Hans Jürgen Baur

VIRIM: a massively parallel processor for real-time volume visualization in medicine

Architecture and applications of a massively parallel processor are described. Volumes of 256×256×128 voxels can be visualized at a frame rate of 10 Hz using volume oriented visualization algorithms. A prototype of the scalable and modular system is currently set up. 3D rotation around an arbilrary rotation axis, perspective, zooming, and arbilrary gray value mapping are provided in real-time. Multiuser access over high-speed networks is possible. A volume oriented visualization algorithm is used that is tailored to the requirements in medicine [5]. With this algorithm, small structures of a size down to the pixel resolution, and structures without defined surfaces can be visualized as well as semitransparent objects. One application of the system is therapy planning in heart surgery.

The Heidelberg ray tracing model

The Heidelberg ray tracing model, developed especially for visualization of medical images, is based on a global illumination model and contains a number of application-specific assumptions. It simulates the projection of a scene with well-defined lighting. A detailed description of the model follows an overview of existing and competing illumination procedures. >

Generation‐dependent control mechanisms in cell proliferation and differentiation—the power of two

Abstract. There is evidence that the proliferation of cells is controlled by the number of divisions after leaving a multi‐potent (stem) cell. A detailed study of the growth of tissue in the small intestinal tract, more precisely the growth of crypts and villi, suggests that not only the proliferation but also the differentiation of cells obey the same biological law. We postulate a theory of a cellular internal control mechanism: the cell‐generation control of differentiation and proliferation. This basic mechanism, together with extemal influences, determines the kinetic behaviour of the crypt‐villus system.

Virim: A massively parallel processor for real-time volume visualization in medicine

Abstract Architecture and applications of a massively parallel system currently developed are described, which allows real-time visualization using volume oriented visualization algorithms. Volumes of 256 × 256 × 128 voxels can be visualized with a frame rate of 10 Hz. The system is scalable and modular, and will allow a multi-user access over high-speed networks. 3D-rotation around arbitrary rotation axis, perspective, zooming and arbitrary grey value mapping are provided in real-time. A volume oriented algorithm is used that is tailored to the requirements in medicine [H.-P. Meinzer et al., IEEE Comp. Graph. Appl. , 34 (Nov. 1991)]. With this algorithm, small structures without defined surfaces, e.g. , tumours, can be visualized as well as semi-transparent objects. One planned application of the system is heart surgery.

Modellierung der Steuerungsmechanismen im Darmepithel

Es wird ein objektorientiertes Simulationsmodell der intestinalen Darmkrypte vorgestellt, mit dem die komplexen Steuerungsmechanismen im Darmepithel modelliert werden konnen. Dabei wird das zu untersuchende biologische Objekt in seine Grundprozesse (‚basic tasks‘, hier Zellen) aufgespalten, die gemeinsam das komplexe biologische Verhalten ergeben. Es wurde ein Satz von Hypothesen uber die Proliferationskontrolle im Dunndarmepithel formuliert und im Simulationsexperiment getestet. Das beobachtete Modellverhalten legt fur die Regulation der Wiederherstellung des stabilen Gleichgewichts des intestinalen Zeltverbandes nach einer cytotoxischen Storung ([3]) einen inhibitiven Kontrollmechanismus nahe.