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This doctoral thesis examines intergenerational knowledge, its antecedents as well as how participation in intergenerational knowledge transfer is related to the performance evaluation of employees. To answer these questions, this doctoral thesis builds on a literature review and quantitative research methods. A systematic literature study shows that empirical evidence on intergenerational knowledge transfer is limited. Building on prior literature, effects of various antecedents at the interpersonal and organizational level regarding their effects on intergenerational and intragenerational knowledge transfer are postulated. By questioning 444 trainees and trainers, this doctoral thesis also demonstrates that interpersonal antecedents impact how trainees participate in intergenerational knowledge transfer with their trainers. Thereby, the results of this study provide support that interpersonal antecedents are relevant for intergenerational knowledge transfer, yet, also emphasize the implications attached to the assigned roles in knowledge transfer (i.e., whether one is a trainee or trainer). Moreover, the results of an experimental vignette study reveal that participation in intergenerational knowledge transfer is linked to the performance evaluation of employees, yet, is susceptible to whether the employee is sharing or seeking knowledge. Overall, this doctoral thesis provides insights into this topic by covering a multitude of antecedents of intergenerational knowledge transfer, as well as how participation in intergenerational knowledge transfer may be associated with the performance evaluation of employees.
In the modeling context, non-linearities and uncertainty go hand in hand. In fact, the utility function's curvature determines the degree of risk-aversion. This concept is exploited in the first article of this thesis, which incorporates uncertainty into a small-scale DSGE model. More specifically, this is done by a second-order approximation, while carrying out the derivation in great detail and carefully discussing the more formal aspects. Moreover, the consequences of this method are discussed when calibrating the equilibrium condition. The second article of the thesis considers the essential model part of the first paper and focuses on the (forward-looking) data needed to meet the model's requirements. A large number of uncertainty measures are utilized to explain a possible approximation bias. The last article keeps to the same topic but uses statistical distributions instead of actual data. In addition, theoretical (model) and calibrated (data) parameters are used to produce more general statements. In this way, several relationships are revealed with regard to a biased interpretation of this class of models. In this dissertation, the respective approaches are explained in full detail and also how they build on each other.
In summary, the question remains whether the exact interpretation of model equations should play a role in macroeconomics. If we answer this positively, this work shows to what extent the practical use can lead to biased results.
This dissertation is dedicated to the analysis of the stabilty of portfolio risk and the impact of European regulation introducing risk based classifications for investment funds.
The first paper examines the relationship between portfolio size and the stability of mutual fund risk measures, presenting evidence for economies of scale in risk management. In a unique sample of 338 fund portfolios we find that the volatility of risk numbers decreases for larger funds. This finding holds for dispersion as well as tail risk measures. Further analyses across asset classes provide evidence for the robustness of the effect for balanced and fixed income portfolios. However, a size effect did not emerge for equity funds, suggesting that equity fund managers simply scale their strategy up as they grow. Analyses conducted on the differences in risk stability between tail risk measures and volatilities reveal that smaller funds show higher discrepancies in that respect. In contrast to the majority of prior studies on the basis of ex-post time series risk numbers, this study contributes to the literature by using ex-ante risk numbers based on the actual assets and de facto portfolio data.
The second paper examines the influence of European legislation regarding risk classification of mutual funds. We conduct analyses on a set of worldwide equity indices and find that a strategy based on the long term volatility as it is imposed by the Synthetic Risk Reward Indicator (SRRI) would lead to substantial variations in exposures ranging from short phases of very high leverage to long periods of under investments that would be required to keep the risk classes. In some cases, funds will be forced to migrate to higher risk classes due to limited means to reduce volatilities after crises events. In other cases they might have to migrate to lower risk classes or increase their leverage to ridiculous amounts. Overall, we find if the SRRI creates a binding mechanism for fund managers, it will create substantial interference with the core investment strategy and may incur substantial deviations from it. Fruthermore due to the forced migrations the SRRI degenerates to a passive indicator.
The third paper examines the impact of this volatility based fund classification on portfolio performance. Using historical data on equity indices we find initially that a strategy based on long term portfolio volatility, as it is imposed by the Synthetic Risk Reward Indicator (SRRI), yields better Sharpe Ratios (SRs) and Buy and Hold Returns (BHRs) for the investment strategies matching the risk classes. Accounting for the Fama-French factors reveals no significant alphas for the vast majority of the strategies. In our simulation study where volatility was modelled through a GJR(1,1) - model we find no significant difference in mean returns, but significantly lower SRs for the volatility based strategies. These results were confirmed in robustness checks using alternative models and timeframes. Overall we present evidence which suggests that neither the higher leverage induced by the SRRI nor the potential protection in downside markets does pay off on a risk adjusted basis.
Theoretical and empirical research assumes a negative development of student achievement motivation over the course of their school careers (i.e., mean-level declines of achievement motivation). However, the exact magnitude of this motivational change remains elusive and it is unclear whether different motivational constructs show similar developmental trends. Furthermore, it is unknown whether motivational declines are related to a particular school stage (i.e., elementary, middle, or high school) or the school transition, and which additional changes are associated with motivational decreases (e.g., changes in student achievement). Finally, previous research has remained inconsistent regarding the question whether ability grouping of students helps prevent motivational declines or results in additional motivational “costs” for students.
This dissertation presents three articles that were designed to address these research questions. In Article 1, a meta-analysis based on 107 independent longitudinal studies investigated student mean-level changes in self-esteem, academic self-concept, academic self-efficacy, intrinsic motivation, and achievement goals from first to 13th grade. Article 2 comprised two longitudinal studies with German adolescents (Study: n = 745 students assessed in four waves in grades 5-7; Study 2: n = 1420 students assessed in four waves in grades 5-8). Both longitudinal studies investigated the separate and the joint development of achievement goals, interest, and achievement in math. In Article 3, a longitudinal study (n = 296 high-ability students assessed in four waves in grades 5-7) investigated the effects of full-time ability grouping on student development of academic self-concept and achievement in math.
The meta-analysis revealed significant decreases in math and language academic self-concept, intrinsic motivation, and mastery and performance-approach goals, whereas no significant changes in self-esteem, general academic self-concept, academic self-efficacy, and performance-avoidance goals were found. Interestingly, motivational declines were not related to school stage or school transition. In Article 2, decreases in interest and mastery, performance-approach, and performance-avoidance goals were indicated by both longitudinal studies. Development of mastery and performance-approach goals was positively related or unrelated to development in interest and achievement, whereas development of performance-avoidance goals was negatively related or unrelated to development of interest and achievement. Finally, the longitudinal study in Article 3 revealed no significant change in student academic self-concept in math over time. Ability grouping showed no positive or negative effects on student academic self-concept. However, high-ability students that were grouped together demonstrated greater gains in their achievement than high-ability students in regular classes.
Why they rebel peacefully: On the violence-reducing effects of a positive attitude towards democracy
Under the impression of Europe’s drift into Nazism and Stalinism in the first half of the 20th century, social psychological research has focused strongly on dangers inherent in people’s attachment to a political system. The dissertation at hand contributes to a more differentiated perspective by examining violence-reducing aspects of political system attachment in four consecutive steps: First, it highlights attachment to a social group as a resource for violence prevention on an intergroup level. The results suggest that group attachment fosters self-control, a well-known protective factor against violence. Second, it demonstrates violence-reducing influences of attachment on a societal level. The findings indicate that attachment to a democracy facilitate peaceful and prevent violent protest tendencies. Third, it introduces the concept of political loyalty, defined as a positive attitude towards democracy, in order to clarify the different approaches of political system attachment. A set of three studies show the reliability and validity of a newly developed political loyalty questionnaire that distinguishes between affective and cognitive aspects. Finally, the dissertation differentiates former findings with regard to protest tendencies using the concept of political loyalty. A set of two experiments show that affective rather than cognitive aspects of political loyalty instigate peaceful protest tendencies and prevent violent ones. Implications of this dissertation for political engagement and peacebuilding as well as avenues for future research are discussed.
Human behavior in regard to financial issues has long been explained in the light of the efficient market hypothesis. Following the strict interpretation of this theory, investors in the financial markets take into account that all relevant information is already included in the market price of an asset. Accordingly, information from the past does not affect future prices as all information is instantly incorporated. However, focussing on the actual behavior of humans, our empirical results indicate that the existing market conditions influence the behavior of stock market investors.
In the introductory chapter, we describe the difficulties of the efficient markets hypothesis in explaining the behavior of investors within a strictly rational frame. In the second chapter, we show that investors do consider the previous market development for their upcoming investment decisions. First, stock market patterns with predominantly positive days trigger significantly more trades than patterns with negative days. And second, after recent upward movements, investors sell proportionally more stocks than they buy. In the third chapter, we expound a theoretical framework that connects investment-related triggers of arousal, such as the performance of own stocks and the general market environment, with investors’ risk appetite in the decision-making processes. Our model predicts that aroused investors accept higher risks by holding stocks longer in comparison to their less aroused peers. In the fourth chapter, we show how two extreme market environments, the bull and the bear market, affect the disposition effect and especially learning to avoid this behavioral bias. Investors are subject to the bias in each market phase but with a far stronger propensity during the bear market. However, we show that investors also make the greatest progress in avoiding the disposition effect during this period.
These results suggest that future studies about investors’ behavior in the financial markets should consider the market environment as an important determinant.
While women's evolving contribution to entrepreneurship is irrefutable, in almost all nations, gender disparity is an existing reality of entrepreneurship. Social and economic outcomes make women entrepreneurship an important area for scholars and governments. In attempts to find reasons for this gender disparity, academic scholars evaluated various factors and recognised perceptual variables as having outstanding explanatory value in understanding women's entrepreneurship. To advance our knowledge of gender disparity in entrepreneurship, the present study explores the influence of entrepreneurial perceptual variables on women's entrepreneurship and considers the critical role of country-level institutional contexts on the women's entrepreneurial propensity. Therefore, this study examines the impact of perceptual variables in different nations. It also offers connections between entrepreneurial perceptions, women entrepreneurship, and institutional contexts as a critical topic for future studies.
Drawing on the importance of perceptual factors, this dissertation investigates whether and how their perception of entrepreneurial networks influences the individuals' decision to initiate a new venture. Prior scholars considered exposure to entrepreneurial role models as one of the most influential factors on the women's inclination towards entrepreneurship; thus, a systemized analysis makes it possible to identify existing research gaps related to this perception. Hence, to draw a clear picture of the relationship between entrepreneurial role models and entrepreneurship, this dissertation provides a systemized overview of prior studies. Subsequently, Chapter 2 structures the existing literature on entrepreneurial role models and reveals that past literature has focused on the different types of role models, the stage of life at which the exposure to role models occurs, and the context of the exposure. Current discourse argues that the women's lower access to entrepreneurial role models negatively influences their inclination towards entrepreneurship.
