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Rangelands are the most widespread land-use systems in drylands, where they often represent the only sustainable form of land-use due to the limited water availability. The intensity of the land-use of such rangeland ecosystems in drylands depends to a large extent on the climatic variability in time and space. Rangeland systems are seriously threatened by climate change, because climate change will alternate the availability of water in time and space. This dissertation therefore deals with the question which role climatic variability plays for the effects of grazing on vegetation in dry rangelands. The relatively intact steppes in central Mongolia were chosen as a model system. They are characterised by low precipitation and high climatic variability in the south (100mm annual precipitation), and comparatively high precipitation and low climatic variability in the north (250mm). The effects of grazing on vegetation on 15 grazing transects were investigated along the climatic gradient. The central elements were the plant species and their abundances on 10m x 10m areas, for which functional characteristics such as height, affiliation of functional groups or leaf nutrients were recorded. The main hypothesis of this dissertation is that grazing has a greater impact on vegetation communities with increasing rainfall. To test this hypothesis, three studies were carried out. In a first study, the research group found that the vegetation communities in the dry area differ strongly along the climatic gradient, while the plant communities in the wetter area differ more strongly along the grazing gradient. The results of the second study suggested that this difference can be explained by a functional environmental filter that becomes weaker from south to north as the niche spectrum increases. The third study has shown that this is likely a function of the higher availability of resources, which at the same time leads to higher grazing pressure, therewith stressing the vegetation especially in years with droughts. In summary, the author concludes that the climate gradient also represents an environmental filter that filters species for certain characteristics, thus having a significant influence on the vegetation. Climatic variability influences the effect of grazing on vegetation, which is particularly problematic where the grazing intensity is high and the species are less adapted to strong climatic fluctuations. Future scenarios predict increasing productivity and therefore increasing livestock density. This may lead to an increase in floristic and functional diversity across the climate gradient, but also to increasing grazing effects and therefore threads for overgrazing. Increasing climatic variability is likely to intensify this thread, especially in the moister regions, whereas the dry rangelands are likely to be more resilient due to the adaptation of the plants to non-equilibrium dynamics.
Recently polyfluoroalkyl compounds (PFCs) were discovered as emerging persistentorganic pollutants. Because of their unique physicochemical properties due to theircombination of lipophilic and hydrophilic characteristics, PFCs have been widely used inmany consumer products, such as polymerisation aids, stain repellents on carpets, textiles, andpaper products for over 50 years. From the production and use of these products, PFCs can bereleased into the environment. Scientific concern about PFCs increased due to their globaldistribution and ubiquitous detection in the environment, especially in marine mammals.An analytical protocol was developed for the analysis of PFCs in water samples andvarious biological matrices. The samples were analysed for 40 PFCs plus 20 isotope-labelledinternal standards using high performance liquid chromatography/negative electrosprayionisation-tandem mass spectrometry (HPLC/(-)ESI-MS/MS). Furthermore, the analyticalquality of the laboratory has been approved in interlaboratory studies.In the first part of this Ph.D. thesis was investigated the occurrence, distribution patternand transportation mechanisms of PFCs in seawater. The rivers had a high influence on thedistribution of PFCs in offshore surface water in the German Bight, with decreasingconcentrations with increasing distance from the coast (see publication I). The research onthe spatial distribution of PFCs in coastal area is very important for the understanding of thetransportation and fate of PFCs in the marine environment. Furthermore, the longitudinal andlatitudinal distribution of PFCs in surface water of the Atlantic Ocean was investigated (seepublication II). The results indicate that trans-Atlantic Ocean currents caused the decreasingconcentration gradient from the Bay of Biscay to the South Atlantic Ocean and theconcentration drop-off close to the Labrador Sea. These data are very useful for globaltransportation models, in which industrial areas are considered as sources, and ocean watersas sinks of PFCs.The second part of this Ph.D. thesis examined the mechanisms and pathways