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In Zeiten eines sich schnell ändernden und vielseitigen Energiemarktes müssen Kohlenstoffmaterialien für verschiedene Anforderungen einsetzbar sein. Dies erfordert flexibel synthetisierbare Kohlenstoffmaterialien bevorzugt aus günstigen und nachhaltigen Kohlenstoffquellen. Es ist allerdings nicht leicht Vorläuferverbindungen auszumachen, welche sich einerseits für verschiedene Herstellungsverfahren eignen und deren Kohlenstoffprodukte andererseits in spezifischen Eigenschaften, wie der Struktur, des Stickstoffanteils, der Oberfläche und der Porengrößen, eingestellt werden können. In diesem Zusammenhang können natürliche Polyphenole, etwa überschüssige Tannine aus der Weinproduktion, eine neue Welt zu hoch funktionalen und vielseitig einstellbaren Kohlenstoffmaterialien mit hohen Ausbeuten öffnen.
Das Hauptziel dieser vorliegenden Thesis war es neue funktionale, einstellbare und skalierbare nanostrukturierte Kohlenstoffmaterialien aus Tanninen (insbesondere Tanninsäure) für unterschiedliche elektrochemische Zwecke zu synthetisieren und zu charakterisieren. Ermöglicht wurde dies durch unterschiedliche synthetische Herangehensweisen, wie etwa der polymeren Strukturdirektion, dem ionothermalen Templatieren und der weichen Templatierung. An Stelle des weitläufig gebräuchlichen, aber kanzerogenen Vernetzungsagens Formaldehyd wurden bei den vorgestellten Synthesen Harnstoff und Thioharnstoff gewählt, um zugleich die synthetisierten Kohlenmaterialien variabel dotieren zu können.
Daher wurden im ersten Teil der Arbeit die Wechselwirkungen, Reaktionen und thermischen Verhaltensweisen von Tanninsäure und Mixturen von Tanninsäure und Harnstoff bzw. Thioharnstoff untersucht, um daraus wichtige Erkenntnisse für die verschiedenen Kohlenstoffsynthesen zu gewinnen.
Durch die Verwendung eines polymeren Strukturierungsagenz Pluronic P123 konnten in einer ersten Kohlenstoffsynthese nachhaltige und dotierbare Kohlenstoffpartikel mit Durchmessern im Nanometerbereich aus Tanninsäure und Harnstoff hergestellt werden. Es konnte dabei gezeigt werden, dass durch die Modifikation der verschiedenen Syntheseparameter die Kohlenstoffnanopartikel gemäß ihres gemittelten Partikeldurchmessers, ihrer BET-Oberfläche, ihrer Komposition, ihrer Leitfähigkeit und ihrer chemischen Stabilität einstellbar sind. Dies eröffnete die Möglichkeit diese Kohlenstoffpartikel als alternatives und nachhaltiges Rußmaterial einzusetzen.
Weiterhin war es durch die ionothermale Templatierung möglich poröse, dotierte und kontrollierbare Kohlenstoffpartikel mit hohen spezifischen Oberflächen aus den gewählten Präkursorverbindungen zu synthetisieren, die sich für den Einsatz in Superkondensatoren eignen.
Auf diesen Erkenntnissen aufbauend konnten mittels der Rotationsbeschichtung poröse binderfreie und strukturierte Kohlenstofffilme synthetisiert werden, die eine spinodale Struktur aufwiesen. Anhand der Modifikation der Stammlösungskonzentration, der Rotationsgeschwindigkeit und der verwendeten Substrate konnten die Filmdicke (100-1000 nm), die Morphologie und Gesamtoberfläche gezielt beeinflusst werden. Die erweiterte elektrochemische Analyse zeigte außerdem ein sehr gut zugängliches Porensystem der porösen Kohlenstofffilme.
Allumfassend konnten demnach verschiedene Synthesewege für Kohlenstoffmaterialien aus Tanninen aufgezeigt werden, die verschiedenartig strukturiert und kontrolliert werden können und sich für diverse Anwendungsgebiete eignen.
