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Stress related disorders increase continuously. It is not yet clear if stress also promotes breast cancer. This dissertation provides an analyses of the current state of research and focuses on the significance of pre-/postnatal stress factors and chronic stress. The derived hypotheses are empirically examined on breast cancer patients. The clinical study investigates the links between those factors and prognosis and outcome.
Contents: I. History of the Korean Civil Code II. Background for Initiation of the Amendment of the Civil Code (Property Law) and their Progress III. Fundamental Direction of the Amendment of the Civil Code (Property Law) IV. Major Foreign Statutes Used as Reference for the Amendment of the Civil Code (Property Law) V. Major Details of the Amendment of the Civil Code (Property Law) VI. Concluding Remarks: Evaluation
1.The Discursive Construction of Black Masculinity: Intersections of Race, Gender, and Sexuality
1.1.The Plight of Black Men: A History of Lynchings and Castrations
1.2.The Discursive Construction of the Black Man as Otherrn
1.3.Black Corporeality and the Scopic Regime of Racism
2. Ralph Ellison's 'Invisible man'
2.1.Invisible Black Men: Between Emasculation and Hypermasculinityrn
2.2.Transcending Invisibility
One of the main tasks in mathematics is to answer the question whether an equation possesses a solution or not. In the 1940- Thom and Glaeser studied a new type of equations that are given by the composition of functions. They raised the following question: For which functions Ψ does the equation F(Ψ)=f always have a solution. Of course this question only makes sense if the right hand side f satisfies some a priori conditions like being contained in the closure of the space of all compositions with Ψ and is easy to answer if F and f are continuous functions. Considering further restrictions to these functions, especially to F, extremely complicates the search for an adequate solution. For smooth functions one can already find deep results by Bierstone and Milman which answer the question in the case of a real-analytic function Ψ. This work contains further results for a different class of functions, namely those Ψ that are smooth and injective. In the case of a function Ψ of a single real variable, the question can be fully answered and we give three conditions that are both sufficient and necessary in order for the composition equation to always have a solution. Furthermore one can unify these three conditions to show that they are equivalent to the fact that Ψ has a locally Hölder-continuous inverse. For injective functions Ψ of several real variables we give necessary conditions for the composition equation to be solvable. For instance Ψ should satisfy some form of local distance estimate for the partial derivatives. Under the additional assumption of the Whitney-regularity of the image of Ψ, we can give sufficient conditions for flat functions f on the critical set of Ψ to possess a solution F(Ψ)=f.
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.
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.
This thesis centers on formal tree languages and on their learnability by algorithmic methods in abstractions of several learning settings. After a general introduction, we present a survey of relevant definitions for the formal tree concept as well as special cases (strings) and refinements (multi-dimensional trees) thereof. In Chapter 3 we discuss the theoretical foundations of algorithmic learning in a specific type of setting of particular interest in the area of Grammatical Inference where the task consists in deriving a correct formal description for an unknown target language from various information sources (queries and/or finite samples) in a polynomial number of steps. We develop a parameterized meta-algorithm that incorporates several prominent learning algorithms from the literature in order to highlight the basic routines which regardless of the nature of the information sources have to be run through by all those algorithms alike. In this framework, the intended target descriptions are deterministic finite-state tree automata. We discuss the limited transferability of this approach to another class of descriptions, residual finite-state tree automata, for which we propose several learning algorithms as well. The learnable class by these techniques corresponds to the class of regular tree languages. In Chapter 4we outline a recent range of attempts in Grammatical Inference to extend the learnable language classes beyond regularity and even beyond context-freeness by techniques based on syntactic observations which can be subsumed under the term 'distributional learning', and we describe learning algorithms in several settings for the tree case taking this approach. We conclude with some general reflections on the notion of learning from structural information.
Social entrepreneurship is a successful activity to solve social problems and economic
challenges. Social entrepreneurship uses for-profit industry techniques and tools to build
financially sound businesses that provide nonprofit services. Social entrepreneurial activities
also lead to the achievement of sustainable development goals. However, due to the complex,
hybrid nature of the business, social entrepreneurial activities are typically supported by macrolevel
determinants. To expand our knowledge of how beneficial macro-level determinants can
be, this work examines empirical evidence about the impact of macro-level determinants on
social entrepreneurship. Another aim of this dissertation is to examine the impact at the micro
level, as the growth ambitions of social and commercial entrepreneurs differ. At the beginning,
the introductory section is explained in Chapter 1, which contains the motivation for the
research, the research question, and the structure of the work.
