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THE NONLOCAL NEUMANN PROBLEM
(2023)
Instead of presuming only local interaction, we assume nonlocal interactions. By doing so, mass
at a point in space does not only interact with an arbitrarily small neighborhood surrounding it,
but it can also interact with mass somewhere far, far away. Thus, mass jumping from one point to
another is also a possibility we can consider in our models. So, if we consider a region in space, this
region interacts in a local model at most with its closure. While in a nonlocal model this region may
interact with the whole space. Therefore, in the formulation of nonlocal boundary value problems
the enforcement of boundary conditions on the topological boundary may not suffice. Furthermore,
choosing the complement as nonlocal boundary may work for Dirichlet boundary conditions, but
in the case of Neumann boundary conditions this may lead to an overfitted model.
In this thesis, we introduce a nonlocal boundary and study the well-posedness of a nonlocal Neu-
mann problem. We present sufficient assumptions which guarantee the existence of a weak solution.
As in a local model our weak formulation is derived from an integration by parts formula. However,
we also study a different weak formulation where the nonlocal boundary conditions are incorporated
into the nonlocal diffusion-convection operator.
After studying the well-posedness of our nonlocal Neumann problem, we consider some applications
of this problem. For example, we take a look at a system of coupled Neumann problems and analyze
the difference between a local coupled Neumann problems and a nonlocal one. Furthermore, we let
our Neumann problem be the state equation of an optimal control problem which we then study. We
also add a time component to our Neumann problem and analyze this nonlocal parabolic evolution
equation.
As mentioned before, in a local model mass at a point in space only interacts with an arbitrarily
small neighborhood surrounding it. We analyze what happens if we consider a family of nonlocal
models where the interaction shrinks so that, in limit, mass at a point in space only interacts with
an arbitrarily small neighborhood surrounding it.
This study investigated correlative, factorial, and structural relationships between scores for ability emotional intelligence in the workplace (measured with the Geneva Emotional Competence Test), as well as fluid and crystallized abilities (measured with the Intelligence Structure Battery), carried out by a 188-participant student sample. Confirming existing research, recognition, understanding, and management of emotions were related primarily to crystallized ability tests measuring general knowledge, verbal fluency, and knowledge of word meaning. Meanwhile, emotion regulation was the least correlated with any other cognitive or emotional ability. In line with research on the trainability of emotional intelligence, these results may support the notion that emotional abilities are subject to acquired knowledge, where situational (i.e., workplace-specific) emotional intelligence may depend on accumulating relevant experiences.
Optimal control problems are optimization problems governed by ordinary or partial differential equations (PDEs). A general formulation is given byrn \min_{(y,u)} J(y,u) with subject to e(y,u)=0, assuming that e_y^{-1} exists and consists of the three main elements: 1. The cost functional J that models the purpose of the control on the system. 2. The definition of a control function u that represents the influence of the environment of the systems. 3. The set of differential equations e(y,u) modeling the controlled system, represented by the state function y:=y(u) which depends on u. These kind of problems are well investigated and arise in many fields of application, for example robot control, control of biological processes, test drive simulation and shape and topology optimization. In this thesis, an academic model problem of the form \min_{(y,u)} J(y,u):=\min_{(y,u)}\frac{1}{2}\|y-y_d\|^2_{L^2(\Omega)}+\frac{\alpha}{2}\|u\|^2_{L^2(\Omega)} subject to -\div(A\grad y)+cy=f+u in \Omega, y=0 on \partial\Omega and u\in U_{ad} is considered. The objective is tracking type with a given target function y_d and a regularization term with parameter \alpha. The control function u takes effect on the whole domain \Omega. The underlying partial differential equation is assumed to be uniformly elliptic. This problem belongs to the class of linear-quadratic elliptic control problems with distributed control. The existence and uniqueness of an optimal solution for problems of this type is well-known and in a first step, following the paradigm 'first optimize, then discretize', the necessary and sufficient optimality conditions are derived by means of the adjoint equation which ends in a characterization of the optimal solution in form of an optimality system. In a second step, the occurring differential operators are approximated by finite differences and the hence resulting discretized optimality system is solved with a collective smoothing multigrid method (CSMG). In general, there are several optimization methods for solving the optimal control problem: an application of the implicit function theorem leads to so-called black-box approaches where the PDE-constrained optimization problem is transformed into an unconstrained optimization problem and the reduced gradient for these reduced functional is computed via