of PFCs inharbor seals (Phoca vitulina) and their temporal trends in the German Bight. Firstly, thewhole body burden of PFCs and their tissue distribution (i.e., liver, kidney, lung, heart, blood,brain, muscle, thyroid, thymus, and blubber) was investigated in harbor seals (seepublication III). This study is relevant for calculation of the bioaccumulation potential ofthese compounds in marine mammals. Secondly, the temporal trends over the last decade andassociations between PFC concentration and the evidence of diseases, spatial distribution, ageand sex were evaluated in archived harbor seal livers (see publication IV). The results showsignificant declining concentrations of many PFCs indicating the replacement of these PFCsby shorter chained and less bioaccumulative compounds.Several studies were performed besides the main issue of the Ph.D. work. Firstly, watersamples were collected along the river Elbe into the North Sea to examine the distribution ofPFCs in the dissolved and particulate phase, their discharge into the North Sea, and theinfluence of waste water treatment plant effluents to the riverine mass flow. Furthermore,surface water samples were collected in the North Sea, Baltic Sea and Norwegian Sea, wherethe occurrence and spatial distribution between river estuaries, coastal waters, in brackish aswell as salt water, and open sea water were compared. Finally, within the frame of a researchstay at the National Institute of Advanced Industrial Science and Technology (AIST) in Japan,the partitioning behaviour of PFCs between pore water and sediment in two sediment coresfrom Tokyo Bay was investigated.This Ph.D. thesis has improved our knowledge of the occurrence and distribution of PFCsin water and biota highlighting association between PFCs and pathological conditions,potential sources and sinks, spatial distribution, and changes in their pattern and long-termperspective trends.
General Mental Ability, the Big Five, and several context specific variables are studied in regard to their relationship with two criteria of expatriate success, namely, adjustment and job performance. Interviews and standardized tests were conducted with a sample of 66 German and Austrian expatriates in South Korea. Results show no relationship with General Mental Ability for neither of the two criteria. Hypotheses for Conscientiousness and Emotional Stability were partially confirmed; Extraversion emerged to be negatively related to other-ratings of adjustment. Several context specific variables were found to be related to the criteria. Drawing from the study’s results, recommendations for future studies in the expatriate domain are provided.
Food forests present a promising solution to address multiple sustainability challenges adaptable to local contexts. As biodiverse multi-strata agroforestry systems, they can provide several ecological, socio-cultural and economic services. They sequester carbon, limit soil erosion and regulate the micro-climate; they offer the opportunity for education on healthy diets and ecology, and they produce food and can create livelihood opportunities. However, despite their obvious benefits, food forests are still a niche concept. To date, research has focused on their ecological and social services; we lack an understanding of food forests as a comprehensive sustainability solution, including their economic dimension, and knowledge on how to develop them. Addressing these gaps, this qualitative research used a solution- and process-oriented methodology guided by transformational sustainability research. In a comparative case study approach, it created an inventory of 209 food forests, followed by interviews and site visits of 14 sites to understand their characteristics and assess their sustainability (Article 1). More indepth, it analyzed the implementation path of seven food forest for success factors, barriers and coping strategies (Article 2). Based on these insights, two experimental case studies were initiated to develop sustainable food forests with practice partners, one based in Phoenix, Arizona, U.S. and one in Lüneburg, Germany. Two studies analyzed the cases' outputs and processes highlighting success factors and challenges, including the role of a sustainable entrepreneurial ecosystem (Article 3, Phoenix case) and key features of productive partnerships to understand why one case succeeded and the other failed (Article 4). Findings include key features of existing and sustainable food forests as well as success factors on how to develop them; namely acquiring a complementary skill set that includes specialty farming and entrepreneurial know-how, securing sufficient start-up funds and long-term land access as well as overcoming regulatory restrictions. Supporting institutions are especially needed to integrate and professionalize the planning stage and provide know-how on alternative business practices. Key features of productive partnerships include an entrepreneurial attitude, access to support functions, long-term orientation and commitment to food system sustainability.
