Departments of Chemistry,
PO BOX 225, Whiteknights,
The University of Reading,
Reading, UK, RG6 6AY
email: {shirley.williams, g.e.fagg}@reading.ac.uk
The uptake of oxygen by blood is expressed experimentally as percentage saturation of blood against oxygen partial pressure. We wished to model the oxygenation uptake at the molecular level as a discrete event computer simulation. It was neces- sary to experiment with the simulation to determine the number of events and their associated parameters. A simple graphical user interface was developed that served as a workbench for running such simulations. The user can speculate on a process, quickly obtain the initial approximations, compare these with measured results and refine the original speculations.
Each experiment involved setting up a Monte Carlo simulation, that was "speeded up" by using PVM to spread the work across a distributed network of workstations. While a simulation was running the graphical user interface could be used to alter parameters and start other simulations that could be executed simultaneously, using a refined version of the PVM spawning procedure to ensure work was always distrib-uted to the least loaded machines in the cluster.
The workbench and corresponding PVM programs were designed so that the number of parameters for a particular model could be dynamically set at run time and varied from one experiment to the next. The number of runs per simulation, the number of processors and a variety of other parameters could also be dynamically changed between experiments, from the graphical user interface.
We experimented with data for blood from various products including: stripped human hemoglobin and shrimp hemocyanin. It was found in each instance that there was a three- or four-tuple of numbers associated with each molecule. Each of the numbers was associated with a pressure at which oxygenation would occur. The first representing a range 0 to infinity, the others representing smaller ranges between 0 and 1. For each number a "power" factor indicated the spread of numbers and a mul-tiplier served to match the units measured.
Using PVM we have developed a workbench that allows interactive investigation of the oxygenation process, using the spare capacity available across a distributed network.