David P. Hansen

Learn More
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)
Tissues that generate specialized cell types in a production line must coordinate developmental mechanisms with physiological demand, although how this occurs is largely unknown. In the Caenorhabditis elegans hermaphrodite, the developmental sex-determination cascade specifies gamete sex in the distal germline, while physiological sperm signaling activates(More)
We confirm the presence of a gender gap in mathematics across many lowand middle-income countries using detailed, comparable test score data. Examining micro level data on school performance linked to household demographics we note that first, the gender gap appears to increase with age. Indeed, the gap nearly doubles when comparing 4th grade and 8th grade(More)
Cardiovascular disease is a major health problem for all Australians and is the leading cause of death in Aboriginal and Torres Strait Islanders. In 2010, more then 50% of all heart attack deaths were due to repeated events. Cardiac rehabilitation programs have been proven to be effective in preventing the recurrence of cardiac events and readmission to(More)
A prospective survey of acute upper gastrointestinal hemorrhage in the major government hospital of Kenya was done using fibre-optic esophagogastroduodenoscopy. Of 66 African patients presenting with hematemesis and melena, a precise visual diagnosis was made in 89%. Duodenal ulcer was most common, accounting for 53%, but esophageal varices occurred in 20%.(More)
Sera from 48 Kenyan Africans with rheumatoid arthritis, 43 patients with other diseases, and 98 blood donors were tested for the presence of rheumatoid factor by latex fixation tests using human European, human African, and rabbit immunoglobulin, and a sheep cell haemagglutination test. In the patients with rheumatoid arthritis the frequency of rheumatoid(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)
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)