Informatik

The pagination problem of complex documents is in placing text and floating objects on pages in such a way that each object appears close to, but not before, its text reference. Current electronic formatting systems do not offer the pagination quality provided by human experts in traditional bookprinting. One reason is that a good placement of text and floating objects cannot be achieved in a single pass over the input. We show that this approach works only in a very restricted document model; but in a realistic setting no online algorithm can approximate optimal pagination quality. Globally computing an optimal pagination critically depends on the measure of quality used. Some measures are known to render the problem NP-hard, others cause unwanted side effects. We propose to use the total number of page turns necessary for reading the document and for looking up all referenced objects. This objective function can be optimized by dynamic programming, in time proportional to the number of text blocks times the number of floating objects. Our implementation takes less than one minute for formatting a chapter of 30 pages. The results compare favorably with layouts obtained by Word, FrameMaker, or LATEX, that were fine-tuned by expert users.

Project MeDoc has built the nucleus of a digital library for computer science literature, including multimedia offerings. The library is operated as a network of distributed clients and servers and is available for use by the German academic community. A set of tools has been developed to administer journals and books as copyrighted material and to give users a uniform access to the library itself, as well as to other network-based information sources from the workplace. Processes and services have been introduced to add, store, retrieve documents to or from the library, and to account for use of licensed material. Initial usage patterns and user behaviour have been studied.

Architectural design patterns (ADPs) are architectural solutions to common architectural design problems. They are an important concept in software architectures used for the design and analysis of architectures. An ADP usually constrains the design of an architecture and, in turn, guarantees some desired properties for architectures implementing it. Sometimes, however, the constraints imposed by an ADP do not lead to the claimed guarantee. Thus, applying such patterns for the design of architectures might result in architectures which do not fulfill their intended requirements. To address this problem, we propose an approach for the verification of ADPs, based on interactive theorem proving. To this end, we introduce a model for dynamic architectures and a language for the specification of ADPs over this model. Moreover, we propose a framework for the interactive verification of such specifications based on Isabelle/HOL. In addition we describe an algorithm to map a specifi cation ...

The subcellular localization of a protein is an important aspect of its function. However, the experimental annotation of locations is not even complete for well-studied model organisms. Text mining might aid database curators to add experimental annotations from the scientific literature. Existing extraction methods have difficulties to distinguish relationships between proteins and cellular locations co-mentioned in the same sentence. LocText was created as a new method to extract protein locations from abstracts and full texts. LocText learned patterns from syntax parse trees and was trained and evaluated on a newly improved LocTextCorpus. Combined with an automatic named-entity recognizer, LocText achieved high precision (P = 86%±4). After completing development, we mined the latest research publications for three organisms: human (Homo sapiens), budding yeast (Saccharomyces cerevisiae), and thale cress (Arabidopsis thaliana). Examining 60 novel, text-mined annotations, we found...

Challenges like interrupted visualization and ar tifacts are common during interventionalsurgerywhileguidingmedicalinterventionaldevices(MIDs)such as needles, catheters, etc. This proclaims the need of efficient accessories for improvingsimultaneoustargetingandvisualizationofMIDsduringinterventional surgeries. Diagnostic devices are often used, but only visual perception is not enoughduetoimage-relatedshortcomings.Thisarticleproposesanovelapproach thatreadsaudiosignalsviamicrophoneattachedtotheproximalendofabiopsy needle to support verification and trackingduring a surgery.Aneedle tracking algorithmwasalso integrated forvisual supportof intervention.Thealgorithm acquirestheaudiosignalduetotissue-needleinteractionandsimultaneouslydetects the needle in the ultrasound frames using progressive regional properties. The proposedcombinationhasability tosolveproblem...

One of the most promising and challenging future uses of head-mounted displays (HMDs) is in applications where virtual environments enhance rather than replace real environments. To obtain an enhanced view of the real environment, the user wears a see-through HMD to see 3D computer-generated objects superimposed on his/her real-world view. This see-through capability can be accomplished using either an optical or a video see-through HMD. We discuss the tradeoffs between optical and video see-through HMDs with respect to technological, perceptual, and human factors issues, and discuss our experience designing, building, using, and testing these HMDs.

A virtual environment, which is created by computer graphics and an appropriate user interface, can be used in many application fields, such as teleopetution, telecommu-nication and real time simulation. Furthermore, if this environment could be shared by multiple users, there would be more potential applications. Discussed in this paper is a case study of building a prototype of a cooperative work environment using a virtual environment, where more than two people can solve pro-blemscooperatively, including design strategies and imple-mentirig issues. An environment where two operators can directly grasp, move or release stereoscopic computer graphics images by hand is implemented. The system is built by combining head position tracking stereoscopic displays , hand gesture input devices and graphics workstations. Our design goal is to utilize this type of interface for a future teleconferencing system. In order to provide good interac-tivity for users, we discuss potential bottlenecks and their solutions. The system allows two users to share a virtual environment and to organize 3-D objects cooperatively.