Bøger udgivet af Cuvillier

The THz frequency band (0.1 ¿ 10 THz) is located in between the well explored optical frequencies and the microwave band. Despite growing research efforts in the last two decades, THz sensing systems are far from robust and cost effective. The development of passive devices for THz applications like waveguides, filters, reflectors and modulators is in the beginning of being established. This work contributes to the field by introducing novel polymer filter structures and a new design of THz fibers. These passive devices are fabricated by using a fiber drawing technique to scale down inscribed patterns in polymer to the THz wavelengths. Moreover, the revolutionary quasi time-domain spectrometer approach is further extended to suit varying sensing applications.This work is structured in four chapters. The first chapter describes THz fundamentals and state-of-the-art THz systems for common time-domain (TDS) and continuous wave (CW) spectrometers. The generation and detection principles are discussed in detail and typical system designs are presented.In the second chapter the fabrication and design process of polymer photonic crystal THz waveguides is presented. An improved near-field THz TDS system is introduced to verify the mode distributions. In addition, a new approach for improving the confinement and stripping of undesired higher order modes is demonstrated.Chapter three presents a new polymer filter structure. The fabrication process scales down inscribed features in a polymer preform by fiber drawing. Thus it is possible to obtain hole diameters of 200 µm and below, which could not be mechanically fabricated. The structures are first simulated and afterwards analyzed by a standard THz TDS system.The last chapter is based on the novel quasi time-domain spectrometer approach introduced by Scheller in 2009 [Opt. Express, Vol. 17, Issue 20]. The CW based generation and detection scheme is presented and in cooperation with the author, a hybrid THz spectrometer and imaging capability is demonstrated. A second system approach ¿ a dual QTDS spectrometer ¿ is set up, demonstrating that QTDS has the potential for customized low-cost and robust THz systems.

This thesis investigates the conflict-free routing of vehicles through a track network, a problem frequently encountered in many applications in transportation and logistics. The most common routing approach for conflictfree routing problems in various settings is a sequential one, where requests are greedily served one after the other in a quickest way without interfering with previously routed vehicles. There is a need for a better theoretical understanding as guarantees on the quality of the routings are often missing. Conflict-free vehicle routing also is of inherent interest as a sister problem of the well-studied packet routing problem.In the first part, we present new theoretical results for the case of bidirectional networks. We consider a natural basic model for conflict-free routing of a set of k vehicles. Previously, no efficient algorithm is known with a sublinear (in k) approximation guarantee and without restrictions on the graph topology. We show that the conflict-free vehicle routing problem is hard to solve to optimality even on paths. Building on a sequential routing scheme, we present an algorithm for trees with makespan bounded by O(OPT) + k. Combining this result with ideas known from packet routing, we obtain a first efficient algorithm with sublinear approximation guarantee, namely an O(¿k)-approximation. Additionally, a randomized algorithm leading to a makespan of O(polylog(k)) ¿ OPT + k is presented that relies on tree embedding techniques applied to a compacted version of the graph to obtain an approximation guarantee independent of the graph size.

Almost one billion people worldwide suffer from hunger. Another billion are malnourished. This is an unacceptable situation. By 2050, we will probably have to feed nine billion people while taking care not to overstretch our planet¿s ecological capacity. Hunger and malnutrition have many causes. One central cause is undoubtedly the fact that agricultural productivity in most developing countries is too low to give the majority of the rural poor adequate income opportunities or to ensure food security for them. This is the very factor that we need to address. So when I assumed office in 2009, I made rural development and food security a political priority of the Federal Ministry for Economic Cooperation and Development (BMZ) again, considerably increasing the Ministry¿s financial commitments in the sector. The volume of relevant commitments is now more than 700 million euros a year. This is more than 10 per cent of my Ministry¿s total budget. The Tropentag is a renowned international forum for development and agricultural research experts to share information and experience as well as knowledge. Numerous organisations and experts from a variety of fields from more than 80 countries are represented. The event provides a good networking opportunity, especially for younger experts. It is intellectual input of this kind that makes a huge difference in whether development policy and development cooperation are successful or not. So it was my pleasure to accept the role of patron for this Tropentag.