There is an ongoing debate about the origin and definition of social entrepreneurship.
Therefore, the numerous phenomena of social entrepreneurship are examined theoretically in
the previous literature. To determine the common consensus on the topic, Chapter 2 presents
the theoretical foundations and definition of social entrepreneurship. The literature shows that
a variety of determinants at the micro and macro levels are essential for the emergence of social
entrepreneurship as a distinctive business model (Hartog & Hoogendoorn, 2011; Stephan et
al., 2015; Hoogendoorn, 2016). It is impossible to create a society based on a social mission without the support of micro and macro-level-level determinants. This work examines the
determinants and consequences of social entrepreneurship from different methodological
perspectives. The theoretical foundations of the micro- and macro-level determinants
influencing social entrepreneurial activities were discussed in Chapter 3
The purpose of reproducibility in research is to confirm previously published results
(Hubbard et al., 1998; Aguinis & Solarino, 2019). However, due to the lack of data, lack of
transparency of methodology, reluctance to publish, and lack of interest from researchers, there
is a lack of promoting replication of the existing research study (Baker, 2016; Hedges &
Schauer, 2019a). Promoting replication studies has been regularly emphasized in the business
and management literature (Kerr et al., 2016; Camerer et al., 2016). However, studies that
provide replicability of the reported results are considered rare in previous research (Burman
et al., 2010; Ryan & Tipu, 2022). Based on the research of Köhler and Cortina (2019), an
empirical study on this topic is carried out in Chapter 4 of this work.
Given this focus, researchers have published a large body of research on the impact of microand
macro-level determinants on social inclusion, although it is still unclear whether these
studies accurately reflect reality. It is important to provide conceptual underpinnings to the
field through a reassessment of published results (Bettis et al., 2016). The results of their
research make it abundantly clear that the macro determinants support social entrepreneurship.
In keeping with the more narrative approach, which is a crucial concern and requires attention,
Chapter 5 considered the reproducibility of previous results, particularly on the topic of social
entrepreneurship. We replicated the results of Stephan et al. (2015) to establish the trend of
reproducibility and validate the specific conclusions they drew. The literal and constructive
replication in the dissertation inspired us to explore technical replication research on social
entrepreneurship. Chapter 6 evaluates the fundamental characteristics that have proven to be key factors in the
growth of social ventures. The current debate reviews and references literature that has
specifically focused on the development of social entrepreneurship. An empirical analysis of
factors directly related to the ambitious growth of social entrepreneurship is also carried out.
Numerous social entrepreneurial groups have been studied concerning this association. Chapter
6 compares the growth ambitions of social and traditional (commercial) entrepreneurship as
consequences at the micro level. This study examined many characteristics of social and
commercial entrepreneurs' growth ambitions. Scholars have claimed to some extent that the
growth of social entrepreneurship differs from commercial entrepreneurial activities due to
objectivity differences (Lumpkin et al., 2013; Garrido-Skurkowicz et al., 2022). Qualitative
research has been used in studies to support the evidence on related topics, including Gupta et
al (2020) emphasized that research needs to focus on specific concepts of social
entrepreneurship for the field to advance. Therefore, this study provides a quantitative,
analysis-based assessment of facts and data. For this purpose, a data set from the Global
Entrepreneurship Monitor (GEM) 2015 was used, which examined 12,695 entrepreneurs from
38 countries. Furthermore, this work conducted a regression analysis to evaluate the influence
of various social and commercial characteristics of entrepreneurship on economic growth in
developing countries. Chapter 7 briefly explains future directions and practical/theoretical
implications.
