rom the beginning, hypermedia application design has been drii'en primarily by technological innovations and constrained by technical feasibility. For the last few years, however, usability methods and results from human factors research have been gaining mon; influence [17]. Despite this trend toward user-oriented development procedures, issues of cognition and human information processing still are widely neglected and barely influence hypermedia design.

INTRODUCTIONDiscussing relevant issues for the next generation of hypermedia systems, Halasz [Hala88] provides also a classification along the following three dimensions: scope, browsing vs. authoring, and target task domain. In this paper, we will especially discuss aspects of the second dimension focussing on support for idea processing and authoring in hypertext systems. Although one cannot classify existing systems by assigning them exclusively to one category of this dimension1 hypertext systems are primarily discussed from the reading and browsing point of view and as support for retrieval. This is also reflected in attempts to transform existing (linear) text sources into hypertext structures in order to pro& from their additional interactive branching capabilities.On the other hand, if one really wants to make use of the full concept of hypertext structures as described by Conklin [ConkS7], this offers new and exciting possibilities for writing and for ways to support this activity. From our point of view [Stre88bl, writing is a complex problem solving and design activity with multiple constraints. The final product -in terms of a hyperdocument -can be viewed as an externalized representation of internal knowledge structures which have been developed by the author. Thus, authoring tools which are especially geared to the preparation of hyperdocuments will offer much better facilities for conveying the message and intention of authors. This way, they can communicate knowledge in a format which is closer to their knowledge structures than it was possible with traditional documents. Integrating additional information about the author's intentions and knowledge structure and shipping it to the reader as part of an electronic document facilitates more comprehensive processing on the recipient's side. It implies that documents produced with these tools keep authors' knowledge structures alive by preserving their argumentation and rhetorical structures which then can be used for subsequent processing. This improves not only reception by human readers but also by text analysis components for machine translation or automated abstracting. While it is very difficult today to analyse argumentative and rhetorical aspects of natural language texts, these documents would contain this information explicitly. We will provide examples of this additional information when discussing the activity and document type "argumentation" which we selected as our task domain.Another starting point for our research is the observation that almost all hypertext systems are -especially with respect to authoring -passive systems, i.e. they do not offer active (intelligent) support to the author by providing feedback, advice, or guiding. Of 1 A clearcut distinction has been employed only with the separation of Concordia and the Document Examiner lJValk871. Hypertext '89 Proceedings 343 November 1989course, the realization of this goal requires the integration of knowledge-based capabilities in a hypertext system. This implies that the arc...

Controlling human-to-human tuberculosis (TB) transmission is key for achieving the targets of the End TB Strategy set by the World Health Organization (WHO) [1, 2]. Stopping TB transmission, in large cities especially, is a challenging top priority worldwide [3]. Metropolitan areas have higher TB case notification rates than the rest of a country, as they concentrate high-risk groups, such as homeless people, drug users and migrants often from (other) high TB incidence settings. Opportunities for transmission are amplified by population density and complex social interactions, regularly leading to large, temporally extended transmission networks [3]. Targeted interventions to interrupt transmission require the combination of effective genotyping of TB strains with enhanced epidemiological investigation. While classic IS6110 DNA fingerprinting and 24-locus MIRU-VNTR (mycobacterial interspersed repetitive units-variable number of tandem repeats) typing provide standardised and easily computable typing results with an online nomenclature system, several studies have now demonstrated that whole-genome sequencing (WGS) has a superior discriminatory power, allowing for an unparalleled resolution of outbreak strains [4-10]. However, predictivity of WGS for detecting transmission in metropolitan areas has not yet been quantified versus most deterministic references, i.e. tangible epidemiological links identified by ad hoc investigation, at extended time and population scales.

Research on understandinglinear texts has shown that comprehension and navigation mainly depend on the reader's ability to construct a coherent mental representation. While the author of a traditional document can use a variety of structural cues to support his readers in building up such a representation, the author of a hyperdocument faces a new problem. If he wants to ensure that his readers understand the entire hyperdocument as a coherent entity, he needs means to indicate its structure in a comprehensible way. In this paper, we propose a construction kit which provides dedicated design objects for this purpose. The design objects can be characterized as building blocks for three functionally different components of a hyperdocument: its content part, organizational part, and presentation part. In addition to the design objects, we propose some design rules which should guide the construction of coherent hy~rdocuments. KEYWORDSDesign of hyperdocuments, coherent hyperdocuments, rhetorics of hypertext, hyperdocument construction kit, Iabelled links, composite nodes, navigation, comprehension of hyperdocuments.

ZusammenfassungZiel der Umgebungsuntersuchung bei Tuberkulose ist neben der aktiven Fallfindung das Aufdecken von Infektionsketten sowie die Verhütung der Weiterverbreitung der Erkrankung. Dabei ist eine sorgfältige Auswahl der Kontaktpersonen notwendig, die sich nach Art und Dauer des Kontaktes richtet, um möglichst frisch Infizierte zu identifizieren und so den Nutzen einer anschließenden präventiven Therapie zu erhöhen und unnötige Testungen von Personen ohne Ansteckungsrisiko zu vermeiden. Seit der letzten Überarbeitung der Empfehlungen zur Umgebungsuntersuchung hat sich die Datenlage zum Einsatz von Interferon-y release-Assays (IGRAs) bei Kindern weiterhin verbessert. Diese werden bevorzugt in der Umgebungsuntersuchung von erwachsenen Kontaktpersonen eingesetzt. Für Kinder unter 15 Jahren können sowohl IGRAs wie auch weiterhin der Tuberkulin-Hauttest gleichwertig verwendet werden. Als präventive Therapie bei nachgewiesener Infektion werden Rifampicin für 4 Monate, Rifampicin und Isoniazid für 3 Monate oder aber Isoniazid für 9 Monate empfohlen.Ausführlich wird auf die Durchführung der Umgebungsuntersuchung in verschiedenen Altersgruppen sowie rechtliche Rahmenbedingungen und sozialmedizinische Aspekte und Herausforderungen eingegangen. Zusätzlich werden Sonderfälle, wie die Umgebungsuntersuchung in Kitas, Schulen oder in anderen Gemeinschaftseinrichtungen, separat dargestellt.