Cross sections and modelling results for TGF- and positron spectrum produced by a negative stepped lightning leader

We model the energy resolved angular distribution of TGFs and of positrons produced by a negative lightning leader stepping upwards in a thundercloud. First we present our new results for doubly differential cross sections for Bremsstrahlung and pair production based on the triply differential cross-sections of Bethe and Heitler. Other cross sections in literature and databases do not cover the appropriate energy range or do not apply to the small atomic numbers of nitrogen and oxygen or do not resolve both energies and emission angles of emitted photons or positrons. Second we have extended the Monte Carlo model of Chao Li towards relativistic electron energies, and we have included the new cross sections as well as Compton scattering of photons and photo ionization. We will present the angular resolved spectrum of TGFs and positrons of stepped negative leaders and compare it with results of other authors

Erfahrungsbericht und Überblick zum Projekt e-GAP - Modellkommune Elektromobilität Garmisch-Partenkirchen: Elektromobilität im ländlich-touristischen Raum als Baustein für eine nachhaltige Entwicklung

Nach der 5-Punkte-Strategie zur Förderung der Elektromobilität der Bayrischen Landesregierung und den Zielen der Bundesregierung im "Nationalen Entwicklungsplan Elektromobilität" ist eine enge Zusammenarbeit zwischen Wissenschaft und Industrie vonnöten. Garmisch-Partenkirchen wird dabei als Modellstadt vorgestellt, in der die Elektromobilität sichtbar ausgebaut werden soll. Dies geschieht insbesondere durch das Projekt "Modellkommune Elektromobilität Garmisch-Partenkirchen e-GAP". Besonderheiten liegen bei dieser Modellkommune in ihrer ländlichen Lage, der alpinen Umgebung und dem hohen Tourismusaufkommen. Gerade in den stark touristisch geprägten Kleinstädten liegt in der Elektromobilität ein besonderes Potenzial. Dabei ist für die Elektromobilität die Schaffung von öffentlicher Ladeinfrastruktur sowie von kleinen Mobilitäts-"Hotspots" von großer Bedeutung.According to the Bavarian state government's 5-point strategy to promote electromobility and the goals of the federal government recorded in the "National Development Plan for Electromobility", close cooperation between science and industry is necessary. Garmisch-Partenkirchen is presented as a pilot town in which electromobility should be notably extended. Here the project "Pilot Municipality Electromobility Garmisch-Partenkirchen e-GAP" is especially significant. The distinguishing features of this pilot municipality are its rural location, alpine surroundings and high levels of tourism. There is particular potential for electromobility in the small towns that are especially popular with tourists. The creation of public charging infrastructure and small mobility hotspots is most important for electromobility

Business Analyse 2017 : eine empirische Untersuchung im deutschsprachigen Raum und Fallbeispiele aus Unternehmen

Der Sammelband Business Analyse 2017 stellt anhand von Befragungsergebnissen und Fallbeispielen die Funktionen und Rollen von Business-Analysten dar

Electron-electron interaction strength in ferromagnetic nickel determined by spin-polarized positron annihilation

The two-photon momentum distribution of annihilating electron-positron pairs in ferromagnetic nickel (Ni) was determined by measuring the spin-polarized two-dimensional angular correlation of annihilation radiation (ACAR). The spectra were compared with theoretical results obtained within LDA+DMFT, a combination of the local density approximation (LDA) and the many-body dynamical mean-field theory (DMFT). The self-energy describing the electronic correlations in Ni is found to make important anisotropic contributions to the momentum distribution which are not present in LDA. Based on a detailed comparison of the theoretical and experimental results the strength of the local electronic interaction U in ferromagnetic Ni is determined as 2.0 +- 0.1 eV

