Trophic interactions as indicators of ecosystem regeneration in disturbed grassland: a stable isotope approach

Stable isotope techniques were used to identify regeneration patterns in the trophic structure of the reassembling communities in order to describe the development of a disturbed grassland ecosystem (Steudnitz) that had been subjected to anthropogenic pollution for more than 30 years. Mean values of the frequency distribution of [delta]15N differences between epigeic arthropods and their diet indicated the adjustment of food web components to their food sources with trophic level enrichments between 3 and 4 [Promille] ('3.4[Promille]-rule') at the most recovered sites. Temporal changes of the animal 15N signatures reflected the development of the food web at the four differently impacted sites. Similar dynamics, i.e., minimal variations between species representing different trophic levels, imply functional stability of the trophic relationships. Moreover, the difference between soil and animal [delta]15N values mirrored the level of functional integration between soil food web and aboveground food web, and, parallel development of the [delta]15N values of epigeic species relative to those of the soil indicated the attainment of stable relations between aboveground and belowground processes. The study highlighted that - due to its 'isotopic memory' - substantial information to understand the functioning of terrestrial ecosystems can be found in the soil

An Econometric Analysis of Convergence : Econometric methods applied to the theory of macroeconomics and economic growth

Master's thesis Business Administration BE501 - University of Agder 2018This master thesis explores the concept of convergence in a macroeconomic perspective and applies econometric methods to economic growth theory. Tests and analysis are performed using a dataset of national accounts from the rich database of The Penn World Tables version 9.0 and the statistical software Stata 15.1. Two sample selections are performed, with observations for 101 and 53 countries from 1970 to 2014. The convergence classifications of β convergence, both absolute and conditional, as well as σ convergence are explained. The concepts of convergence are related to their respective research question. Do poorer economies tend to grow faster than richer economies? Do inequalities between poorer economies and richer economies tend to decrease? Do economies converge towards a common or unique steady state? Macroeconomic and economic growth theory is discussed and explained through neoclassical growth theory and new growth theory. The Solow model from neoclassical growth theory and the R&D model from new growth theory are mathematically derived and empirically tested to explore the dynamics of economic growth and to answer the question of the concept of absolute convergence. Other applied tests are growth-initial level regressions, which tests for β convergence, and standard deviation time series, which tests for σ convergence. The research provides empirical evidence that poorer economies do tend to grow faster than richer economies, but with unreliable results due to issues of non-normality and heteroscedasticity. Empirical evidence also suggests that income dispersion of OECD countries is steadily increasing and that income dispersion of the full sample of 101 countries decreased from 1970 to 1988. The standard deviation time series test does not give a conclusive answer for the full sample after 1988. Due to issues of heteroscedasticity and autocorrelation, generalized least squares method is used to give the best linear unbiased estimator of the parameters of the Solow model. Empirical evidence show that capital’s share is 60% and not 1/3 as the theory suggests. By adding human capital as in the theory of the augmented Solow model, empirical evidence shows a much lower capital’s share of 20%. Individual heterogeneity suggests that countries follow unique paths to their own equilibrium level of economic growth given the parameters of the Solow model. The resulting evidence from the conducted tests and analysis successfully provides satisfactory answers to the research questions of this master thesis

