Bøger udgivet af Cuvillier

In der vorliegenden Arbeit wird die klassische Annahme von normalverteilten zufälligen Effekten im Rahmen gemischter Modelle durch zwei flexiblere Verteilungsannahmen ersetzt, die im Besonderen Gruppen von Individuen bilden können. Im ersten Ansatz wird eine penalisierte Mischung aus Normalverteilungen basierend auf dem ¿group lassö- und dem ¿fused lassö¿-Ansatz für die Verteilung der zufälligen Effekte angenommen. In einem alternativen Ansatz wird eine approximierte Dirichlet-Prozess-Mischung als Verteilung der zufälligen Effekte herangezogen, die die Clustereigenschaft des Dirichlet-Prozesses zum Aufdecken einer Gruppenstruktur ausnützt. Dabei wird das Konzept der Dirichlet-Prozesse in die Likelihood-Inferenz übertragen, indem ein EM-Algorithmus zum Schätzen von linearen gemischten Modellen mit approximierter Dirichlet-Prozess-Mischung vorgestellt wird. Des Weiteren wird dieser Ansatz auf den Fall additiv gemischter Modelle erweitert, wobei hier ein penalisierter Spline zur Modellierung des Zeiteffekts verwendet wird. Für diese Modellklasse wird außerdem eine rein bayesianische Schätzung basierend auf Markov-Ketten-Monte-Carlo-Methoden vorgestellt. Anwendungsbeispiele und Simulationsstudien veranschaulichen den Nutzen der vorgestellten Verfahren

KurzbeschreibungDie Familie der Oxophytodiensäurereduktasen (OPR) in Arabidopsis thaliana besteht aus 6 Mitgliedern. Außer OPR3, das ein Schlüsselenzym in der Jasmonsäurebiosynthese ist, scheinen die OPRs in den Detoxifizierungsprozess von Lipidperoxidationsprodukten bei abiotischem Stress involviert zu sein.Die Funktionsverlustmutanten von OPR1, 2 und 4 zeigen deutliche Schädigungen unter Starklichtstress, wohingegen die genetische Komplementation zu wildtypischen Verhältnissen führt, was eine Rolle bei Starklichstress bestätigt. Zudem akkumulieren zahlreiche Stress verwandte Metaboliten in den opr-Mutanten. OPR4 besitzt außerdem eine Seneszenz fördernde Funktion. OPR1 und 2 sind im Cytosol lokalisiert und können die Doppelbindung von, durch Lipidperoxidation entstandenen, ¿,¿-ungesättigten Carbonylen in vitro reduzieren. Heterolog exprimiertes OPR4, auf der anderen Seite, ist kaum löslich und besitzt keine katalytische Aktivität. Seine Relokalisation in Processing Bodies bei Stress bestätigt jedoch seine Stress verwandte Funktion.DescriptionThe oxophytodienoic acid reductase (OPR) family in Arabidopsis thaliana consists of six members. Except from OPR3, which is a key regulator in jasmonic acid biosynthesis, the OPRs seem to be involved in the detoxification of lipid peroxidation products during abiotic stress.The loss-of-function mutants of OPR1, 2 and 4 are highly sensitive to highlight stress and genetic complementation of these mutants restore wild-type levels, confirming a role in high-light stress tolerance. In addition, several stress-related metabolites accumulate in the opr mutants. OPR4 has also a senescence promoting function. OPR1 and 2 are localized in the cytosol and are able to reduce the double bond of lipid peroxidation-derived ¿,¿-unsaturated carbonyls in vitro. OPR4, on the other hand, is hardly soluble when expressed heterologously and possesses no catalytic activity. However, its relocalization to processing bodies after stress proves its stress-related function.