Orthogonal systems for heterologous protein expression as well as for the engineering of synthetic gene regulatory circuits in hosts like Saccharomyces cerevisiae depend on synthetic transcription factors (synTFs) and corresponding cis-regulatory binding sites. We have constructed and characterized a set of synTFs based on either transcription activator-like effectors or CRISPR/Cas9, and corresponding small synthetic promoters (synPs) with minimal sequence identity to the host’s endogenous promoters. The resulting collection of functional synTF/synP pairs confers very low background expression under uninduced conditions, while expression output upon induction of the various synTFs covers a wide range and reaches induction factors of up to 400. The broad spectrum of expression strengths that is achieved will be useful for various experimental setups, e.g., the transcriptional balancing of expression levels within heterologous pathways or the construction of artificial regulatory networks. Furthermore, our analyses reveal simple rules that enable the tuning of synTF expression output, thereby allowing easy modification of a given synTF/synP pair. This will make it easier for researchers to construct tailored transcriptional control systems.
In the present work side-chain polystyrenes were synthesized and characterized, in order to be applied in multilayer OLEDs fabricated by solution process techniques. Manufacture of optoelectronic devices by solution process techniques is meant to decrease significantly fabrication cost and allow large scale production of such devices.
This dissertation focusses in three series, enveloped in two material classes. The two classes differ to each other in the type of charge transport exhibited, either ambipolar transport or electron transport. All materials were applied in all-organic solution processed green Ir-based devices.
In the first part, a series of ambipolar host materials were developed to transport both charge types, holes and electrons, and be applied especially as matrix for green Ir-based emitters. It was possible to increase devices efficacy by modulating the predominant charge transport type. This was achieved by modification of molecules electron transport part with more electron-deficient heterocycles or by extending the delocalization of the LUMO. Efficiencies up to 28.9 cd/A were observed for all-organic solution-process three layer devices.
In the second part, suitability of triarylboranes and tetraphenylsilanes as electron transport materials was studied. High triplet energies were obtained, up to 2.95 eV, by rational combination of both molecular structures. Although the combination of both elements had a low effect in materials electron transport properties, high efficiencies around 24 cd/A were obtained for the series in all-organic solution-processed two layer devices.
In the last part, benzene and pyridine were chosen as the series electron-transport motif. By controlling the relative pyridine content (RPC) solubility into methanol was induced for polystyrenes with bulky side-chains. Materials with RPC ≥ 0.5 could be deposited orthogonally from solution without harming underlying layers. From the best of our knowledge, this is the first time such materials are applied in this architecture showing moderate efficiencies around 10 cd/A in all-organic solution processed OLEDs.
Overall, the outcome of these studies will actively contribute to the current research on materials for all-solution processed OLEDs.
I. Ceric ammonium nitrate (CAN) mediated thiocyanate radical additions to glycals
In this dissertation, a facile entry was developed for the synthesis of 2-thiocarbohydrates and their transformations. Initially, CAN mediated thiocyanation of carbohydrates was carried out to obtain the basic building blocks (2-thiocyanates) for the entire studies. Subsequently, 2-thiocyanates were reduced to the corresponding thiols using appropriate reagents and reaction conditions. The screening of substrates, stereochemical outcome and the reaction mechanism are discussed briefly (Scheme I).
Scheme I. Synthesis of the 2-thiocyanates II and reductions to 2-thiols III & IV.
An interesting mechanism was proposed for the reduction of 2-thiocyanates II to 2-thiols III via formation of a disulfide intermediate. The water soluble free thiols IV were obtained by cleaving the thiocyanate and benzyl groups in a single step. In the subsequent part of studies, the synthetic potential of the 2-thiols was successfully expanded by simple synthetic transformations.