This work presents a fully semiconductor-based laser source that meets the requirements of coherent optical communication links in space and further allows to benefit from the numerous advantages of semiconductor lasers. A hybrid master oscillator power amplifier(MOPA) concept enables narrow-linewidth high-power operation.The experimental part of this thesis describes how the linewidth of the laser sources is characterized with a beat note measurement technique. A novel heterodyne linewidth measurement setup with a weak frequency lock of the two lasers features a virtually unlimited resolution. The analysis of the beat note signal is carried out by evaluating radio frequency beat note spectra as well as frequency noise spectra.Further, the characteristics of DFB and DBR lasers optimized for narrow linewidth operation are compared in terms of spectral stability, linewidth, and performance in a master oscillator power amplifier system. DBR lasers with an overall length of 4mm anda front facet reflectivity of 30% feature an intrinsic linewidth of 2 kHz at 180mW and a FWHM linewidth as small as 180 kHz up to an output power of 180mW. An intrinsic linewidth of 2 kHz is, to our knowledge, the smallest linewidth that has been reported in the literature so far.The concept of a hybrid integrated MOPA has been developed and the assembly procedure and the characteristics of the micro-integrated MOPA system are presented.The MOPA is realized on a footprint of 10 × 5mm2. The MOPA system features an output power of more than 1W, a FWHM linewidth of 100 kHz and an intrinsic linewidthof 3.6 kHz. To our knowledge, this is the first micro-integrated MOPA concept that simultaneously features narrow linewidth and addresses the requirements of spaceborne laser sources like mechanical stability, compactness, and efficiency.

Equine melanomas are the most common neoplasms in older grey horses. Until now, no curative therapy is established. Xenogenic DNA vaccination represents a promising therapeutic approach.Goal of the present study was to evaluate the safety and clinical efficacy of vaccination of grey horses with natural occurring melanomas with MIDGE-Th1® vectors encoding for equine (eq) IL12 and eqILRAP-IL18 alone or in combination with human gp100 (hgp100) or human tyrosinase (htyr).Three groups (each n=9) of adult grey horses with variable numbers of melanomas received three intramuscular and three intradermal peritumoral vaccinations. Each group was treated with MIDGE-Th1® vectors coding for eqIL12 and eqILRAP-IL18. One group (group gp100) was additionally treated with 500 ¿g hgp100MIDGE-Th1® and one group with 500 ¿g htyrMIDGE-Th1® (group tyr). The third group did not receive additional DNA (group IL12/18). Vectors were complexed with the transfection agent SAINT-18.The injections were performed on days 1, 22 and 78 intradermally around one selected melanoma (locally treated melanoma) and intramuscularly as a systemic treatment. A general examination of the horses and evaluation of local reactions at the injection site were performed daily during hospitalisation (on the day of each injection and 3 days after each injection as well as on day 120). In each horse the locally treated melanoma and up to 8 non-locally treated melanomas were measured before each injection and on day 120 by calliper and ultrasound. The relative volumes were calculated in relation to day 1 (100%).For the evaluation of the generation of specific CD8+ cytotoxic T-cells against hgp100 and htyr, peripheral blood mononuclear cells (PBMCs) isolated before each injection and on day 120, were stimulated in vitro with autologous dermal cells transfected with hgp100 or htyr. Interferon ¿ (IFN ¿) as a response to this specific stimulation was measured by intracellular immunofluorescence staining.