Studie zum One-Shot Prozess an Holz-Kunststoff-Verbunden

Environmental changes force industries to use renewable and degradable materials for lightweight solutions to solve weight and therefore CO2. One highly prioritized topic is the combination of wood materials with biodegradable plastics. Especially when processing these materials, it is essential to develop efficient processes to reduce obstacles and enable the application in serial use. To take advantage of the mechanical behaviour of the wood structure it is necessary to investigate the combination of thin solid wood with plastic. Regarding large-scale production, an injection moulding process is addressed in this study. When processing raw material cutting operations are used. To use the shear cutting process has several advantages: it is a cost effective process with short cycle times. Also no thermal influence or water immersion occur on the working material (like in laser beam or water jet methods), so material sensitive on this can be worked by shearing. But as a disadvantage a working force is applied. This work aims to show the findings this working fore on 5mm wood solids and the influence of the created surface on the bonding between plastic and wood cutting edge. The process connections and dependencies of shear cutting and injection moulding are investigated. Different wood materials were used to analyse the effects of cutting and material parameters (e.g. moisture, forces) on the cutting edge quality (e.g. structural damage). To detect the effect of different cutting edge qualities on the joint between wood and plastic component tensile specimen were tested.Umweltveränderungen zwingen die Industrie, erneuerbare und abbaubare Materialien für Leichtbaulösungen zu verwenden, um Gewicht und damit CO2 einzusparen. Ein hochpriorisiertes Thema ist die Kombination von Holzwerkstoffen mit biologisch abbaubaren Kunststoffen. Besonders bei der Verarbeitung dieser Materialien ist es wichtig, effiziente Prozesse zu entwickeln, um Hindernisse für den Markteintritt zu reduzieren und die Anwendung im Serieneinsatz zu ermöglichen. Um das mechanische Verhalten der Holzfaserstruktur auszunutzen, ist es notwendig, die Kombination von dünnem Holz mit Kunststoff zu untersuchen. Im Hinblick auf die Großserienproduktion wird in dieser Studie das Spritzgussverfahren adressiert. Die Anwendung des Scherschneidverfahrens hat einige Vorteile: Es ist ein kostengünstiges Verfahren mit kurzen Zykluszeiten. Auch findet keine thermische Beeinflussung oder Eintauchen in Wasser auf das zu bearbeitende Material statt (wie beim Laserstrahl- oder Wasserstrahlverfahren), sodass darauf empfindliches Material durch Schneiden bearbeitet werden kann. Als Nachteil wird jedoch eine Arbeitskraft aufgebracht. Ziel dieser Arbeit ist es, die Erkenntnisse zu zeigen, die die scherende Bearbeitung an 5mm Holzwerkstoffen und der folgende Einfluss der erzeugten Oberfläche auf die Verbindung zwischen Kunststoff und Holz hat. Die Prozesszusammenhänge und -abhängigkeiten von Scherschneiden und Spritzgießen werden untersucht. Es wurden verschiedene Holzwerkstoffe verwendet, um die Auswirkungen von Schnitt- und Materialparametern (z.B. Feuchtigkeit, Kräfte) auf die Schnittkantenqualität (z.B. Strukturschäden) zu analysieren. Um den Einfluss unterschiedlicher Schnittkantenqualitäten auf die Verbindung zwischen Holz- und Kunststoffbauteil zu erkennen, wurden Zugproben untersucht

Spectroscopic investigations of Np(V/VI) redox speciation in hyperalkaline TMA-(OH, Cl) solutions

The redox chemistry of Np(V/VI) was investigated in ∼0.6M tetramethylammonium hydroxide/chloride (TMA-(OH, Cl)) solutions with 9 ≤ −log [H+] ≤ 13.5. Redox conditions were defined by the absence or presence of ClO− as oxidizing agent (Na-salt, 5×10−3M and 5×10−2M). The high total Np concentration ([Np]tot ∼ 2×10−3M) led to the precipitation of solid phases in some of the samples. The carbonate concentration (as impurity of TMA-OH) was 2-3×10−3M. UV-vis/NIR spectra obtained from the supernatant in TMA-(OH, Cl) solutions and absence of ClO− showed clear Np(V) features, identified as NpO2+, NpO2CO3− and (NpO2)x(CO3)y(OH)zx−2y−z. No NIR features were observed within 800nm ≤ λ ≤ 1300nm for samples with ClO−. XANES edge energies and features of these samples confirmed the predominance of Np(V) in the absence of ClO− and Np(VI) in the presence of ClO−, by comparison to XANES reference spectra of Np(III/IV/V/VI) prepared within the present work by in-situ electrolysis. Asimilar Np redox distribution was observed for the solid phases based on XANES and EXAFS measurements. EXAFS spectra indicative of NpVO2OH(s) and NpVIO3· xH2O(s) were obtained for samples in absence and presence of ClO−, respectively. The formation of aNa-Np(VI) phase in 5×10−2M ClO− and −log [H+] ∼ 12 was also indicated from the EXAFS, chemical analysis and SEM-EDS. These results indicate that Np(VI) aqueous species and solid compounds prevail far below the oxidation border of water in alkaline solutions and also far below the EH border calculated with the current NEA data selection [1]. These observations are further supported by correlations of literature thermodynamic data for actinides (U, Np, Pu and Am), which predict the formation of NpO2(OH)3− and NpO2(OH)42− aqueous species with stability constants (log *βº1,3 and log *βº1,4) similar to those available for U(VI

Digital development, inequalities & the Sustainable DevelopmentGoals: What does‘Leave No-One Behind’mean for ICT4D?