Additionally, although the research on women entrepreneurship has proliferated in recent years, little is known about how entrepreneurial perceptual variables form women's propensity towards entrepreneurship in various institutional contexts. The work of Koellinger et al. (2013), hereafter KMS, is one of the most influential papers that investigated the influence of perceptual variables, and it showed that a lower rate of women entrepreneurship is associated with a lower level of their entrepreneurial network, perceived entrepreneurial capability, and opportunity evaluation and with a higher fear of entrepreneurial failure. Thus, this dissertation replicates the work of KMS. Chapter 3 explicitly investigates the influence of the above perceptions on women's entrepreneurial propensity. This research has drawn data from the Global Entrepreneurship Monitor, a cross-national individual-level data set (2001-2006) covering 236,556 individuals across 17 countries. The results of this chapter suggest that gender disparities in entrepreneurial propensity are conditioned by differences in entrepreneurial perceptual variables. Women's lower levels of perceived entrepreneurial capability, entrepreneurial role models and opportunity evaluation and their higher fear of failure lead to lower entrepreneurial propensity.
To extend and generalise the relationship between perceptions and women's entrepreneurial propensity, in Chapter 4, two studies are conducted based on replicated research. Extension 1 generalises the results of KMS by using the same analysis on more recent data. Accordingly, this research implemented the same analysis on 372,069 individuals across the same countries (2011-2016). The recent data show that although gender disparity became significantly weaker, the gender gap is still in men's favour. However, similarly to the replicated study, this research revealed that perceptual factors explain a larger part of the gender disparity. To strengthen prior empirical evidence, in extension 2, utilising a sample of 1,029,863 individuals from 71 countries (2011-2016), the study conducted the same measures and analysis in a more global setting. By including developing countries, gender disparity in entrepreneurial propensity decreased significantly. The study revealed that the relative significance of the influences of perceptions' differs significantly across nations; however, perceptions have a worldwide effect. Moreover, this research found that the ratio of nascent women entrepreneurs in less developed countries to those in more developed nations is 2. More precisely, a higher level of economic development negatively influences the impact of perceptions on women's entrepreneurial propensity.
Whereas prior scholars increasingly underlined the importance of perceptions in explaining a large part of gender disparities in entrepreneurship, most of the prior investigations focused on nascent (early-stage) entrepreneurship, and evidence on the relationship between perceptions and other types of self-employment, such as innovative entrepreneurship, is scant. Innovation is a confirmed key driver of a firm's sustainability, higher competitive capability, and growth. Therefore, Chapter 5 investigates the influence of perceptions on women's innovative entrepreneurship. The chapter points out that entrepreneurial perceptions are the main determinants of the women's decision to offer a new product or service. This chapter also finds that women's innovative entrepreneurship is associated with the country's specific economic setting.
Overall, by underlining the critical role of institutional contexts, this dissertation provides considerable insights into the interaction between perceptions and women entrepreneurship, and its results have implications for policymakers and practitioners, who may find it helpful to consider women entrepreneurship in systemized challenges. Formal and informal barriers affect women's entrepreneurial perceptions and can differ from one country to the other. In this sense, it is crucial to design operational plans to mitigate formal and stereotypical challenges, and thus, more women will be able to start a business, particularly in developing countries in which women significantly comprise a smaller portion of the labour markets. This type of policy could write the "rules of the game" such that these rules enhance the women's propensity towards entrepreneurship.
Spatial Queues
(2000)
In the present thesis, a theoretical framework for the analysis of spatial queues is developed. Spatial queues are a generalization of the classical concept of queues as they provide the possibility of assigning properties to the users. These properties may influence the queueing process, but may also be of interest for themselves. As a field of application, mobile communication networks are modeled by spatial queues in order to demonstrate the advantage of including user properties into the queueing model. In this application, the property of main interest is the user's position in the network. After a short introduction, the second chapter contains an examination of the class of Markov-additive jump processes, including expressions for the transition probabilities and the expectation as well as laws of large numbers. Chapter 3 contains the definition and analysis of the central concept of spatial Markovian arrival processes (shortly: SMAPs) as a special case of Markov-additive jump processes, but also as a natural generalization from the well-known concept of BMAPs. In chapters 4 and 5, SMAPs serve as arrival streams for the analyzed periodic SMAP/M/c/c and SMAP/G/infinity queues, respectively. These types of queues find application as models or planning tools for mobile communication networks. The analysis of these queues involves new methods such that even for the special cases of BMAP inputs (i.e. non-spatial queues) new results are obtained. In chapter 6, a procedure for statistical parameter estimation is proposed along with its numerical results. The thesis is concluded by an appendix which collects necessary results from the theories of Markov jump processes and stochastic point fields. For special classes of Markov jump processes, new results have been obtained, too.
The vision of a future information and communication society has prompted leading politicians in the United States, the European Union and Japan to influence or even lead the economic and social transition in the context of an active technology policy. The technological development of society, however, is a product of a complex interplay of technological, economic and socio-political constraints. These constraints limit the political decision-making and implementation abilities. Moreover, facts and information are continuously changing during a paradigmatic technological, economic and social shift, which limits political decision-making abilities. This study compares political decision-making to promote computer-mediated communications in the Triad since the beginning of the 1980s, on four levels: the development of a political vision, the long-term aims and strategies, technology policy (e.g. the promotion of technological development and competition policy) and regulatory policy (e.g. universal access, protection of privacy and intellectual property). While technology policy tends to be uncontroversial, during a paradigmatic shift regulatory policy is difficult and lengthy. Nevertheless, the inclusion of interest groups, which rise during this paradigmatic shift and which are close to the technologies and their societal consequences, help to aid decision-making processes. In this context, politics in the United States has been more successful that in the European Union and especially Japan. Although this study predates the rise of eCommerce over the Internet, it addresses many of the themes underlying it. Of these themes, many remain politically unsettled, both on national, supranational and especially international levels. For example, for encryption and secure payments, which are necessary for eCommerce, no international standards do yet exist. The issue of taxation has hardly been opened for discussions. In sum, this study does not only offer a historical overview of the development of the Internet, but it also discusses issues of continuing present concern.
XML (Extensible Markup Language) ist ein sequentielles Format zur Speicherung und Übermittlung strukturierter Daten. Obwohl es ursprünglich für die Dokumentenverarbeitung entwickelt wurde, findet XML heute Verwendung in nahezu allen Bereichen der Datenverarbeitung, insbesondere aber im Internet. Jede XML-Dokumentenverarbeitungs-Software basiert auf einem XML-Parser. Der Parser liest ein Dokument in XML-Syntax ein und stellt es als Dokumentbaum der eigentlichen Anwendung zur Verfügung. Dokumentenverarbeitung ist dann im wesentlichen die Manipulation von Bäumen. Moderne funktionale Programmiersprachen wie SML und Haskell unterstützen Bäume als Basis-Datentypen und sind daher besonders gut für die Implementierung von Dokumentenverarbeitungs-Systemen geeignet. Um so erstaunlicher ist es, dass dieser Bereich zum größten Teil von Java-Software dominiert wird. Dies ist nicht zuletzt darauf zurückzuführen, dass noch keine vollständige Implementierung der XML-Syntax als Parser in einer funktionalen Programmiersprache vorliegt. Eine der wichtigsten Aufgaben in der Dokumentenverarbeitung ist Querying, d.h. die Lokalisierung von Teildokumenten, die eine angegebene Strukturbedingung erfüllen und in einem bestimmten Kontext stehen. Die baumartige Auffassung von Dokumenten in XML erlaubt die Realisierung des Querying mithilfe von Techniken aus der Theorie der Baumsprachen und Baumautomaten. Allerdings müssen diese Techniken an die speziellen Anforderungen von XML angepasst werden. Eine dieser Anforderungen ist, dass auch extrem große Dokumente verarbeitet werden müssen. Deshalb sollte der Querying-Algorithmus in einem einzigen Durchlauf durch das Dokument ausführbar sein, ohne den Dokumentbaum explizit im Speicher aufbauen zu müssen. Diese Arbeit besteht aus zwei Teilen. Der erste Teil beschreibt den XML- Parser fxp, der vollständig in SML programmiert wurde. Insbesondere werden die Erfahrungen mit SML diskutiert, die während der Implementierung von fxp gewonnen wurden. Es folgt eine Analyse des Laufzeit-Verhaltens von fxp und ein Vergleich mit anderen XML-Parsern, die in imperativen oder objekt- orientierten Programmiersprachen entwickelt wurden. Im zweiten Teil beschreiben wir einen Algorithmus zum Querying von XML- Dokumenten, der auf der Theorie der Waldautomaten fundiert ist. Er findet alle Treffer einer Anfrage in höchstens zwei Durchläufen durch das Dokument. Für eine wichtige Teilklasse von Anfragen kann das Querying sogar in einem einzelnen Durchlauf realisiert werden. Außerdem wird die Implementierung des Algorithmus in SML mit Hilfe von fxp dargestellt.
The study at hand deals with madness as it is represented in English Canadian fiction. The topic seemed most interesting and fruitful for analysis due to the fact that as the ways madness has been defined, understood, described, judged and handled differ quite profoundly from society to society, from era to era, as the language, ideas and associations surrounding insanity are both strongly culture-relative and shifting, madness as a theme of myth and literature has always been a excellent vehicle to mirror the assumptions and arguments, the aspirations and nostalgia, the beliefs and values, hopes and fears of its age and society. Thus, while the overall intent of this study is to elucidate some discernible patterns of structure and style which accompany the use of madness in Canadian literature, to investigate the varying sorts of portrayal and the conventions of presentation, to interpret the use of madness as literary devices and to highlight the different statements which are made, the continuity, variation, and changes in the theme of madness provide an informing principle in terms of certain Canadian experiences and perceptions. By examining madness as it represents itself in Canadian literature and considering the respective explorations of the deranged mind within their historical context, I hope to demonstrate that literary interpretations of madness both reflect and question cultural, political, religious and psychological assumptions of their times and that certain symptoms or usages are characteristic of certain periods. Such an approach, it is hoped, might not only contribute towards an assessment of the wealth of associations which surround madness and the ambivalence with which it is viewed, but also shed some light on the Canadian imagination. As such this study can be considered not only as a history of literary madness, but a history of Canadian society and the Canadian mind.