The aim of this project was the development and targeted optimization of recombinant protein production with Bacillus megaterium. Based on a genetically defined model strain with plasmid based production of the gene for the green fluorescent protein (GFP), at first, the optimization of the basic culture parameters pH-value, temperature and dissolved oxygen concentration was performed. Further empirical analysis included an evaluation of different carbon sources and vitamin requirements. The use of GFP hereby enabled fast and simple detection of the production performance. Subsequently, recombinant protein production was also assessed on the cellular level ¿ using system wide transcriptome and proteome analysis. Then, this was transferred to production processes at industrial scale, investigating limiting effects occurring in large scale bioreactors, i.e. heterogeneities in oxygen and substrate supply. Initially, a two compartment scale-down plant was developed for this purpose. Suboptimal feeding of the substrate induced extensive substrate- and oxygen gradients which had a negative effect on the GFP yield. With the help of advanced scale-down experiments, the metabolic origin of this detrimental production was investigated. In highly resolved time intervals the availability of free intracellular amino acids in B. megaterium was analyzed. Five strongly limiting amino acids were identified. In a subsequent large scale production the addition of these amino acids to the feed solution resulted in a 100 % increased GFP yield. Finally, the results from the model strain were successfully transferred to the production of a homologous protein, the levansucrase SacB. This enzyme is an important biocatalyst in the food industry for the production of prebiotic ingredients. In high cell density cultivations, a high product level, which was significantly higher than that of any other extracellular proteins, produced so far with B. megaterium, could be obtained. Hereby, the process allowed the use of raw glycerol, a waste product from biodiesel industry, as raw material for high titer and quality of the recombinant product.

Various lines of research evidence have demonstrated that adverse pre-, peri- and postnatal life conditions might have negative influences on life stage neurodevelopment as well as on psychological and somatic health in children, adolescence and adult life. In particular, findings in children are still scarce and the etiological and maintaining underlying mechanisms are not fully understood. For this reason, we aimed to examine the influence of pre-, peri- and postnatal adverse conditions, such as prenatal stress, week of gestation, low birth weight and birth size on psychosomatic health as well as on psychosocial functioning in ten-year-old children. The main focus was on prenatal stress and its influence on birth outcomes and psychosomatic health between birth and the age of ten years.Data I: Therefore, 96 ten-year-old children were investigated after being categorized into the groups of high, medium or low prenatal stress children. The categorization was based on the operational process considering two main prenatal factors: a complication-free pregnancy or the occurrence of preterm contractions and accordingly a risk of preterm birth and thus the administration of synthetic glucocorticoids. Glucocorticoid application serves to accelerate fetal lung maturation and consequently to prevent the newborn morbidity and mortality in cases of a childbirth before the 34th gestational week. Data analyses show significant group differences in the psycho-social level of functioning and psychological abnormalities. Perinatal outcomes seem to have no significant influence on children¿s psychosocial status at age ten years. A total variance of 8.6% to 13.10% of the independent psychological variables is explained through pre- and postnatal adverse conditions. Furthermore, children with high prenatal stress have a near 8-fold higher risk of psychological abnormalities. Children with medium prenatal stress have an almost five times higher risk compared to children of the low prenatal stress group. Postnatal adverse conditions also lead to an up to 11-fold heightened risk of psychological abnormalities.

Antibodies and antibody fragments are most important tools for therapeutic and diagnosticapplications. An increasing demand of these high potential drugs makes less costintensive production systems most desirable. Compared to mammalian cell culturemicrobial production platforms are beneficial with regards to reaching high productiontiters, scale up approaches, regulatory aspects and reduced costs of goods. Amongstthese production systems those that are having the ability of an additional productsecretion are most advantageous as the downstream processing costs are decisivelyreduced.In this work Bacillus megaterium, as a Gram positive model organism, was used toextensively study the production and secretion of the antibody fragment D.13 scFv. Forthe bioprocess optimization a holistic approach was followed. First the aim was toestablish a high productive defined cultivation medium. Different media components likecarbon sources, metal ions and ammonium concentrations were screened throughoutvarious cultivation platforms ranging from micro titer plates to shaking flasks. Statisticaldesign of experiments and a genetic algorithm approach were used to establish anappropriate defined high production medium. As a second step the process was transferredto the bioreactor scale of several liter cultivation volume. An optimal bioprocessstrategy based on alternating growth and starvation phases was established to gain highproduct titers of antibody fragment D1.3 scFv. As a final step an up-scale to a 100 Lbioreactor was done accounting for an advanced process control and considering ¿goodmanufacturing practice¿ guidelines. The advanced bioprocess monitoring tool of flowcytometry was used to gain deeper insights on microbial physiology at single cell levelregarding cell viability, cell integrity and production intensity. This knowledge was used fora sophisticated cell physiology based bioprocess development and optimization. Furthermoreculture heterogeneities were measured and characterized for B. megateriumproducing antibody fragment D1.3 scFv under controlled bioreactor conditions. To obtainadditional information about the regulatory processes occurring inside the cell on geneexpression level a transcriptome analysis was performed comparing cells with anincreased production and secretion status to less producing and non-producing cells.These cutting-edge technologies of flow cytometry and transcriptome analysis revealedpossible bottlenecks of the overall bioprocess¿ performance and product secretion ofantibody fragments with B. megaterium as production platform and form a robust basis forrational strain optimization and advanced process designs.

