Comparison of the accommodation theories of Coleman and of Helmholtz by finite element simulations

Purpose: The accommodation process of the human eye is still a controversial subject. Coleman assumes that the lens, together with the zonula fibers, forms a diaphragm which is held in a catenary shape due to the pressure difference between the aqueous and vitreous body of the lens. The aim of the paper is to compare the results of two simulations (according to the Helmholtz and to the Coleman theories) with ultrasonographic data. Methods: An axisymmetric static finite element model of the lens was generated using the literature data for geometry, material properties and loads. The refractive power of the lens was calculated for two different ages (29 and 45 years). Results: The application of a pressure to the posterior lens surface did not yield an increase in refractive power change during accommodation. Rather a decrease in accommodation related refractive power was found. Conclusions: Physiologically relevant refractive power changes are obtained by a simulation in accordance with the Helmholtz theory. A simulation in accordance with the Coleman theory does not yield physiological values of refractive power change

Towards an energy aware DBMS: energy consumptions of sorting and join algorithms

Database management systems comprise various algorithms for efficiently retrieving and managing data. Typically, algorithm efficiency or performance is correlated with execution speed. However, the uptime of battery powered mobile- and embedded systems strongly depends on the energy consumption of the involved components. This paper reports our results concerning the energy consumption of different implementations of sorting and join algorithms. We demonstrate that high performance algorithms often require more energy than slower ones. Furthermore, we show that dynamically exchanging algorithms at runtime results in a better throughput

Simulator adaptation at runtime for component-based simulation software

Component-based simulation software can provide many opportunities to compose and configure simulators, resulting in an algorithm selection problem for the user of this software. This thesis aims to automate the selection and adaptation of simulators at runtime in an application-independent manner. Further, it explores the potential of tailored and approximate simulators - in this thesis concretely developed for the modeling language ML-Rules - supporting the effectiveness of the adaptation scheme.Komponenten-basierte Simulationssoftware kann viele Möglichkeiten zur Komposition und Konfiguration von Simulatoren bieten und damit zu einem Konfigurationsproblem für Nutzer dieser Software führen. Das Ziel dieser Arbeit ist die Entwicklung einer generischen und automatisierten Auswahl- und Adaptionsmethode für Simulatoren. Darüber hinaus wird das Potential von spezifischen und approximativen Simulatoren anhand der Modellierungssprache ML-Rules untersucht, welche die Effektivität des entwickelten Adaptionsmechanismus erhöhen können

Transition metal-catalyzed carbonylation of nitrogen-containing heterocycles via C-H activation

The dissertation is mainly concerned with the development of transition metal-catalyzed carbonylation of nitrogen-containing compounds via C-H activation. We have described a palladium-catalyzed carbonylation of aromatic C-H bonds with alcohols using Mo(CO)6. We synthesized 3-methyleneisoindolin-1-ones and 2-phenylisoindolin-1-ones via C-H carbonylation using Mo(CO)6. A convenient procedure for the synthesis of 3-acylindoles has been established via C-H carbonylation. Furthermore, we have described a copper-catalyzed double carbonylation reaction using C6O6∙8H2O