The accumulation of lipid peroxide-derived aldehydes and ketones generated by the oxidation of polyunsaturated fatty acids of membrane lipids by reactive oxygen species (ROS) can significantly damage plant cells. In this study, an enzyme family possibly involved in the detoxification of these reactive carbonyls in plants was investigated. The members of this small enzyme family are flavin-dependent oxidoreductases and are related to Yeast Old Yellow enzyme. In A. thaliana they are represented by six members designated as 12-oxophytodienoate reductases (OPRs). This name is derived from OPR3 which catalyzes the reduction of oxophytodienoic acid, a key step in the jasmonic acid biosynthetic pathway. However, little is known about the physiological significance of the remaining OPR isoenzymes. The characterization of A. thaliana loss-of-function mutants for AtOPR1, 2 and 4 indicates a role for OPR isozymes in the alleviation of (photo)oxidative stress by detoxification of lipid peroxidation products. The single lossof-function mutants of AtOPR5 and AtOPR6, on the other hand, show no phenotype, most likely because the two genes are identical in the promoter and coding regions and yield identical transcripts.In order to explore AtOPR5/6 gene function in plant stress responses and to overcome their functional redundancy, RNA interference was employed to silence both genes. AtOPR5/6 RNAi-silenced plants exhibited high sensitivity toward (photo)oxidative stress, resulting in a decrease in the efficiency of photosystem II photochemistry and photoinhibition. The increased high-light sensitivity in AtOPR5/6 RNAi-silenced plants is reminiscent of plants impaired in the detoxification of reactive carbonyls suggesting that OPR5/6 may serve a similar function in vivo. Such a role is further supported by the increased susceptibility to the electrophilic lipid derivative methyl vinyl ketone (MVK). MVK-induced cell death events were significantly higher in opr1 and opr2 mutants and AtOPR5/6 RNAi-silenced plants as compared to MVK-treated wild type.In order to study the detoxification process in more detail, AtOPR5/6 had to be purified in sufficient quantities. Conditions of AtOPR5/6 expression and purification were optimized, since the enzyme tended to aggregate and accumulate in insoluble form as inclusion bodies. Denaturation and refolding turned out to be the most effective way to generate considerable amounts of stable and soluble OPR5/6. However, no activity was detected for AtOPR5/6, possibly because of a unique substrate specificity, or else, because of an inactive conformation of the protein.Similar high-light sensitive phenotypes of the opr1, 2, and 4 single mutants and AtOPR5/6 RNAi-silenced plants indicated that the genes act non-redundantly in stress acclimation. Previous findings showed different tissue-specific expression patterns of AtOPR1, 2 and 4, which may account for apparently non-redundant function of the AtOPRs. Here, the expression analysis was extended to the AtOPR5 promoter. Transgenic plants expressing the ¿-glucuronidase (GUS) reporter gene driven by the AtOPR5/6 gene promoter were analyzed. AtOPR5/6 promoter activity differed from that of other AtOPRs, being high in hypocotyls and in the fully expanded rosette leaves but not in etiolated dark grown seedlings, reproductive organs and roots. Furthermore, sub-cellular localization experiments revealed that AtOPR5/6 is targeted to the Golgi apparatus. These finding suggest that the different OPRs play complementary roles in the detoxification process to control the cellular homeostasis of stress metabolites in different plant tissues and in different subcellular compartments.

Wasser ¿ Kraftstoff Gemische reduzieren schädliche Rohemissionen in Verbrennungs-motoren. Dabei sind Mikroemulsionen gewöhnlichen Emulsionen aufgrund ihrer thermodyna-mischen Stabilität und der Verteilung des Wassers auf der Nanoskala überlegen. Strey undMitarbeiter zeigten bereits 2003 in einer Patentanmeldung [DE10334897A1] den Nutzen vonbikontinuierlich strukturierten Mikroemulsionen bei der Verbrennung in Dieselmotoren auf.In der vorliegenden Arbeit wurden Kraftstoffmikroemulsionen des Typs Wasser/Gefrier-schutzmittel ¿ Kraftstoff ¿ Ölsäure/Ethanolamin/Ölsäurediethanolamid mit Wasseranteilenvon bis zu 40 Gew.-% formuliert, die ein temperaturinvariantes Phasenverhalten aufweisen.Emissionen von Dieselmotoren, besonders Schwarzruß und NOX, wurden als Funktion desWassergehaltes untersucht. Durch die Verwendung von vollständig verbrennbaren, günstigenund aus Biomasse gewonnenen Tensiden, konnten Dieselmikroemulsionen im Hinblick aufEmissionen, zukünftige Preisentwicklung und Nachhaltigkeit optimiert werden. Des Weiterenerlaubte die Solubilisierung von Wasser in marinem Gasöl (MGO) eine Ausdehnung derAnwendung auf den heavy duty-Bereich von marinen off-shore-Energiegeneratoren.Schließlich wurden mit dem neuen Gas-to-Liquid Kraftstoff (GtL) ein vollständigerneuerbarer und sauberer Mikroemulsionskraftstoff formuliert. Die Struktur optimalerWasser ¿ Kraftstoffmikroemulsionen wurde mittels Kleinwinkelneutronenstreuung (SANS),dynamischer Lichtstreuung (DLS), Transmissionselektronenmikroskopie (TEM) undKernmagnetresonanz (NMR-) Diffusometrie sowie Messungen der elektrischen Leitfähigkeituntersucht und nachgewiesen. Gemeinsam ergaben diese sich gegenseitig ergänzendenTechniken ein in sich konsistentes Bild einer bikontinuierlichen Struktur. Mit dervorliegenden Arbeit gewinnt man ein tiefes Verständnis von Kraftstoffmikroemulsionen miteiner Einordnung der Eigenschaften in den wissenschaftlichen Kontext. In Zusammenarbeitmit den heavy-duty-Motorenbauern mtu und MAN konnte eine simultane und drastischeReduktion des Schwarzrußes um bis zu 96 % sowie der Stickoxide um bis zu 60 %, mehr alsbisher je erreicht, nachgewiesen werden bei gleichzeitigem Rückgang des spezifischenVerbrauchs.