The doctoral thesis deals with high power InGaAs/GaAsP/AlGaAs quantum well diode lasers grown on a GaAs substrate with emission wavelengths in the range of 1050 nm ¿ 1150 nm.The objective of this thesis is the development of diode lasers with extremely narrow vertical laser beam divergence without any resulting decrease in the optical output power compared to current state of the art devices.The work is focused on the design of the internal laser structure (epitaxial structure), with the goal of optical mode expansion (thus reduction of the beam divergence), and the experimental investigation of the electro-optical properties of the processed laser devices. Diagnosis of the factors limiting the performance is also performed. The optical mode expansion is realized by increasing the thickness of the waveguide layers. Structures with a very thick optical cavity are named in this work as Super Large Optical Cavity structures (SLOC).The vertical optical mode is modeled by solving the one-dimensional waveguide equation, and the far-field profiles are obtained from the Fourier transform of the electrical field at the laser facet (near-field). Calculations are performed by using the software tool QIP. The electro-optical properties (such as vertical electrical carrier transport and power-voltagecurrent characteristics, without self-heating effect) are simulated using the WIAS-TeSCA software. Both software tools are described in this thesis.

Die vorliegende Arbeit beschäftigt sich mit Oberflächendiffusion und Strukturbildung an Oberflächen, speziell im Fall Silber auf Silizium. Unterschiedliche Methoden werden kombiniert um Si(001) und Si(111) Oberflächen als auch dazwischen liegende Orientierungen zu untersuchen. niedrigenergetische Elektronenmikroskopie (LEEM) und photoemissions Elektronenmikroskopie (PEEM) wurden verwendet um die Wachstumsdynamik und den Einfluss von Oberflächendiffusion auf die Strukturbildung an Oberflächen unter Ultrahochvakuum (UHV) Bedingungen zu untersuchen. Es wurden ein- und multi-kristalline Ag Inseln und selbstorganisierte Ag Drähte auf unterschiedlichen Si Oberflächen untersucht. Hierfür wurde Ag bei hohen Temperaturen auf Oberflächen aufgebracht, wobei die meisten Untersuchungen in-situ erfolgten. Die Struktur der Ag Inseln und Drähte und deren Orientierung zum Substrat wurde hauptsächlich mit niederenergetischer Elektronenbeugung an kleinen Bereichen (µ-LEED), hochauflösender niederenergetischer Elektronenbeugung (SPA-LEED) und Rasterelektronenmikroskopie (SEM) untersucht. Für die SEM Untersuchungen wurden die präparierten Proben aus dem UHV entnommen um sie in ein SEM zu transferieren und eine statistisch bessere Aussagekraft zu erreichen.Ag(001) und Ag(111) Inseln wurden bei Temperaturen von bis zu 700°C gewachsen. Mit steigender Wachstumstemperatur verändert sich die überwiegende Form der Inseln von hexagonal zu dreieckig. Die relative Drehung zum Substrat wurde Untersucht und mit einem modifizierten gitter-koinzidenz Modell (CSL) verglichen. Der Vergleich zeigt eine ausgesprochen gute Übereinstimmung der experimentellen Daten mit der Theorie, bei der praktisch alle Drehwinkel erklärt werden.