II. Transformations of the 2-thiocarbohydrates
The 2-thiols were utilized for convenient transformations including sulfa-Michael additions, nucleophilic substitutions, oxidation to disulfides and functionalization at the anomeric position. The diverse functionalizations of the carbohydrates at the C-2 position by means of the sulfur linkage are the highlighting feature of these studies. Thus, it creates an opportunity to expand the utility of 2-thiocarbohydrates for biological studies.
Reagents and conditions: a) I2, pyridine, THF, rt, 15 min; b) K2CO3, MeCN, rt, 1 h; c) MeI, K2CO3, DMF, 0 °C, 5 min; d) Ac2O, H2SO4 (1 drop), rt, 10 min; e) CAN, MeCN/H2O, NH4SCN, rt, 1 h; f) NaN3, ZnBr2, iPrOH/H2O, reflux, 15 h; g) NaOH (1 M), TBAI, benzene, rt, 2 h; h) ZnCl2, CHCl3, reflux, 3 h.
Scheme II. Functionalization of 2-thiocarbohydrates.
These transformations have enhanced the synthetic value of 2-thiocarbohydrates for the preparative scale. Worth to mention is the Lewis acid catalyzed replacement of the methoxy group by other nucleophiles and the synthesis of the (2→1) thiodisaccharides, which were obtained with complete β-selectivity. Additionally, for the first time, the carbohydrate linked thiotetrazole was synthesized by a (3 + 2) cycloaddition approach at the C-2 position.
III. Synthesis of thiodisaccharides by thiol-ene coupling.
In the final part of studies, the synthesis of thiodisaccharides by a classical photoinduced thiol-ene coupling was successfully achieved.
Reagents and conditions: 2,2-Dimethoxy-2-phenylacetophenone (DPAP), CH2Cl2/EtOH, hv, rt.
Scheme III. Thiol-ene coupling between 2-thiols and exo-glycals.
During the course of investigations, it was found that the steric hindrance plays an important role in the addition of bulky thiols to endo-glycals. Thus, we successfully screened the suitable substrates for addition of various thiols to sterically less hindered alkenes (Scheme III). The photochemical addition of 2-thiols to three different exo-glycals delivered excellent regio- and diastereoselectivities as well as yields, which underlines the synthetic potential of this convenient methodology.
The title compound was prepared by the reaction of 1,4,10,13-tetraoxa-7,16-diazacyclo-octadecane with 4-chloro-2-methyl-phenoxyacetic acid in a ratio of 1:2. The structure has been proved by the data of elemental analysis, IR spectroscopy, NMR ( 1 H, 13 C) technique and by X-ray diffraction analysis. Intermolecular hydrogen bonds between the azonium protons and oxygen atoms of the carboxylate groups were found. Immunoactive properties of the title compound have been screened. The compound has the ability to suppress spontaneous and Con A-stimulated cell proliferation in vitro and therefore can be considered as immunodepressant.
Graphs are ubiquitous in Computer Science. For this reason, in many areas, it is very important to have the means to express and reason about graph properties. In particular, we want to be able to check automatically if a given graph property is satisfiable. Actually, in most application scenarios it is desirable to be able to explore graphs satisfying the graph property if they exist or even to get a complete and compact overview of the graphs satisfying the graph property.
We show that the tableau-based reasoning method for graph properties as introduced by Lambers and Orejas paves the way for a symbolic model generation algorithm for graph properties. Graph properties are formulated in a dedicated logic making use of graphs and graph morphisms, which is equivalent to firstorder logic on graphs as introduced by Courcelle. Our parallelizable algorithm gradually generates a finite set of so-called symbolic models, where each symbolic model describes a set of finite graphs (i.e., finite models) satisfying the graph property. The set of symbolic models jointly describes all finite models for the graph property (complete) and does not describe any finite graph violating the graph property (sound). Moreover, no symbolic model is already covered by another one (compact). Finally, the algorithm is able to generate from each symbolic model a minimal finite model immediately and allows for an exploration of further finite models. The algorithm is implemented in the new tool AutoGraph.
Swearing in a public place
(2017)
The paper deals with the usage of swear words on the online forum "reddit". Three research questions are dealt with:
How often are swear words used?
