Development and application of setup for ac magnetic field in neutron scattering experiments

We report on a new setup developed for neutron scattering experiments in periodically alternating magnetic fields at the sample position. The assembly consisting of rf generator, amplifier, wide band transformer, and resonance circuit. It allows to generate homogeneous ac magnetic fields over a volume of a few cm(3) and variable within a wide range of amplitudes and frequencies. The applicability of the device is exemplified by ac polarized neutron reflectometry (PNR): a new method established to probe remagnetization kinetics in soft ferromagnetic films. Test experiments with iron films demonstrate that the ac field within the accessible range of frequencies and amplitudes produces a dramatic effect on the PNR signal. This shows that the relevant ac field parameters generated by the device match well with the scales involved in the remagnetization processes. Other possible applications of the rf unit are briefly discussed.     

Fast Active THz Cameras with Ranging Capabilities

We report on the realization of two active, fully electronic THz cameras, both operating at room temperature, but at different frequencies (645 GHz and 300 GHz, respectively). Active illumination together with the frequency-modulated-continuous-wave (FMCW) approach allows us to implement unique features such as phase-sensitive detection, suppression of spurious reflections and high resolution ranging. The measuring of the phase of the THz wave allows for sub-wavelength depth resolution while the ranging capabilities enable us to acquire an absolute depth map of objects under test with accuracy in the mm range. With both systems, we are able to acquire images with more than 55,000 pixels (phase and amplitude) in 9 seconds and the dynamic range exceeds 35 dB. The typical object distance is about 75–150 cm and the image size is in the order of hundreds of cm² suitable for stand off detection of concealed weapons.     

Graphene sublattice symmetry and isospin determined by circular dichroism in angle-resolved photoemission spectroscopy

The Dirac-like electronic structure of graphene originates from the equivalence of the two basis atoms in the honeycomb lattice. We show that the characteristic parameters of the initial state wave function (sublattice symmetry and isospin) can be determined using angle-resolved photoemission spectroscopy (ARPES) with circularly polarized synchrotron radiation. At a photon energy of hν = 52 eV, transition matrix element effects can be neglected allowing us to determine sublattice symmetry and isospin with high accuracy using a simple theoretical model.     

Reduction of springback using simultaneous stretch-bending processes

Springback due to the elastic material behaviour can lead to shape errors that cause geometrical and dimensional inaccuracies in sheet metal forming processes, especially in bending operations. In order to reduce springback, the technique of integrating stretching with bending in sheet metal forming processes has been investigated. The object of this paper is to explain how to reduce the effect of the elastic component in the material behaviour using simultaneous stretching and bending so that a method is established for applying plastic forming during the main process, without changing the tool design. This study focuses on three main points: the stretching method, the stretching direction and the stretching length. In regard to swing- and v-bending processes, the springback factor is used as the standard evaluation to investigate these effects using Finite Element simulation. The springback factors are compared for four processes: Bending process without stretching (WS), pre-stretching and bending process (PB), pre-stretching plus simultaneous stretching and bending (PSB) and simultaneous stretching and bending (SB). The simulation results are then verified through experimentation. Based on the validated results, simultaneous stretching can then be subsequently applied to the existing stretch-forming process, which consists of pre-stretching and bending. Using this process, springback was successfully reduced which confirms the efficiency of SB process.     

Identification of the fish species of raw or cold-smoked salmon and salmon caviar by single-strand conformation polymorphism (SSCP) analysis

Differentiation between ten salmonid fish species belonging to the genera Salmo, Oncorhynchus and Salvelinus was achieved by single strand conformation polymorphism analysis (SSCP) of PCR products of mitochondrial and nuclear genes. Amplicons (300–460 bp in size) of the genes for cytochrome b, parvalbumin and growth hormone gave species-specific patterns of single-stranded DNA in native polyacrylamide gel electrophoresis (PAGE). The method was successfully used to identify products from raw or cold-smoked salmon, as well as from salmon roe.     

Structure of Cs0.5[Nb2.5W2.5O14] analysed by focal-series reconstruction and crystallographic image processing

The structure of the oxygen sub-lattice in Cs_0.5[Nb_2.5W_2.5O₁₄] is investigated for the first time by advanced electron-optical methods. Since Cs_0.5[Nb_2.5W_2.5O₁₄] resembles the crystal structure of the so-called M1 phase of Mo–V–Nb–Te–O, which is the best catalyst for the selective oxidation of propane to acrylic acid, the structure analysis of the oxygen sub-lattice can contribute substantially to a better understanding of this catalytic process. The so far only partially known structure of the complex metal oxide Cs_0.5[Nb_2.5W_2.5O₁₄] is investigated by combining modern methods of high-resolution transmission electron microscopy with crystallographic image processing techniques. Average atom positions in the a–b plane are determined from the phase of the exit-plane wave function, which was numerically reconstructed from a focal series of spherical-aberration-corrected electron micrographs. The experimentally determined atom positions agree well with a structure model obtained by first-principles calculations for the underlying M₅O₁₄ (M = Nb, W) framework. Moreover, several deviations from the periodic structure, which may influence the catalytic properties of the structurally similar M1 phase, are observed. The obtained results demonstrate that aberration-corrected high-resolution transmission electron microscopy is a reliable alternative for the analysis of periodic structures, in particular when traditional methods for crystallographic structure determination like XRD or neutron diffraction cannot be applied.     

What Does Grid Computing Cost?

Grid computing has gained considerable attention in research and industry. High expectations are associated with the approach. However, so far only few papers have been published about the costs caused by Grid computing. In this article we pursue two main goals: to analyze the different types of costs and to determine the total costs of a resource provider. Our approach is based on the discussion of general cost categories that have to be taken into account. We give concrete numbers for the different categories and use these numbers to estimate the costs in two real life Grids: the EGEE project and the Grid of the pharmaceutical company Novartis. A summarizing discussion concludes the paper.     

Das Verbot der pränatalen Diagnostik spätmanifestierender Erkrankungen im deutschen Gendiagnostikgesetz – eine Diskussion medizinischer und rechtlicher Aspekte und deren Implikation für die medizinethische Diskussion

Definition of the problem The German Genetic Diagnosis Act (Genetic Diagnosis Act, GenDG) became effective on February 1, 2010. Although this act was welcomed by many, the debate surrounding some regulatory areas, for example, screening newborns, continues. One aspect of this new legislation, however, has received little attention: the prohibition of prenatal diagnosis of so-called late-onset diseases—where first symptoms only develop after completion of the 18th year of life—constitutes an internationally unique prohibition. In this publication, we would like to contribute to a more differentiated discussion of § 15(2) GenDG that sanctions this diagnosis. Arguments and conclusion There are arguments supporting this prohibition (especially the right of the child not to know). However, based on medical concerns as well as an analysis of ethical and legal pros and cons, we conclude that maintaining this general prohibition of diagnosing late-onset diseases might be insufficient as well as inconsistent with other regulations; thus, possible alternatives are discussed.