Techniques to Measure Solar Flux Density Distribution on Large-Scale Receivers

Flux density measurement applied to central receiver ystems delivers the spatial distribution of the concentrated solar radiation on the receiver aperture, measures receiver input power, and monitors and might control heliostat aimpoints. Commercial solar tower plants have much larger aperture surfaces than the receiver prototypes tested in earlier research and development (R&D) projects. Existing methods to measure the solar flux density in the receiver aperture face new challenges regarding the receiver size. Also, the requirements regarding costs, accuracy, spatial resolution, and measuring speed are different. This paper summarizes existent concepts, presents recent research results for techniques that can be applied to large-scale receivers and assesses them against a catalog of requirements. Direct and indirect moving bar techniques offer high measurement accuracy, but also have the disadvantage of large moving parts on a solar tower. In the case of external receivers, measuring directly on receiver surfaces avoids moving parts and allows continuous measurement but may be not as precise. This promising technique requires proper scientific evaluation due to specific reflectance properties of current receiver materials. Measurement-supported simulation techniques can also be applied to cavity receivers without installing moving parts. They have reasonable uncertainties under ideal conditions and require comparatively low effort

Genetic diversity and genetic differentiation in Daphnia metapopulations with subpopulations of known age

If colonization of empty habitat patches causes genetic bottlenecks, freshly founded, young populations should be genetically less diverse than older ones that may have experienced successive rounds of immigration. This can be studied in metapopulations with subpopulations of known age. We studied allozyme variation in metapopulations of two species of water fleas (Daphnia) in the skerry archipelago of southern Finland. These populations have been monitored since 1982. Screening 49 populations of D. longispina and 77 populations of D. magna, separated by distances of 1.5–2180 m, we found that local genetic diversity increased with population age whereas pairwise differentiation among pools decreased with population age. These patterns persisted even after controlling for several potentially confounding ecological variables, indicating that extinction and recolonization dynamics decrease local genetic diversity and increase genetic differentiation in these metapopulations by causing genetic bottlenecks during colonization. We suggest that the effect of these bottlenecks may be twofold, namely decreasing genetic diversity by random sampling and leading to population-wide inbreeding. Subsequent immigration then may not only introduce new genetic material, but also lead to the production of noninbred hybrids, selection for which may cause immigrant alleles to increase in frequency, thus leading to increased genetic diversity in older populations

Founder events as determinants of within-island and among-island genetic structure of Daphnia metapopulations

The genetic structure of metapopulations offers insights into the genetic consequences of local extinction and recolonization. We studied allozyme variation in rock pool metapopulations of two species of waterfleas (Daphnia) with the aim to understand how these dynamics influence genetic differentiation. We screened 138 populations of D. magna and 65 populations of D. longispina from an area in the archipelago of southern Finland. The pools from which they were sampled are separated by distances between 1.5 and 4710 m and located on a total of 38 islands. The genetic population structure of the two species was strikingly similar, consistent with their similar metapopulation ecology. The mean FPT value (differentiation among pools with respect to the total metapopulation) was 0.55 and a hierarchical analysis showed that genetic differentiation was strong (>0.25) among pools within islands as well as among whole islands. Within islands, pairwise genetic differentiation increased with geographic distance, indicating isolation by distance due to spatially limited dispersal. Previous studies have shown strong founder events occurring during colonization in our metapopulation. We suggest that the genetic population structure in the studied metapopulations is largely explained by three consequences of these founder events: (i) strong drift during colonization, (ii) local inbreeding, which results in hybrid vigour and increased effective migration rates after subsequent immigration, and (iii) effects of selection through hitchhiking of neutral genes with linked loci under selection

5-Fluoro pyrimidines: labels to probe DNA and RNA secondary structures by 1D 19F NMR spectroscopy

19F NMR spectroscopy has proved to be a valuable tool to monitor functionally important conformational transitions of nucleic acids. Here, we present a systematic investigation on the application of 5-fluoro pyrimidines to probe DNA and RNA secondary structures. Oligonucleotides with the propensity to adapt secondary structure equilibria were chosen as model systems and analyzed by 1D 19F and 1H NMR spectroscopy. A comparison with the unmodified analogs revealed that the equilibrium characteristics of the bistable DNA and RNA oligonucleotides were hardly affected upon fluorine substitution at C5 of pyrimidines. This observation was in accordance with UV spectroscopic melting experiments which demonstrated that single 5-fluoro substitutions in double helices lead to comparable thermodynamic stabilities. Thus, 5-fluoro pyrimidine labeling of DNA and RNA can be reliably applied for NMR based nucleic acid secondary structure evaluation. Furthermore, we developed a facile synthetic route towards 5-fluoro cytidine phosphoramidites that enables their convenient site-specific incorporation into oligonucleotides by solid-phase synthesi