the adjoint approach. Another possibilities are Quasi-Newton methods, which approximate the Hessian by a low-rank update based on gradient evaluations, Krylov-Newton methods or (reduced) SQP methods. The use of multigrid methods for optimization purposes is motivated by its optimal computational complexity, i.e. the number of required computer iterations scales linearly with the number of unknowns and the rate of convergence, which is independent of the grid size. Originally multigrid methods are a class of algorithms for solving linear systems arising from the discretization of partial differential equations. The main part of this thesis is devoted to the investigation of the implementability and the efficiency of the CSMG on commodity graphics cards. GPUs (graphic processing units) are designed for highly parallelizable graphics computations and possess many cores of SIMD-architecture, which are able to outperform the CPU regarding to computational power and memory bandwidth. Here they are considered as prototype for prospective multi-core computers with several hundred of cores. When using GPUs as streamprocessors, two major problems arise: data have to be transferred from the CPU main memory to the GPU main memory, which can be quite slow and the limited size of the GPU main memory. Furthermore, only when the streamprocessors are fully used to capacity, a remarkable speed-up comparing to a CPU is achieved. Therefore, new algorithms for the solution of optimal control problems are designed in this thesis. To this end, a nonoverlapping domain decomposition method is introduced which allows the exploitation of the computational power of many GPUs resp. CPUs in parallel. This algorithm is based on preliminary work for elliptic problems and enhanced for the application to optimal control problems. For the domain decomposition into two subdomains the linear system for the unknowns on the interface is solved with a Schur complement method by using a discrete approximation of the Steklov-Poincare operator. For the academic optimal control problem, the arising capacitance matrix can be inverted analytically. On this basis, two different algorithms for the nonoverlapping domain decomposition for the case of many subdomains are proposed in this thesis: on the one hand, a recursive approach and on the other hand a simultaneous approach. Numerical test compare the performance of the CSMG for the one domain case and the two approaches for the multi-domain case on a GPU and CPU for different variants.
Roof and wall slates are fine-grained rocks with slaty cleavage, and it is often difficult to determine their mineral composition. A new norm mineral calculation called slatecalculation allows the determination of a virtual mineral composition based on full chemical analysis, including the amounts of carbon dioxide (CO2), carbon (C), and sulfur (S). Derived norm minerals include feldspars, carbonates, micas, hydro-micas, chlorites, ore-minerals, and quartz. The mineral components of the slate are assessed with superior accuracy compared to the petrographic analysis based on the European Standard EN 12326. The inevitable methodical inaccuracies in the calculations are limited and transparent. In the present paper, slates, shales, and phyllites from worldwide occurrences were examined. This also gives an overview of the rocks used for discontinuous roofing and external cladding.
Sample surveys are a widely used and cost effective tool to gain information about a population under consideration. Nowadays, there is an increasing demand not only for information on the population level but also on the level of subpopulations. For some of these subpopulations of interest, however, very small subsample sizes might occur such that the application of traditional estimation methods is not expedient. In order to provide reliable information also for those so called small areas, small area estimation (SAE) methods combine auxiliary information and the sample data via a statistical model.
The present thesis deals, among other aspects, with the development of highly flexible and close to reality small area models. For this purpose, the penalized spline method is adequately modified which allows to determine the model parameters via the solution of an unconstrained optimization problem. Due to this optimization framework, the incorporation of shape constraints into the modeling process is achieved in terms of additional linear inequality constraints on the optimization problem. This results in small area estimators that allow for both the utilization of the penalized spline method as a highly flexible modeling technique and the incorporation of arbitrary shape constraints on the underlying P-spline function.
In order to incorporate multiple covariates, a tensor product approach is employed to extend the penalized spline method to multiple input variables. This leads to high-dimensional optimization problems for which naive solution algorithms yield an unjustifiable complexity in terms of runtime and in terms of memory requirements. By exploiting the underlying tensor nature, the present thesis provides adequate computationally efficient solution algorithms for the considered optimization problems and the related memory efficient, i.e. matrix-free, implementations. The crucial point thereby is the (repetitive) application of a matrix-free conjugated gradient method, whose runtime is drastically reduced by a matrx-free multigrid preconditioner.
