Effects of Moderate Nitrate and Low Sulphate Depositions on the Status of Soil Base Cation Pools and Recent Mineral Soil Acidification at Forest Conversion Sites with European Beech (“Green Eyes”) Embedded in Norway Spruce and Scots Pine Stands

High N depositions of past decades brought changes to European forests including impacts on forest soil nutrition status. However, the ecosystem responses to declining atmospheric N inputs or moderate N depositions attracted only less attention so far. Our study investigated macronutrient (N, S, Ca2+, Mg2+, K+ ) pools and fluxes at forest conversion sites over 80 years old in Central Germany with European beech (so-called “Green Eyes” (GE)). The GE are embedded in large spruce and pine stands (coniferous stands: CS) and all investigated forest stands were exposed to moderate N deposition rates (6.8 ± 0.9 kg ha−1 yr−1 ) and acidic soil conditions (pHH2O 59%) and CS (>66%). The litter fall base cation return at GE (59 ± 6 kg ha−1 yr−1 ) is almost twice as large as the base cation deposition (30 ± 5 kg ha−1 yr−1 ) via throughfall and stemflow. At CS, base cation inputs to the topsoil via litter fall and depositions are at the same magnitude (24 ± 4 kg ha−1 yr−1 ). Macronutrient turnover is higher at GE and decomposition processes are hampered at CS maybe through higher N inputs. Due to its little biomass and only small coverage, the herbaceous layer at GE and CS do not exert a strong influence on macronutrient storage. Changes in soil base cation pools are tree species-, depth- and might be time-dependent, with recently growing forest floor stocks. An ongoing mineral soil acidification seems to be related to decreasing mineral soil base cation stocks (through NO3 − and especially SO4 2− leaching as well as through tree uptake)

Opportunities for Gas-Phase Science at Short-Wavelength Free-Electron Lasers with Undulator-Based Polarization Control

Free-electron lasers (FELs) are the world's most brilliant light sources with rapidly evolving technological capabilities in terms of ultrabright and ultrashort pulses over a large range of accessible photon energies. Their revolutionary and innovative developments have opened new fields of science regarding nonlinear light-matter interaction, the investigation of ultrafast processes from specific observer sites, and approaches to imaging matter with atomic resolution. A core aspect of FEL science is the study of isolated and prototypical systems in the gas phase with the possibility of addressing well-defined electronic transitions or particular atomic sites in molecules. Notably for polarization-controlled short-wavelength FELs, the gas phase offers new avenues for investigations of nonlinear and ultrafast phenomena in spin orientated systems, for decoding the function of the chiral building blocks of life as well as steering reactions and particle emission dynamics in otherwise inaccessible ways. This roadmap comprises descriptions of technological capabilities of facilities worldwide, innovative diagnostics and instrumentation, as well as recent scientific highlights, novel methodology and mathematical modeling. The experimental and theoretical landscape of using polarization controllable FELs for dichroic light-matter interaction in the gas phase will be discussed and comprehensively outlined to stimulate and strengthen global collaborative efforts of all disciplines

The GRAVITY+ Project: Towards All-sky, Faint-Science, High-Contrast Near-Infrared Interferometry at the VLTI

The GRAVITY instrument has been revolutionary for near-infrared interferometry by pushing sensitivity and precision to previously unknown limits. With the upgrade of GRAVITY and the Very Large Telescope Interferometer (VLTI) in GRAVITY+, these limits will be pushed even further, with vastly improved sky coverage, as well as faint-science and high-contrast capabilities. This upgrade includes the implementation of wide-field off-axis fringe-tracking, new adaptive optics systems on all Unit Telescopes, and laser guide stars in an upgraded facility. GRAVITY+ will open up the sky to the measurement of black hole masses across cosmic time in hundreds of active galactic nuclei, use the faint stars in the Galactic centre to probe General Relativity, and enable the characterisation of dozens of young exoplanets to study their formation, bearing the promise of another scientific revolution to come at the VLTI.Comment: Published in the ESO Messenge

Effizienzmessung im Sparkassensektor am Beispiel regionaler Cluster

Die Primärinstitute der Sparkassen-Finanzgruppe standen über viele Jahre im Zentrum nationaler und internationaler Kritik. Ausschlaggebend war stets das besondere Geschäftsmodell der Sparkassen. Insbesondere die Erfüllung des (nicht quantifizierbaren) öffentlichen Auftrags erlaubt es den Sparkassen, ineffizient zu wirtschaften, so die Kritiker. Im Zuge der internationalen Finanzkrise hat sich jedoch gezeigt, dass die Sparkassen gerade aufgrund ihres Geschäftsmodells einen wesentlichen Beitrag zur Stabilität des deutschen Bankenmarktes geleistet haben.Die demographischen Veränderungen verlangen jedoch zukünftig noch größere Flexibilität der Sparkassen in der Ausgestaltung ihrer Geschäftsmodelle. Von besonderer Bedeutung ist in diesem Zusammenhang effizientes Wirtschaften. Der Autor untersucht daher empirisch, unter Berücksichtigung regionaler und soziodemographischer Aspekte, die Effizienz der deutschen Sparkassen unter produktiven Gesichtspunkten für den Zeitraum von 1994–2008. Die methodische Umsetzung erfolgt auf Basis der Data Envelopment Analysis (DEA), einem nichtparametrischen Verfahren zur Effizienzmessung. Speziell als effizient klassifizierte Sparkassen in strukturschwachen Gebieten werden detaillierter analysiert, um geschäftspolitische Implikationen für die Sparkassen abzuleiten, denen zukünftig ähnlich negative Veränderungen des Geschäftsgebietes bevorstehen

Development of a Revolver Type Undulator

A revolver type undulator is developed for the SASE section of the FLASH Free-Electron Laser (FEL) at DESY. Currently, a 1,2GeV linear accelerator injects electrons into two undulator lines to provide fully coherent VUV light to different experimental stations in two experimental halls. The more recently built FLASH2 branch consists of 12 planar undulators with a fixed magnet structure of ~32mm period length. Within plans for refurbishment of the original FLASH1 undulator section and also to open up new operation schemes with an extended photon energy range, an undulator development was started that allows for a change of different magnet structures. Once installed, it will be possible to change the wavelength range or the FEL operation scheme within a short period of time. Magnet structures can then be switched at any time without any observable effect on the electron beam orbit or the photon beam position. The single design steps are described in the following article: profile of requirements, choice of an applicable changing mechanism, development of a new magnet structure, the position of the bearing points, a new floor assembly and improvement of the cantilever arm

Variable period undulator with tunable polarization

The proposed magnetic structure allows to control all the parameters of the sinusoidal magnetic field $B(s)=B_{0}·sin(2πs/λ_{U}+ϕ)$ of permanent magnet undulator: amplitude $B_0$, period length $λ_U$, and phase $ϕ$. The magnetic structure consists of diametrically magnetized cylindrical magnets at fixed positions. The field is adjusted by motorized rotation of each magnet. Tuning of radiated wavelength by changing the period length instead of field amplitude is more effective and results in a wider wavelength range and higher photon flux, especially for free electron lasers. Individual adjustment of the magnets allows for creating arbitrary shaped magnetic field and also for embedding other elements like phase shifters, dipoles, or multipole lenses into the undulator magnetic structure