Yearbook 2006

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Complexity in the world of intermetallic phases

Max Planck Institute for Chemical Physics of Solids Makongo, Julien Pierre Amelie; Burkhardt, Ulrich; Prots, Yurii; Niewa, Rainer; Kreiner, Guido
Complex metallic alloy phases are intermetallic compounds with prominent features compared to simple metallic systems. They are based on giant unit cells comprising up to more than thousands atoms per cell, hierarchical structures and inherent disorder phenomena. The characteristic features originate from a cluster substructure, which controls short and long range order as well as the physical properties. more

Cu(II)-Materials – Crystal chemistry meets Magnetism

Max Planck Institute for Chemical Physics of Solids Rosner, Helge; Schnelle, Walter; Schmitt, Miriam; Janson, Oleg (St. Petersburg State University, Russland); Gerlach, Sylvia; Schmidt, Marcus; Huang, Ya-Xi; Liu, Wei; Gippius, Andrei (Moscow State University, Russland); Johannes, Michelle Dawn (NRL Washington, USA); Drechsler, Stefan-Ludwig (IFW Dresden); Richter; Johannes (Universität Magdeburg); Kniep, Rüdiger
Low-dimensional cuprate compounds show a variety of intriguing magnetic properties. We demonstrate that a combination of electronic structure and model calculations together with experimental results and crystal-chemical considerations can provide a deep understanding of this compound family on microscopic grounds. more
Observations of nearby neutrons stars with the X-ray observatory XMM-Newton revealed a surprising discovery: variations in the X-ray spectrum of RX J0720.4-3125 were found over only a few years. The likely conclusion is that the neutron star precesses. The study of precession may provide an interesting tool to learn more about the inner structure of neutron more

Far Away Galaxy under the Microscope

Max Planck Institute for Extraterrestrial Physics Förster Schreiber, Natascha M.; Genzel, Reinhard; Tacconi, Linda J.
Using SINFONI, a novel near-infrared imaging spectrometer combined with an adaptive optics system, our SINS survey has discovered rapidly forming and large disk galaxies three billion years after the Big Bang, shedding new light on how galaxies were assembled in the young Universe. more

The GERDA Experiment to seach for neutrinoless double beta-decay

Max Planck Institute for Physics Abt, I., Caldwell, A., Jelen, M., Lenz, D., Liu, J., Liu, X., Kröninger, K., Majorovits, B., Stelzer, F.
The GERDA experiment will search for neutrinoless double beta-decay at LNGS (Laboratori Nazionali del Gran Sasso), Italy. The aim of the first phase is to scrutinize the positive claim of a part of the Heidelberg-Moscow collaboration after approximately one year of measurement. The second phase will further push the sensitivity to a neutrino mass of as low as 200 meV. A new 18-fold segmented true coaxial n-type germanium detector was developed in collaboration with Canberra-France. more
Small systems with sizes on the micrometer scale behave differently from their bulk metal counterparts. This can be investigated by comparing the signatures of many-body effects. Indeed, electrons in those mesoscopic systems such as experimentally accessible quantum dots show a different response to a sudden perturbation than the conduction electrons in metals. This leads to characteristic deviations of the x-ray absorption properties from the well-understood metallic case. more
Methane is the second most important anthropogenic greenhouse gas after carbon dioxide. Biogenic methane was previously thought to solely occur in nature when organic material is decomposed by microorganisms and in the absence of oxygen. Recent work of the Max Planck Institute for Nuclear Physics has shown that vegetation produces methane under aerobic conditions and releases it to the atmosphere. more
Gamma-ray astronomy measures the highest-energy photons from the Universe and thus the most energetic objects and processes which generate them. The H.E.S.S. experiment in Namibia investigates the sky at those energies. Several of the new results and their interpretation are reported here. more

