A BPMN extension to support discrete-event simulation for healthcare applications:an explicit representation of queues, attributes and data-driven decision points

Stakeholder engagement in simulation projects is important, especially in healthcare where there is a plurality of stakeholder opinions, objectives and power. One promising approach for increasing engagement is facilitated modelling. Currently, the complexity of producing a simulation model means that the ‘model coding’ stage is performed without the involvement of stakeholders, interrupting the possibility of a fully-facilitated project. Early work demonstrated that with currently-available software tools we can represent a simple healthcare process using Business Process Model and Notation (BPMN) and generate a simulation model automatically. However, for more complex processes, BPMN currently has a number of limitations, namely the ability to represent queues and data-driven decision points. To address these limitations, we propose a conceptual design for an extension to BPMN (BPMN4SIM) using Model Driven Architecture. Application to an elderly emergency care pathway in a UK hospital shows that BPMN4SIM is able to represent a more-complex business process

Frequency domain measurements of the fluorescence lifetime of ribonuclease T1.

Using multifrequency phase/modulation fluorometry, we have studied the fluorescence decay of the single tryptophan residue of ribonuclease T1 (RNase T1). At neutral pH (7.4) we find that the decay is a double exponential (tau 1 = 3.74 ns, tau 2 = 1.06 ns, f1 = 0.945), in agreement with results from pulsed fluorometry. At pH 5.5 the decay is well described by a single decay time (tau = 3.8 ns). Alternatively, we have fitted the frequency domain data by a distribution of lifetimes. Temperature dependence studies were performed. If analyzed via a double exponential model, the activation energy for the inverse of the short lifetime component (at pH 7.4) is found to be 3.6 kcal/mol, as compared with a value of 1.0 kcal/mol for the activation energy of the inverse of the long lifetime component. If analyzed via the distribution model, the width of the distribution is found to increase at higher temperature. We have also repeated, using lifetime measurements, the temperature dependence of the acrylamide quenching of the fluorescence of RNase T1 at pH 5.5. We find an activation energy of 8 kcal/mol for acrylamide quenching, in agreement with our earlier report