Towards Analyzing and Synthesizing Protocols

The production of error-free protocols or complex process interactions is essential to reliable communications. This paper presents techniques for both the detection of errors in protocols and for prevention of errors in their design. The methods have been used successfully to detect and correct errors in existing protocols. A technique based on a reachability analysis is described which detects errors m a design. This "perturbation technique" has been implemented and has successfully detected inconsistencies or errors in existing protocol designs including both X.21 and X.25. The types of errors handled are state deadlocks, unspecified receptions, nonexecutable interactions, and state smbiguities. These errors are discussed and their effects considered. An interactive design technique is then described that prevents design errors. The technique is based on a set of production rules which guarantee that complete reception capability is provided in the interacting processes. These rules have been implemented in the form of a tracking algorithm that prevents a designer from creating unspecified receptions and nonexecutable interactions and monitors for the presence of state deadlocks and ambiguities.     

A new treatment procedure in stress urinary incontinence (SUI): suburethral prolene sling under local anesthesia

An original technique for the treatment of USI under local anaesthesia is described. It consists of insertion of a Prolene sling under the middle part of the urethra. This sling is not placed under tension, but simply supports the suburethral region. In a series of 22 patients without prolapse requiring surgical correction and presenting USI confirmed by clinical examination, 20 were totally cured by this technique and the postoperative voiding flow rate was not decreased. This technique therefore appears to be simple, non-dysuric and effective.     

Reliability Optimization in Multiloop Communication Networks

The rapidly growing interest in loop communication systems is accompanied by an increasing need to improve their reliability and reduce their vulnerability. This paper analyzes the reliability of multistage loop networks. Analytical expressions for topologies exhibiting maximum availability are obtained in terms of key-component down-time ratios. These optimal topologies are expressed in terms of terminal connections per subloop and subloops per higher level loops. The availability performance of these optimal topologies is investigated. Finally, the availability improvement obtainable by going to higher stage loop networks is investigated.