Although 40 million people lived in West Africa with 4% in cities in 1930, in 1990 there were about 190 million with 40% being in cities. Projected figures for 2020 indicate that 63% of the estimated population of 430 million will be found in urban cities. Nigeria is not exempted from this scenario. Providing food and fiber for the population will be a burden to all.This publication contains selected refereed research papers from the Alexander Von Humboldt international conference held in Nigeria in December, 2010. The research papers cover several disciplines from the sciences, social sciences, and humanities to policy studies.The first chapter contained the paper on urban governance. It dealt with urban resources and their environment to problems with Nigeria cities and prescribed the way forward. The paper that followed was on the role of primary agriculture in processing and nutrition in urban food security. It looked at the historical antecedents of urbanization and the strategies for improved food and nutrition security in urban cities. About four papers examined the issues surrounding climate change and building green productive cities. Case studies were presented and their implications were analyzed.There were other papers on urban waste management in different parts of Nigeria. The challenges of thermal discomfort and heat stress were highlighted with implication for building design. There were research reports on urban health complications in cities which gave comprehensive analysis of the magnitude of such burden if associated constraints were not tackled.There were other papers dealing with environmental hazards which drew attention to the environmental sanitation level and the nature or water and food hygiene. Finally there was a paper that examined the issues surrounding desertification and lessons to be learnt from experiences of Israel, Turkey and Egypt.

The doctoral thesis ¿Quasi-spectral finite difference methods: Convergence analysis and application to nonlinear optical pulse propagation¿ by Tristan Kremp addresses the theory and application of so-called quasi-spectral finite differences. Contrary to the common Taylor approach, these are by construction exact for trigonometric instead of algebraic polynomials. With any fixed discretization spacing, this allows for a higher accuracy, e.g., when differencing functions that have a band-pass like Fourier spectrum.In this dissertation, the convergence of such quasi-spectral finite differences is proven for the first time. It is shown that the highest possible order of convergence is the same as for the Taylor approach, i.e., it is basically identical to the total number of summands in the finite difference. This order is achieved if all frequencies, for which the quasi-spectral finite difference is exact, vanish sufficiently fast in comparison to the discretization spacing. This condition can be easily incorporated in the finite difference weights construction, which can be achieved by spectral interpolation or least-squares optimization, respectively. Employing previously unknown Haar (or Chebyshev) systems that consist of combinations of algebraic and trigonometric monomials, the equivalence of both methods of construction is proven.In a semidiscretization framework, these finite differences are, for the first time, combined with exponential split-step integrators for an efficient solution of linear or nonlinear evolution equations. It is shown that a simple modification of the common symmetric split-step integrator guarantees its second-order convergence even in the presence of general nonlinearities.An important example of such a partial differential equation is the nonlinear Schrödinger equation (NLSE). In contrast to the standard literature, the NLSE is derived here directly from Maxwell¿s equations, without the common assumption that the second spatial derivative in the direction of the propagation can be neglected, and without the assumption that the multiplicative nonlinear term behaves as a constant with respect to the Fourier transformation. A practically relevant application is the propagation of wavelength division multiplexing (WDM) signals in optical fibers. Compared to other semidiscretization techniques such as finite elements, wavelet collocation and the pseudo-spectral methods (split-step Fourier method) that are mostly employed by the industry, the quasi-spectral finite differences allow, at the same accuracy, for a substantial reduction of the computation time.