The goal of this thesis is to transfer the logarithmic barrier approach, which led to very efficient interior-point methods for convex optimization problems in recent years, to convex semi-infinite programming problems. Based on a reformulation of the constraints into a nondifferentiable form this can be directly done for convex semi- infinite programming problems with nonempty compact sets of optimal solutions. But, by means of an involved max-term this reformulation leads to nondifferentiable barrier problems which can be solved with an extension of a bundle method of Kiwiel. This extension allows to deal with inexact objective values and subgradient information which occur due to the inexact evaluation of the maxima. Nevertheless we are able to prove similar convergence results as for the logarithmic barrier approach in the finite optimization. In the further course of the thesis the logarithmic barrier approach is coupled with the proximal point regularization technique in order to solve ill-posed convex semi-infinite programming problems too. Moreover this coupled algorithm generates sequences converging to an optimal solution of the given semi-infinite problem whereas the pure logarithmic barrier only produces sequences whose accumulation points are such optimal solutions. If there are certain additional conditions fulfilled we are further able to prove convergence rate results up to linear convergence of the iterates. Finally, besides hints for the implementation of the methods we present numerous numerical results for model examples as well as applications in finance and digital filter design.
This work is concerned with the numerical solution of optimization problems that arise in the context of ground water modeling. Both ground water hydraulic and quality management problems are considered. The considered problems are discretized problems of optimal control that are governed by discretized partial differential equations. Aspects of special interest in this work are inaccurate function evaluations and the ensuing numerical treatment within an optimization algorithm. Methods for noisy functions are appropriate for the considered practical application. Also, block preconditioners are constructed and analyzed that exploit the structure of the underlying linear system. Specifically, KKT systems are considered, and the preconditioners are tested for use within Krylov subspace methods. The project was financed by the foundation Stiftung Rheinland-Pfalz für Innovation and carried out in joint work with TGU GmbH, a company of consulting engineers for ground water and water resources.
Due to the breath-taking growth of the World Wide Web (WWW), the need for fast and efficient web applications becomes more and more urgent. In this doctoral thesis, the emphasis will be on two concrete tasks for improving Internet applications. On the one hand, a major problem of many of today's Internet applications may be described as the performance of the Client/Server-communication: servers often take a long time to respond to a client's request. There are several strategies to overcome this problem of high user-perceived latencies; one of them is to predict future user-requests. This way, time-consuming calculations on the server's side can be performed even before the corresponding request is being made. Furthermore, in certain situations, also the pre-fetching or the pre-sending of data might be appropriate. Those ideas will be discussed in detail in the second part of this work. On the other hand, a focus will be placed on the problem of proposing hyperlinks to improve the quality of rapid written texts, at first glance, an entirely different problem to predicting client requests. Ultra-modern online authoring systems that provide possibilities to check link-consistencies and administrate link management should also propose links in order to improve the usefulness of the produced HTML-documents. In the third part of this elaboration, we will describe a possibility to build a hyperlink-proposal module based on statistical information retrieval from hypertexts. These two problem categories do not seem to have much in common. It is one aim of this work to show that there are certain, similar solution strategies to look after both problems. A closer comparison and an abstraction of both methodologies will lead to interesting synergetic effects. For example, advanced strategies to foresee future user-requests by modeling time and document aging can be used to improve the quality of hyperlink-proposals too.
The discretization of optimal control problems governed by partial differential equations typically leads to large-scale optimization problems. We consider flow control involving the time-dependent Navier-Stokes equations as state equation which is stamped by exactly this property. In order to avoid the difficulties of dealing with large-scale (discretized) state equations during the optimization process, a reduction of the number of state variables can be achieved by employing a reduced order modelling technique. Using the snapshot proper orthogonal decomposition method, one obtains a low-dimensional model for the computation of an approximate solution to the state equation. In fact, often a small number of POD basis functions suffices to obtain a satisfactory level of accuracy in the reduced order solution. However, the small number of degrees of freedom in a POD based reduced order model also constitutes its main weakness for optimal control purposes. Since a single reduced order model is based on the solution of the Navier-Stokes equations for a specified control, it might be an inadequate model when the control (and consequently also the actual corresponding flow behaviour) is altered, implying that the range of validity of a reduced order model, in general, is limited. Thus, it is likely to meet unreliable reduced order solutions during a control problem solution based on one single reduced order model. In order to get out of this dilemma, we propose to use a trust-region proper orthogonal decomposition (TRPOD) approach. By embedding the POD based reduced order modelling technique into a trust-region framework with general model functions, we obtain a mechanism for updating the reduced order models during the optimization process, enabling the reduced order models to represent the flow dynamics as altered by the control. In fact, a rigorous convergence theory for the TRPOD method is obtained which justifies this procedure also from a theoretical point of view. Benefiting from the trust-region philosophy, the TRPOD method guarantees to save a lot of computational work during the control problem solution, since the original state equation only has to be solved if we intend to update our model function in the trust-region framework. The optimization process itself is completely based on reduced order information only.
The main purpose of this dissertation is to solve the following question: How will the emergence of the Euro influence the currency composition of the NICs?monetary reserves? Taiwan and Thailand are chosen as our investigation subjects. There are two sorts of motives for central banks' reserve holdings, i.e., intervention-related motives and portfolio-related motives. The need for reserve holdings resulting from intervention-related motives are justified because of the costs resulting from exchange rate instability. On the other hand, we use the Tobin-Markowitz model to justify the need for monetary reserves held for portfolio-related motives. The operational implication of this distinction is the separation of monetary reserves into two tranches corresponding to different objectives. An analysis of a central bank's transaction balance is a money quality analysis. Such an analysis has to do with transaction costs and non-pecuniary rates of return. The facts point out, that the Euro's emergence will not change the fact that the USD will continue to be the major currency of transaction balances of the central banks in Taiwan and Thailand. In order to answer the question about diversification of monetary reserves as idle balance in the two NICs, we carry out an analysis of the portfolio approach, which is based on the basic ideas of the Tobin-Markowitz model. This analysis shows that Taiwan and/or Thailand respectively cannot reduce risk at a given rate of return or increase the rate of return at a given risk by diversifying their monetary reserves as idle balance from the USD to the Euro.
In this thesis we focus on the development and investigation of methods for the computation of confluent hypergeometric functions. We point out the relations between these functions and parabolic boundary value problems and demonstrate applications to models of heat transfer and fluid dynamics. For the computation of confluent hypergeometric functions on compact (real or complex) intervals we consider a series expansion based on the Hadamard product of power series. It turnes out that the partial sums of this expansion are easily computable and provide a better rate of convergence in comparison to the partial sums of the Taylor series. Regarding the computational accuracy the problem of cancellation errors is reduced considerably. Another important tool for the computation of confluent hypergeometric functions are recurrence formulae. Although easy to implement, such recurrence relations are numerically unstable e.g. due to rounding errors. In order to circumvent these problems a method for computing recurrence relations in backward direction is applied. Furthermore, asymptotic expansions for large arguments in modulus are considered. From the numerical point of view the determination of the number of terms used for the approximation is a crucial point. As an application we consider initial-boundary value problems with partial differential equations of parabolic type, where we use the method of eigenfunction expansion in order to determine an explicit form of the solution. In this case the arising eigenfunctions depend directly on the geometry of the considered domain. For certain domains with some special geometry the eigenfunctions are of confluent hypergeometric type. Both a conductive heat transfer model and an application in fluid dynamics is considered. Finally, the application of several heat transfer models to certain sterilization processes in food industry is discussed.
This work is concerned with arbitrage bounds for prices of contingent claims under transaction costs, but regardless of other conceivable market frictions. Assumptions on the underlying market are held as weak as convenient for the deduction of meaningful results that make good economic sense. In discrete time we also allow for underlying price processes with uncountable state space. In continuous time the underlying price process is modeled by a semimartingale. For the most part we could avoid any stronger assumptions. The main problems with which we deal in this work are the modelling of (proportional) transaction costs, Fundamental Theorems of Asset Pricing under transaction costs, dual characterizations of arbitrage bounds under transaction costs, Quantile-Hedging under transaction costs, alternatives to the Black-Scholes model in continuous time (under transaction costs). The results apply to stock and currency markets.
Since the end of the British Empire, which had provided white Australians with points of view, attitudes and stereotypes of the world - including perceptions of their own role in it -, rediscovering an international identity has been an Australian quest. Many turned to European roots; others to the Aboriginal landscape; Blanche d"Alpuget and Christopher J. Koch are two who have ventured into Asia for the culturally and spiritually regenerative materials necessary to redefine Australia in the post-colonial world. They have taken Eastern concepts of "self", and "soul" and forged them with the Australian obsession of fear and desire of contact with the "other" in a looking-glass of hybrid, Austral-Asian myth to reveal the true soul of Australian identity. Along with a brief historical and literary background to the triangular relationship between white Australia, Asia, and the West, this study- goal is to identify some of the Southeast Asian symbols, myths and literary structures which Koch and d"Alpuget integrate into the Western tradition. Central elements include: dichotomies as of personality, righteousness, and virtue; the "Otherworld", where one may approach enlightenment, but at the risk of falling into self-delusion; archetypes of the Hindu divine feminine; Eastern roots of Koch- themes of the "double man"; concepts of the forces of "light" and "dark"; the semiotics of time and meaning; and the central Eastern metaphor of the mirror by which Australia creates interdependent images of itself and of Asia.
Hardware bugs can be extremely expensive, financially. Because microprocessors and integrated circuits have become omnipresent in our daily live and also because of their continously growing complexity, research is driven towards methods and tools that are supposed to provide higher reliability of hardware designs and their implementations. Over the last decade Ordered Binary Decision Diagrams (OBDDs) have been well proven to serve as a data structure for the representation of combinatorial or sequential circuits. Their conciseness and their efficient algorithmic properties are responsible for their huge success in formal verification. But, due to Shannon's counting argument, OBDDs can not always guarantee the concise representation of a given design. In this thesis, Parity Ordered Binary Decision Diagrams are presented, which are a true extension of OBDDs. In addition to the regular branching nodes of an OBDD, functional nodes representing a parity operation are integrated into the data structure, thus resulting in Parity-OBDDs. Parity-OBDDs are more powerful than OBDDs are, but, they are no longer a canonical representation. Besides theoretical aspects of Parity-OBDDs, algorithms for their efficient manipulation are the main focus of this thesis. Furthermore, an analysis on the factors that influence the Parity-OBDD representation size gives way for the development of heuristic algorithms for their minimization. The results of these analyses as well as the efficiency of the data structure are also supported by experiments. Finally, the algorithmic concept of Parity-OBDDs is extended to Mod-p-Decision Diagrams (Mod-p-DDs) for the representation of functions that are defined over an arbitrary finite domain.