Evaluation of desalination techniques for treating the brackish water of Olushandja sub-basin
(2014)
The groundwater of Olushandja sub-basin as part of Cuvelai basin in central-northern Namibia is saline with TDS content varying between 4,000ppm to 90,000ppm. Based on climatic conditions, this region can be classified as a semi-arid to arid region with an annual rainfall during summer time varying between 200mm to 500mm. The mean annual evaporation potential is about 2,800mm, which is much higher than the annual rainfall. The southern block of this sub-basin is of low population density. It has not been covered by the supply networks for electricity and water. Therefore, the inhabitants are forced to use the untreated groundwater from the hand-dug wells for their daily purposes. This groundwater is not safe for human consumption and therefore needs to be desalinated for that purpose. The goal of this thesis has been to select a suitable desalination technology for that region. The technology to be selected is from those which use renewable energy sources, which have capacity of production from 10m3 to 100m3 per day, which are simple and robust against existing harsh environmental conditions and have already been implemented successfully in some place. Based on these criteria, the technologies which emerged from the literature are: multistage flashing (MSF), multi effect distillation (MED), multi effect humidification (MEH), membrane distillation (MD), reverse osmosis (RO) and electro dialysis reversed (ED). Out of these technologies, RO & ED are based on membrane techniques and MSF, MED & MEH use thermal processes whereas MD technology uses a hybrid process of thermal and membrane techniques for desalinating the water. For evaluation of technical performance, environmental sustainability and financial feasibility of the above mentioned desalination techniques, the following criteria have been used: gained output ratio, recovery rate, pretreatment requirements, sensitivity to feed water quality, post treatment, operating temperature, operating pressure, scaling and fouling potential, corrosion susceptibility, brine disposal, prime energy requirement, mechanical and electrical power output, heat energy, running costs and water generation costs. The data regarding the performance standards of the successfully implemented desalination techniques have been obtained from the literature of performance benchmarks. The Utility Value Analysis Tool of the Rafter-Group of Multi-Criteria Analysis (MCA) has been used for measuring the performance score of a technology. To perform the utility analysis, an evaluation matrix has to be constructed through the following procedures: selection of the decision options (or assessment groups), identification of the evaluation criteria, measurement of performance and transformation of the units. Then the criteria under the objective groups are assigned a level of importance for determining their weights.To perform the sensitivity analysis the level of importance of a criterion is changed by giving more weight or rate to the assessment group of interest (or study). Within the assessment group of interests, the best performing desalination technology has been selected according to the outcome of the sensitivity analysis. The important conclusions of this study are the identification of the capabilities of thermal and membrane based small scale desalination technologies and their applicability based on site specific needs. The sensitivity analysis indicates that the MED technology is the most environmental friendly technology that uses minimum energy and produces least concentrated brine for disposal. The ED technology has emerged to be technically suitable, but it is only applicable when source water has less than 12.000 ppm salt content. The MSF process has favorable thermal efficiency and it is insensitive to feed water quality. Its major drawbacks are energy needs and post treatment requirements that affected its net score. The MD and MSF process have scored the lowest for the technical and economic assessment groups and are concluded not to be suitable for Olushandja sub-basin. The MEH process is cheaper and technically more appropriate than the MED in the two assessment groups. Based on the above mentioned evaluations, this study concluded that Olushandja sub-basin needs more data collection on the geological profile, distinctive identification of aquifers and evidence on the interaction between the aquifers. From the best available data obtained, it could not be established with certainty where the highest level of salinity can be found in the profile, or how the geological profile is layered. More data on ground water quality for spatial overview of the trends and pattern of the sub-basin will be useful in drawing better conclusion on the specific desalination technology needed which is suitable for a specified village or living space.
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 main topic of this treatise is the solution of two problems from the general theory of linear partial differential equations with constant coefficients. While surjectivity criteria for linear partial differential operators in spaces of smooth functions over an open subset of euclidean space and distributions were proved by B. Malgrange and L. Hörmander in 1955, respectively 1962, concrete evaluation of these criteria is still a highly non-trivial task. In particular, it is well-known that surjectivity in the space of smooth functions over an open subset of euclidean space does not automatically imply surjectivity in the space of distributions. Though, examples for this fact all live in three or higher dimensions. In 1966, F. Trèves conjectured that in the two dimensional setting surjectivity of a linear partial differential operator on the smooth functions indeed implies surjectivity on the space of distributions. An affirmative solution to this problem is presented in this treatise. The second main result solves the so-called problem of (distributional) parameter dependence for solutions of linear partial differential equations with constant coefficients posed by J. Bonet and P. Domanski in 2006. It is shown that, in dimensions three or higher, this problem in general has a negative solution even for hypoelliptic operators. Moreover, it is proved that the two dimensional case is again an exception, because in this setting the problem of parameter dependence always has a positive solution.
