A model of breast carcinogenesis and recurrence after radiotherapy

Breast conserving surgery and adjuvant radiotherapy are the standard treatment of early stage breast cancer. We present simulations of a mathematical model of breast carcinogenesis and identify fields of mutated cells in the breast (formed during puberty or pregnancy) as a potential source of local recurrence after treatment with radiotherapy. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

The smoothed number of Pareto-optimal solutions in bicriteria integer optimization

Mathematical Programming - A well-established heuristic approach for solving bicriteria optimization problems is to enumerate the set of Pareto-optimal solutions. The heuristics following this...     

Self-assembling of chain molecules in low dimensions: A Monte Carlo study

We studied the self-assembling of linear chain molecules in insoluble monolayers due to attractive interactions. We used lattice Monte Carlo simulations in a two-dimensional system. The molecules consist of segments occupying adjacent lattice sites. The head segments are confined to move along a line whereas the chain segments can arrange in a plane above the heads. Only one interaction parameter is applied. At high densities and small interaction energy the system shows percolation behavior. At moderate and small densities it can be characterized by a monotonous cluster size distribution. Self-assembling occurs at small densities for strong attractive interactions. The corresponding cluster size distributions indicate preferred cluster sizes which depend upon density and interaction strength. With increasing density the clusters grow. The internal cluster structure depends on the cluster size and the interaction parameter. The clusters tend to minimize their total energy. Molecules at cluster margins contribute less to the cluster energy and are mainly disordered. They cause that the cluster properties strongly depend on the cluster size. Large clusters only have minimum energy if the molecules in the cluster are in stretched-out conformation. With decreasing interaction strength the clusters get disordered thereby producing less energy-minimized domain boundaries.     

Monoaryl-Substituted Norbornadiene Photoswitches as Molecular Solar Thermal Energy Storage Compounds: Synthesis and Investigation

In the search for improved photochromic systems that may be used for the efficient reversible conversion of light into chemical energy, eight monoaryl-substituted norbornadienes are presented, which carry naphthyl, anthracenyl, or donor-acceptor-phenyl substituents to establish an extended π system. The substrates were synthesized by Suzuki-Miyaura coupling reactions, and their absorption properties, the key parameters of the photochromic equilibrium, and the energy storage density of the quadricyclane products were examined. It was observed that these compounds have favorable properties for chemical energy storage. Specifically, 2-(1-naphthyl)norbornadiene showed a pronounced red shift of the absorption, a long half-life (35 d) and a relatively high energy storage density (361 KJ/Kg) of the respective quadricyclane. Therefore, the so far neglected monoaryl-norbornadienes represent a useful and complementary class of compounds that should be considered in the development of efficient molecular solar thermal energy storage (MOST) compounds, which can reversibly convert sunlight into chemical energy.