A Framework for Hazardous Materials Transport Risk Assessment

In this paper, we provide a framework for quantitative risk assessment in hazardous materials transport. We first outline a basic model where population centers are approximated by points on a plane with the assumption that in the case of an incident all residents in a population center will experience the same consequences. Different versions of this model have been used by other authors in the literature. This model may be valid if the hazardous materials route goes by small population centers. Then we extend this basic model to assess risks of shipping hazardous materials through large population centers that cannot be modeled as single points on a plane. In the extended model, large population centers are treated as two-dimensional objects on the plane, which allows for a more accurate treatment of consequences than the basic model. To the extent of our knowledge the extended model is novel. We provide numerical examples for both the basic and the extended models, and finish by discussing limitations of the suggested risk assessment framework.     

Designing Personalized Treatment: An Application to Anticoagulation Therapy

In this study, we develop an analytical framework for personalizing the anticoagulation therapy of patients who are taking warfarin. Consistent with medical practice, our treatment design consists of two stages: (i) the initiation stage, modeled using a partially‐observable Markov decision process, during which the physician learns through systematic belief updates about the unobservable patient sensitivity to warfarin, and (ii) the maintenance stage, modeled using a Markov decision process, during which the physician relies on his formed belief about patient sensitivity to determine the stable, patient‐specific, warfarin dose to prescribe. We develop an expression for belief updates in the POMDP, establish the optimality of the myopic policy for the MDP, and derive conditions for the existence and uniqueness of a myopically optimal dose. We validate our models using a real‐life patient data set gathered at the Hematology Clinic of the Jewish General Hospital in Montreal. The proposed analytical framework and case study enable us to develop useful clinical insights, for example, concerning the length of the initiation period and the importance of correctly assessing patient sensitivity.