1. The optimum solution for the difficulties during conductor deformation was to use the ex situ precursor powder which is not sensitive to heat treatments in the range of temperatures needed for the working stress release of the sheath metal. Two different ex situ powders are studied: homemade ex situ (based on mechanically alloyed in situ powder) and commercial powder with reduced crystallite size achieved by high energy ball milling.2. As the first approach, ex situ powder is prepared using mechanical alloying. A detailed phase analysis shown secondary phases, such as MgO and MgB4+x. A high critical current density for unsintered tapes and wires was obtained. It is observed that non of the applied final heat treatments of the conductors improve their superconducting properties. It is assumed that, heat treatments influence the crystallite size which is explained by MgO at the grain boundaries blocking grain growth. Additional milling or chemical treatment of the powder to clean the grains is needed to accomplish a smaller particle size. However, if medium Jc values are sufficient, the MA in-ex situ powder is an interesting precursor powder for conductors needed for the react & wind method of superconducting coil preparation, because the final heat treatment of a such a conductor is not needed.

Research on stress and stress-related health impairments mainly focuses on classic stress hormones, such as cortisol and catecholamines. Testosterone, the predominant male sex hormone, in turn, is poorly studied in stress research despite its negative associations with many ¿classic¿ stress-related disorders, such as depression, diabetes or obesity in middle-aged and elderly men. This work examines the role of testosterone in the acute response to stress in elderly men and focuses on social status and parental bonding as possible psychobiological determinants of stress-related testosterone responses. Moreover, relations to stress hormones, subjective stress experience, hemoconcentration, aggression, masculinity, quality of life, depressed mood and obesity are investigated.

Social comparison (SC) processes between romantic partners have been shown to occur each and every day. In this thesis, an experimental design was applied, which induced SC in couples by a systematic variation of performance feedback in a manipulated pretend IQ test. Sixty-two healthy heterosexual couples were randomly assigned to four experimental groups, in which either men (N=16 couples), or women (N=16 couples) were provided with a superior performance feedback and compared to couples, who received equal feedback (N=15 couples) or no feedback (N=15 couples). The immediate affective as well as physiological responses of partners to SC were assessed using repeated measures of mood and the level of the gonadal hormones Testosterone (T) and Estradiol (E2) and the stress hormone Cortisol ©. Our results revealed that women were subjectively as well as physiologically more affected by SC, indicated by significant changes in mood and the level of the gonadal hormones T and E2. In a second study, couples engaged in a decision making task, which was coded for the assessment of interpersonal behavior on the dimensions of dominance and affiliation. Salivary T and E2 were assessed prior to the interaction and were tested for their predictive value of females¿ and males¿ expressed social behavior towards their partners. Estradiol levels in women were positively associated with the total amount of friendly behavior.

The synthesis of model systems is of great interest for understanding metalloenzyme active site features, and for developing biomimetic catalysts. Compartmental ligands based on macrocyclic systems and on 3,5-disubstituted pyrazolate bridges are well suited. Especially the latter ones were generated to synthesis highly preorganised bimetallic complexes with tuneable metal¿¿¿metal separations in the range 3.5¿4.5 Å. Appending second sphere functions for H-bonding interactions may enhance, in a biomimetic approach, the activation of bound substrates or the stabilisation of catalytic intermediates. With these ligands, synthetic and functional model complexes based on the proteins urease, phosphotriesterase and hemocyanin should be synthesised and characterised on their binding properties and their abilities to transform biorelevant substrates like urea, phosphoesters and dioxygen. For their characterisation and catalytical properties several analytical methods like UV/vis, IR, NMR and resonance Raman spectroscopy as well as mass spectrometry were used.