The aim of this dissertation was to characterize leptin and the different components of the IGF-system in offspring of sows fed with different protein contents throughout pregnancy and to ascertain long term consequences caused by an inadequate nutritional environment in utero. German Landrace gilts (n=78) were fed gestation diets (~15.4 MJ ME/kg) of either low (LP, 6%; n=26), adequate (AP, 12%; n=26), or high (HP, 30%; n=24) protein content. For sampling at day 94 of gestation, 26 gilts with their fetuses were investigated. At parturition, the offspring of the remaining 52 gilts were cross fostered to nursing sows fed a standard lactation diet. Fetal and birth weight of all investigated offspring were recorded and classified into 2 different fetal body weight classes (Fbwc ¿ or > 0.65 kg) or birth weight classes (Bbwc ¿ or > 1.3 kg). In addition, the litter size of any gilt was classified into two groups (Lsgr ¿ or > 12 piglets). Blood and liver samples from 306 piglets in total were collected. In detail, fetuses of day 94 of gestation (dpc), and piglets at their 1st, 28th and 188th day of life (dpn) were sampled. Blood samples were assayed for IGF-1, IGF-2 and leptin by ELISA and for IGF binding proteins via a quantitative, non-radioactive Western ligand blotting protocol established and optimized herein. Liver samples were assayed for IGF-1 receptor by use of ELISA. The concentrations of leptin in offspring were not affected by maternal diet over all postnatal days. With the exception of dpn 1, the IGF-1 concentrations remained unchanged in response to maternal dietary treatment. Piglets born to mothers fed the LP diet had decreased IGF-1 concentrations compared to piglets born to HP mothers (P

Photovoltaic (PV) is attracting increasing interest as an important contribution to renewable energy supply. Organic photovoltaic (OPV) is a comparable young PV technology with a great potential towards low cost solar power. This is due to the intrinsic advantage of the incorporated organic semiconductors which are soluble. Solution processing allows high throughput coating and printing processes. Hence, energy intensive high temperature and vacuum steps can be avoided which reduces the fabrication costs and keeps energy payback times low. The performance of organic solar cells strongly depends on the structure of the solution cast photoactive layer which comprises a polymer-fullerene blend. The blend structure evolves during the film drying step which has been studied in this thesis.Starting point of this work was the hypothesis that drying process parameters are suitable for systematically tuning the structure formation during drying of solution cast polymer-fullerene films in order to generate optimized structures with improved photovoltaic performance. For the evaluation of this hypothesis the structure formation of the polymer-fullerene system Poly(3-hexylthiophene-2,5-diyl):[6,6]-Phenyl C61-butyric acid methyl ester (P3HT:PCBM) was investigated incorporating i) thin film drying kinetics, ii) phase behavior of polymer-fullerene solutions, iii) structure formation and iv) the drying process-structure-property relationship of solar cells. The generality of the obtained results has been studied in comparison with the behavior of Poly{[4,40-bis(2-ethylhexyl)dithieno(3,2-b;20,30-d)silole]-2,6-diyl-alt-(2,1,3-benzothidiazole)-4,7-diyl} (PSBTBT).