How are these swear words received by other users?
Does the topic of the conversation have an influence on the reception and amount of usage of swear words?
The corpus from which the results are taken comprises almost 900 million words. The words are taken from February 2017. Compared to other, similar studies, the corpus is considerably larger and contempory.
In addition, the theoretical part discusses the linguistic basics of swear words. These include concepts such as the theory of politeness, the topic of taboos and its corresponding words and censorship. This is done to explain the factors that influence the use and application of swear words and to explain why swearwords are so special in comparison to other word groups. In addition, further research results from other corpora are presented and compared with the results afterwards. This includes corpora that are also composed of online communication, as well as corpora that reproduce spoken language. The results from all the corpora presented deal with results from the English language.
The results of this study indicate that the swear words on "reddit" are used approximately as often as they are on other platforms. The perception of these swear words is mostly positive, which suggests that the use of swear words on "reddit" is not perceived as impolite. In addition, an influence of the discussion topic on the frequency and reception of swear words could be determined.
Nowadays, the need to protect the environment becomes more urgent than ever. In the field of chemistry, this translates to practices such as waste prevention, use of renewable feedstocks, and catalysis; concepts based on the principles of green chemistry. Polymers are an important product in the chemical industry and are also in the focus of these changes. In this thesis, more sustainable approaches to make two classes of polymers, polypeptoids and polyesters, are described.
Polypeptoids or poly(alkyl-N-glycines) are isomers of polypeptides and are biocompatible, as well as degradable under biologically relevant conditions. In addition to that, they can have interesting properties such as lower critical solution temperature (LCST) behavior. They are usually synthesized by the ring opening polymerization (ROP) of N-carboxy anhydrides (NCAs), which are produced with the use of toxic compounds (e.g. phosgene) and which are highly sensitive to humidity. In order to avoid the direct synthesis and isolation of the NCAs, N-phenoxycarbonyl-protected N-substituted glycines are prepared, which can yield the NCAs in situ. The conditions for the NCA synthesis and its direct polymerization are investigated and optimized for the simplest N-substituted glycine, sarcosine. The use of a tertiary amine in less than stoichiometric amounts compared to the N-phenoxycarbonyl--sarcosine seems to accelerate drastically the NCA formation and does not affect the efficiency of the polymerization. In fact, well defined polysarcosines that comply to the monomer to initiator ratio can be produced by this method. This approach was also applied to other N-substituted glycines.
Dihydroxyacetone is a sustainable diol produced from glycerol, and has already been used for the synthesis of polycarbonates. Here, it was used as a comonomer for the synthesis of polyesters. However, the polymerization of dihydroxyacetone presented difficulties, probably due to the insolubility of the macromolecular chains. To circumvent the problem, the dimethyl acetal protected dihydroxyacetone was polymerized with terephthaloyl chloride to yield a soluble polymer. When the carbonyl was recovered after deprotection, the product was insoluble in all solvents, showing that the carbonyl in the main chain hinders the dissolution of the polymers. The solubility issue can be avoided, when a 1:1 mixture of dihydroxyacetone/ ethylene glycol is used to yield a soluble copolyester.
Anthropogenically amplified erosion leads to increased fine-grained sediment input into the fluvial system in the 15.000 km2 Kharaa River catchment in northern Mongolia and constitutes a major stressing factor for the aquatic ecosystem. This study uniquely combines the application of intensive monitoring, source fingerprinting and catchment modelling techniques to allow for the comparison of the credibility and accuracy of each single method. High-resolution discharge data were used in combination with daily suspended solid measurements to calculate the suspended sediment budget and compare it with estimations of the sediment budget model SedNet. The comparison of both techniques showed that the development of an overall sediment budget with SedNet was possible, yielding results in the same order of magnitude (20.3 kt a- 1 and 16.2 kt a- 1).