Die klassische Unternehmens-Informations-Technology (IT) unterliegt zurzeit fundamentalen Veränderungen. IT gestützte Innovationen in Nicht-IT-Firmen sind der aktuelle Trend in der Information-Systems (IS)-Forschung. Unternehmen müssen eine Strategie entwickeln, um die klassische Rolle von IT-Abteilungen zu überwinden und dem Trend folgen zu können. Dieser Trend betrifft auch traditionelle Industrien, z.B. im Energiesektor. Durch den Einsatz von intelligenten Netzen können Energiekonzerne die Anforderungen an das Stromnetz besser vorhersehen und somit besser auf sie reagieren. Die IT übernimmt eine wichtige Rolle im Innovationsprozess des Unternehmens. Diese kumulative Dissertation beinhaltet vier Studien zum Thema Innovationsmanagement basierend auf 1461 Interviews und der Analyse von 354 Fragebögen. Die Ergebnisse helfen Managern, ihre Führungsstrategien an die veränderte Situation anzupassen, um ihre Abteilung zum Innovationstreiber zu transformieren. Das Ziel dieser Arbeit ist, die Wichtigkeit und die beeinflussenden Faktoren der Neigung zur Innovation eines Mitarbeiters herauszuheben und Managern zu helfen, ein innovatives Klima in ihrer Abteilung zu erzeugen.The role of enterprise information technology (IT) is undergoing a fundamental shift. IT enabled innovations in non-IT companies are one of the upcoming trends in the IS research community. To adapt to the associated changes, firms must develop a strategy that helps overcome the conventional role of IT. Even traditional industries undergo a shift in their innovation strategies, seen, e.g., in the energy sector, whose transformation is fostered by new technologies, such as smart networks to better predict maintenance and improve grid management. IT thus becomes a major element of the firm¿s innovation process. This cumulative thesis presents four studies on IT innovation management based on 1461 interviews and 354 questionnaires. The results help managers to adjust their leadership strategies and to transform their departments to innovation drivers. The aim of this thesis is to understand the important factors of employees¿ innovation intention to help managers create innovative climates within their departments.

This work deals with the improvement of tube performance by using a novel method of second-harmonic suppression. The common techniques of harmonic suppression inside the tube are introduced and discussed with respect to their suitability for modern space applications. A filter helix delay line is presented as a useful approach for harmonic suppression in these applications and its design parameters are introduced. Its effect in traveling-wave tube operation is simulated with the code ¿MVTRAD-Reflections¿ proprietary to Thales Electronic Systems. Three different filter helix designs are developed and tested, one in an L-band tube and two in S-band tubes. Improvement of the output power, i.e. increase of the first and suppression of the second harmonic as well as a higher energy of the electron beam at the output are the main design goals. The influence of the filter helix design parameters on the tube output is investigated. They are optimized to achieve the designated design goals. In simulation and measurement, the performance of the tubes is analyzed and compared to that of the tubes without a filter helix. In addition, the influence of the reflection at the output coupler on filter helix performance is investigated.

In the propellant tanks of a spacecraft it is of high importance to position the liquid propellant stably at the outlet or use mechanisms to transport it reliably to the desired position during all flight phases. For this purpose, special devices are placed at the outlet which use the capillary forces of a liquid as the driving mechanism controlling the liquid distribution. These capillary forces result from the phenomenon, that a liquid between two solid bodies builds a curved free surface which drives the liquid to movement. Due to mass reduction or functional purposes these solid structures may be perforated. The perforation of the solid structures changes the capillary transport capability of the implemented devices. In literature, several analyses can be found about the singular aspects of capillary transport between solids, in channels of changing cross-sectional area and multi channel systems. However, the combined process of capillary transport between perforated plates has not been analysed yet.In this present study the main geometrical aspects of perforated plates are investigated by means of a parameter variation. The impact of this variation on the capillary transport capability is documented. Three methods are used to analyse behaviour of the liquid propellant: As a first step, a one-dimensional model is built using and combining existing models for the representation of the different fluid mechanical aspects. Secondly, an experiment was set up and tests were performed in order to obtain reliable data which were used to thirdly, validate a numerical model. This numerical model was used to consolidate the experimental study. The results of these three methods were compared using different parameter variations. Six geometrical measures were identified as independent geometrical parameters occuring in parallel perforated plates.A variation of each of these parameters was conducted and its impact on the capillary transport capability analysed. For the one-dimensional model two additional factors have been introduced, which were calculated using the numerical and experimental data. These two factors could be determined as constant or independently calculable values.

