Measurement of a low-absorption sample of OH-reduced fused silica

Low-absorption optics made of OH-reduced fused silica are a key technology for future gravitational wave detectors such as the Advanced LIGO. We developed a sensitive method to measure the absorption inside the beam splitter of the GEO 600, taking advantage of the effect of thermal lensing. Using this method, we derived a bulk absorption of less than 0.25 ppm/cm for a piece of Suprasil 311 SV at a wavelength of 1064 nm. To the best of our knowledge, this is the lowest value of light absorption inside fused silica reported so far in the literature.     

Electron transfer dynamics of bistable single-molecule junctions

We present transport measurements of single-molecule junctions bridged by a molecule with three benzene rings connected by two double bonds and with thiol end-groups that allow chemical binding to gold electrodes. The I-V curves show switching behavior between two distinct states. By statistical analysis of the switching events, we show that a 300 meV mode mediates the transition between the two states. We propose that breaking and reformation of a S-H bond in the contact zone between molecule and electrode explains the observed bistability.     

Polymer Films Composed of Surface‐Bound Nanofilaments with a High Aspect Ratio,Molecularly Imprinted with Small Molecules and Proteins

Hierarchically nanostructured materials that combine two or more levels of structuring and that exhibit a combination of useful features have gained considerable interest over recent years. Here, the generation of surface‐bound nanofilaments with a high aspect ratio by nanomolding on a nanoporous template surface is described. The filaments, at the same time, carry molecularly imprinted binding sites. The dye fluorescein and the protein myoglobin are used as model templates for imprinting. The surfaces exhibit specific binding as revealed by fluorescence microscopy. The wetting properties of the surfaces depend on the dimensions of the nanofilaments and on the nature of the polymer. It is believed that these materials can potentially be useful for applications in biosensors and biochips.     

Specifying the dynamic behavior of management systems

Decision making in any complex system is a very difficult task. In Man, decisions are reached as a result of trying to satisfy both conscious and unconscious goals. To emulate this in a computer system we need to find a way of representing goals and modeling the decision making process. This paper describes a model for decision making in the context of the management of distributed computer systems, and discusses the implications for the representation of goals and other information used during the decision making process. The work described in this paper was performed in the ESPRIT II project DOMAINS. This project is concerned with developing an architecture for the integrated management of all resources in a networked system. The emphasis of this paper lies in modeling rather than implementation.     

A learning architecture based on reinforcement learning for adaptive control of the walking machine LAURON

The learning of complex control behaviour of autonomous mobile robots is one of the actual research topics. In this article an intelligent control architecture is presented which integrates learning methods and available domain knowledge. This control architecture is based on Reinforcement Learning and allows continuous input and output parameters, hierarchical learning, multiple goals, self-organized topology of the used networks and online learning. As a testbed this architecture is applied to the six-legged walking machine LAURON to learn leg control and leg coordination.     

Insufficient incentives for investment in electricity generations

In theory, competitive electricity markets provide incentives for efficient investment in generation capacity. We show that if consumers and investors are risk averse, investment is efficient only if investors in generation capacity can sign long-term contracts with consumers. Otherwise the uncovered price risk increases financing costs, reduces equilibrium investment levels, distorts technology choice towards less capital-intensive generation and reduces consumer utility. We observe insufficient levels of long-term contracts in existing markets, possibly because retail companies are not credible counter-parties if their final customers can switch easily between them. With a consumer franchise, retailers can sign long-term contracts, but this solution comes at the expense of retail competition. Alternative capacity mechanisms to stimulate investment are discussed.     

Structure analysis of acetylated and non-acetylated O-linked MUC1-glycopeptides by post-source decay matrix-assisted laser desorption/ionization mass spectrometry

We have investigated the potential of structural elucidation of O-linked glycopeptides by post-source decay matrix-assisted laser desorption ionization mass spectrometry (PSD-MALDI-MS). In order to establish detailed fragmentation patterns and to dissect fragment ions with and without carbohydrate content, the same O-linked MUC1-derived glycopeptides with acetylated and non-acetylated sugars were analysed and compared. Furthermore, we were interested to examine possible differences in the fragmentation between glycopeptides with acetylated and non-acetylated sugars. The obtained PSD-MALDI-MS spectra showed a rather complete set of fragmentation data which allows to localize the glycan on the peptide, in parallel with sequencing a short glycan and the backbone peptide. Fragmentations of the sugars were dominated by inter-ring cleavages at the glycosidic bond. Intra-ring cleavage did also occur from the non-reducing end, but to a much lower extent. The fragmentation of the peptide backbone was not changed either by acetylated or non-acetylated sugars. Glycosylated peptide fragments occurred as fully glycosylated fragment ions, partially deglycosylated ions and completely deglycosylated ions, and was not influenced by the acetylation of sugars. However, differences occurred in the quality and quantity of fragment ions from the non-reducing end of the glycan part when comparing acetylated with non-acetylated glycopeptides.     

Spatially resolved monitoring of crystalline suprastructure and molecular orientation in α‐ and β‐nucleated polypropylene pipes using differential scanning calorimetry,infrared microscopy,and polarized light microscopy

Differently nucleated polypropylene (PP) pipes were studied by polarized light and infrared (IR) microscopy and differential scanning calorimetry (DSC). Although Fourier transform IR microscopy (µFTIR) excels by high spatial resolution and ease of measurement over the classical approach with manually prepared sections and individual analysis, a disadvantage is that the vibrational bands used to calculate the degree of crystallinity may be influenced by the polymorphism of PP. While this does not play a role for the α‐polymorph, in the case of β‐nucleated PP the calculated profile of crystallinity derived from the so called crystallinity bands depends on the direction of inspection. We could show that in the case of β‐nucleation the results from µFTIR and DSC of cross‐sections can be correlated, and thus the crystallinity profile obtained from µFTIR becomes independent from the direction of consideration. Consequently the advantages of µFTIR with regard to spatial resolution and reproducibility can now be exploited for β‐nucleated PP as well. Using the differently nucleated specimen we give the first practical validation of a previously on a theoretical basis derived model to determine the molecular orientation in all three dimensions (machine, transverse, and normal). It could be shown that the profiles of molecular orientation are a function of both, the extrusion process with its post extrusion cooling conditions, and the type of nucleating agent. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4182–4190, 2013