Beetles on Scots pine : biodiversity and strata

Gewöhnliche Ausschnitte unserer Kulturlandschaft sind oft schlechter untersucht als unter Schutz stehende Landschaftsbestandteile. So war z.B. die Artenausstattung mancher Naturwälder eher bekannt als die Artenausstattung der umliegenden Nutzwälder. Durch die Initiativen und Forschungsprojekte u.a. von Ammer & al. (1995) wurde dann deutlich, dass auch Nutzwälder einen wertvollen Beitrag zur Artenvielfalt leisten können. Bei der Erforschung der Nutzwälder sind jedoch Kiefernforste nach wie vor vernachlässigt worden. Nur Arbeiten von Möller (2000) und Möller & Jakobitz (2003) in Brandenburg stellten hier wichtige Schritte dar, neuerdings ergänzt durch z.B. Reike & al. (2005). Im Folgenden werden neu ausgewertete Daten aus einem vom BMBF geförderten Forschungsprojekt vorgestellt, in dem sehr umfassende Grunderhebungen der in genutzten Kiefernforsten Brandenburgs vorkommenden Arthropoden durchgeführt wurden (Schulz & al. 2004, Majunke & al. 2005). Die folgenden Auswertungen konzentrieren sich auf die Artendiversität der an Kiefern (Pinus sylvestris L.) erfassten Käfer in Kiefernreinbeständen und auf die stratenspezifische Verteilung.Coleoptera were studied in three different pure stands of Scots pine (Pinus sylvestris L.) in Brandenburg (Germany) in the years 2000 to 2001. In order to catch beetles in different strata 36 standard traps were installed from the ground up to the canopy in each forest. 40836 specimen were determined to species level and 695 species were determined altogether. More than 430 beetle species were caught in each pine forest. These were more species than expected, but less than in other (mixed) forests of Germany. Only app. 54 % of all species were typical for forests (374 species altogether, 250 - 260 in each forest). A lot of species typical for open habitats benefit from the open and warm conditions in pine forests. 200 to 400 beetle species were collected in each stratum of the tree (e.g. 254 in the canopy). Flight interception traps in app. 2 m height yielded the best results collecting the largest amount of individuals (app. one third of all specimen) and the largest number of species (441). For future investigations in pine forests this method is therefore recommended if trapping has to be limited

Single and multiple electromagnetic scattering by size -shape distributions of small nonspherical particles

Thesis (Ph.D.) University of Alaska Fairbanks, 1998A comprehensive model for light scattering by size-shape distributions of randomly oriented nonspherical particles is developed. The model uses spheroids as model particles. The vector Helmholtz equation is solved with a new separation of variables (SVM) approach that allows one to calculate the ensemble-averaged single scattering optical properties of ensembles of randomly oriented particles analytically. Since the use of the SVM in spheroidal coordinates properly accounts for the geometry of the particles, the method is applicable to a large range of shapes ranging from elongated prolate needles via spheres to flat oblate disks. The relation between geometric symmetries of particles and symmetry relations of the electromagnetic scattering solution is investigated systematically in the general framework of the theory of point groups. The results are exploited in the model for increasing the computational efficiency. A comprehensive vector radiative transfer model is in part developed in this work. This radiative transfer model takes the output of the single scattering model as input and computes the Stokes vector components in a vertically inhomogeneous, plane parallel medium as a function of polar and azimuth angle and as a function of optical depth. The single scattering model is applied to investigate the impact of particle shape on the optical properties of size-shape distributions of randomly oriented particles, such as aerosol layers or ice clouds in the atmosphere. The optical properties are found to be much more sensitive to a variation in the effective aspect ratio than to a variation in the effective variance of a shape-distribution. The results of this study are used as input to the vector radiative transfer model in order to study the shape-sensitivity of the radiation field in a macroscopic medium containing a size-shape distribution of randomly oriented particles. It is found that both the radiance, and the degree of linear polarization, and the degree of circular polarization are strongly shape-sensitive in most viewing directions

Wave packet dynamics in triplet states of Na2 attached to helium nanodroplets

The dynamics of vibrational wave packets excited in Na2 dimers in the triplet ground and excited states is investigated by means of helium nanodroplet isolation (HENDI) combined with femtosecond pump-probe spectroscopy. Different pathways in the employed resonant multi-photon ionization scheme are identified. Within the precision of the method, the wave packet dynamics appears to be unperturbed by the helium droplet environment