As an interface between an individual and its environment, the skin is a major site of direct exposure to exogenous substances. Once absorbed, these substances may interact with different biomolecules within the skin. The aryl hydrocarbon receptor (AhR) signaling pathway is one mechanism whereby the skin responds to exposures, predominantly through the induction or upregulation of metabolizing enzymes. One known physiological role of the AhR in many tissues is its involvement in the control of cell cycle progression. In skin, almost nothing is known about this physiological function. Moreover, the question whether frequently used naturally occurring phenolic derivatives like eugenol and isoeugenol impact on the AhR within the skin has rarely been studied so far. Eugenol and isoeugenol are due to their odour referred to as fragrances. The ubiquitous distribution of eugenol and isoeugenol results in an almost unavoidable contact with these substances in our daily lives. Despite this fact, their molecular mechanisms of action in skin are poorly understood. There is evidence supporting the hypothesis that these substances may impact on the AhR. On the one hand, eugenol is shown to induce cytochrome P450 1A1 (CYP1A1), a well-known target gene of the AhR. On the other hand, their known anti-proliferative properties might also be mediated by the AhR, based on its physiological function. In order to proof this hypothesis, it was investigated whether eugenol and isoeugenol impact on the AhR signaling pathway in skin cells. Results revealed that eugenol as well as isoeugenol impact on the AhR signaling pathway in skin cells. Both substances caused the translocation of the AhR into the nucleus, induced the expression of the well-known AhR target genes CYP1A1 and AhR repressor (AhRR) and exhibited impact on cell cycle progression. Both substances caused an AhR-dependent cell cycle arrest in skin cells, modulated protein levels of several cell cycle regulatory proteins, inhibited DNA synthesis and thereby reduced cell numbers. The comparison of wildtype cells to AhR knockdown cells revealed an influence of the AhR on cell cycle progression in skin cells in the absence of exogenous ligands. AhR knockdown cells exhibited a slower progression through the cell cycle caused by an accumulation of cells in the G0/G1 phase of the cell cycle and a decreased DNA synthesis rate. Modulation of cell cycle regulatory proteins involved in the transition from the G0/G1 to the S phase of the cell cycle was altered in AhR knockdown cells as well. To conclude, eugenol as well as isoeugenol were able to impact on the AhR signaling pathway in skin cells. Their molecular mechanisms of action are similar to those of classical AhR ligands, although their structural characteristics strongly differ from that of these ligands. In the absence of exogenous ligands the AhR promotes cell cycle progression in many tissues and this knowledge could be expanded on skin-derived cells within the scope of this thesis.
In this thesis, we mainly investigate geometric properties of optimal codebooks for random elements $X$ in a seperable Banach space $E$. Here, for a natural number $ N $ and a random element $X$ , an $N$-optimal codebook is an $ N $-subset in the underlying Banach space $E$ which gives a best approximation to $ X $ in an average sense. We focus on two types of geometric properties: The global growth behaviour (growing in $N$) for a sequence of $N$-optimal codebooks is described by the maximal (quantization) radius and a so-called quantization ball. For many distributions, such as central-symmetric distributions on $R^d$ as well as Gaussian distributions on general Banach spaces, we are able to estimate the asymptotics of the quantization radius as well as the quantization ball. Furthermore, we investigate local properties of optimal codebooks, in particular the local quantization error and the weights of the Voronoi cells induced by an optimal codebook. In the finite-dimensional setting, we are able to proof for many interesting distributions classical conjectures on the asymptotic behaviour of those properties. Finally, we propose a method to construct sequences of asymptotically optimal codebooks for random elements in infinite dimensional Banach spaces and apply this method to construct codebooks for stochastic processes, such as fractional Brownian Motions.
