From Sequential Layers to Distributed Processes, Deriving a minimum weight spanning tree algorithm

Analysis and design of distributed algorithms and protocols are difficult issues. An important cause for those difficulties is the fact that the logical structure of the solution is often invisible in the actual implementation. We introduce a framework that allows for a formal treatment of the design process, from an abstract initial design to an implementation tailored to specific architectures. A combination of algebraic and axiomatic techniques is used to verify correctness of the derivation steps. This is shown by deriving an implementation of a distributed minimum weight spanning tree algorithm in the style of [GHS]

Prevalence of co-morbidity and its relationship to treatment among unselected patients with Hodgkin's disease and non Hodgkin's lymphoma, 1993-l996

A population-based series of patients with cancer is likely to comprise more patients with serious co-morbidity than clinical trials because of restrictive eligibility criteria for the latter. Since co-morbidity may influence decision-making, we studied the age-specific prevalence of co-morbidity and its relationship to applied treatment. Data on all 194 patients with Hodgkin's disease (HD) and on 904 patients with non-Hodgkin's lymphoma (NHL) diagnosed between 1993 and 1996 were derived from the Eindhoven Cancer Registry. In the age-group below 60 years, 87% of patients with HD and 80% with NHL did not have a co-morbid condition. The prevalence of serious co-morbidity was 56% for patients with Hodgkin's disease who were 60 years and over and 43% and 61% for non Hodgkin patients who were 60-69 years and 70 years and over, respectively. The most common co-morbid conditions were cardiovascular disease (18%), hypertension (13%), chronic obstructive pulmonary disease (COPD; 13%), and diabetes mellitus (10%) for elderly Hodg kin's patients. For non-Hodgkin's patients of 60-69 years and 70 years and over, cardiovascular disease (15 and 22%, respectively), hypertension (14 and 14%, respectively), COPD (6 and 10% respectively), and diabetes mellitus (8 and 10% respectively) were the most prevalent co-morbid conditions. The presence of co-morbidity was not related to stage or grade of disease at diagnosis. In the presence of co-morbidity, 50% less chemotherapy was administered to elderly patients with Hodgkin's disease and 10-15% less to elderly patients with non-Hodgkin's lymphoma. The presence of co-morbidity was associated with a decreased overall survival within the first 4 months after diagnosis in both Hodgkin's disease and non-Hodgkin's lymphoma for all age-groups. In conclusion, serious co-morbidity was found for more than half of all lymphoma patients who were 60 years and older. Elderly patients with serious co-morbidity received chemotherapy less often, which is likely to affect survival adversely, as was indicated by a decreased survival within the first 4 months after diagnosis