Novel proteins for the activation of molecular switches in plants

Max Planck Institute of Molecular Physiology Berken, Antje; Fricke, Inka; Scrima, Andrea; Thomas, Christoph; Weyand, Michael; Wittinghofer, Alfred
Rho-proteins act as molecular switches that regulate vital processes in eucaryotic organisms. Their activation is essential for the processing of multiple internal and external stimuli. Scientists at the MPI in Dortmund recently discovered the responsible activating proteins in plants, which apparently represent the direct link to signal perceiving cell surface receptors. Although these proteins differ significantly from their analogues in animals and fungi, they still follow a general reaction mechanism. more
The activities of enzyme classes in a living organism can be displayed by activity-based profiling. This technology is based on the use of tagged small molecules, which covalently bind to enzymes in an activity-dependent manner. The Plant Chemetics group is developing and applying this technology and other novel chemistry tools to reveal the dynamics of enzyme activities during plant-pathogen interactions. more
The architecture of flowering plants shows an enormous heterogeneity. This variability is, to a large extent, caused by the different branching patterns of the vegetative and flowering shoots. Side-shoots originate from secondary meristems, which are formed in the axils of leaves. In tomato and in Arabidopsis, the gene LATERAL SUPPRESSOR (Ls/LAS) encodes a transcription factor controlling the initiation of axillary meristems during vegetative development. The gene is expressed in a narrow domain of the leaf axil and conditions the competence of the meristem founder cells. Transcription factors of the MYB class are also required for axillary meristem formation in specific zones along the shoot axis. Furthermore, plant architecture is strongly influenced by differential outgrowth of the axillary buds. Recently, it has been demonstrated that, in addition to the archetypical plant hormones auxin and cytokinin, bud outgrowth is regulated by a new root derived signal. more
The transfer of genes from organelles to the nucleus and the conversion of such prokaryotic genes into functional eukaryotic genes occur only on large evolutionary timescale and thus have escaped rigorous experimental analysis. The design of stringent selection schemes for gene transfer from the plastid to the plant’s nuclear genome has now made it possible to reproduce such extremely rare events in the laboratory. more
Various materials – tungsten, beryllium, and fibre-reinforced graphites – exhibiting different advantages and disadvantages are under discussion as wall materials for the plasma vessel of fusion devices, particularly ITER. The properties of graphite were investigated in detail. One disadvantage here is the deposition of amorphous hydrocarbon layers on the vessel walls. This, however, can be prevented. more
An operation scenario suitable for a fusion power plant should feature high thermal insulation of the hot plasma in conjunction with good stability properties. In order to allow the two quantities to be optimised simultaneously, one has to understand the underlying mechanisms involved, i. e. the nonlinear interaction of turbulent particle and energy transport with large-scale instabilities. One example is the “Improved H-mode“ discovered in ASDEX Upgrade. more
Three novel techniques for micro- and nanostructuring soft and delicate materials, such as polymers are presented. Compared with conventional processes they have the advantage of being low-cost, fast, and straightforward. They are based on simple physical and chemical effects: polymers can be crosslinked with plasma or UV-irradiation, and they can be locally solved or swollen with solvents. more
At the MPI for Polymer Research, the combination of chemistry and biology resulted in the development of novel experimental strategies for investigation of membrane proteins. Employing the well-known strategy of in-vitro transcription and translation, proteins with subtle sensing capabilities, such as olfactory receptors, are generated and characterized. To obtain such proteins, an artificial membrane system is generated and a cell extract containing the genetic information of the receptor species of interest is added on the membrane surface. The protein synthesis machinery in the cell extract is still functional and inserts the olfactory receptor molecules into the lipid membrane. Finally, we can investigate the resulting proteins by optical and biochemical methods. more
Multiple Sclerosis (MS) is a heterogenous, chronic inflammatory, demyelinating disease of the central nervous system (CNS). Despite of many research efforts the cause of MS is unknown. Today new techniques allow the investigation of nearly the whole genome, transcriptome and proteome. The Max-Planck-Institute of Psychiatry uses these techniques to explore the pathogenesis of MS and to open the possibility for an individualized therapy. more
How did our evolutionary ancestors make sense of their world? What strategies did they use, for example, to find food? Fossils do not preserve thoughts. Therefore, an cross-institutional research group at the Max Planck Institutes for Psycholinguistics and Evolutionary Anthropology use an alternative research method: comparative psychological research. In this way, they discovered that some of the strategies shaped by evolution are evidently masked early on by the cognitive development process unique to humans. more
Infants recognize their first words long before they start speaking. What enables them to do so? A popular idea is that they track the transitional probabilities from one syllable to the next. Scientists at the MPI for Psycholinguistic found that this strategy works less well if the complexity of real languages is taken into account. Hence, they propose prosody, the "melody" of language, as an alternative starting point to learn one's first words. more
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