Producing high quality optical systems at reasonable cost is a challenge andsolutions enabling cost-efficient production in small to medium quantities needto be developed in order for Germany to stay competitive on the global market.Both, performance and cost are largely influenced by manufacturing andassembly tolerances and frequently compensation such as alignment is requiredto achieve the demanded performance.This dissertation systematically develops combinatorial assembly as acompensation strategy which does not require iterations and as such is suitablefor automated production of small series. A pool of components andsubassemblies, necessary for the assembly of a series of systems, ischaracterized prior to the assembly and measurement results are stored in adatabase. Then, optimal component combinations are found during a modelbasedselection process.The application of combinatorial assembly to optical systems requires a delicatechoice of parameters for characterization, modules and tolerances beforecomponents are manufactured. Predicting the as-built performance ofcombinatorially assembled systems with high accuracy is therefore necessaryand a dedicated tolerance analysis concept based on Monte Carlo analyses isproposed. The concept is universally applicable to problems that can bemodelled with ray-tracing and is implemented using a combination of raytracingsoftware, logic calculator and database. This makes it possible toaccurately analyze the impact of tolerances, production volume and additionaluncertainties on the performance of combinatorially assembled optical systems.For optimal compensation, tolerance distributions should match each other in aspecific way and it is illustrated that this can be difficult to realize for some lensdesigns due to manufacturing limits. In order to reduce this restriction, designstrategies increasing combinatorial compensation are derived. Adapting theoptical design from the outset to suit combinatorial assembly can shifttolerance sensitivities from one component to another. Compensation can beenhanced and the influence of uncharacterized parameters reduced. In usingcombinatorial assembly in conjunction with desensitization, systems with highernominal performance yet reduced tolerance demands can be build. This is anentirely new approach and a first step towards a more integrated developmentof optical systems.

Migration of tilt grain boundaries (GBs) in aluminum has been simulated in a wide temperature range with various magnitudes of driving force. It is found that under different conditions GBs migrate through either a diffusionless or a diffusional mechanism. The essence of the diffusionless mechanism is determined to be GB dislocation glide. This mechanism agrees with many previously reported mechanisms, consisting of the collective motion of atom groups, the four-atom shuffling and the boundary motion by glide of primary/secondary GB dislocations. GB dislocation glide therefore serves as a generalized mechanism for all of them. The diffusional mechanism is merely observed to occur for high-angle GBs at high temperatures when a relatively small driving force of several MPa is applied. For these GBs featured in thick and highly disordered structures, GB migration is controlled by GB diffusion. The effects of structural constraints, temperature, GB misorientation and driving force magnitude, on the activation of either mechanism as well as on concrete GB migration behaviors are discussed. Based on these discussions, two GB migration mechanism maps for polycrystals are proposed. The mechanism maps can well explain many contradictory findings obtained previously in both experiments and simulations. In addition, GB mobilities are evaluated at a high temperature. The simulated values are physically reasonable as high-angle GBs move faster than low-angle GBs and the maximum mobility occurs around 40° misorientation. The mobility of a ¿7 GB even approaches the maximum experimental value obtained in ultra-high-purity bicrystals.

There was a time when scholars and coaches advised athletes to avoid strength training because it was believed that it would make them slow and muscle-bound and would thereby have a negative impact on their athletic performance. Another concern was that strength training would have a detrimental effect on joints and ligaments. Athletes faced the dilemma of needing strength to perform at a certain level without the increase in muscle weight caused by strength training. Science seemed to prove that gaining muscle weight makes athletes slower since force, (body) mass and acceleration interact with each other (f= m × a). Based on this formula a (acceleration) decreases, when m (body mass) is increased.Many athletes already knew from personal experience that in fact this was not inevitably the case. If the increase in body weight is mainly caused by hypertrophy of fast-twitch muscle fibre, athletes can indeed move faster even when there is a slight increase in body weight. Since muscle hypertrophy often goes along with a reduction of body fat, body weight changes may be negligible.In the meantime, the beneficial effects of strength training for many aspects of fitness and performance have been proven. It has become generally accepted that resistance training not only improves performance of competitive athletes in many sports but also offers multiple health benefits. Strength training is a topic that is being researched and studied from many different perspectives as shown in the diverse contributions to this book. These aspects include: Strength testing in basketball, eccentrics and HIT, applying social cognitive theories of behaviour to explain resistance exercise participation, muscle conditioning for soccer players, protein supplementation strategies, repetition speed and TUT in single- vs. multiple-set training, insights gained from kinematic and kinetic analyses of movement which make it obvious that children are not miniature adults, outcome-effects of high intensity pre- vs. post-exhaustion in hypertrophy training, and the effects of high intensity interval training on insulin action.