Radionuclide sediment tracing, using Be-7, Cs-137 and Pb-210 was applied to differentiate sediment sources for particles < 10μm from hillslope and riverbank erosion and showed that riverbank erosion generates 74.5% of the suspended sediment load, whereas surface erosion contributes 21.7% and gully erosion only 3.8%. The contribution of the single subcatchments of the Kharaa to the suspended sediment load was assessed based on their variation in geochemical composition (e.g. in Ti, Sn, Mo, Mn, As, Sr, B, U, Ca and Sb). These variations were used for sediment source discrimination with geochemical composite fingerprints based on Genetic Algorithm driven Discriminant Function Analysis, the Kruskal–Wallis H-test and Principal Component Analysis. The contributions of the individual sub-catchment varied from 6.4% to 36.2%, generally showing higher contributions from the sub-catchments in the middle, rather than the upstream portions of the study area.
The results indicate that river bank erosion generated by existing grazing practices of livestock is the main cause for elevated fine sediment input. Actions towards the protection of the headwaters and the stabilization of the river banks within the middle reaches were identified as the highest priority. Deforestation and by lodging and forest fires should be prevented to avoid increased hillslope erosion in the mountainous areas. Mining activities are of minor importance for the overall catchment sediment load but can constitute locally important point sources for particular heavy metals in the fluvial system.
This review analyzes the potential role and long-term effects of field perennial polycultures (mixtures) in agricultural systems, with the aim of reducing the trade-offs between provisioning and regulating ecosystem services. First, crop rotations are identified as a suitable tool for the assessment of the long-term effects of perennial polycultures on ecosystem services, which are not visible at the single-crop level. Second, the ability of perennial polycultures to support ecosystem services when used in crop rotations is quantified through eight agricultural ecosystem services. Legume-grass mixtures and wildflower mixtures are used as examples of perennial polycultures, and compared with silage maize as a typical crop for biomass production. Perennial polycultures enhance soil fertility, soil protection, climate regulation, pollination, pest and weed control, and landscape aesthetics compared with maize. They also score lower for biomass production compared with maize, which confirms the trade-off between provisioning and regulating ecosystem services. However, the additional positive factors provided by perennial polycultures, such as reduced costs for mineral fertilizer, pesticides, and soil tillage, and a significant preceding crop effect that increases the yields of subsequent crops, should be taken into account. However, a full assessment of agricultural ecosystem services requires a more holistic analysis that is beyond the capabilities of current frameworks.
Theoretischer Hintergrund:Supervision spielt eine zentrale Rolle zum Wissens- und Kompetenzerwerb sowie in der Qualitätssicherung.
Fragestellung:Ziel war es, den aktuellen Forschungsstand zur Supervision im Rahmen der kognitiven Verhaltenstherapie abzubilden, um daraus Schlussfolgerungen für die zukünftige Forschung abzuleiten.
Methode:Zur Evidenzsynthese wurde ein Scoping Review durchgeführt, das die Darstellung zentraler Konzepte, aktueller Evidenz und möglicher Forschungsbedarfe ermöglichte. Neben einer systematischen Literaturrecherche wurden Vorwärts- und Rückwärtssuchstrategien eingesetzt.
Ergebnisse:Eingeschlossen wurden zwölf Publikationen basierend auf zehn empirischen Studien. Alle Studien beschrieben Ausbildungssettings, aber nur wenige untersuchten übende Interventionen (z. B. Rollenspiele). Häufig wurden Effekte subjektiv erfasst, die methodische Qualität der Begleitstudien variierte.
Schlussfolgerungen:Notwendig sind weitere methodisch hochwertige Studien, experimentell orientiert oder in der klinischen Praxis, die die Supervisionsforschung bereichern können.
Studium nach Bologna
(2017)
Ziel des vorliegenden dritten Bandes der Potsdamer Beiträge zur Hochschulforschung ist es, ausgewählte Aspekte der Hochschuldebatte um Studium und Lehre zu beleuchten und mit empirischen Befunden zu vertiefen. Im Fokus stehen solche aktuellen Debatten wie die Gestaltung des Studieneingangs, die Erhöhung der Beschäftigungsbefähigung, die Qualität der Praktika sowie Probleme der Lehrerbildung. Dabei wird die Hochschuldebatte in Deutschland durch einschlägige Beiträge aus anderen, west- und osteuropäischen Ländern erweitert.