Mobile computing poses different requirements on middleware than more traditional desktop systems interconnected by fixed networks. Not only the characteristics of mobile network technologies as for example lower bandwidth and unreliability demand for customized support. Moreover, the devices employed in mobile settings usually are less powerful than their desktop counterparts. Slow processors, a fairly limited amount of memory, and smaller displays are typical properties of mobile equipment, again requiring special treatment. Furthermore, user mobility results in additional requirements on appropriate middleware support. As opposed to the quite static environments dominating the world of desktop computing, dynamic aspects gain more importance. Suitable strategies and techniques for exploring the environment e.g. in order to discover services available locally are only one example. Managing resources in a fault-tolerant manner, reducing the impact ill-behaved clients have on system stability define yet another exemplary prerequisite. Most state of the art middleware has been designed for use in the realm of static, resource rich environments and hence is not immediately applicable in mobile settings as set forth above. The work described throughout this thesis aims at investigating the suitability of different middleware technologies with regard to application design, development, and deployment in the context of mobile networks. Mostly based upon prototypes, shortcomings of those technologies are identified and possible solutions are proposed and evaluated where appropriate. Besides tailoring middleware to specific communication and device characteristics, the cellular structure of current mobile networks may and shall be exploited in favor of more scalable and robust systems. Hence, an additional topic considered within this thesis is to point out and investigate suitable approaches permitting to benefit from such cellular infrastructures. In particular, a system architecture for the development of applications in the context of mobile networks will be proposed. An evaluation of this architecture employing mobile agents as flexible, network-side representatives for mobile terminals is performed, again based upon a prototype application. In summary, this thesis aims at providing several complementary approaches regarding middleware support tailored for mobile, cellular networks, a field considered to be of rising importance in a world where mobile communication and particularly data services emerge rapidly, augmenting the globally interconnecting, wired Internet.
This doctoral dissertation examines two authors of German descent who are representatives for the development of Canadian literature and its regional focus on the prairies: Frederick Philip Grove (1879-1948) and Robert Kroetsch (*1927). Kroetsch, in his essays and talks, has repeatedly referred to Grove as one of his "literary ancestors". Although there exist monographs and numerous articles on both authors, the present study is the first-ever comparative approach. This study's main access is provided by the motif of disguise and masquerade, which plays a central role in the authors' works. Even if critics have looked at the traditional motif (cf. Homer's Odyssey, or many Renaissance plays) in Kroetsch's writing sporadically, and have used it to examine Grove's biography, no approach has attempted a larger contextualization within/among both writers' oeuvres. According to Lloyd Davis, however, the motif can be seen as "representing the cultural dialogism, rather than any particular thesis, of selfhood" (Davis 16). Hence, it helps interrogate a topic that within Canada - the former colony and current multicultural immigrant society - had and has a specific relevance. As an analytical tool, the motif allows for highlighting both the similarities and the differences between the œuvres of Grove and Kroetsch as key-figures of a (post)colonial literature of Western Canada on the one hand, and for general questions pertaining to the characterisation of figures, the definition of narrative positions and even of genres on the other hand. Following the preface, two theoretical chapters outline conceptions of identity and their deducible forms and functions of disguise and masquerade, including a discussion of John Richardson's Wacousta (1832), which is the first Canadian example for the motif's constitutive use. The second major section sketches, in two separate chapters, the poetics and mentalities (Mentalitätsgeschichte) of each writer within the context of their complete works by looking at biographical data as well as the critics' assessments. After immigrating into Manitoba in 1912, Grove soon became the first representative of a literary prairie-realism. Before, he had faked his suicide in 1909 and stripped off his 'original' identity as the German translator (e.g., Wilde, Wells, Flaubert) as well as modestly successful poet and novelist Felix Paul Greve to leave behind debts and a notorious lover and to reinvent himself in the New World. The protean role-plays of 'FPG' - decoded only 23 years after his death - are manifested in his creation of literary characters, in a "collectivity of identities" (Cavell 12) or number of metonymic personae that keep his critics busy to this date. Providing a different story, Kroetsch's family of German background immigrated into Canada in the mid-19th-century. Kroetsch has been thematizing his native province, Alberta, just as much as general national dispositions or questings in the course of his literary career spanning five decades now. His progressive and experimental writing has earned him, for instance, the label of "Mr Canadian Postmodern" by Linda Hutcheon (Canadian Postmodern 183). Particularly important among his specifically postmodern instruments is the principle of archaeology as derived from Foucault and employed as both metaphor and method; further methodological tools are Barthes' theories on reading/writing as an erotic act, Bakhtin's notion of (the) carnival(ization of literature) and a great sensibility for the myths as well as oral traditions of the North American Natives. If the third section analyzes two of FPG's novels to illustrate his transfer, or literal translation, from a German to a Canadian cultural context, the fourth section represents this study's core with three one-to-one comparisons of the two writers' central prose texts. In spite of all affinities between both authors, however, this section already indicates what section five further underlines: Kroetsch clearly transcends Grove's achievements (which ultimately reduce all his characters and texts to nothing but his own will- and wishful projections and identity-configurations); on the level of narrativity, genre and gender, Kroetsch not only goes far beyond parodying Grove, but proves to be an innovator whose mis-en-scène of the motif of disguise provides both more psychological depth and relevance for socio-historical contexts. This comparative study has been informed by research in the Special Archives and Collections at the University of Manitoba (Grove Papers) and at the University of Calgary (Kroetsch Papers), by related talks at Lund, Belfast and Winnipeg as well as by an occasional quotation from an interview I conducted with Robert Kroetsch as early as 1996.
Today, usage of complex circuit designs in computers, in multimedia applications and communication devices is widespread and still increasing. At the same time, due to Moore's Law we do not expect to see an end in the growth of the complexity of digital circuits. The decreasing ability of common validation techniques -- like simulation -- to assure correctness of a circuit design enlarges the need for formal verification techniques. Formal verification delivers a mathematical proof that a given implementation of a design fulfills its specification. One of the basic and during the last years widely used data structure in formal verification are the so called Ordered Binary Decision Diagrams (OBDDs) introduced by R. Bryant in 1986. The topic of this thesis is integration of structural high-level information in the OBDD-based formal verification of sequential systems. This work consist of three major parts, covering different layers of formal verification applications: At the application layer, an assertion checking methodology, integrated in the verification flow of the high-level design and verification tool Protocol Compiler is presented. At the algorithmic layer, new approaches for partitioning of transition relations of complex finite state machines, that significantly improve the performance of OBDD-based sequential verification are introduced. Finally, at the data structure level, dynamic variable reordering techniques that drastically reduce the time required for reordering without a trade-off in OBDD-size are described. Overall, this work demonstrates how a tighter integration of applications by using structural information can significantly improve the efficiency of formal verification applications in an industrial setting.
Today obesity has been recognized as a disease. Evidence suggests that obesity often has Genetic, environmental, psychological and other factors. Growing evidence points to heredity as a strong determining factor of obesity. The characterization of uncoupling proteins (UCP) represents a major breakthrough of genetic factors towards understanding the molecular basis for energy expenditure and therefore likely to have important implication for the cause and treatment of human obesity. UCPs as mitochondrial anion carriers which creates a pathway that allows dissipation of the proton electrochemical gradient therefore which when deregulated are key risk factors in the development of obesity and other eating disorders. In order to better understand the roles of both UCP2 and UCP3 which considered as prime candidate genes involved in the pathogenesis of obesity, this study elucidate (1) Genomic organization: The human UCP2 (3) gene spans over 8.7 kb (7.5 kb) distributed on 8 (7) exons. Three UCP genes may have evolved from a common ancestor or are the result from gene duplication events. Two mRNA transcripts are generated from hUCP3 gene, the long and short form of hUCP3 is differing by the presence or absence of 37 amino acid residues at the C-terminus. (2) Mutational analysis revealed a mutation in exon 4 of hUCP2 resulting in the substitution of an alanine by a valine at codon 55 and an insertion polymorphism in exon 8 consisted of a 45 bp repeat located 150 bp downstream of the stop codon in the 3'-UTR. The allele frequencies of both polymorphisms were not significantly elevated in a subgroup of children characterized by low Resting Metabolic Rates (RMR). (3) Promoter Analysis showed that the promoter region of hUCP2 lacks a classical TATA or CAAT box. Functional characterization of hUCP2 promoter showed that minimal promoter activity was observed within 65 bp upstream of the transcriptional start site. 75 bp further upstream a strong cis-acting regulatory element was identified which significantly enhanced basal promoter activity. The regulation of human UCP2 gene expression involves complex interactions among positive and negative regulatory elements. the 5"-flanking region of the hUCP3 gene were characterized in which contains both TATA and CAAT boxes as well as consensus motifs for PPRE, TRE, CRE and muscle-specific MyoD and MEF2 sites. Functional characterization identified a cis-acting negative regulatory element between - 2983 and -982 while the region between -982 and -284 showed greatly increased basal promoter activity suggesting the presence of a strong enhancer element. Promoter activity was particularly enhanced in the murine skeletal muscle cell line C2C12 reflecting the tissue-selective expression pattern of UCP3.
Hydrodynamic processes play a fundamental role in the distribution of salt within mangrove-fringed estuaries and mangrove forests. In this thesis, two hydrodynamic processes and their ecological implications were examined. (1) Passive Irrigation and Functional Morphology of Crustacean Burrows in Rhizophora-forests. The mangrove Rhizophora excludes more than 90% of the seawater salt at water intake at the roots. By means of conductivity methods and resin casting, it was found that crustacean burrows play a key role in the removal of excess salt from the root zone. Salt diffuses from the roots into the burrows, and is efficiently flushed from the burrows by rainwater infiltration and tidal irrigation. The burrows contribute significantly to favourable conditions for the growth of Rhizophora trees. (2) Trapping of Mangrove Propagules due to Density-driven Secondary Circulation in Tropical Estuaries. In North East Australian estuaries, mangrove propagules are drifted upstream by density-driven axial surface convergences. Propagules accumulate in hydrodynamic traps upstream from suitable habitat, where they are trapped at least for the entire tropical dry season. Axial convergences may provide an efficient barrier for propagule exchange across estuaries. In such estuaries, mangrove populations can be regarded as floristically isolated, not unlike island communities, even though the populations lie on a continuous coastline. This effect may contribute to the disjunct distribution observed in some mangrove species. The outcomes of this work contribute to the understanding of the importance of salt as a growth and habitat-restricting factor in the mangrove environment.