This research work aims to create a theoretical base for new urban planning guidelines involving a comprehensive study of housing in Damascus with emphasis on social and cultural factors. The research starts with a historical review of the Muslim City in general and distinguishes between cities that existed before Islam and then were conquered and modified by Muslims and cities established by Muslim Authority. The focus is only on the residential quarters in the city and the local market, mosque and etc (outside the old walled city of Damascus). Other Muslim city urban elements such as Grand mosque, caliph's residency, Citadel and etc. are not in the scope of this study. A brief historical review of Damascus before and during Islam and the development of residential quarters are illustrated. Later, the study analyzes the traditional residential quarter and explores the building guidelines that governed the evolution of the built form of the quarter. Then, the study explores the multi-faceted changes (economic, social and political) that the Middle Eastern region went through, in the last century, in general and the effect of those changes on the city form, case of Damascus. The effect will be traced through examining the decrees that the Authority issued in order to govern land reform and manage public and private domains. Then, the study looks at the ramifications of those decrees on the urban form of Damascus. It also investigates the decrees that were the guide for new planning and organizing developments. The study will inspect the end products of the planning and organizing process by studying several cases of building permits. Then, provides morphology of the new residential sub-quarter and its urban form. Based on lessons learned from the previous decades of housing policy, the study will recommend foundation for governmental norms to produce responsive physical and social urban forms.
The doctoral dissertation deals with the problems of the diagnosis of rolling bearings using recurrence analysis. The main topic is the influence of radial internal clearance on the change of dynamics in a self-aligning double-row ball bearing with a tapered bore, in which the axial preload can control this parameter in a wide range. The dissertation began with an analysis of the state of knowledge. In the next part of the dissertation, the thesis was formulated and activities related to its proving were defined. The theoretical part was supplemented with the basics related to vibroacoustic diagnostics of rolling bearings and presented methods that can be used for their diagnostics. The research on proving the thesis was started with the preparation of a mathematical model in which a change in the damping coefficient in the field of radial clearance was adopted, a difference in the clearance value for a given row of balls was proposed, and the influence of shape errors and radial shaft endplay on the dynamics of the tested bearing was taken into account. During the dynamics tests, the radial clearance was adopted as a bifurcation parameter, and on the basis of the bifurcation diagram, it was possible to indicate the characteristic areas of bearing operation due to the radial internal clearance. In order to verify the model, experimental tests were carried out with a series of bearings in which the radial clearance was changed in a wide range possible to be physically realized. Recurrence analysis was used for both the dynamic response obtained from model and experimental studies. Owing to the comparative analysis of the dynamic response, recurrence quantificators were selected that are most susceptible to changes in radial clearance to bearing dynamics. Moreover, as a result of the research, it was possible to select a narrow range of radial clearance, ensuring the smoothest operation of the tested bearing.
This chapter is structured into two sub chapters, studied and written by two research-groups, titled: (1) Tales of Challenge (2) Tales of Success. The chapter concludes with a common summary of all findings. In both sub chapters the same approach was applied. Semi-structured interviews were conducted and analyzed according to Mayring (2000) to collect perspectives from practice and research. Some interviews were conducted by each research group separately and some together. Also, a method inspired by Photovoice was used to gain a deeper understanding of specific challenges and drivers in the respective projects. Inspired by the Photovoice method (Wang and Burris, 1997), interviewees were asked to share a picture and short description answering a question posed by the researchers to gain a deeper understanding of specific challenges and drivers in the respective projects. Our shared main character, Joice, will keep popping up during this chapter to share her experience.