Zuckerrüben können während der Lagerung von verschiedenen Fäulniserregern befallen werden, die erhebliche Zuckerverluste verursachen und die Verarbeitungsqualität in der Zuckerfabrik verschlechtern. Bisher ist nur wenig über das Mikroorganismenspektrum und Faktoren, die dessen Zusammensetzung bestimmen, bekannt. Ziel der vorliegenden Arbeit war es, den Einfluss von Genotyp, Anbauumwelt und Lagerungstemperatur auf die mikrobielle Besiedlung von Zuckerrüben während der Lagerung zu beschreiben. Die Zusammensetzung des Mikrobioms gelagerter Zuckerrüben wurde mit Hilfe eines Microarray basierten Nachweisverfahrens und der Hochdurchsatzsequenzierung bestimmt.In mehreren unabhängigen Lagerungsversuchen unter kontrollierten Bedingungen konnte erstmalig gezeigt werden, dass die mikrobielle Besiedlung und damit verbunden das Auftreten von Lagerfäule entscheidend durch die Lagerungstemperatur und die Anbauumwelt beeinflusst wird. Signifikante Genotypeffekte, die auf eine Resistenz gegenüber Fäulniserregern hindeuten, ließen sich ebenso reproduzierbar nachweisen. Das Speziesspektrum wurde dominiert von den Arten Botrytis cinerea, Fusarium spp. und Penicillium spp. Die mikrobielle Besiedlung der Zuckerrüben hatte eine Reduktion des Zuckerertrages und eine Verschlechterung der Verarbeitungsqualität zur Folge. Bedeutung und Konsequenz der Ergebnisse für die praktische Zuckerrübenlagerung werden diskutiert.

The production of biodiesel is often criticized because of the use of eatable oils like palm oil, soybean oil or rape seed oil. Therefore, researchers from Austria, South Korea, and Germany investigated waste oils from different production processes. In detail, fish oil and rubber tree oil were transesterified with methanol to produce biodiesel.These highly unsaturated biodiesels were tested in a single cylinder diesel engine with respect to their regulated and non-regulated emissions and their health effects. Additionally, the biodiesels were partly hydrogenated to improve the oxidation stability.

To allow DSL systems to support an always increasing amount of high-rate applications and run them stably, high data rates need to be guaranteed at a limited amount of computational complexity available for crosstalk mitigation. In this dissertation, first a channel estimation technique and channel adaptation procedures are presented as sufficiently accurate channel state information is the basis for many crosstalk reduction methods. The proposed techniques lead to increased performance of DSL systems. In the second and main part, crosstalk mitigation methods to fulfill data rate constraints in DSL networks are introduced. They achieve the high data rate targets at a low computational complexity.Die Übertragungsrate moderner DSL Systeme ist durch Übersprechen begrenzt, dennoch soll eine steigende Zahl von hochratigen Applikationen unterstützt werden. Um deren stabile Nutzung zu ermöglichen, müssen hohe Datenraten auch bei begrenztem Rechenaufwand für die Übersprechreduzierung garantiert werden. Diese Dissertation präsentiert zuerst leistungsfähige Techniken zur Kanalschätzung, da eine Kanalkenntnis für viele Reduktionsverfahren grundlegend ist. Im Hauptteil der Arbeit werden Methoden zur Reduzierung von Übersprechen gezeigt, mit denen Datenratenanforderungen in DSL Netzwerken erfüllt werden können. Sie erlauben ein Erreichen der Datenratenziele bei geringer benötigter Rechenkomplexität.

In traditional times, learning mainly referred to one-off or end-all school learning, neglected or rejected other learning forms, and had a partial economic center doctrine. However, along with the quick development of scientific technology and economy, as well as the advance of knowledge and the capital value of manpower, traditional school learning could not meet personal demand and needs of society¿s continuous development. Lifelong learning began to play an important role in an upheaval of the social policy.

This work aims at investigating the viability of using reaction bonded aluminum oxide (RBAO) to produce fiber-reinforced all-oxide composites with a reduced amount of shrinkage-related cracks. A novel manufacturing route is therefore developed, in which thermoplastic prepregs are manufactured by a two-step impregnation process using organic-based suspensions. Composites with both RBAO and a reference all-oxide matrix are produced and characterized. A detailed analysis of the microstructure and mechanical properties of the produced composites allows for a critical evaluation of the developed processing route, as well as of the use of a RBAO matrix in all-oxide composites.Ziel dieser Arbeit ist die Untersuchung der Realisierbarkeit, reaktionsgebundenes Aluminiumoxid (RBAO) zu nutzen, um langfaserverstärkte oxidkeramische Verbundwerkstoffe mit einer geringeren Menge an durch Schrumpfung bedingten Rissen herzustellen. Dazu wird ein neues Verfahren entwickelt, bei dem thermoplastische Prepregs durch ein zweistufiges Imprägnierungsverfahren unter Verwendung von organisch basierten Suspensionen hergestellt werden. Es werden Verbundwerkstoffe mit sowohl RBAO als auch einer oxidischen Referenzmatrix produziert und charakterisiert. Eine detaillierte Analyse der Mikrostruktur und der mechanischen Eigenschaften der hergestellten Verbundwerkstoffe ermöglicht eine kritische Bewertung des entwickelten Herstellungsverfahrens sowie der Verwendung der RBAO-Matrix in oxidkeramischen Verbundwerkstoffen.