Until today the effects of many chlorinated hydrocarbons (e.g. DDT, PCBs) against the specific organisms are still a subject of controversial discussions. It was also the case for potential endocrine effects to influence the spermatogenesis correlated with possible changes of the population's vitality. To clear this situation, three questions could be at the centre of attention: 1) Do the chemicals cause a special harmful effect on the male reproductive tract? 2) Could some particular chemical mixtures act to bind and activate the human estrogen receptor (hER)? 3) Are the life stages of an organism specially sensitive to the effects of chemicals and therefore be established as Screening-Test-System? the connected effects of DDT and Arochlor 1254 as single substance and in 1:1 mixture according to their estrogenic effectiveness on zebrafish (Brachydanio rerio) were therefore investigated. the concentrations of the pesticides and their mixture ranged between 0.05-µg/l and 500-µg/l and separated by a factor of 10. It was turned out that the test concentrations of 500-µg/l were too toxic to zebrafish in all the cases. The experiment was followed up with four concentrations of DDT, A54 as well as their 1:1 mixture anew each separated by a factor of 10 and ranging between 0.05-µg/l and 50-µg/l. The bioaccumulation test within 8 days showed that the zebrafish accumulated the chemicals, but no equilibrum was reached and the concentration 0.05-µg/l was established as No Observed Effect Concentration (NOEC). Putting up on these analyses, the investigation of the life cycle (LC) starting with fertilized eggs demonstrated a reduction in the rate of hatchability, reproduction and length of fish emerged. These reductions involved the duration of the life cycle stages (LCS) which consequently lasted longer than expected. Exposure time and level of the tested chemicals accelerated the occurrence of these effects which were more significant when the chemical mixtures were used too. To establish whether the parameter assessed were correlated to the male reproductive tract, the quality, quantity and life span of sperm were assessed using the methods of Leong (1988) and Shapiro et al (1994). The sperm degeneration observed, led us to investigate the spermatogenesis and the ultrastructure of the testes. This last experiment showed a significant reduction of the late stage of spermatogenesis and the heterophagic vacuoles which play an important role in the spermatid maturation. It could therefore be concluded that, DDT and A54 could act synergically and cause disorders of the male reproductive tract of male zebrafish and influence also their growth.
Software and interactive systems that adapt their behavior to the user are often referred to as Adaptive Systems. These systems infer the user's goals, knowledge or preferences by observing the user's actions. A synposis of 43 published studies demonstrated that only few of the existing systems are evaluated empirically. Most studies failed to show an advantage of the user model. A new framework is proposed that categorizes existing studies and defines an evaluation procedure which is able to uncover failures and maladaptations in the user model. It consists of four layers: evaluation of input data, evaluation of inference, evaluation of adaptation decision and evaluation of total interaction. Exemplary, the framework has been applied to the HTML-Tutor, an online-course that adapts to the learners' knowledge. Several empirical studies are described that test the accuracy of the user models, and explore the effects of adaptation to knowledge respectively prior knowledge. Generalization issues of the approach are discussed.
My dissertation is concerned with contemporary (Anglo-)Canadian immigrant fiction and proposes an analytic grid with which it may be appreciated and compared more adequately. As a starting-point serves the general observation that the works of many Canadian immigrant writers are characterised by a focus on their respective home cultures as well as on their Canadian host culture. Following the ground-breaking work of Northrop Frye, Margaret Atwood and David Staines, the categories of "there" and "here" are suggested in order to reflect this double encoding of Canadian immigrant literature. However, "here" and "there" are more than spatial configurations in that they represent a concern with issues of multiculturalism and postcolonialism. Both of which are informed by an emphasis on difference and identity, and difference and identity are also what the narratives of M.G. Vassanji, Neil Bissoondath and Rohinton Mistry are preoccupied with. My study sets out to show two things: On the one hand, it attempts to exemplify the complexity and interrelatedness of "there" and "here" in a representative fashion. Hence in their treatments of difference, M.G. Vassanji, Neil Bissoondath and Rohinton Mistry come up with comparable identity constructions "here" and "there" respectively. On the other hand, special attention is paid to the strategies by which Vassanji, Bissoondath and Mistry construct difference and corroborate their respective understandings of identity.
ASEAN and ASEAN Plus Three: Manifestations of Collective Identities in Southeast and East Asia?
(2003)
East Asia is a region undergoing vast structural changes. As the region moved closer together economically and politically following the breakdown of the bipolar world order and the ensuing expansion of intra-regional interdependencies, the states of the region faced the challenge of having to actively recast their mutual relations. At the same time, throughout the 1990s, the West became increasingly interested in trans- and inter-regional dialogue and cooperation with the emerging economies of East Asia. These developments gave rise to a "new regionalism", which eventually also triggered debates on Asian identities and the region's potential to integrate. Before this backdrop, this thesis analyzes in how far both the Association of Southeast Asian Nations (ASEAN), which has been operative since 1967 and thus embodies the "old regionalism" of Southeast Asia, and the ASEAN Plus Three forum (APT: the ASEAN states plus China, Japan and South Korea), which has come into existence in the aftermath of the Asian economic crisis of 1997, can be said to represent intergovernmental manifestations of specific collective identities in Southeast and East Asia, respectively. Based on profiles of the respective discursive, behavioral and motivational patterns as well as the integrative potential of ASEAN and APT, this study establishes in how far the member states adhere to sustainable collective patterns of interaction, expectations and objectives, and assesses in how far they can be said to form specific 'ingroups'. Four studies on collective norms, readiness to pool sovereignty, solidarity and attitudes vis-Ã -vis relevant third states show that ASEAN has evolved a certain degree of collective identity, though the Association's political relevance and coherence is frequently thwarted by changes in its external environment. A study on the cooperative and integrative potential of APT yields no manifest evidence of an ongoing or incipient pan-East Asian identity formation process.
In this thesis, we study the convergence behavior of an efficient optimization method used for the identification of parameters for underdetermined systems. The research is motivated by optimization problems arising from the estimation of parameters in neural networks as well as in option pricing models. In the first application, we are concerned with neural networks used to forecasting stock market indices. Since neural networks are able to describe extremely complex nonlinear structures they are used to improve the modelling of the nonlinear dependencies occurring in the financial markets. Applying neural networks to the forecasting of economic indicators, we are confronted with a nonlinear least squares problem of large dimension. Furthermore, in this application the number of parameters of the neural network to be determined is usually much larger than the number of patterns which are available for the determination of the unknowns. Hence, the residual function of our least squares problem is underdetermined. In option pricing, an important but usually not known parameter is the volatility of the underlying asset of the option. Assuming that the underlying asset follows a one-factor continuous diffusion model with nonconstant drift and volatility term, the value of an European call option satisfies a parabolic initial value problem with the volatility function appearing in one of the coefficients of the parabolic differential equation. Using this system equation, the estimation of the volatility function is described by a nonlinear least squares problem. Since the adaption of the volatility function is based only on a small number of observed market data these problems are naturally ill-posed. For the solution of these large-scale underdetermined nonlinear least squares problems we use a fully iterative inexact Gauss-Newton algorithm. We show how the structure of a neural network as well as that of the European call price model can be exploited using iterative methods. Moreover, we present theoretical statements for the convergence of the inexact Gauss-Newton algorithm applied to the less examined case of underdetermined nonlinear least squares problems. Finally, we present numerical results for the application of neural networks to the forecasting of stock market indices as well as for the construction of the volatility function in European option pricing models. In case of the latter application, we discretize the parabolic differential equation using a finite difference scheme and we elucidate convergence problems of the discrete scheme when the initial condition is not everywhere differentiable.
There is considerable evidence for an association between chronic dysregulation of the hypothalamus-pituitary adrenal (HPA) axis, atrophy of the hippocampus (HC) and cognitive and mood changes in clinical populations and in aging. The present thesis investigated this relationship in young healthy male subjects. Special emphasis was put on measures of HC volume and function derived from structural and functional magnetic resonance imaging (MRI). Higher cortisol levels after awakening were observed in subjects with higher levels of depressive symptomatology. Larger HC volume was associated with higher cortisol levels after awakening and in response to acute stress, whereas cognitive performance was impaired in subjects with larger HC volumes. Hippocampal activation during picture encoding was reduced after stress induction, and positive associations between activation and cognitive performance before stress were not present anymore afterwards. The present findings underscore the importance of structural and functional brain imaging for psychoneuroendocrinological research. The investigation of the association between cortisol levels and hippocampal integrity in young healthy subjects elicited unexpected results and adds to the understanding of HPA dysfunction and HC atrophy in clinical and aged populations.
Since November 1997, we started to focus on the population ecology of two sympatric Sinonatrix snakes in the Chutzuhu swamp, northern Taiwan. At the same time we also examined some specimens from Senckenberg Natural History Museum, Frankfurt am Main and accumulated field data of some observation made on S. percarinata suriki from Fushan botanical garden, Sanping and Gaoshu, Taiwan. According to the specimens examined, we suspect that the close phylogeny of S. percarinata suriki may come from two ancestors, northeast Taiwan population closest to Fujien or Zehjiang and the southwest population closest to Guandong or Vietnam. This pattern was also represented in some molecular phylogeny studies of freshwater fish in Taiwan. There were 22,462 trap-nights, taken from the Chutzuhu swamp, during the period November 1999 to September 2001 and 361 snakes were collected, comprising five species and 617 snake-times. The population sizes were based on the Lincoln-Peterson index and were estimated to be 988-±326 in S. annularis and 129-±78 in S. percarinata suriki. Movement and home range data showed S. annularis is a restricted activity water snake and S. percarinata suriki possesses great mobility in spatial patterns, but movement ability seems to be influenced by the size of the aquatic environment. S. annularis is live-bearing, on average 8.19 neonates and this principally occurs in September; S. percarinata suriki lays 6-24 eggs, but due to insufficient observations no conclusions can be drawn. It must be noted that oviposition was also noted in September. The reproductive mode may reflect on thermal requirement differences of the two sympatric snakes. S. annularis tended to be a fish (98%) eater and S. percarinata suriki take 50% fish and 50% frogs in their diet. Middle to high ground cover marshland appears to be the favorite microhabitat of S. annularis, and S. percarinata suriki seems prefer open creeks and ditches. The population condition of S. annularis in the Chutzuhu swamp seems to be rapidly deteriorating and this trend is also reflected in the BCI declines, low proportion stomach contents and diseases of S. annularis. Water seems to be the major influencing factor and strongly correlates with the conservation strategy. Conservation proposals for S. annularis in the Chutzuhu swamp will be formulated. During this study period we also developed an efficient technique for snake morphological data accumulation and image database, with the aid of the following devices, PC notebook and scanner, which is adapted for practical field studies. We also want to propose a component system for the establishment of a fundamental snake population databases (FPDS) for long-term snake ecological studies and monitoring herein.
Many real-life phenomena, such as computer systems, communication networks, manufacturing systems, supermarket checkout lines as well as structural military systems can be represented by means of queueing models. Looking at queueing models, a controller may considerably improve the system's performance by reducing queue lengths, or increasing the throughput, or diminishing the overhead, whereas in the absence of a controller the system behavior may get quite erratic, exhibiting periods of high load and long queues followed by periods, during which the servers remain idle. The theoretical foundations of controlled queueing systems are led in the theory of Markov, semi-Markov and semi-regenerative decision processes. In this thesis, the essential work consists in designing controlled queueing models and investigation of their optimal control properties for the application in the area of the modern telecommunication systems, which should satisfy the growing demands for quality of service (QoS). For two types of optimization criterion (the model without penalties and with set-up costs), a class of controlled queueing systems is defined. The general case of the queue that forms this class is characterized by a Markov Additive Arrival Process and heterogeneous Phase-Type service time distributions. We show that for these queueing systems the structural properties of optimal control policies, e.g. monotonicity properties and threshold structure, are preserved. Moreover, we show that these systems possess specific properties, e.g. the dependence of optimal policies on the arrival and service statistics. In order to practically use controlled stochastic models, it is necessary to obtain a quick and an effective method to find optimal policies. We present the iteration algorithm which can be successfully used to find an optimal solution in case of a large state space.