The study ¿Business Aviation Study Switzerland 2022¿ examines the impact, benefits and trends of Business Aviation with a specific emphasis on the Swiss market. Outlining the economic impact by focusing on the national and regional Swiss Business Aviation airports and their related stakeholder benefits, the study highlights Business Aviation as an integral part and backbone of the highly efficient Swiss aviation system. In 2021, Switzerland recorded close to 100,000 Business Aviation aircraft movements ¿ exceeding the level of 2019. In light of the COVID-19 related crisis of scheduled airline traffic, Business Aviation has proven resilient temporarily increasing its share in total aircraft movements to 27 %. Thus, Business Aviation remains a reliable and irreplaceable partner securing Switzerland¿s connectivity, particularly in times of crisis. Looking to the future, Business Aviation opens up the opportunity to act as an innovation driver and technological pioneer paving the way for sustainable aviation in the long term.

Die zunehmende Methodenvielfalt stellt Chemieinformatiker immer mehr vor die Herausforderung, die optimale Methode für ein bestimmtes Vorhersagemodell zu wählen. Die neu vorgestellten Methoden zeigen sich hinsichtlich ihrer Vorhersageleistung gegenüber literaturbekannten Standard-Methoden vielfach überlegen oder kompetitiv. Nach der Implementierung dieser neuen Methoden schneiden diese allerdings vielfach schlechter ab als erwartet. Die scheinbare Überlegenheit kann die Folge einer sog. optimistischen Verzerrung bzw. eines Überoptimismus sein. Darunter ist eine fehlinterpretierte Überlegenheit einer Methode oder generell die systematische Verzerrung von Studienergebnissen zu verstehen. Das Ziel dieser Arbeit ist es, den Effekt des Überoptimismus anhand inadäquater externer Validierung und anhand von Beispielen ausgewählter neuer Klassifikationsmethoden aus der Literatur zu untersuchen. Anhand dieser Beispiele wird deutlich, wie einfach Überoptimismus in Studienergebnisse einfließen kann und dass einfache Änderungen des Studiendesigns optimistische Verzerrungen reduzieren können.

Chemical reactions between ions and neutral gas are very important in the interstellar medium, since they usually have much lower barriers than neutral-neutral reactions. Thus, they are more likely to take place at low temperatures. In this work, the endothermic reactions of CH2D+, H2D+, and N+ with H2 have been investigated in a temperature variable 22-pole ion trap. Under the chosen conditions inside the trap the chemical processes are comparable to those in typical astrophysical environments.At low temperatures, the reactions mentioned above depend very sensitively on the translational and internal energies of the reaction partners. This dependence can be utilized to gain information on the energy levels or the population of the internal states. Based on this sensitivity, two different types of investigations were performed in this work. High resolution spectra of CH2D+ were obtained, resulting in improved predictions for pure rotational transitions. First steps were made towards a detailed understanding of the processes in laser induced reactions, often leading to non-Gaussian line profiles. In addition, the influence of internal states on ion-molecule reactions allowed to determine the purity of para hydrogen samples and yielded insight into the reaction kinetics of the system N+ + H2.