Die Reihe versteht sich als Forum verschiedener Akteure aus der Hochschulforschung, die die Diskussion zur Qualitätsentwicklung in Lehre und Studium mit ihren Impulsen aus Analysen und empirischen Ergebnissen bereichern sollen. Der Band richtet sich an alle, die sich für die Entwicklung an Hochschulen interessieren.
Decades of research have demonstrated that physical stress (PS) stimulates bone remodeling and affects bone structure and function through complex mechanotransduction mechanisms. Recent research has laid ground to the hypothesis that mental stress (MS) also influences bone biology, eventually leading to osteoporosis and increased bone fracture risk. These effects are likely exerted by modulation of hypothalamic–pituitary–adrenal axis activity, resulting in an altered release of growth hormones, glucocorticoids and cytokines, as demonstrated in human and animal studies. Furthermore, molecular cross talk between mental and PS is thought to exist, with either synergistic or preventative effects on bone disease progression depending on the characteristics of the applied stressor. This mini review will explain the emerging concept of MS as an important player in bone adaptation and its potential cross talk with PS by summarizing the current state of knowledge, highlighting newly evolving notions (such as intergenerational transmission of stress and its epigenetic modifications affecting bone) and proposing new research directions.
Background: Functional abdominal pain (FAP) is not only a highly prevalent disease but also poses a considerable burden on children and their families. Untreated, FAP is highly persistent until adulthood, also leading to an increased risk of psychiatric disorders. Intervention studies underscore the efficacy of cognitive behavioral treatment approaches but are limited in terms of sample size, long-term follow-up data, controls and inclusion of psychosocial outcome data.
Methods/Design: In a multicenter randomized controlled trial, 112 children aged 7 to 12 years who fulfill the Rome III criteria for FAP will be allocated to an established cognitive behavioral training program for children with FAP (n = 56) or to an active control group (focusing on age-appropriate information delivery; n = 56). Randomization occurs centrally, blockwise and is stratified by center. This study is performed in five pediatric gastroenterology outpatient departments. Observer-blind assessments of outcome variables take place four times: pre-, post-, 3- and 12-months post-treatment. Primary outcome is the course of pain intensity and frequency. Secondary endpoints are health-related quality of life, pain-related coping and cognitions, as well as selfefficacy.
Discussion: This confirmatory randomized controlled clinical trial evaluates the efficacy of a cognitive behavioral intervention for children with FAP. By applying an active control group, time and attention processes can be controlled, and long-term follow-up data over the course of one year can be explored.
The interdisciplinary workshop STOCHASTIC PROCESSES WITH APPLICATIONS IN THE NATURAL SCIENCES was held in Bogotá, at Universidad de los Andes from December 5 to December 9, 2016. It brought together researchers from Colombia, Germany, France, Italy, Ukraine, who communicated recent progress in the mathematical research related to stochastic processes with application in biophysics.
The present volume collects three of the four courses held at this meeting by Angelo Valleriani, Sylvie Rœlly and Alexei Kulik.
A particular aim of this collection is to inspire young scientists in setting up research goals within the wide scope of fields represented in this volume.
Angelo Valleriani, PhD in high energy physics, is group leader of the team "Stochastic processes in complex and biological systems" from the Max-Planck-Institute of Colloids and Interfaces, Potsdam.
Sylvie Rœlly, Docteur en Mathématiques, is the head of the chair of Probability at the University of Potsdam.
Alexei Kulik, Doctor of Sciences, is a Leading researcher at the Institute of Mathematics of Ukrainian National Academy of Sciences.