Quantum-dot-like states in molybdenum disulfide nanostructures due to the interplay of local surface wrinkling, strain, and dielectric confinement

The observation of quantum light emission from atomically thin transition metal dichalcogenides has opened a new field of applications for these material systems. The corresponding excited charge-carrier localization has been linked to defects and strain, while open questions remain regarding the microscopic origin. We demonstrate that the bending rigidity of these materials leads to wrinkling of the two-dimensional layer. The resulting strain field facilitates strong carrier localization due to its pronounced influence on the band gap. Additionally, we consider charge carrier confinement due to local changes of the dielectric environment and show that both effects contribute to modified electronic states and optical properties. The interplay of surface wrinkling, strain-induced confinement, and local changes of the dielectric environment is demonstrated for the example of nanobubbles that form when monolayers are deposited on substrates or other two-dimensional materials

C-Terminal truncation of NR2A subunits impairs synaptic but not extrasynaptic localization of NMDA receptors

NMDA receptors interact via the extended intracellular C-terminal domain of the NR2 subunits with constituents of the postsynaptic density for purposes of retention, clustering, and functional regulation at central excitatory synapses. To examine the role of the C-terminal domain of NR2A in the synaptic localization and function of NR2A-containing NMDA receptors in hippocampal Schaffer collateral–CA1 pyramidal cell synapses, we analyzed mice which express NR2A only in its C-terminally truncated form. In CA1 cell somata, the levels, activation, and deactivation kinetics of extrasynaptic NMDA receptor channels were comparable in wild-type and mutant NR2A^(ΔC/ΔC) mice. At CA1 cell synapses, however, the truncated receptors were less concentrated than their full-length counterparts, as indicated by immunodetection in cultured neurons, synaptosomes, and postsynaptic densities. In the mutant, the NMDA component of evoked EPSCs was reduced in a developmentally progressing manner and was even more reduced in miniature EPSCs (mEPSCs) elicited by spontaneous glutamate release. Moreover, pharmacologically isolated NMDA currents evoked by synaptic stimulation had longer latencies and displayed slower rise and decay times, even in the presence of an NR2B-specific antagonist. These data strongly suggest that the C-terminal domain of NR2A subunits is important for the precise synaptic arrangement of NMDA receptors

The Corona crisis and the stability of the European banking sector A repeat of the Great Financial Crisis? Bertelsmann Stiftung Repair and Prepare Strengthening Europe May 2020.

The Corona crisis1 has had a devastating effect on the global economy and could end up being worse than the Great Financial Crisis (GFC). Some commentators have already suggested that the decline in economic activity could be the most marked for several centuries. Unlike the GFC, the Corona crisis was triggered by an external shock. Govern- ments responded to this shock by offering liquidity to the real economy, either directly or indirectly by guaranteeing new bank lending. So far European banks have weathered the storm but will they be able to withstand a prolonged economic down- turn? This paper suggests that the fortunes of European banking systems will depend on the economic recovery we experience. If we witness a “V-shaped” recovery as cur- rently forecast by the European Commission, for example, then banks in the majority of EU member states might be able to survive unscathed. The picture could look very dif- ferent if the recovery turns out to be more sluggish though. The paper suggests that capital ratios – one of the key benchmarks used to assess the stability of banking systems – could drop dramatically in a number of member states such as France and Spain to well below what super- visors generally consider to be “sound” even under stress conditions. With the situation looking less severe in other member states such as Germany or the Netherlands, this could renew political tensions seen last during the euro area sovereign debt crisis. The paper is structured as follows. Section “The Corona crisis” presents the latest economic forecasts and con- trasts the current crisis with the GFC. In Section “Could the Corona crisis undermine the financial stability of the Euro- pean banking sector?” the paper draws on the results of the 2018 EBA adverse stress test. Comparing the 2018 EBA adverse scenario with a plausible “ticked-shaped” recov- ery post-Corona, the paper presents illustrative impacts on capital ratios in a selected number of EU member states. Section “Concluding Comments” looks at the role of Euro- pean-wide policy responses to deal with the crisis and what the Corona crisis might mean for the future of the EU’s Banking Union and Capital Markets Union