As for the entire embedded-systems domain, the complexity of safety-critical systems is growing rapidly. Additionally, the rate of errors in such devices also increases for instance due to silicon shrinking. Hence, error-free operation under in-specification operating conditions cannot be assumed for next-generation safety-critical devices.As a rule of thumb the key design parameters for such systems performance, price and reliability are almost always contradicting design goals. This work addresses the related design space, highlights the challenges and discusses the trade-offs.Of unique interest is the reliability under real-time aspects. Naturally, there are error-handling protocols, error-correcting codes, and modular redundancy available. However, the effect of errors always has an influence on system timing. Even if an error is handled and corrected, it remains unclear under which situations timing requirements are met. This leads to the absurd situation that a device such as an advanced driver assistance system produces correct data even under errors but fails to deliver service because hard deadlines are missed.We present the ASTEROID architecture as a next-generation high-performance, real-time platform which addresses reliability and thus safety aspects. ASTEROID differs from other MPSoC platforms in its cross-layer error handling approach. The hardware implements the bare minimum to support the operating system with support for redundant computing, allowing the software to flexibly schedule tasks for redundant or regular execution. This architecture was joint work between TU Braunschweig and TU Dresden. In this work, we present the hardware architecture and discuss the real-time performance under errors in a compositional way. Therefore, we consider errors in communication (be it on-chip as well as off-chip) and errors in the processing core itself.The scientific contributions are first to extend compositional performance analysis (CPA) also by covering error effects, second to cover end-to-end error protocols with CPA, third to provide execution models and analysis for redundant execution and finally to bound the likelihood of timing violations in communication and computation under a given error model.

The cryogenic nucleation pulse chamber was converted for room temperature experiments.The functionality of the chamber was tested by measuring homogeneous nucleation rate isotherms of water at 220, 230 and 240 K. The newly measured nucleation rates agree well with previous data from the room temperature nucleation pulse chamber and from literature. The critical nucleus size from the new data deviates slightly from the older results.The chamber was then converted back to the cryogenic settings and the pulse settings from the room temperature experiments were used in an attempt to measure nucleation rates of argon. Nucleation rates of argon could be measured at 64, 65 and 66 K. A smoothing algorithm was applied to the pressure signal and the nucleation time calculated with the integration method usually used in, among others, supersonic nozzles and laminar flow diffusion chambers. The rates show a temperature trend which is consistent with expectations, but deviate from the classical nucleation theory by up to 42 orders of magnitude. The rates also show significant deviation from the empirical correction function by Iland et al. Homogeneous nucleation onset data for nitrogen was used to determine the nucleus growth rate at T = 52, 54 and 56.5 K, with particle number densities in the range 14193 Nd / cm3 582819. The particle growth rates show the same good agreement with the growth theory by Fuchs and Sutugin as previous measurements of argon and water. The growth rates show the expected temperature dependence of significantly faster growth at high temperatures, largely due to the larger amount of condensible vapor within the system at higher temperatures. The temperature change due to the ongoing expansion after the onset of nucleation was included in the growth rate calculations, but was found to have only a small effect on the predicted growth rate.Growth rates were also measured for pure nitrogen and were found to be slower than predicted by the Fuchs-Sutugin growth theory, despite the onset of nucleation being videntical to those of a mixture of nitrogen and carrier gas.

In short-range communication 1 mm step-index polymer optical fiber (SI-POF) established itself as a reasonable alternative to the traditional data communication media. The commercial systems with SI-POF use a single wavelength for data transmission. This thesis investigates the utilization of several optical carriers for parallel transmission of data channels over a single fiber, known as wavelength division multiplexing (WDM), in order to increase the capacity of SI-POF link. The focus of research is on (1) demultiplexing techniques for SI-POF, (2) high-speed WDM transmission over SI-POF and (3) channel allocation for POF WDM systems.For WDM an optical demultiplexer is a key component. The thesis concentrates on the demultiplexing techniques employing thin-film interference filters and a concave diffraction grating. A four-channel interference filter-based SI-POF demultiplexer was realized using a precisely adjustable opto-mechanical setup. It provided low IL ( 30 dB), outperforming other interference filter-based SI-POF demultiplexers reported so far. Theoretical and experimental analysis of an already realized SI-POF demultiplexer based on a concave diffraction grating was carried out. The results confirmed the wavelength separating function of the device. However, a poor grating quality due to unstable parameters of the ruling process led to high IL (> 20 dB) and low channel isolation (

