Michalis Vaitis

Assessing bee species richness in two Mediterranean communities: importance of habitat type and sampling techniques

The decline of bees has raised concerns regarding their conservation and the maintenance of ecosystem services they provide to bee-pollinated wild flowers and crops. Although the Mediterranean region is a hotspot for bee species richness, their status remains poorly studied. There is an urgent need for cost-effective, reliable, and unbiased sampling methods that give good bee species richness estimates. This study aims: (a) to assess bee species richness in two common Mediterranean habitat types: semi-natural scrub (phrygana) and managed olive groves; (b) to compare species richness in those systems to that of other biogeographic regions, and (c) to assess whether six different sampling methods (pan traps, variable and standardized transect walks, observation plots and trap nests), previously tested in other European biogeographic regions, are suitable in Mediterranean communities. Eight study sites, four per habitat type, were selected on the island of Lesvos, Greece. The species richness observed was high compared to other habitat types worldwide for which comparable data exist. Pan traps collected the highest proportion of the total bee species richness across all methods at the scale of a study site. Variable and standardized transect walks detected the highest total richness over all eight study sites. Trap nests and observation plots detected only a limited fraction of the bee species richness. To assess the total bee species richness in bee diversity hotspots, such as the studied habitats, we suggest a combination of transect walks conducted by trained bee collectors and pan trap sampling.

The Callimachus approach to distributed hypermedia

We present the issues and design of the naming architecture of Callitnachus an open distributed hypermedia system.

Some Notes on Behavior in Structural Computing

Behavior has only recently received the attention of structural computing research. Thus, the exact relation of behavior to structure is to a large extent unspecified. Current structural computing research still views behavior as something that is orthogonal to structure: something that has to be added on top of it. In this paper, we attempt to create a framework to discuss the notions of structure, function and behavior. We argue that a structure exhibits behavior, behaviors effects function, and function enables purpose. Moreover, we point out propagation as an inherent behavioral capability of relationships. This discussion aims at providing the ground to recognize the variant and invariant behaviors found in structures.

Towards hypermedia support for database systems

Using a dynamic hypermedia engine (DHE), we propose to automate the following features for database systems, both on and off the Web. First we automatically generate links based on the databases relational (physical) schema and its original (non-normalized) entity-relationship specification. Second, the application developer can specify which kinds of database elements are related to diverse elements in the same or different database application, or even another software system. Our current DHE prototype illustrates these for a relational database management system. We propose integrating data warehousing applications into the DHE. We also propose incorporating data mining as a new kind of automated link generation. Passing the application element selected by a user, a data mining system that would discover interesting relationships for that element. DHE would then map each relationship to a link.

Building Hypertext Interfaces to Existing Relational Databases

This paper presents a methodology for constructing hypertext views over existing relational databases. First, the database semantics are extracted in the form of an EER schema, using database reverse engineering techniques. Then, the EER schema is used for the definition of the node and link types of hypertext views. This two-stage approach has the benefit that the hypertext designer considers only a conceptual model of the database. Moreover, the instances of node and link types are dynamically computed; no data replication takes place. An experimental set of tools that support the methodology has been developed and used in a realistic case study.

Broadening Structural Computing towards Hypermedia Development

The success of structural computing depends heavily on the degree such systems can support structuring tasks that are well known within the hypermedia community. In this paper we outline issues of hypermedia development from a structural computing point of view. Although such issues are addressed for the navigational domain, the need for hypermedia modeling and design in other hypermedia domains is left open to discussion.