As the oldest genre in New Zealand literature written in English, poetry always played a significant role in the country's literary debate and was generally considered to be an indicator of the country's cultural advancement. Throughout the 20th century, the question of home, of where it is and what it entails, became a crucial issue in discussing a distinct New Zealand sense of identity and in strengthening its independent cultural status. The establishment of a national sense of home was thus of primary concern, and poetry was regarded as the cultural marker of New Zealand's independence as a nation. In this politically motivated cultural debate, the writing of women was only considered on the margin, largely because their writing was considered too personal and too intimately tied together with daily life, especially domestic life, as to be able to contribute to a larger cultural statement. Such criticism built on gender role stereotypes, like for instance women's roles as mothers and housewives in the 1950s. The strong alignment of women with the home environment is not coincidental but a construct that was, and still is, predominantly shaped by white patriarchal ideology. However, it is in particular women's, both Pakeha and Maori, thorough investigation into the concept of home from within New Zealand's society that bears the potential for revealing a more profound relationship between actual social reality and the poetic imagination. The close reading of selected poems by Ursula Bethell, Mary Stanley, Lauris Edmond and J.C. Sturm in this thesis reveals the ways in which New Zealand women of different backgrounds subvert, transcend and deconstruct such paradigms through their poetic imagination. Bethell, Stanley, Edmond and Sturm position their concepts of home at the crossroads between the public and the private realm. Their poems explore the correspondence between personal and national concerns and assess daily life against the backdrop of New Zealand's social development. Such complex socio-cultural interdependence has not been paid sufficient attention to in literary criticism, largely because a suitable approach to capturing the complexity of this kind of interconnectedness was lacking. With Spaces of Overlap and Spaces of Mediation this thesis presents two critical models that seek to break the tight critical frames in the assessment of poetic concepts of home. Both notions are based on a contextualised approach to the poetic imagination in relation to social reality and seek to carve out the concept of home in its interconnected patterns. Eventually, this approach helps to comprehend the ways in which women's intimate negotiations of home translate into moments of cultural insight and transcend the boundaries of the individual poets' concerns. The focus on women's (re)negotiations of home counteracts the traditionally male perspective on New Zealand poetry and provides a more comprehensive picture of New Zealand's cultural fabric. In highlighting the works of Ursula Bethell, Mary Stanley, Lauris Edmond and J.C. Sturm, this thesis not only emphasises their individual achievements but makes clear that a traditional line of New Zealand women's poetry exists that has been neglected far too long in the estimation of New Zealand's literary history.
This dissertation develops a rationale of how to use fossil data in solving biogeographical and ecological problems. It is argued that large amounts of fossil data of high quality can be used to document the evolutionary processes (the origin, development, formation and dynamics) of Arealsystems, which can be divided into six stages in North America: the Refugium Stage (before 15,000 years ago: > 15 ka), the Dispersal Stage (from 8,000 to 15,000 years ago: 8.0 - 15 ka), the Developing Stage (from 3,000 to 8,000 years ago: 3.0 - 8.0 ka), the Transitional Stage (from 1,000 to 3,000 years ago: 1 - 3 ka), the Primitive Stage (from 5,00 to 1,000 years ago: 0.5 - 1 ka) and the Human Disturbing Stage (during the last 500 years: < 0.5 ka). The division into these six stages is based on geostatistical analysis of the FAUNMAP database that contains 43,851 fossil records collected from 1860 to 1994 in North America. Fossil data are one of the best materials to test the glacial refugia theory. Glacial refugia represent areas where flora and fauna were preserved during the glacial period, characterized by richness in species and endemic species at present. This means that these (endemic) species should have distributed purely or primarily in these areas during the glacial period. The refugia can therefore be identified by fossil records of that period. If it is not the case, the richness in (endemic) species may not be the result of the glacial refugia. By exploring where mammals lived during the Refugium Stage (> 15 ka), seven refugia in North America can be identified: the California Refugium, the Mexico Refugium, the Florida Refugium, the Appalachia Refugium, the Great Basin Refugium, the Rocky Mountain Refugium and the Great Lake Refugium. The first five refugia coincide well with De Lattin- dispersal centers recognized by biogeographical methods using data on modern distributions. The individuals of a species are not evenly distributed over its Arealsystem. Brown- Hot Spots Model shows that in most cases there is an enormous variation in abundance within an areal of a species: In a census, zero or only a very few individuals occur at most sample locations, but tens or hundreds are found at a few sample sites. Locations where only a few individuals can be sampled in a survey are called "cool spots", and sites where tens or hundreds of individuals can be observed in a survey are called "hot spots". Many areas within the areal are uninhabited, which are called "holes". This model has direct implications for analyzing fossil data: Hot spots have a much higher local population density than cool spots. The chances to discover fossil individuals of a species are much higher in sediments located in a "hot spot" area than in a "cool spot" area. Therefore much higher MNIs (Minimum Number of Individuals) of the species should be found in fossil localities located in the hot spot than in the cool spot area. There are only a few hot spots but many cool spots within an areal of a single hypothetical species, consequently only a few fossil sites can provide with much high MNIs, whereas most other sites can only provide with very low MNIs. This prediction has been proved to be true by analysis of 70 species in FAUMAP containing over 100 fossil records. The temporal and spatial variation in abundance can be reconstructed from the temporospatial distribution of the MNIs of a species over its Arealsystem. Areas with no fossil records from the last thousands of years may be holes, and sites with much higher MNIs may be hot spots, while locations with low MNIs may be cool spots. Although the hot spots of many species can remain unchanged in an area over thousands of years, our study shows that a large shift of hot spots occurred mainly around 1,500-1,000 years ago. There are three directions of movement: from the west side to the east side of the Rockies, from the East of the USA to the east side of the Rockies and from the west side of the Rockies to the Southwest of the USA. The first two directions of shift are called Lewis and Clark- pattern, which can be verified with the observations mad by Lewis and Clark during their expedition in 1805-1806. The historical process of this pattern may well explain the 200-year-old puzzle why big game then abundant on the east side were rare on the west side of the Rocky Mountains noted by modern ecologists and biogeographers. The third direction of shift is called Bayham- pattern. This pattern can be tested by the model of Late Holocene resource intensification first described by Frank E. Bayham. The historical process creating the Bayham pattern will challenge the classic explanation of the Late Holocene resource intensification. An environmental change model has been proposed to account for the shift of hot spots. Implications of glacial refugia and hot spots areas for wildlife management and effective conservation are discussed. Suggestions for paleontologists and zooarchaeologists regarding how to provide more valuable information in their future excavation and research for other disciplines are given.
The collapse of the tailings pond of the Aznalcállar open pit mine (West of Seville, Spain) in April 1998 left more than 4000 ha of arable land and floodplains contaminated with heavy metal containing pyrite sludge. After a first remediation campaign a considerable contamination remained in the soil. The present study evaluates the possibilities of reflectance spectroscopy and airborne hyperspectral remote sensing for the qualitative and quantitative assessment of heavy metal contamination and the acidification risk related to the mining accident. Based on an extensive data set consisting of geochemical analyses and reflectance measurements of more than 300 soil samples different chemometrics methods (multiple linear regression, partial least squares and artificial neural networks) are tested for computation of concentrations of soil constituents on the basis of the spectral reflectance. Spectral mixture analysis is applied for the analysis of the spatial distribution of the contamination. The abundance information derived from spectral mixture analysis is turned into quantitative information incorporating an artificial mixture experiment. The results of this experiment provide a link between sludge abundance and sludge weight, allowing as a consequence calculation of the amount of residual sludge per pixel, the acidification potential and other parameters important for remediation planning. The application of laboratory, field and imaging spectroscopy for providing quantitative information about the contamination levels in their spatial context is a good complement to conventional methods. The advantage is the reduction of the time and labour-intensive geochemical analysis, because after the model calibration, further samples can be analysed directly with the chemometric models. Furthermore, the spatial distribution can be mapped with imaging spectroscopy data helping in a more precise remediation planning.
My study attempts to illustrate the generic development of the family novel in the second half of the twentieth century. At its beginning stands a preliminary classification of the various types of family fiction as they are referred to in secondary literature, which is then followed by a definition of the family novel proper. With its microscopic approach to novels featuring the American family and its (post-)postmodern variations, my study marks a first step into as yet uncharted territory. Assuming that the family novel has emerged as a result of the twentieth century's emphasis on the modern nuclear family, focuses on the family as a gestalt rather than on a single protagonist, and is concerned with issues of social and cultural significance, this study examines how the family, its forms and its conflicts are functionalized for the respective author's cultural critique. From post-war to post-millennium, family novelists have sketched the American family in various precarious conditions, and their texts are critical assessments of contemporary socioeconomic and cultural conditions. My close reading of John Cheever's The Wapshot Chronicle (1957), Don DeLillo's White Noise (1985) and Jonathan Franzen's The Corrections (2001) intends to reveal, shared values as well as significant differences on a formal as well as on a thematic level. As my examination of the respective novel shows, authors react to social and cultural change with new functionalizations of the family in fiction. Unlike the general assumption of literary crticism, family novels do not approach new cultural developments in a conventional or even traditionalist manner. A comparison of White Noise with The Wapshot Chronicle demonstrates that DeLillo's postmodern family novel transcends the rather nostalgic perspective of Cheever's 1950s work. Similarly, Jonathan Franzen's fin de millennium family novel The Corrections holds a post-postmodern position, which can be aptly described by Franzen's own term 'tragical realism'. The significant changes and developments of the family novel in the past five decades demonstrate the need for a continuous reassessment of the genre, and in this respect, my study is merely a beginning.
