On implementations of loose abstract data type specifications and their vertical composition

In an approach for the implementation of loose abstract data type specifications that completely distinguishes between the syntactical level of specifications and the semantical level of models, vertical implementation composition is defined compatibly on both levels. Implementations have signatures, models, and sentences where the latter also include hidden components, which allows for useful normal form results. We illustrate the stepwise development of implementations as well as their composition by some examples and describe the incorporation of the concept into an integrated software development and verification system

Parameterization-by-use for hierarchically structured objects

A formal model for hierarchical objects is presented. The hierarchical structure between objects is defined by a general notion of use relationship. Used objects may be regarded as formal parameters leading to the definition of parameter applications and a new parameterization concept called parameterization-by-use. We study hierarchies with all applications and give a canonical closure construction to generate such hierarchies. We show how these consepts can be incorporated into a specification language for hierarchically structured objects

Hierarchical structures and dynamic parameterization without parameters

Hierarchical structuring and parameterization concepts are investigated. It is argued that such concepts can be studied independently of a particular domain of application and orthogonally to the design of the ‘flat’ objects. A dynamic parameterization concept which disposes of the static declaration of formal parameters is proposed and realized in a hierarchy definition language. The methods suggested are illustrated by applying them to algebraic specifications, and it is shown how the approach extends the notion of an institution by a general structuring and parameterization concept

Specification, horizontal composition and parameterization of algebraic implementations

Loose specifications of abstract data types (ADTs) have many non-isomorphic algebras as models. An implementation between two loose Specifications should therefore consider many abstraction functions together with their source and target algebras. Just like specifications are stepwise refined to restrict their class of models, implementations should be stepwise refinable to restrict the class of abstraction functions. In this scenario specifications and implementations can be developed interwovenly. We suggest to have implementation specifications analogously to loose ADT specifications: Implementations have signatures, models, axioms and sentences thus constituting an institution. Implementation specifications are the theories of this institution and refinements between implementation specifications are its theory morphisms. In this framework, implementations between parameterized specifications and horizontal composition of implementations turn out to be special cases of the more powerful concept of parameterized implementations, which allow to instantiate an implementation by substituting a subimplementation by another implementation

Blended Learning in der Universität : Eine Fallstudie zur Vorbereitung und Durchführung

Die Professur für BWL und Wirtschaftsinformatik am Fachbereich Wirtschaftswissenschaften der Justus-Liebig-Universität Gießen ist für die Grundstudiumsvorlesung \u27Grundzüge der Wirtschaftsinformatik\u27 und das begleitende PC-Tutorium zur verantwortlich, das jedes Wintersemester (WS) angeboten wird. Die Lerninhalte des vorlesungsbegleitenden PC-Tutoriums sind neben dem Vorlesungsstoff für die Abschlußklausur am Ende des WS relevant. Im WS 04/05 wurden ca. 480 Studierende auf 22 Präsenztutoriengruppen verteilt – im WS 05/06 ist die gleiche Studierendenzahl zu verzeichnen. Im WS 04/05 fand das PC-Tutorium letztmals als reine Präsenzveranstaltung im PC-Pool des FB 02 statt, der mit seinen PC-Arbeitsplätzen die Teilnehmerzahl einer Tutoriumsgruppe auf 24 beschränkt. Für die 22 PC-Tutorien des WS 04/05 wurden elf studentische Hilfskräfte über 4 Monate (November bis Februar) als Präsenztutoren mit je zwei wöchentlichen Tutoriumssitzungen beschäftigt. Um diesen beträchtlichen Personalmittelaufwand deutlich zu reduzieren, wird das PC-Tutorium im WS 05/06 im Rahmen eines Blended-Learning-Konzeptes über ein Mixtum von Präsenzelementen und Web-Based-Trainings angeboten. Im vorliegenden Arbeitspapier wird dieses Konzept theoretisch fundiert, entwickelt und seine Umsetzung in die Praxis beschrieben

Erstellung eines BAC/PAC-Contigs auf SSC 6q1.2 und vergleichende Analyse dieser Genomregion

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Nitrogen fixation in eukaryotes – New models for symbiosis