The United Nations’Sustainable Development Goals (SDGs) place greatemphasis on inequalities and pledge toleave no-one behind. For thefield of digital development, this objective presents a particularchallenge. While digital technologies can be utilized to reduce certaininequalities, they are also linked to reproductive mechanisms,reinforcing existing inequalities. In the context of an increasingdigitalization of development, particular attention must therefore bepaid to the link between digital inequalities and the quest to leave no-one behind. This article analyses the integration of intersectionalinequalities in the SDG framework and the resulting need for coherentpolicies, and demonstrates the parallels between this challenge and thereproductive nature of digital inequalities. On this basis, we argue thatthe issue of digital inequalities should be mainstreamed indevelopment programming in order to avoid worsening existinginequalities through digital development

Does Hepatic Steatosis Influence the Detection Rate of Metastases in the Hepatobiliary Phase of Gadoxetic Acid-Enhanced MRI?

The aim of this exploratory study was to evaluate the influence of hepatic steatosis on the detection rate of metastases in gadoxetic acid-enhanced liver magnetic resonance imaging (MRI). A total of 50 patients who underwent gadoxetic acid-enhanced MRI (unenhanced T1w in- and opposed-phase, T2w fat sat, unenhanced 3D-T1w fat sat and 3-phase dynamic contrast-enhanced (uDP), 3D-T1w fat sat hepatobiliary phase (HP)) were retrospectively included. Two blinded observers (O1/O2) independently assessed the images to determine the detection rate in uDP and HP. The hepatic signal fat fraction (HSFF) was determined as the relative signal intensity reduction in liver parenchyma from in- to opposed-phase images. A total of 451 liver metastases were detected (O1/O2, n = 447/411). O1/O2 detected 10.9%/9.3% of lesions exclusively in uDP and 20.2%/15.5% exclusively in HP. Lesions detected exclusively in uDP were significantly associated with a larger HSFF (area under curve (AUC) of receiver operating characteristic (ROC) analysis, 0.93; p 30%) is a potential pitfall for the detection of metastases in HP

Application of composite coatings as protection/contacting layers for metallic highchromium- content SOFC interconnect material

Oxidation of the surface of metallic chromium oxide forming metallic interconnect (MIC) can cause up to one third of the total SOFC stack degradation during the long-time operation at elevated (750 - 850 °C) temperatures. The application of protective coatings is the most effective method not only for reduction of the growth of oxide scales but also for prevention of evaporation of Cr-containing species from MIC and of the poisoning of the air electrode. Two approaches to form the protective layers on the surface of CFY interconnect material with high chromium content (~ 94 %) have been tested. The CuNiMn-spinel (CNM) coatings were deposited using the wet powder spraying (WPS) of the slurries. As an alternative approach physical vapour deposition (PVD) method was used to apply thin metallic films on the surface of MIC and to form the protection layer by in-situ oxidation under the stack relevant conditions. The experiments were carried out at first using the model samples of different geometries to evaluate the properies and efficiency of the coatings. Composite pastes with addition of perovskite powders were also tested, because the CNM layers densify at SOFC operating conditions and shrinkage during long-term operation can cause the decrease of the contact area between the components and accelerate the degradation of the stack performance. The experiments have shown that the perovskite additive can efficiently reduce the shrinkage compared to the pure CNM material and match it well to the shrikage of other stack components. Moreover, the perovskite additive do not deteriorate the electrical properties of the composite since the perovskites have electrical conductivity comparable to CNM. The PVD coatings were tested in combination with CNM containing contacting layers applied by screen printing to reduce the chromium release rate. The experiments have shown a good compatibility and mechanical stability between the contacting layer and PVD protective coating during operation and thermal cycling. The materials and composites have been characterized by scanning electron microscopy (SEM/EDX), optical dilatometry and electrical conductivity measurements. Finally, the most promising material combinations obtained for model samples were transferred to SOFC stacks MK35x and evaluated under real operation condition.Federal Ministry for Economic Affairs and Energy (BMWi) for funding of these researches (support code 03ET6120A)

Real-Time Dynamics with Fermions on a Lattice

The 1+1 dimensional abelian Higgs model with fermions is a toy model for the theory of electroweak baryogenesis. We study the dynamics of the model with axially coupled fermions in real-time. The model is defined on a spacetime lattice to preserve gauge invariance and to obtain numerical stability in a simple way. We take into account the phenomenon of lattice fermion doubling. The dynamics is approximated by treating the inhomogeneous Bose fields classically, which is justified in a large N_f approximation. The back reaction on the Bose fields due to fermion field fluctuations is calculated using a mode function expansion. We discuss and present numerical results for the response of fermions to sphaleron transitions, the renormalizability of the effective equations of motion and non-perturbative dynamics in the framework of non-equilibrium quantum field theory. The long-time behaviour of the system is discussed and we speculate about applications to finite density calculations.Comment: 34 pages + 20 eps figures, improved presentation, discussion of the figures and figure captions expanded, references added; to appear in Nucl.Phys.