In recent years, the study of dynamical systems has developed into a central research area in mathematics. Actually, in combination with keywords such as "chaos" or "butterfly effect", parts of this theory have been incorporated in other scientific fields, e.g. in physics, biology, meteorology and economics. In general, a discrete dynamical system is given by a set X and a self-map f of X. The set X can be interpreted as the state space of the system and the function f describes the temporal development of the system. If the system is in state x ∈ X at time zero, its state at time n ∈ N is denoted by f^n(x), where f^n stands for the n-th iterate of the map f. Typically, one is interested in the long-time behaviour of the dynamical system, i.e. in the behaviour of the sequence (f^n(x)) for an arbitrary initial state x ∈ X as the time n increases. On the one hand, it is possible that there exist certain states x ∈ X such that the system behaves stably, which means that f^n(x) approaches a state of equilibrium for n→∞. On the other hand, it might be the case that the system runs unstably for some initial states x ∈ X so that the sequence (f^n(x)) somehow shows chaotic behaviour. In case of a non-linear entire function f, the complex plane always decomposes into two disjoint parts, the Fatou set F_f of f and the Julia set J_f of f. These two sets are defined in such a way that the sequence of iterates (f^n) behaves quite "wildly" or "chaotically" on J_f whereas, on the other hand, the behaviour of (f^n) on F_f is rather "nice" and well-understood. However, this nice behaviour of the iterates on the Fatou set can "change dramatically" if we compose the iterates from the left with just one other suitable holomorphic function, i.e. if we consider sequences of the form (g∘f^n) on D, where D is an open subset of F_f with f(D)⊂ D and g is holomorphic on D. The general aim of this work is to study the long-time behaviour of such modified sequences. In particular, we will prove the existence of holomorphic functions g on D having the property that the behaviour of the sequence of compositions (g∘f^n) on the set D becomes quite similarly chaotic as the behaviour of the sequence (f^n) on the Julia set of f. With this approach, we immerse ourselves into the theory of universal families and hypercyclic operators, which itself has developed into an own branch of research. In general, for topological spaces X, Y and a family {T_i: i ∈ I} of continuous functions T_i:X→Y, an element x ∈ X is called universal for the family {T_i: i ∈ I} if the set {T_i(x): i ∈ I} is dense in Y. In case that X is a topological vector space and T is a continuous linear operator on X, a vector x ∈ X is called hypercyclic for T if it is universal for the family {T^n: n ∈ N}. Thus, roughly speaking, universality and hypercyclicity can be described via the following two aspects: There exists a single object which allows us, via simple analytical operations, to approximate every element of a whole class of objects. In the above situation, i.e. for a non-linear entire function f and an open subset D of F_f with f(D)⊂ D, we endow the space H(D) of holomorphic functions on D with the topology of locally uniform convergence and we consider the map C_f:H(D)→H(D), C_f(g):=g∘f|_D, which is called the composition operator with symbol f. The transform C_f is a continuous linear operator on the Fréchet space H(D). In order to show that the above-mentioned "nice" behaviour of the sequence of iterates (f^n) on the set D ⊂ F_f can "change dramatically" if we compose the iterates from the left with another suitable holomorphic function, our aim consists in finding functions g ∈ H(D) which are hypercyclic for C_f. Indeed, for each hypercyclic function g for C_f, the set of compositions {g∘f^n|_D: n ∈ N} is dense in H(D) so that the sequence of compositions (g∘f^n|_D) is kind of "maximally divergent" " meaning that each function in H(D) can be approximated locally uniformly on D via subsequences of (g∘f^n|_D). This kind of behaviour stands in sharp contrast to the fact that the sequence of iterates (f^n) itself converges, behaves like a rotation or shows some "wandering behaviour" on each component of F_f. To put it in a nutshell, this work combines the theory of non-linear complex dynamics in the complex plane with the theory of dynamics of continuous linear operators on spaces of holomorphic functions. As far as the author knows, this approach has not been investigated before.
The German Mittelstand is closely linked to the success of the German economy. Mittelstand firms, thereof numerous Hidden Champions, significantly contribute to Germany’s economic performance, innovation, and export strength. However, the advancing digitalization poses complex challenges for Mittelstand firms. To benefit from the manifold opportunities offered by digital technologies and to defend or even expand existing market positions, Mittelstand firms must transform themselves and their business models. This dissertation uses quantitative methods and contributes to a deeper understanding of the distinct needs and influencing factors of the digital transformation of Mittelstand firms. The results of the empirical analyses of a unique database of 525 mid-sized German manufacturing firms, comprising both firm-related information and survey data, show that organizational capabilities and characteristics significantly influence the digital transformation of Mittelstand firms. The results support the assumption that dynamic capabilities promote the digital transformation of such firms and underline the important role of ownership structure, especially regarding family influence, for the digital transformation of the business model and the pursuit of growth goals with digitalization. In addition to the digital transformation of German Mittelstand firms, this dissertation examines the economic success and regional impact of Hidden Champions and hence, contributes to a better understanding of the Hidden Champion phenomenon. Using quantitative methods, it can be empirically proven that Hidden Champions outperform other mid-sized firms in financial terms and promote regional development. Consequently, the results of this dissertation provide valuable research contributions and offer various practical implications for firm managers and owners as well as policy makers.