This cumulative thesis extends the econometric literature on testing for cointegration in nonstationary panel data with cross-sectional dependence. Its self-contained chapters consist of two publications and two publication manuscripts which present three new panel tests for the cointegrating rank and an empirical study of the exchange rate pass-through to import prices in Europe. The first chapter introduces a new cointegrating rank test for panel data where the dependence is assumed to be driven by unobserved common factors. The common factors are first estimated and subtracted from the observations. Then an existing likelihood-ratio panel cointegration test is applied to the defactored data. The distribution of the test statistic, computed from defactored data, is shown to be asymptotically equivalent to that of a test statistic computed from cross-sectionally independent data. The second chapter proposes a new panel cointegrating rank test based on a multiple testing procedure, which is robust to positive dependence between the individual units' test statistics. The assumption of a certain type of positive dependence is shown by simulations not to be violated in panels with dependence structures commonly assumed in practice. The new test is applied to find empirical support of the monetary exchange rate model in a panel of eight OECD countries. The third chapter puts forward a new panel cointegration test allowing for both cross-sectional dependence and structural breaks. It employs known individual likelihood-ratio test statistics accounting for breaks in the deterministic trend and combines their p-values by a novel modification of the Inverse Normal method. The average correlation between the probits is inferred from the average cross-sectional correlation between the residuals of the individual VAR models in first differences. The fourth chapter studies the exchange rate pass-through to import prices in a panel of nineteen European countries through the prism of panel cointegration. Empirical evidence supporting a theoretical long-run equilibrium relationship between the model's variables is found by the newly proposed panel cointegration tests. Two different panel regression models, which take both cointegration and cross-sectional dependence into account, provide most recent estimates of the exchange rate pass-through elasticities.
The Model of Culture Fit explains the way in which socio-cultural environment influences internal work culture and human resource management practices. This model was tested using 1,954 employees from business organisations in 10 countries. Participants completed a 57-item questionnaire which measured managerial perceptions of four socio-cultural dimensions, six internal work culture dimensions and HRM practices in three areas ...
The emission of anthropogenic trace substances into the aquatic environment continuously poses challenges to water suppliers. The contamination of raw waters with organic trace substances requires complex water treatment processes to secure drinking water quality. The routine monitoring of these raw waters as well as the behavior and fate of organic trace substances during different treatment processes is of great interest to recognize and counter potential dangers at an early stage. Non-target screening using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) allows the detection of thousands of compounds within a single run and covers known as well as unknown substances. Compared to the established analytical techniques, this is a decisive advantage for the monitoring of raw and process waters during water treatment. While the analytical technique LC-HRMS has undergone significant developments in recent years, the algorithms for data processing reveal clear weaknesses. This dissertation therefore deals with reliable processing strategies for LC-HRMS data. The first part of this work seeks to highlight the problematics of false positive and false negative findings. Based on repeated measurements, various strategies of data processing were assessed with regard to the repeatability of the results. To ensure that real peaks were barely or not removed by the filtering procedure, samples were spiked with isotope-labeled standards. The results emphasize that the processing of sample triplicates results in sufficient repeatability and that the signal fluctuation across the triplicates emerged as a powerful filtering criteria. The number of false positives and false negatives could be significantly reduced by the developed strategies which consequently improve the validity of the data. The second part of this thesis addresses the development of processing strategies particularly aimed at assessing water treatment processes. The detected signals were tracked across the treatment process and classified based on their fold changes. A more reliable signal classification was achieved by implementing a recursive integration approach. Special integration algorithms allow a reliable signal classification even though the signal to be compared was below the intensity threshold. Different combinations of replicates of process influents and effluents were processed for evaluating the repeatability. The good repeatability was indicated by the results of both the plausibility checks and the ozonation process (ozonation of pretreated river water) and thus points to high reliability. The applicability of the developed strategies to real world applications is demonstrated in the last part of this work. Besides the prioritization of the generated results, the main focus was the identification of recognized compounds. The developed strategies clearly improve the validity of the underlying data. The combination of LC-HRMS analysis with reliable processing strategies opens up multiple possibilities for a more comprehensive monitoring of water resources and for the assessment of water treatment processes. The processing strategies and validation concepts may be easily transferred to other research fields.