In this thesis, stochastic dynamics modelling collective motions of populations, one of the most mysterious type of biological phenomena, are considered. For a system of N particle-like individuals, two kinds of asymptotic behaviours are studied : ergodicity and flocking properties, in long time, and propagation of chaos, when the number N of agents goes to infinity. Cucker and Smale, deterministic, mean-field kinetic model for a population without a hierarchical structure is the starting point of our journey : the first two chapters are dedicated to the understanding of various stochastic dynamics it inspires, with random noise added in different ways. The third chapter, an attempt to improve those results, is built upon the cluster expansion method, a technique from statistical mechanics. Exponential ergodicity is obtained for a class of non-Markovian process with non-regular drift. In the final part, the focus shifts onto a stochastic system of interacting particles derived from Keller and Segel 2-D parabolicelliptic model for chemotaxis. Existence and weak uniqueness are proven.
Understanding the distribution of species is fundamental for biodiversity conservation, ecosystem management, and increasingly also for climate impact assessment. The presence of a species in a given site depends on physiological limitations (abiotic factors), interactions with other species (biotic factors), migratory or dispersal processes (site accessibility) as well as the continuing
effects of past events, e.g. disturbances (site legacy). Existing approaches to predict species distributions either (i) correlate observed species occurrences with environmental variables describing abiotic limitations, thus ignoring biotic interactions, dispersal and legacy effects (statistical species distribution model, SDM); or (ii) mechanistically model the variety of processes determining species distributions (process-based model, PBM). SDMs are widely used due to their easy applicability and ability to handle varied data qualities. But they fail to reproduce the dynamic response of species distributions to changing conditions. PBMs are expected to be superior in this respect, but they need very specific data unavailable for many species, and are often more complex and require more computational effort. More recently, hybrid models link the two approaches to combine their respective strengths.
In this thesis, I apply and compare statistical and process-based approaches to predict species distributions, and I discuss their respective limitations, specifically for applications in changing environments. Detailed analyses of SDMs for boreal tree species in Finland reveal that nonclimatic predictors - edaphic properties and biotic interactions - are important limitations at the treeline, contesting the assumption of unrestricted, climatically induced range expansion. While the estimated SDMs are successful within their training data range, spatial and temporal model transfer fails. Mapping and comparing sampled predictor space among data subsets identifies spurious extrapolation as the plausible explanation for limited model transferability. Using these findings, I analyze the limited success of an established PBM (LPJ-GUESS) applied to the same problem. Examination of process representation and parameterization in the PBM identifies implemented processes to adjust (competition between species, disturbance) and missing processes that are crucial in boreal forests (nutrient limitation, forest management). Based on climatic correlations shifting over time, I stress the restricted temporal transferability of bioclimatic limits used in LPJ-GUESS and similar PBMs. By critically assessing the performance of SDM and PBM in this application, I demonstrate the importance of understanding the limitations of the
applied methods.
As a potential solution, I add a novel approach to the repertoire of existing hybrid models. By simulation experiments with an individual-based PBM which reproduces community dynamics resulting from biotic factors, dispersal and legacy effects, I assess the resilience of coastal vegetation to abrupt hydrological changes. According to the results of the resilience analysis, I then modify temporal SDM predictions, thereby transferring relevant process detail from PBM to
SDM. The direction of knowledge transfer from PBM to SDM avoids disadvantages of current hybrid models and increases the applicability of the resulting model in long-term, large-scale applications. A further advantage of the proposed framework is its flexibility, as it is readily extended to other model types, disturbance definitions and response characteristics.
Concluding, I argue that we already have a diverse range of promising modelling tools at hand, which can be refined further. But most importantly, they need to be applied more thoughtfully. Bearing their limitations in mind, combining their strengths and openly reporting underlying assumptions and uncertainties is the way forward.
