David P. Hansen

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OBJECTIVE To classify automatically lung tumor-node-metastases (TNM) cancer stages from free-text pathology reports using symbolic rule-based classification. DESIGN By exploiting report substructure and the symbolic manipulation of systematized nomenclature of medicine-clinical terms (SNOMED CT) concepts in reports, statements in free text can be(More)
Emergency departments around Australia use a range of software to capture data on patients' reason for encounter, presenting problem and diagnosis. The data collected are mainly based on descriptions and codes of the International Classification of Diseases, 10th revision, Australian modification (ICD-10-AM), with each emergency department having a tailored(More)
In this paper, we study the maintenance of role-based access control (RBAC) models in database environments using transitive closure relations. In particular, the algorithms that express and remove redundancy from a component, a RBAC state, and from conflict constraints. The transitive closure relations on a RBAC state specify the reachability among user(More)
OBJECTIVE To develop a system for the automatic classification of Cancer Registry notifications data from free-text pathology reports. METHOD The underlying technology used for the extraction of cancer notification items is based on the symbolic rule-based classification methodology, whereby formal semantics are used to reason with the systematised(More)
AbstrAct In this article we investigate how approximate query processing (AQP) can be used in medical multidatabase systems. We identify two areas where this estimation technique will be of use. First, approximate query processing can be used to preprocess medical record linking in the mul-tidatabase. Second, approximate answers can be given for aggregate(More)
Twenty-one consecutive Black African patients with severe pure mitral stenosis were evaluated hemodynamically. It was found that advanced mitral stenosis presents itself in Kenya at a very young age (22.9 +/- 9.6 years, mean +/- S.D.), with all but three patients under thirty. Left ventricular angiography demonstrated significant impairment of left(More)
76 Kenyan Africans with classical or definite rheumatoid arthritis are described. Their age, sex ratio, and pattern of joint involvement closely resembled that seen in Europe and the USA and differed from that described in West Africa and rural South Africa. However, they showed a marked lack of systemic nonarticular complications, with relatively little(More)
The constructions of Haar wavelet synopses for large data sets have proven to be useful tools for data approximation. Recently, research on constructing wavelet synopses with a guaranteed maximum error has gained attention. Two relevant problems have been proposed: One is the size bounded problem that requires the construction of a synopsis of a given size(More)