This thesis is devoted to a study of flame aerosol deposition (FAD) of advanced phosphor coatings. FAD combines synthesis of phosphor particles by flame spray pyrolysis with their deposition onto a substrate in a single processing step. Y2O3:Eu phosphor was chosen as the main test material.The mean particle size of the phosphor powder produced by droplet-to-particle conversion (DPC) of aqueous solutions of rare earth nitrates could be varied in the range 180 ¿ 500 nm. It was found that the screens deposited from concentrated precursor solutions ( ~ 0.5 µm) achieved the brightness of the standard screens made of commercial phosphor powder ( ~ 3.5 µm). At the same time, the coating density corresponding to the maximum light emission in the transmission mode for excitation at 254 nm could be substantially reduced (0.5 vs. 2.0 mg/cm2). In the range of vacuum UV, performance of the phosphor was strongly influenced by the roughness of the particle surface. It was demonstrated that smooth Y2O3:Eu phosphor particles could be synthesized in the premixed propane/air flames by adding polymerizable organic components to the precursor solution. Alternatively, phosphor particles with improved surface morphology could be obtained by substitution of nitrate salts in the precursor solution with Y2O3:Eu nanoparticles.As opposed to Y2O3:Eu, particles of amorphous Y3Al5O12:Tb phosphor prepared by the standard DPC-FAD had nearly perfect morphology. It could be suggested that crystallization of the phosphor host during the residence time of particles in the flame is responsible for the roughness of their surface. Screens of Y2O3:Eu nanophosphor ( = 24 nm) were deposited by chemical vapor deposition (CVC-)FAD from the precursor solution prepared by dissolving rare earth nitrates in ethanol and 2-ethylhexanoic acid. The optimal screen density for excitation at 254 nm was 1.2 mg/cm2; the maximum transmission-mode luminescence intensity reached approximately one third of that of the commercial reference. The light scattering in the visible range was reduced by up to two orders of magnitude. As a result, the nanophosphor coatings maintained nearly constant brightness in a very wide range of coating densities. It was demonstrated that light reflection from the supporting substrate and porosity of the coating significantly influence its photoluminescent performance.It can be expected that compacted nanophosphor coatings excited in the VUV-range could facilitate the diffraction-limited resolution of the displayed images. Rapidness of the screen deposition should be emphasized as the major common advantage of both modifications of FAD.

Indonesia is a favourite ecotourism destination in Southeast Asia and tourism in general plays an important role in the Indonesian economy. Being one of the world¿s largest archipelagos¿, with more than 17,503 islands sprawling across the Indian Ocean, Indonesia is one of the third top global megabiodiversity hotspots with rich natural ecosystems ranging from rainforests to mangrove systems and a high degree of insular endemism. The Indonesian archipelago is divided into two ecological regions ¿ the Sundaland (Asian zoogeographical region) and Wallacea (Australasian zoogeographical region) by the Wallace line. This line runs between the islands Bali and Lombok. Indonesia also boasts of a rich marine biodiversity with 20 % of the world¿s coral reefs and is biogeographically a part of the coral triangle. Nearly 45 % of Indonesia is still covered by natural ecosystems and one of the reasons for this is that only 6000 out of the 17,000 islands are permanently inhabited. While Sumatra and Java are the most popular tourist destinations, Indonesia also has one of the world¿s longest coastlines with popular beaches and island resorts in Bali, Lombok and Bintan islands. The waters around these islands also provide excellent and economical diving opportunities, with a very high coral diversity as for example in Bunaken Marine National Park in the northern tip of Sulawesi island and the Raja Ampat area in west Papua which according to Conservation International claims to have the highest marine diversity. Indonesia also has a rich cultural diversity with most of these cultural sites listed as world heritage sites. Ecotourism in Indonesia can be used not only as a tool for conservation of biodiversity but also to promote sustainable development especially for the local communities. While promoting ecotourism, it should also be seen that nature and culture are not harmed or destroyed. The International German Alumni Summer School aimed at addressing the issues of ecotourism potential and development in Indonesia and other countries in South-East Asia on an interdisciplinary platform and find solutions for sustainable and practically applicable nature conservation efforts.

In rural areas, services and facilities are widely scattered; people have to travel considerable distances to carry out daily activities and accessibility is closely linked to transport mobility. Inadequate or unaffordable mobility opportunities or the complete lack thereof limit the access to goods, services and social life and thus contribute to social exclusion. Particularly women and elderly people living in rural areas are vulnerable to be faced with unsatisfactory accessibility; this can have a significant impact on their quality of life. These studies explore mobility options and related accessibility issues important to women in rural Aberdeenshire, Scotland, and to elderly people in the district of Holzminden, Germany, to gain an understanding of potential obstacles in accessing activities of importance for them.The district of Holzminden is already heavily affected by demographic ageing and dwindling. It can therefore serve as a model region for approaching accessibility problems associated with demographic change: due to lower and changing demands, the maintenance of certain public and private services and facilities is becoming financially unviable. The ensuing decline in the provision of basic services in the countryside disadvantages elderly people in particular because they have less access to private means of transport and are more affected by health-related mobility restrictions.