Given a compact set K in R^d, the theory of extension operators examines the question, under which conditions on K, the linear and continuous restriction operators r_n:E^n(R^d)→E^n(K),f↦(∂^α f|_K)_{|α|≤n}, n in N_0 and r:E(R^d)→E(K),f↦(∂^α f|_K)_{α in N_0^d}, have a linear and continuous right inverse. This inverse is called extension operator and this problem is known as Whitney's extension problem, named after Hassler Whitney. In this context, E^n(K) respectively E(K) denote spaces of Whitney jets of order n respectively of infinite order. With E^n(R^d) and E(R^d), we denote the spaces of n-times respectively infinitely often continuously partially differentiable functions on R^d. Whitney already solved the question for finite order completely. He showed that it is always possible to construct a linear and continuous right inverse E_n for r_n. This work is concerned with the question of how the existence of a linear and continuous right inverse of r, fulfilling certain continuity estimates, can be characterized by properties of K. On E(K), we introduce a full real scale of generalized Whitney seminorms (|·|_{s,K})_{s≥0}, where |·|_{s,K} coincides with the classical Whitney seminorms for s in N_0. We equip also E(R^d) with a family (|·|_{s,L})_{s≥0} of those seminorms, where L shall be a a compact set with K in L-°. This family of seminorms on E(R^d) suffices to characterize the continuity properties of an extension operator E, since we can without loss of generality assume that E(E(K)) in D^s(L).
In Chapter 2, we introduce basic concepts and summarize the classical results of Whitney and Stein.
In Chapter 3, we modify the classical construction of Whitney's operators E_n and show that |E_n(·)|_{s,L}≤C|·|_{s,K} for s in[n,n+1).
In Chapter 4, we generalize a result of Frerick, Jordá and Wengenroth and show that LMI(1) for K implies the existence of an extension operator E without loss of derivatives, i.e. we have it fulfils |E(·)|_{s,L}≤C|·|_{s,K} for all s≥0. We show that a large class of self similar sets, which includes the Cantor set and the Sierpinski triangle, admits an extensions operator without loss of derivatives.
In Chapter 5 we generalize a result of Frerick, Jordá and Wengenroth and show that WLMI(r) for r≥1 implies the existence of a tame linear extension operator E having a homogeneous loss of derivatives, such that |E(·)|_{s,L}≤C|·|_{(r+ε)s,K} for all s≥0 and all ε>0.
In the last chapter we characterize the existence of an extension operator having an arbitrary loss of derivatives by the existence of measures on K.
Variational inequality problems constitute a common basis to investigate the theory and algorithms for many problems in mathematical physics, in economy as well as in natural and technical sciences. They appear in a variety of mathematical applications like convex programming, game theory and economic equilibrium problems, but also in fluid mechanics, physics of solid bodies and others. Many variational inequalities arising from applications are ill-posed. This means, for example, that the solution is not unique, or that small deviations in the data can cause large deviations in the solution. In such a situation, standard solution methods converge very slowly or even fail. In this case, so-called regularization methods are the methods of choice. They have the advantage that an ill-posed original problem is replaced by a sequence of well-posed auxiliary problems, which have better properties (like, e.g., a unique solution and a better conditionality). Moreover, a suitable choice of the regularization term can lead to unconstrained auxiliary problems that are even equivalent to optimization problems. The development and improvement of such methods are a focus of current research, in which we take part with this thesis. We suggest and investigate a logarithmic-quadratic proximal auxiliary problem (LQPAP) method that combines the advantages of the well-known proximal-point algorithm and the so-called auxiliary problem principle. Its exploration and convergence analysis is one of the main results in this work. The LQPAP method continues the recent developments of regularization methods. It includes different techniques presented in literature to improve the numerical stability: The logarithmic-quadratic distance function constitutes an interior point effect which allows to treat the auxiliary problems as unconstrained ones. Furthermore, outer operator approximations are considered. This simplifies the numerical solution of variational inequalities with multi-valued operators since, for example, bundle-techniques can be applied. With respect to the numerical practicability, inexact solutions of the auxiliary problems are allowed using a summable-error criterion that is easy to implement. As a further advantage of the logarithmic-quadratic distance we verify that it is self-concordant (in the sense of Nesterov/Nemirovskii). This motivates to apply the Newton method for the solution of the auxiliary problems. In the numerical part of the thesis the LQPAP method is applied to linearly constrained, differentiable and nondifferentiable convex optimization problems, as well as to nonsymmetric variational inequalities with co-coercive operators. It can often