Start-up incentives targeted at unemployed individuals have become an important tool of the Active Labor Market Policy (ALMP) to fight unemployment in many countries in recent years. In contrast to traditional ALMP instruments like training measures, wage subsidies, or job creation schemes, which are aimed at reintegrating unemployed individuals into dependent employment, start-up incentives are a fundamentally different approach to ALMP, in that they intend to encourage and help unemployed individuals to exit unemployment by entering self-employment and, thus, by creating their own jobs. In this sense, start-up incentives for unemployed individuals serve not only as employment and social policy to activate job seekers and combat unemployment but also as business policy to promote entrepreneurship. The corresponding empirical literature on this topic so far has been mainly focused on the individual labor market perspective, however. The main part of the thesis at hand examines the new start-up subsidy (“Gründungszuschuss”) in Germany and consists of four empirical analyses that extend the existing evidence on start-up incentives for unemployed individuals from multiple perspectives and in the following directions:
First, it provides the first impact evaluation of the new start-up subsidy in Germany. The results indicate that participation in the new start-up subsidy has significant positive and persistent effects on both reintegration into the labor market as well as the income profiles of participants, in line with previous evidence on comparable German and international programs, which emphasizes the general potential of start-up incentives as part of the broader ALMP toolset. Furthermore, a new innovative sensitivity analysis of the applied propensity score matching approach integrates findings from entrepreneurship and labor market research about the key role of an individual’s personality on start-up decision, business performance, as well as general labor market outcomes, into the impact evaluation of start-up incentives. The sensitivity analysis with regard to the inclusion and exclusion of usually unobserved personality variables reveals that differences in the estimated treatment effects are small in magnitude and mostly insignificant. Consequently, concerns about potential overestimation of treatment effects in previous evaluation studies of similar start-up incentives due to usually unobservable personality variables are less justified, as long as the set of observed control variables is sufficiently informative (Chapter 2).
Second, the thesis expands our knowledge about the longer-term business performance and potential of subsidized businesses arising from the start-up subsidy program. In absolute terms, the analysis shows that a relatively high share of subsidized founders successfully survives in the market with their original businesses in the medium to long run. The subsidy also yields a “double dividend” to a certain extent in terms of additional job creation. Compared to “regular”, i.e., non-subsidized new businesses founded by non-unemployed individuals in the same quarter, however, the economic and growth-related impulses set by participants of the subsidy program are only limited with regard to employment growth, innovation activity, or investment. Further investigations of possible reasons for these differences show that differential business growth paths of subsidized founders in the longer run seem to be mainly limited by higher restrictions to access capital and by unobserved factors, such as less growth-oriented business strategies and intentions, as well as lower (subjective) entrepreneurial persistence. Taken together, the program has only limited potential as a business and entrepreneurship policy intended to induce innovation and economic growth (Chapters 3 and 4).
And third, an empirical analysis on the level of German regional labor markets yields that there is a high regional variation in subsidized start-up activity relative to overall new business formation. The positive correlation between regular start-up intensity and the share among all unemployed individuals who participate in the start-up subsidy program suggests that (nascent) unemployed founders also profit from the beneficial effects of regional entrepreneurship capital. Moreover, the analysis of potential deadweight and displacement effects from an aggregated regional perspective emphasizes that the start-up subsidy for unemployed individuals represents a market intervention into existing markets, which affects incumbents and potentially produces inefficiencies and market distortions. This macro perspective deserves more attention and research in the future (Chapter 5).
The Star Excursion Balance Test (SEBT) is effective in measuring dynamic postural control (DPC). This research aimed to determine whether DPC measured by the SEBT in young athletes (YA) with back pain (BP) is different from those without BP (NBP). 53 BP YA and 53 NBP YA matched for age, height, weight, training years, training sessions/week and training minutes/session were studied. Participants performed 4 practice trials after which 3 measurements in the anterior, posteromedial and posterolateral SEBT reach directions were recorded. Normalized reach distance was analyzed using the mean of all 3 measurements. There was no statistical significant difference (p > 0.05) between the reach distance of BP (87.2 ± 5.3, 82.4 ± 8.2, 78.7 ± 8.1) and NBP (87.8 ± 5.6, 82.4 ± 8.0, 80.0 ± 8.8) in the anterior, posteromedial and posterolateral directions respectively. DPC in YA with BP, as assessed by the SEBT, was not different from NBP YA.