Objective: Only 20-25% of the variance for the two to four-fold increased risk of developing breast cancer among women with family histories of the disease can be explained by known gene mutations. Other factors must exist. Here, a familial breast cancer model is proposed in which overestimation of risk, general distress, and cancer-specific distress constitute the type of background stress sufficient to increase unrelated acute stress reactivity in women at familial risk for breast cancer. Furthermore, these stress reactions are thought to be associated with central adiposity, an independent well-established risk factor for breast cancer. Hence, stress through its hormonal correlates and possible associations with central adiposity may play a crucial role in the etiology of breast cancer in women at familial risk for the disease. Methods: Participants were 215 healthy working women with first-degree relatives diagnosed before (high familial risk) or after age 50 (low familial risk), or without breast cancer in first-degree relatives (no familial risk). Participants completed self-report measures of perceived lifetime breast cancer risk, intrusive thoughts and avoidance about breast cancer (Impact of Event Scale), negative affect (Profile of Mood States), and general distress (Brief Symptom Inventory). Anthropometric measurements were taken. Urine samples during work, home, and sleep were collected for assessment of cortisol responses in the naturalistic setting where work was conceptualized as the stressful time of the day. Results: A series of analyses indicated a gradient increase of cortisol levels in response to the work environment from no, low, to high familial risk of breast cancer. When adding breast cancer intrusions to the model with familial risk status predicting work cortisol levels, significant intrusion effects emerged rendering the familial risk group non-significant. However, due to a lack of association between intrusions and cortisol in the low and high familial risk group separately, as well as a significant difference between low and high familial risk on intrusions, but not on work cortisol levels, full mediation of familial risk group effects on work cortisol by intrusions could not be established. A separate analysis indicated increased levels of central but not general adiposity in women at high familial risk of breast cancer compared to the low and no risk groups. There were no significant associations between central adiposity and cortisol excretion. Conclusion: A hyperactive hypothalamus-pituitary-adrenal axis with a more pronounced excretion of its end product cortisol, as well as elevated levels of central but not overall adiposity in women at high familial risk for breast cancer may indicate an increased health risk which expands beyond that of increased breast cancer risk for these women.
The optimal control of fluid flows described by the Navier-Stokes equations requires massive computational resources, which has led researchers to develop reduced-order models, such as those derived from proper orthogonal decomposition (POD), to reduce the computational complexity of the solution process. The object of the thesis is the acceleration of such reduced-order models through the combination of POD reduced-order methods with finite element methods at various discretization levels. Special stabilization methods required for high-order solution of flow problems with dominant convection on coarse meshes lead to numerical data that is incompatible with standard POD methods for reduced-order modeling. We successfully adapt the POD method for such problems by introducing the streamline diffusion POD method (SDPOD). Using the novel SDPOD method, we experiment with multilevel recursive optimization at Reynolds numbers of Re=400 and Re=10,000.
The main aim of "Her Idoll Selfe"? Shaping Identity in Early Modern Women- Self-Writings is to offer fresh readings of as yet little-read early modern women- texts. I look at a variety of texts that are either explicitly concerned with the constitution of the writer- self, such as the autobiographies by Lady Grace Mildmay and Martha Moulsworth, or in which the preoccupation with the self is of a more indirect nature, as in the mothers" advice books by Elizabeth Grymeston, Dorothy Leigh, Elizabeth Richardson or the anonymous M. R., or even in women- poetry, drama and religious verse. I situate the texts in the context of early modern discourses of femininity and subjectivity to pursue the question in how far it was possible for early modern women to achieve a sense of agency in spite of their culturally marginal position. In that, my readings aim to contribute to the ongoing critical process of decentring the early modern period. At the same time, I draw on contemporary theory as a methodological tool that can open up further dimensions of the texts, especially in places where the texts provide clues and parallels that lend themselves to a theoretical approach. Conversely, the texts themselves shed interesting light on feminist and poststructuralist theory and can serve as testing grounds for the current critical fascination with fragmentation and hybridity. Having outlined the theoretical and methodological framework of my study, I then analyse the women- writings with reference to a matrix of paradigmatic dimensions that encompass their most prominently recurring themes: the notion of writing the self, relationships between self and other, demarcations of private and public, the women- notorious preoccupation with self-loss and death, as well as the recurrent theme of the "golden meane". I suggest that this motif can provide the vital cue to early modern women- constitution of self. The idea of a precarious "golden meane" links in with to parallel discourses of moderation and balance at the time, but reinterprets them in a manner that can present a workable and innovative paradigm of subjectivity. Instead of subscribing to a model of decentred selfhood, early modern women- presentations of self suggest that a concluding but contested compromise is a workable strategy to achieve a form of selfhood that can responsibly be lived with.
Two areas were selected to represent major process regimes of Mediterranean rangelands. In the County of Lagads (Greece), situated east of the city of Thessaloniki, livestock grazing with sheep and goats is a major factor of the rural economy. In suitable areas, it is complemented by agricultural use. The region of Ayora (Spain) is located west of the city of Valencia. It is one of regions most affected by fires in Spain. First of all, long time series of satellite data were compiled for both regions on the basis of Landsat sensors, which cover the time until 1976 (Ayora) and 1984 (Lagadas) with one image per year. Using a rigorous processing scheme, the data were geometrically and radiometrically corrected Specific attention was given to an exact sensor calibration, the radiometric intercalibration of Landsat-TM and "MSS. Proportional cover of photosynthetically active vegetation was identified as a suitable quantitative indicator for assessing the state of rangelands. Using Spectral Mixture Analysis (SMA) it was inferred for all data sets. The extensive data base procured this way enabled to map fire events in the Ayora area based on sequential diachronic sets and provide fire dates, perimeter as well as fire recurrence for each pixel. The increasing fire frequency in the past decades is in large parts attributed to the accelerated abandonment of the area that leads to an encroachment of shrublands and the accumulation of combustible biomass. On the basis of the fire mapping results, a spatial and temporal stratification of the data set allowed to asses plant recovery dynamics on the landscape level through linear trend analysis. The long history of fire events in the Mediterranean frequently leads to processes of auto-succession. Following an initial dominance of herbaceous vegetation this commonly leads to similar plant communities as the ones present before the fire. On a temporal axis, this results in typical exponential post-fire trajectories which could also be shown in this study. The analysis of driving factors for post-fire dynamics confirmed the importance of aspect and slope. Locations with lower amounts of solar irradiation and favourable water supply yielded faster recovery rates and higher post-fire vegetation cover levels. In most cases, the vegetation cover levels observed before the fire were not reached within the post-fire observation period. In the area of Lagadas, linear trend analysis and additional statistical parameters were used to infer a degradation index. This could be used to illustrate a complex pattern of stability, regeneration and degradation of vegetation cover. These different processes and states are found in close proximity and are clearly determined by topography and elevation. Following a sequence of analyses, it was found that in particular steep, narrow valleys show positive trends, while negative trends are more abundant on plain or gently undulating areas. Considering the local grazing regime, this spatial differentiation was related to the accessibility of specific locations. Subsequently, animal numbers on community level were used to calculate efficient stocking rates and assess the temporal development of their relation with vegetation cover. This calculation of temporal trajectories illustrated that only some communities show the expected negative relation. To the contrary, a positive relation or even changing relation patterns are observed. This signifies recent concentration and intensification processes in the grazing scheme, as a result of which animals are kept in sheds, where additional feedstuffs are provided. In these cases, free roaming of livestock animals is often confined to some hours every day, which explains the spatial preference of easily accessible areas by the shepherds. Beyond these temporal trends, it was analysed whether the grazing pattern is equally reflected in a spatial trend. Making use of available geospatial information layers, the efforts required to reach each location was expressed as a cost. Then, cost zones could be defined and woody vegetation cover as a grazing indicator could be inferred for the different zones. Animal sheds were employed as starting features for this piospheric analysis, which could be mapped from very high spatial resolution Quickbird image data. The result was a clearly structured gradient showing increasing woody vegetation cover with increasing cost distance. On the basis of these two pilot studies, the elements of a monitoring and interpretation framework identified at the beginning of the work were evaluated and a formal interpretation scheme was presented.
This study investigates the endemic centres of Indonesian animals and the biodiversity across geographical gradients. At the same time, it also evaluated different lines suggested for separating the Oriental and Australian faunal region in the Indonesian region. The analyses have mainly used the present-day distribution of terrestrial vertebrates, especially the smallest ranges of species and subspecies. The results show that faunal migration of Oriental and Australian lineages to the Indonesian Archipelago may have been happening since the Palaeocene period and more importantly, island drifts might have facilitated such migration. These events caused major reorganisation of island positions and island forms, which in turn resulted in faunal extinction around the mid-Pliocene. Some islands, especially in the Wallacea region, emerged very late and as a result nowadays they are lacking endemic forms. There are currently at least seven endemic centres, which can be recognised, i.e. Borneo, Java, Sumatra, Sulawesi, North Moluccas, New Guinea and the Lesser Sundas/Banda Arcs. The affinities between these endemic centres revealed that there are two clusters of islands in the Indonesian Archipelago. These different clusters suggest in turn the shifts of biogeographical lines in the Indonesian Archipelago. Furthermore, oscillation in climate, eustatic sea level changes and fluctuations in vegetation in the Quaternary period had much affected the distribution pattern of animals. There was a phase of expansion for montane oak forests, grasslands and woodlands during the period 18,000-14,000 years ago in East Indonesia and 16,500-12,000 years ago in West Indonesia. Such an expansion led to the increased isolation of rainforests and of the faunas adapted to them. These periods are also indicated by the lowering of the tree line which facilitated montane fauna to disperse across lower elevations. At 8,000-9,000 years ago, the climate became warmer and slightly wetter. The mid- to upper montane forests expanded to their full altitudinal range, while montane oak forest, grassland, and woodland areas had contracted. The oscillation in climate, eustatic sea level changes and fluctuations in vegetation in turn determines much the formation of numerous sub endemic centres, which today can be found within the mainland. Recently, there are 14 sub endemic centres on Borneo, 8 on Java, 16 on Sumatra, 14 on Sulawesi and 14 on New Guinea. From the conservation management point of view, the identification of such sub endemic centres would generate valuable information for the protection effort.
The subject of this thesis is hypercyclic, mixing, and chaotic C0-semigroups on Banach spaces. After introducing the relevant notions and giving some examples the so called hypercyclicity criterion and its relation with weak mixing is treated. Some new equivalent formulations of the criterion are given which are used to derive a very short proof of the well-known fact that a C0-semigroup is weakly mixing if and only if each of its operators is. Moreover, it is proved that under some "regularity conditions" each hypercyclic C0-semigroup is weakly mixing. Furthermore, it is shown that for a hypercyclic C0-semigroup there is always a dense set of hypercyclic vectors having infinitely differentiable trajectories. Chaotic C0-semigroups are also considered. It is proved that they are always weakly mixing and that in certain cases chaoticity is already implied by the existence of a single periodic point. Moreover, it is shown that strongly elliptic differential operators on bounded C^1-domains never generate chaotic C0-semigroups. A thorough investigation of transitivity, weak mixing, and mixing of weighted compositioin operators follows and complete characterisations of these properties are derived. These results are then used to completely characterise hypercyclicity, weak mixing, and mixing of C0-semigroups generated by first order partial differential operators. Moreover, a characterisation of chaos for these C0-semigroups is attained. All these results are achieved on spaces of p-integrable functions as well as on spaces of continuous functions and illustrated by various concrete examples.
