a biphasic effect on the production of specific anti-herpes viral antibodies in vitro. At higher concentrations antibody production is reduced, at lower concentrations it is enhanced. In a proportion of donors whose cells do not produce specific antibody when cultured with antigen alone, the lower concentrations of beta(More)
In a wide range of emerging applications, from disaster management to intelligent sensor networks, teams of software agents can be deployed to effectively solve complex distributed problems. To achieve this, agents typically need to communicate locally sensed information to each other. However, in many settings, there are heavy constraints on the(More)
This paper considers randomized strategyproof approximations to distance rationalizable voting rules. It is shown that the Random Dictator voting rule (return the top choice of a random voter) nontrivially approximates a large class of distances with respect to unanimity. Any randomized voting rule that deviates too greatly from the Random Dictator voting(More)
Twenty-four patients have received bone marrow transplantation for severe aplastic anaemia at the Westminster Hospitals since 1974. Twelve patients are long term survivors. Infectious complications in association with graft rejection, graft versus host disease or prolonged neutropenia were the major cause of death. In the last 18 months the introduction of(More)