be observed that the sequence of iterates reaches the boundary of the feasible set before being close to an optimal solution. Against this background, we present the strategy of under-relaxation, which robustifies the LQPAP method. Furthermore, we compare the results with an appropriate method based on Bregman distances (BrPAP method). For differentiable, convex optimization problems we describe the implementation of the Newton method to solve the auxiliary problems and carry out different numerical experiments. For example, an adaptive choice of the initial regularization parameter and a combination of an Armijo and a self-concordance step size are evaluated. Test examples for nonsymmetric variational inequalities are hardly available in literature. Therefore, we present a geometric and an analytic approach to generate test examples with known solution(s). To solve the auxiliary problems in the case of nondifferentiable, convex optimization problems we apply the well-known bundle technique. The implementation is described in detail and the involved functions and sequences of parameters are discussed. As far as possible, our analysis is substantiated by new theoretical results. Furthermore, it is explained in detail how the bundle auxiliary problems are solved with a primal-dual interior point method. Such investigations have by now only been published for Bregman distances. The LQPAP bundle method is again applied to several test examples from literature. Thus, this thesis builds a bridge between theoretical and numerical investigations of solution methods for variational inequalities.
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.
The development of our society contributed to increased occurrence of emerging substances (pesticides, pharmaceuticals, personal care products, etc.) in wastewater. Because of their potential hazard on ecosystems and humans, Wastewater Treatment Plants (WWTPs) need to adapt to better remove these compounds. Technology or policy development should however comply with sustainable development, e.g. based on Life Cycle Assessment (LCA) metrics. Nevertheless, the reliability or consistency of LCA results can sometimes be debatable. The main objective of this work was to explore how LCA can better support the implementation of innovative wastewater treatment options, in particular including removal benefits. The method was applied to support solutions for pharmaceuticals elimination from wastewater, regarding: (i) UV technology design, (ii) choice of advanced technology and (iii) centralized or decentralized treatment policy. The assessment approach followed by previous authors based on net impacts calculation seemed very promising to consider both environmental effects induced by treatment plant operation and environmental benefits obtained from pollutants removal. It was therefore applied to compare UV configuration types. LCA outcomes were consistent with degradation kinetics analysis. For the comparison of advanced technologies and policy scenarios, the common practice (net impacts based on EDIP method) was compared to other assessments, to better consider elimination benefits. First, USEtox consensus was applied for the avoided (eco)toxicity impacts, in combination with the recent method ReCiPe for generated impacts. Then, an eco-efficiency indicator (EFI) was developed to weigh the treatment efforts (generated impacts based on EDIP and ReCiPe methods) by the average removal efficiency (overcoming (eco)toxicity uncertainty issues). In total, the four types of comparative assessment showed the same trends: (i) ozonation and activated carbon perform better than UV irradiation, and (ii) no clear advantage distinguished between policy scenarios. It cannot be however concluded that advanced treatment of pharmaceuticals is not necessary because other criteria should be considered (risk assessment, bacterial resistance, etc.) and large uncertainties were embedded in calculations. Indeed, a significant part of this work was dedicated to the discussion of uncertainty and limitations of the LCA outcomes. At the inventory level, it was difficult to model technology operation at development stage. For impact assessment, the newly developed characterization factors for pharmaceuticals (eco)toxicity showed large uncertainties, mainly due to the lack of data and quality for toxicity tests. The use of information made available under REACH framework to develop CFs for detergent ingredients tried to cope with this issue but the benefits were limited due to the mismatch of information between REACH and USEtox method. The highlighted uncertainties were treated with sensitivity analyses to understand their effects on LCA results. This research work finally presents perspectives on the use of transparently generated data (technology inventory and (eco)toxicity factors) and further development of EFI indicator. Also, an accent is made on increasing the reliability of LCA outcomes, in particular through the implementation of advanced techniques for uncertainty management. To conclude, innovative technology/product development (e.g. based on circular economy approach) needs the involvement of all types of actors and the support from sustainability metrics.