Visualization of particle interactions in granular media.

Interaction between particles in so-called granular media, such as soil and sand, plays an important role in the context of geomechanical phenomena and numerous industrial applications. A two scale homogenization approach based on a micro and a macro scale level is briefly introduced in this paper. Computation of granular material in such a way gives a deeper insight into the context of discontinuous materials and at the same time reduces the computational costs. However, the description and the understanding of the phenomena in granular materials are not yet satisfactory. A sophisticated problem-specific visualization technique would significantly help to illustrate failure phenomena on the microscopic level. As main contribution, we present a novel 2D approach for the visualization of simulation data, based on the above outlined homogenization technique. Our visualization tool supports visualization on micro scale level as well as on macro scale level. The tool shows both aspects closely arranged in form of multiple coordinated views to give users the possibility to analyze the particle behavior effectively. A novel type of interactive rose diagrams was developed to represent the dynamic contact networks on the micro scale level in a condensed and efficient way.

Moment invariants for the analysis of 2D flow fields.

We present a novel approach for analyzing two-dimensional (2D) flow field data based on the idea of invariant moments. Moment invariants have traditionally been used in computer vision applications, and we have adapted them for the purpose of interactive exploration of flow field data. The new class of moment invariants we have developed allows us to extract and visualize 2D flow patterns, invariant under translation, scaling, and rotation. With our approach one can study arbitrary flow patterns by searching a given 2D flow data set for any type of pattern as specified by a user. Further, our approach supports the computation of moments at multiple scales, facilitating fast pattern extraction and recognition. This can be done for critical point classification, but also for patterns with greater complexity. This multi-scale moment representation is also valuable for the comparative visualization of flow field data. The specific novel contributions of the work presented are the mathematical derivation of the new class of moment invariants, their analysis regarding critical point features, the efficient computation of a novel feature space representation, and based upon this the development of a fast pattern recognition algorithm for complex flow structures.

Self-concept in male and female adolescents with congenital heart disease.

Cognitive achievement, behavioural problems, and various dimensions of personality were assessed in 48 male and female patients with congenital heart disease (CHD) aged from 12 to 16 years in comparison to a control group. The CHD group showed a lower speed of cognitive processing but seemed to have less state-anxiety and to possess a higher superego strength. Male adolescents with CHD presented with a reduced perceived capacity and self-esteem. This was not true for adolescent girls with CHD. The negative self-concept of boys with CHD may be partly explained by reduced physical ability interfering with peer relationships.

Occlusion of the right subclavian artery after insertion of a transoesophageal echocardiography probe in a neonate.

We present a case of occlusion of the right arm's blood supply in a neonate with a lusorian artery, a rare anomaly of the right subclavian artery, after insertion of a transoesophageal echocardiography (TOE) probe and discuss the impact of a lusorian artery on intraoperative TOE monitoring.