The influence of the dopamine agonist Ritalin-® on performance in a card sorting task involving a monetary reward component was tested in 43 healthy male participants. It was investigated whether Ritalin-® would have differential behavioral effects as a function of the participants' parental bonding experiences and the personality variable "Novelty Seeking". When activity and performance accuracy were stimulated my monetary reward, Ritalin-® reduced activity in response to reward and added to the reward-induced increase in performance accuracy. However, performance accuracy after drug challenge was improved only in the low care participants. In the high care participants, it was contrarily impaired. This observation suggests that the successful therapeutic administration of Ritalin-® in ADHD may be influenced by early life parental care. Suggesting an association between the personality dimension of "Novelty Seeking" and the dopamine system, high "Novelty Seeking" scores positively correlated with sensitivity to Ritalin-® challenge.
Fibromyalgia is a disorder of unknown etiology characterized by widespread, chronic musculoskeletal pain of at least three month duration and pressure hyperalgesia at specific tender points on clinical examination. The disorder is accompanied by a multitude of additional symptoms such as fatigue, sleep disturbances, morning stiffness, depression, and anxiety. In terms of biological disturbances, low cortisol concentrations have been repeatedly observed in blood and urine samples of fibromyalgia patients, both under basal and stress-induced conditions. The aim of this dissertation was to investigate the presence of low cortisol concentrations (hypocortisolism) and potential accompanying alterations on sympathetic and immunological levels in female fibromyalgia patients. Beside the expected hypocortisolism, a higher norepinephrine secretion and lower natural killer cell levels were found in the patient group compared to a control group consisting of healthy, age-matched women. In addition, an increased activity of some pro-inflammatory markers was observed thus leading to alterations in the balance of pro-/anti-inflammatory activity. The results underline the relevance of simultaneous investigations of interacting bodily systems for a better understanding of underlying biological mechanisms in stress-related disorders.
The fragmentation of landscapes has an important impact on the conservation of biodiversity. The genetic diversity is an important factor for a population- viability, influenced by the landscape structure. However, different species with differing ecological demands react rather differently on the same landscape pattern. To address this feature, we studied ten xerothermophilous butterfly species with differing habitat requirements (habitat specialists with low dispersal power in contrast to habitat generalists with low dispersal power and habitat generalists with higher dispersal power). We analysed allozyme loci for about 10 populations (Ã 40 individuals) of each species in a western German study region with adjoining areas in Luxemburg and north-eastern France. The genetic diversity and genetic differentiation between local populations was discussed under conservation genetic aspects. For generalists we detected a more or less panmictic structure and for species with lower abundance and sedentarily behaviour the effect of isolation by distance. On the other hand, the isolation of specialists was mostly reflected by strong genetic differentiation patterns between the investigated populations. Parameters of genetic diversity were mostly significantly higher in generalists, compared to specialists. Substructures within populations as an answer of low intrapatch migration, low population densities and high population fluctuations could be shown as well. Aspects of landscape history (the historical distribution of habitats resulting of the presence of limestone areas) and the changes of extensive sheep pasturing and the loss of potential habitats in the last few decades (recent fragmentation) are discussed against the gained genetic data-set of the ten butterflies.
It has been the overall aim of this research work to assess the potential of hyperspectral remote sensing data for the determination of forest attributes relevant to forest ecosystem simulation modeling and forest inventory purposes. A number of approaches for the determination of structural and chemical attributes from hyperspectral remote sensing have been applied to the collected data sets. Many of the methods to be found in the literature were up to now just applied to broadband multispectral data, applied to vegetation canopies other than forests, reported to work on the leaf level or with modelled data, not validated with ground truth data, or not systematically compared to other methods. Attributes that describe the properties of the forest canopy and that are potentially open to remote sensing were identified, appropriate methods for their retrieval were implemented and field, laboratory and image data (HyMap sensor) were acquired over a number of forest plots. The study on structural attributes compared statistical and physical approaches. In the statistical section, linear predictive models between vegetation indices derived from HyMap data and field measurements of structural forest stand attributes were systematically evaluated. The study demonstrates that for hyperspectral image data, linear regression models can be applied to quantify leaf area index and crown volume with good accuracy. For broadband multispectral data, the accuracy was generally lower. The physically-based approach used the invertible forest reflectance model (INFORM), a combination of well established sub-models FLIM, SAIL and LIBERTY. The model was inverted with HyMap data using a neural network approach. In comparison to the statistical approach, it could be shown that the reflectance model inversion works equally well. In opposition to empirically derived prediction functions that are generally limited to the local conditions at a certain point in time and to a specified sensor type, the calibrated reflectance model can be applied more easily to different optical remote sensing data acquired over central European forests. The study on chemical forest attributes evaluated the information content of HyMap data for the estimation of nitrogen, chlorophyll and water concentration. A number of needle samples of Norway spruce were analysed for their total chlorophyll, nitrogen and water concentrations. The chemical data was linked to needle spectra measured in the laboratory and canopy spectra measured by the HyMap sensor. Wavebands selected in statistical models were often located in spectral regions that are known to be important for chlorophyll detection (red edge, green peak). Predictive models were applied on the HyMap image to compute maps of chlorophyll concentration and nitrogen concentration. Results of map overlay operations revealed coherence between total chlorophyll and zones of stand development stage and between total chlorophyll and zones of soil type. Finally, it can be stated that the hyperspectral remote sensing data generally contains more information relevant to the estimation of the forest attributes compared to multispectral data. Structural forest attributes, except biomass, can be determined with good accuracy from a hyperspectral sensor type like HyMap. Among the chemical attributes, chlorophyll concentration can be determined with good accuracy and nitrogen concentration with moderate accuracy. For future research, additional dimensions have to be taken into account, for instance through exploitation of multi-view angle data. Additionally, existing forest canopy reflectance models should be further improved.
The allergic contact dermatitis (ACD) to small molecular weight compounds is a common inflammatory skin reaction. ACD is restricted to industrialized countries, has an enormous sociomedical and socioeconomic impact. About 2,800 compounds from the six million chemicals known in our environment are believed to have allergic, and to a lesser degree also contact-sensitizing or immunogenic properties causing allergic contact dermatitis. ACD results from T cell responses to harmless, low molecular weight chemicals (haptens) applied to the skin. Haptens are not directly recognized by the cells of the immune system. They need to be presented by subsets of antigen presenting cells to the cells of the immune system. In this regard, epidermal Langerhans cells (LC) and the cells into which they mature (dendritic cells) are believed to play a pivotal role in the sensitization process for ACD. LC are able to bind the haptens, internalize them, and present them to naive T cells and induce thereby the development of effector T cells. They are so-called professional antigen presenting cells. This process is initiated and maintained by the release of several mediators, which are released by various cells after their contact with the haptens. One of the first proteins secreted into the environment is interleukin (IL)-1ß. This cytokine is produced and secreted minutes after an antigen enters the cell. It is commonly believed that the large amounts of this protein and other cytokines such as granulocyte-colony stimulation factor (GM-CSF) and tumor necrosis factor alpha (TNF-ï¡) needed for the initiation and activation of ACD are coming first from other cells residing in the skin, e.g., keratinocytes, monocytes and macrophages. These cytokines provide the danger signals needed for the activation of the Langerhans cell (LC), which then produce via a positive feedback loop various cytokines themselves. In addition, other proteins such as chemokines influence the generation of danger signals, migration, homing of T cells in the local lymph nodes as well as the recruitment of T cells into the skin. Thus, a small molecular compounds or hapten needs to be able to induce danger signals in order to become immunogenic. In this study, we investigated whether para-phenylenediamine (PPD), an arylamine and common contact allergen, is able to induce danger signals and likely provide the signals needed for an initiation of an immune response[162, 163]. PPD is used as an antioxidant, an ingredient of hair dyes, intermediate of dyestuff, and PPD is found in chemicals used for photographic processing. But up to date, it has not been clearly demonstrated if PPD itself is a sensitizing agent. Thus, this study aimed on the potential of PPD to provide the danger signals by studying IL-1β, TNF-ï¡, and monocyte chemoattractant proteins (MCP-1) in human monocytes, peripheral blood mononuclear cells (PBMC) from healthy volunteers, and also in two human monocyte cell lines namely U937, and THP-1. This study found that PPD decreased dose- and time-dependently the expression and release of three relevant mediators involved in the generation of danger signals. Namely, PPD reduced the mRNA and protein levels for IL-1ß, TNF-ï¡, and MCP-1 in primary human monocytes from various donors. These findings were extended and validated by investigations using the cell line U937. The data were highly specific for PPD, and no such results were gained for its known auto oxidation product called Bandrowski- base or for meta-phenylenediamine (MPD), and ortho-phenylenediamine (OPD). Therefore, we can speculate that this effect is likely to be dependent on the para-substitution. Based on these results we conclude that PPD itself is not able to mount a cascade for the induction of danger signals. It should be mentioned that it is still possible that PPD induces danger signals for sensitization by other unknown processes. Therefore, more research is still needed focusing on this subject especially in professional antigen presenting cells in order to solve the still open question whether PPD itself sensitizes naive T cells or if PPD is solely an allergen. Independently we found unexpectedly that PPD as well as other haptens such as 2, 4-Dinitrochlorobenzene, nickelsulfate, as well as some terpenoide increased clearly the expression of CC chemokin receptor 2 (CCR2), the receptor for the chemokine MCP-1. Up to date, the main importance for the CCR2 receptor comes from results demonstrating that CCR2 is critical for the migration of monocytes after encounter with bacterial lipopolysaccharides. Under these circumstances the receptor disappears from the cell surface and is down regulated. An up regulation of CCR2 has not been reported for haptens, and deserves further investigations.
The midcingulate cortex has become the focus of scientific interest as it has been associated with a wide range of attentional phenomena. This survey found evidence indicating the relevance of gender and handedness for measures of regional cortical morphology. Although gender was associated with structural variations concerning the neuroanatomy of the midcingulum bundle as well, handedness did not emerge in the analyses of white matter characteristics as significant factor. Hemispheric differences were found at the level of both gray and white matter. Turning to the functional implications of neuroanatomical variations and comparing subjects with a pronounced and a low degree of midcingulate folding, which indicates differential expansions of cytoarchitectural areas, behavioral and electrophysiological differences in the processing of interference became evident. A high degree of leftward midcingulate fissurization was associated with better behavioral performance, presumably caused by a more effective conflict-monitoring system triggering fast and automatic attentional filtering mechanisms. Subjects exhibiting a lower degree of midcingulate fissurization rather seem to rely on more effortful control processes. These results carry implications not only concerning neuronal representations of individual differences in attentional processes, but might also be of relevance for the refinement of models for mental disorders.