University of Konstanz

About: University of Konstanz is a education organization based out in Konstanz, Baden-Württemberg, Germany. It is known for research contribution in the topics: Population & Membrane. The organization has 12115 authors who have published 27401 publications receiving 951162 citations. The organization is also known as: University of Constance & Universität Konstanz.

Direct observation of domain-wall configurations transformed by spin currents.

Abstract: Direct observations of current-induced domain-wall propagation by spin-polarized scanning electron microscopy are reported. Current pulses move head-to-head as well as tail-to-tail walls in submicrometer ${\mathrm{Fe}}_{20}{\mathrm{Ni}}_{80}$ wires in the direction of the electron flow, and a decay of the wall velocity with the number of injected current pulses is observed. High-resolution images of the domain walls reveal that the wall spin structure is transformed from a vortex to a transverse configuration with subsequent pulse injections. The change in spin structure is directly correlated with the decay of the velocity.

Fragmentation of Landscape as a Cause for Genetic Subdivision in Bank Voles

Abstract: We studied the barrier effects of various roadways on the genetic subdivision of bank vole (Clethrionomys glareolus) populations. Allele frequencies, genetic variability, and genetic distances of natural populations were calculated based on polymorphism of seven microsatellite markers. We compared bank vole populations in control areas without such barriers with animals from both sides of a country road, a railway, and a highway. Using F and R statistics, we demonstrated significant population subdivision in bank vole populations separated by the highway, but not in populations on either side of the other roadways or in the control area. Correlations between geographic and genetic distances were revealed by an extended method based on a Mantel analysis. This allowed us to measure genetic barrier effects and express them as additional geographic distances. For instance, statistically significant differences in allele frequencies in all seven loci examined existed among populations in southern Germany and Switzerland, which are separated by the Rhine River and Lake Constance. The real geographic distance between bank vole populations in Konstanz and those in Lengwil, Switzerland, was 6 km. According to this analysis the genetic barrier effect of the Rhine could be defined as an additional distance of 7.7 km. This study shows for the first time that not only old geographic barriers but also more recent fragmentation of landscape by, for example, highways has an important effect on gene flow and the genetic substructuring of populations, which should be considered in future environmental impact assessments. Resumen: En este trabajo estudiamos los efectos de barrera de varias vias de comunicacion terrestre en la subdivision genetica en poblaciones de ratones de campo ( Clethrionomys glareolus). Las frecuencias de alelos, la variabilidad genetica y las distancias geneticas de poblaciones naturales fueron calculadas en base a polimorfismos de siete marcadores microsatelite. Comparamos las poblaciones de ratones de campo en areas de control sin las barreras mencionadas contra animales de ambos lados de una carretera rural, una via de ferrocarril y una autopista. Mediante el uso de estadisticas F y R, demostramos una subdivision poblacional significativa en poblaciones de ratones separados por la autopista, pero no entre poblaciones en ambos lados de las otras vias de comunicacion o en el area control. Un metodo extendido basado en un analisis Mantel revelo correlaciones entre las distancias geograficas y las distancias geneticas. Esto nos permitio medir los efectos de barreras geneticas y expresarlos como distancias geograficas adicionales. Por ejemplo, las diferencias estadisticamente significativas en las frecuencias de alelos en los siete locus examinados existieron en poblaciones al sur de Alemania y Suiza, las cuales estan separadas por el rio Rin y el lago Constance. La distancia geografica real entre las poblaciones de ratones en Constanz y aquellas en Lenwil, Suiza fue de 6 km. De acuerdo con este analisis el efecto de la barrera genetica del rio Rin podria ser definida como una distancia adicional de 7.7 km. Este estudio muestra por primera vez que no solo las barreras geograficas de antano sino tambien la fragmentacion mas reciente del paisaje como la ocasionada por autopistas, por ejemplo, tienen un efecto importante en el flujo de genes y la subestructuracion de poblaciones. Esto debe ser considerado en evaluaciones futuras de impacto ambiental.

Crystal structure of MalK, the ATPase subunit of the trehalose/maltose ABC transporter of the archaeon Thermococcus litoralis

Abstract: The members of the ABC transporter family transport a wide variety of molecules into or out of cells and cellular compartments. Apart from a translocation pore, each member possesses two similar nucleoside triphosphate-binding subunits or domains in order to couple the energy-providing reaction with transport. In the maltose transporter of several Gram-negative bacteria and the archaeon Thermo coccus litoralis, the nucleoside triphosphate-binding subunit contains a C-terminal regulatory domain. A dimer of the subunit is attached cytoplasmically to the translocation pore. Here we report the crystal structure of this dimer showing two bound pyrophosphate molecules at 1.9 A resolution. The dimer forms by association of the ATPase domains, with the two regulatory domains attached at opposite poles. Significant deviation from 2-fold symmetry is seen at the interface of the dimer and in the regions corresponding to those residues known to be in contact with the translocation pore. The structure and its relationship to function are discussed in the light of known mutations from the homologous Escherichia coli and Salmonella typhimurium proteins.

Diffusing-wave spectroscopy

Abstract: Since its invention about a decade ago, dynamic multiple light scattering has found many applications in various areas of soft condensed matter science. It has become a particularly important quantitative tool in colloid physics because of its applicability to systems containing very high concentrations of scatterers, and its extreme sensitivity to small motions. Recent advances of this technique, currently called diffusing-wave spectroscopy because of the diffusive transport of the light waves, include remote optical measurements of frequency-dependent viscoelasticity, studies of the microscopic dynamical processes in flowing sand and aging foam, a theoretical description of dynamic scattering from orientational fluctuations in liquid crystals and imaging of dynamic heterogeneities buried inside a turbid background medium.