Antitumor activity has been demonstrated against Ehrlich, L.1210 leukemia, and to a less extent against TA3 mammary carcinoma ascites cells by a group of short chain fatty acids. Activity is confined to the finely suspended ester forms of the acids and seems to be associated with the carboxyl end of the molecule. The compounds appear to have no effect upon the production of normal white blood cells.

Planning to deliver excellent service by balancing demand and supply in the context of a set of business policies is not an easy task. How an organisation dynamically deploys its resources and people in response to external demand determines how quickly an organisation can deliver service to its customers. To model this you need to represent the flows of work through the organisation, the resources available and the relationships between intake of work, outputs, workstacks and time-to-deliver. You also need to understand how flexible the organisation is in dealing with uncertain and fluctuating intakes and the policies the organisation adopts in deploying this flexibility. We have constructed a model of the operations of a telecommunications company that incorporates all of these elements using the system dynamics approach. This paper describes how the model is constructed and gives examples of how it can be used to explain observed behaviours. It also explains how it has been used to guide decision making on resource requirements and the optimum mix between proactive and reactive approaches to service assurance. IntroductionFor a service company, the speed with which it can respond to demands, such as for new orders for installation and reported faults, is a key performance metric. It is a key driver for customer satisfaction because the customer only sees two main aspects of the overall process -how quickly the job was completed, and the quality of that work.Service delivery is a complex interplay between the intake of work and the deployment of resources to carry it out. Performance depends on how the different work areas are linked, the resource pools that are available to carry out the work, the flexibility there is in moving resources from one work area to another, and the speed of response to changing demand as management seeks to maintain control over service levels. Moreover, the amount of incoming work may itself depend on how much work is carried out elsewhere in the organisation and therefore on the resource levels in other areas. Thus, within the overall system there are 'balancing' processes that seek to keep things under control as well as 'reinforcing' processes that tend to make everything spiral out of control.The system dynamics approach [1,2] is ideally suited to model these types of issues, where complex interactions between the components of the service operations determine how performance changes over time with several interacting feedback processes [3]. This was the rationale behind the development of a system dynamics model aimed at guiding strategic decisions related to the access operations of BT at a time when they are being established as a separate regulated business ('Openreach' [4]). The modelling team worked closely with senior management and planning teams to help address a range of questions.• Will existing resource levels deliver the desired service delivery performance?• What would be required to improve performance? • What would happen if resource levels were reduced?• What i...

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