Abstract
In the present article we model the treatment of mechanically ventilated patients with nosocomial pneumonia using a generalized net. The model can be used by clinicians for diagnosis and clinical and microbiological follow-up of nosocomial pneumonia, to the decision to change the ventilator regime, to begin weaning from mechanical ventilation, or to stop the weaning trials.

Abstract
The lack of dynamic double-side regulation models for E-Marketplaces is a main reason for their lack of success as advanced open trading places.In this paper, a new model - DYNEX - is developed to generate homogeneous markets of goods or services and to optimize for each homogeneous market the trading price and the negotiation process between buyers and sellers.

Abstract
As new standards for technology specifications related to XML are unveiled, and stable tools to implement them become available, the widespread usage of XML as an universal format for data exchange between heterogeneous systems (using the Internet), will increasingly become a reality. Therefore, in order to deal efficiently with the large amounts of XML data that will be generated in the near future it is imperative to find efficient alternatives for the storage and management of this special kind of data. For that matter, object-oriented databases seem to be a good alternative. In this paper, we begin with an analysis of the different alternatives available to store and manage XML data. After that, we concentrate our attention on the Object-Oriented (OO) database approach and, in that context, we present a first set of rules that allow the translation from a simple database schema specified in ODL (Object Definition Language) into a schema specified in XML-SCHEMA. In the near future we intend not only to expand this set with new rules that will handle other, more complex, OO modeling constructs, but also to create another set Of transformation rules to work the other way round (i. e. from XML-SCHEMA to ODL). Our aim is to cover all the possible modeling situations one may come across in OO database schemas specified in ODL.

Abstract
The XML (eXtensible Mark-up Language), proposed by the W3C (World Wide Web Consortium) as the new standard for data representation and exchange in the Internet, is a document mark-up (meta) language that seems adequate to the needs of today's World Wide Web. With the proliferation of XML documents in the Web, it is necessary to store and query them efficiently. In this article, it is our purpose to investigate the different approaches currently available to the storage and management of XML data. Moreover, we intend to analyse the main characteristics of some of the XML query languages, which have been proposed both by the Database and Internet communities, namely XML-QL, XQL, Quilt, and Xquery. The latter has been proposed by the W3C Query Working Group with the purpose of providing a standard for a XML query language. We believe that a query language such as Xquery will certainly accelerate the utilization of XML as an alternative approach to data storage, since it will make possible to interrogate, efficiently and in unpredictable ways (queries ad hoc), XML documents.

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