BACKGROUND: Nitrogen, a component of many bio-molecules, is essential for growth and development of all organisms. Most nitrogen exists in the atmosphere, and utilisation of this source is important as a means of avoiding nitrogen starvation. However, the ability to fix atmospheric nitrogen via the nitrogenase enzyme complex is restricted to some bacteria. Eukaryotic organisms are only able to obtain fixed nitrogen through their symbiotic interactions with nitrogen-fixing prokaryotes. These symbioses involve a variety of host organisms, including animals, plants, fungi and protists. RESULTS: We have compared the morphological, physiological and molecular characteristics of nitrogen fixing symbiotic associations of bacteria and their diverse hosts. Special features of the interaction, e.g. vertical transmission of symbionts, grade of dependency of partners and physiological modifications have been considered in terms of extent of co-evolution and adaptation. Our findings are that, despite many adaptations enabling a beneficial partnership, most symbioses for molecular nitrogen fixation involve facultative interactions. However, some interactions, among them endosymbioses between cyanobacteria and diatoms, show characteristics that reveal a more obligate status of co-evolution. CONCLUSION: Our review emphasises that molecular nitrogen fixation, a driving force for interactions and co-evolution of different species, is a widespread phenomenon involving many different organisms and ecosystems. The diverse grades of symbioses, ranging from loose associations to highly specific intracellular interactions, might themselves reflect the range of potential evolutionary fates for symbiotic partnerships. These include the extreme evolutionary modifications and adaptations that have accompanied the formation of organelles in eukaryotic cells: plastids and mitochondria. However, age and extensive adaptation of plastids and mitochondria complicate the investigation of processes involved in the transition of symbionts to organelles. Extant lineages of symbiotic associations for nitrogen fixation show diverse grades of adaptation and co-evolution, thereby representing different stages of symbiont-host interaction. In particular cyanobacterial associations with protists, like the Rhopalodia gibba-spheroid body symbiosis, could serve as important model systems for the investigation of the complex mechanisms underlying organelle evolution

Assessment of Quay and Yard Transshipment Operations Under Proximity Limitations in Multi-Terminal Container Ports

The assignment of storage locations and space has a considerable impact on the performance of container terminals. This holds especially in multi-terminal transshipment ports where the planning of inbound and outbound container flows needs to consider space limitations and travel distances for reallocations, causing both intra- and inter-terminal transports. Thus, in this work, we study the impact of closeness limitations on quay and yard areas when conducting transshipment operations at multi-terminal transshipment ports. In doing so, a mathematical formulation and several scenarios covering different distance policies for limiting the allocation of containers before vessel loading or unloading operations are assessed. At a tactical level, this paper provides insights on assignment decisions while assessing distance-based policies that can be incorporated in practice

SPESY : Eine integrierte Softwareentwicklungs- und Verifikationsumgebung

SPESY ist die Unterstützungsumgebung eines integrierten Softwareentwicklungs- und Verifikationssystems. Nach einer Einführung werden alle dem SPESY-Benutzer zur Verfügung stehende Kommandos beschrieben und das Verhalten des Systems an Hand von Dialogprotokollen erläutert.SPESY is the support environment of an integrated software development and verification system. Following an introduction, all commands being available for the user are described. The system's behaviour is illustrated using session protocols

Einbindung des ECOLOG-Modells "E3Net" und Integration neuer methodischer Ansätze in das IKARUS-Instrumentarium (ECOLOG II)

Ziel des Forschungsvorhabens „Einbindung des ECOLOG-Modells ‘E³Net’ und Integration neuer methodischer Ansätze in das IKARUS-Instrumentarium (ECOLOG II)' war es, veschiedene Modellbildungsansätze und Werkzeuge für die energiewirtschaftliche Analyse zu einem Instrumentarium zusammenzufügen. Dazu wurde auf die Projekte IKARUS „Instrumente für Klimagasreduktionsstrategien' und ECOLOG „Entwicklung eines Computermodells mit linearer Optimierung zur Abbildung eines regionalisierten Energiesystems am Beispiel Gesamtdeutschlands' aufgebaut. Das Projekt ECOLOG II umfaßt Weiterentwicklungen in den folgenden sechs Aufgabenbereichen: (1) Integration von E³Net in das IKARUS-Instrumentarium; (2) Nichtlineare Modellansätze für E³Net; (3) Makroökonomische Erweiterung von E³Net; (4) Entwicklung und Anwendung eines multisektoralen Energiewirtschaftsmodells NEWAGE; (5) Entwicklung eines Simulationsansatzes für Energiesystemmodelle PlaNet; (6) Erweiterung der Analysemöglichkeiten von NetWork. Im Rahmen des Forschungsvorhabens wurden eine Kopplung der FIZ-Technik-Datenbank an die Datenbank NetWork, eine Verbindung der FIZ-LP-Datenbank mit NetWork, eine Überführung des IKARUS-LP-Datensatzes in eine Fallstudie für das optimierende Energiesystemmodell E³Net, ein optimierendes Energiesystemmodell mit preiselastischer Nachfrage E³Micro, ein Gleichgewichtsmodell NEWAGE, das prototypisch ein prozeßtechnisches Energieversorgungsmodell in ein übergeordnetes gesamtwirtschaftliches Modell integriert, ein Simulationsmodell PlaNet sowie ein Netzwerkdesigner und -analyst (NDA) realisiert und durch exemplarische Fallstudien, die im Kontext des IKARUS-Instrumentariums stehen, getestet