Jonathan Unger

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We are developing a control program for a unique radiation therapy machine. The program is safety-critical, executes several concurrent tasks, and must meet real-time deadlines. Development employs both formal and traditional methods: we produce an informal speciication in prose (supplemented by tables, diagrams and a few formulas) and a formal description(More)
This report presents a formal (mathematical) speciication for the operator's console of a computer-controlled radiation therapy machine equipped with a multileaf collima-tor. This formal speciication, rather than the prose speciication, serves as the primary reference source for programming and test planning. Speciied functions include selecting treatment(More)
This report describes a new computer control system for a radiation therapy machine with an isocentric gantry and a multileaf collimator. It discusses the motivation and rationale for some of the features and development activities, and reports several measures of development effort, performance, and quality, determined after almost two years of operating(More)
We wrote a formal speciication in Z for the graphical user interface of a radiation therapy machine. We implemented our speciication in a Pascal dialect on a workstation that uses the X window system to manage the keyboard and display. We initially model the user interface as a collection of separate Z operation schemas corresponding to sections in the(More)
re social movements fated to become more conservative as they become more organ-ized? Weber offered a cogent explanation for why many social movement organizations follow this path. Modern organizations, he argued, inculcate in their members a bureaucratic orientation toward rules and organizational hierarchies ; this is especially true of organizational(More)
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