This thesis aimed to contribute to a better understanding of the determinants of pro-environmental behavior by exploring the yet unexamined predictive value of psychobiological factors. Two empirical studies were conducted to investigate how pro-environmental behavior relates to baseline hormone concentrations as well as acute psychosocial stress in men. In the first study, we found that testosterone was negatively associated with self-reported energy-saving behavior exclusivelywhen cortisol levels were low. These results provide first evidence for an endocrine correlate of pro-environmental behavior and at the same time reinforce the importance of considering reciprocal hormone systems simultaneously. In the second study, we found that acute stress significantly increased the propensity to donate for the environment, but only in men with low pro-environmental orientation. Moreover, their decision to donate was positively related to the cortisol stress response as well as the emotion regulation strategy mood repair, and associated with an increase in calmness. In contrast, stress generally diminished the donated amount of money, irrespectively of participants¿ pro-environmental orientation. In conclusion, the present thesis provides novel evidence for the role of psychobiological factors in the prediction of pro-environmental behavior.

Bio-derived, fully biodegradable closed-cell micro- and nanocellular foams from gliadin, an abundantly available wheat storage protein, were produced in a newly derived foaming procedure using nitrogen or carbon dioxide as blowing agent. First, dry gliadin powder or gliadin film was plasticized, resulting in a viscoelastic paste that was then subjected to an atmosphere of nitrogen or carbon dioxide in a high-pressure cell. Subsequent tempering, followed by a sudden release of pressure and cooling resulted in closed-cell micro- or nanocellular foams. Depending on the type of blowing agent and the processing parameters, the foam morphology was tunable. Foams prepared via the proposed procedure exhibit the smallest cell sizes, highest cell number density, and highest porosity ever reported for foaming of wheat proteins. The procedure is simple and low cost, possibly leading to a technical realization and constituting a promising new approach for utilization of unique natural potential, e.g. for high technical quality (short purpose) packaging, insulation, and application materials that are easily and environmentally friendly recyclable, and even edible.Organische, vollständig bioabbaubare geschlossenzellige mikro- und nanozellular strukturierte Schäume aus Gliadin, einem weltweit in großen Mengen verfügbaren Weizenspeicherprotein, werden in einem neu abgeleiteten Schäumverfahren mittels der Treibmittel Stickstoff oder Kohlenstoffdioxid hergestellt. Dazu wurde trockenes Gliadinpulver oder Gliadinfolie zunächst plastifiziert, wodurch eine viskoelastische Paste erhalten wurde, die im Folgenden mit dem Treibmittel in einer Hochdruckzelle gesättigt wurde. Anschließendes Tempern gefolgt von einem schlagartigen Druckabfall führt zur Bildung von geschlossenzelligen mikro- bzw. nanozellular strukturierten Schäumen, deren Morphologie in Abhängigkeit von dem verwendeten Treibmittel und den Prozessparametern eingestellt werden kann. So wurden die kleinsten Zelldurchmesser, die höchsten Zellanzahldichten und die höchste Porosität generiert, die bislang für Weizenproteinschäume berichtet wurde. Das Verfahren ist einfach und technisch realisierbar und bietet einen vielversprechenden Ansatz für die Nutzung einzigartiger natürlicher Proteineigenschaften, z.B. zur Herstellung technisch hochqualitativer und zugleich leicht und umweltfreundlich zu recycelnder und sogar essbaren (Kurzzeit-) Verpackungs-, Isolations- und Applikationsmaterialien.

This dissertation demonstrates the implementation of ultra-wideband (UWB) radar sensors using commercial off-the-shelf electronics. The sensors are based on the correlation of binary pseudo noise sequences (M-sequences), combining low transmit power requirements with excellent noise and interference suppression.A ranging system is introduced that is able to track moving objects with a standard deviation of 1.73mm at 2m range. Subsequently, a system is developed which can synchronize itself to a reference sequence with 1.96ps RMS jitter. This synchronization system uses an analog correlating control loop (delay lock loop) to achieve tracking of the reference to 0.38% of one chip.The final application shown is a ground penetrating radar (GPR). The system is comprised of three elements: an FPGA, an output driver for the transmitter and a commercial analog-to-digital converter. Comparative measurements on buried pipes and cables prove that this system has achieved detection capability comparable to commercially available pulsed GPRs.