A big challenge for agriculture in the 21st century is the provision of food safety to fast growing world- population, which not only demands the well utilisation of the available agricultural resources but also to develop new advancements in the mass production of food crops. Wheat is the third largest food crop of the world and Pakistan is the eighth largest wheat producing country globally. Rice is the second most important staple food of Pakistan after wheat, grown in all provinces of the country. Maize is the world- top ranking food crop followed by wheat and rice. The harvested produts have to be stored in different types of storage structures on small or large scale for food as well as seed purpose. In Pakistan, the harvested grains are stored for the whole year till the introduction of fresh produce in order to ensure the regular food supply throughout the year. However, it is this extended storage period making the commodity more vulnerable to insect attacks. Rhyzopertha dominica (Coleoptera: Bostrychidae), Cryptolestes ferrugineus (Coleoptera: Laemophloeidae), Tribolium castaneum (Coleoptera: Tenebrionidae) and Liposcelis spp. (Psocoptera: Liposcelididae) are the major and most damaging insect pests of stored products all around the world. Various management strategies have been adopted for stored grain insect pests mostly relying upon the use of a broad spectrum of insecticides, but the injudicious use of these chemicals raised various environmental and human health related issues, which necessitate the safe use of the prevailing control measures and evaluation of new and alternative control methods. The application of new chemical insecticides, microbial insecticides (particularly entomopathogenic fungi) and the use of inert dusts (diatomaceous earths) is believed amongst the potential alternatives to generally used insecticides in stored grain insect management system. In the current investigations, laboratory bioassays conducted to evaluate the effects of combining Imidacloprid (new chemistry insecticide) with and without Protect-It (diatomaceous earth formulation) against R. dominica, L. paeta, C. ferrugineus and T. castaneum, on three different grain commodities (i.e. wheat, maize and rice) revealed differences in adult mortality levels among grains and insect species tested. Individually, Imidacloprid was more effective as compared with Protect-It alone and the highest numbers of dead adults were recorded in wheat. The insecticidal efficacy of B. bassiana with Protect-It and DEBBM was also assessed against all test insect species under laboratory conditions. The findings of these studies revealed that the more extended exposure period and the higher combined application rate of B. bassiana and DEs provided the highest mortality of the test insect species. The progeny emergence of each insect species was also greatly suppressed where the highest dose rates of the combined treatments were applied. The residual efficacy of all three control measures Imidacloprid, B. bassiana and DEBBM formulation was also evaluated against all test insect species. The bioassays were carried out after grain treatments and monthly for 6 months. The results indicated that the adult mortality of each test insect species was decreased within the six month storage period, and the integarted application of the test grain protectants enhanced the mortality rates than their alone treatments. The maximum mortality was noted in the combined treatment of DEBBM with Imidacloprid. At the end, the effectiveness of B. bassiana, DEBBM and Imidacloprid applied alone as well as in combinations, against all above mentioned test insect species was also evaluated under field conditions in trials conducted in four districts of Punjab, Pakistan. For each district, a significant difference was observed between treatments, while the combined treatments gave better control of test species as compared with them alone. The least number of surviving adults and minimum percentage of grain damage was observed for the DEBBM and Imidacloprid combination, but DEBBM with B. bassiana provided the best long-term protection as compared with the remaining treatments.
The presented research aims at providing a first empirical investigation on lexical structure in Chinese with appropriate quantitative methods. The research objects contain individual properties of words (part of speech, polyfunctionality, polysemy, word length), the relationships between properties (part of speech and polyfunctionality, polyfunctionality and polysemy, polysemy and word length) and the lexical structure composed by those properties. Some extant hypotheses in QL, such as distributions of polysemy and the relationship between word length and polysemy, are tested on the data of Chinese, which enrich the applicability of the laws with a language not tested yet. Several original hypotheses such as the distribution of polyfunctionality and the relationship between polyfunctionality and polysemy are set up and inspected.
The daily dose of health information: A psychological view on the health information seeking process
(2021)
The search for health information is becoming increasingly important in everyday life, as well as socially and scientifically relevant Previous studies have mainly focused on the design and communication of information. However, the view of the seeker as well as individual
differences in skills and abilities has been a neglected topic so far. A psychological perspective on the process of searching for health information would provide important starting points for promoting the general dissemination of relevant information and thus improving health behaviour and health status. Within the present dissertation, the process of seeking health information was thus divided into sequential stages to identify relevant personality traits and skills. Accordignly, three studies are presented that focus on one stage
of the process respectively and empirically test potential crucial traits and skills: Study I investigates possible determinants of an intention for a comprehensive search for health information. Building an intention is considered as the basic step of the search process.
Motivational dispositions and self-regulatory skills were related to each other in a structural equation model and empirically tested based on theoretical investigations. Model fit showed an overall good fit and specific direct and indirect effects from approach and avoidance
motivation on the intention to seek comprehensively could be found, which supports the theoretical assumptions. The results show that as early as the formation of intention, the psychological perspective reveals influential personality traits and skills. Study II deals with the subsequent step, the selection of information sources. The preference for basic characteristics of information sources (i.e., accessibility, expertise, and interaction) is related to health information literacy as a collective term for relevant skills and intelligence as a personality trait. Furthermore, the study considers the influence of possible over- or underestimation of these characteristics. The results show not only a different predictive
contribution of health literacy and intelligence, but also the relevance of subjective and objective measurement.
Finally, Study III deals with the selection and evaluation of the health information previously found. The phenomenon of selective exposure is analysed, as this can be considered problematic in the health context. For this purpose, an experimental design was implemented in which a varying health threat was suggested to the participants. Relevant information was presented and the selective choice of this information was assessed. Health literacy was tested
as a moderator in a function of the induced threat and perceived vulnerability, triggering defence motives on the degree of bias. Findings show the importance of the consideration of the defence motives, which could cause a bias in the form of selective exposure. Furthermore, health literacy even seems to amplify this effect.
Results of the three studies are synthesized, discussed and general conclusions are drawn and implications for further research are determined.
Legalisation cannot be fully explained by interest politics. If that were the case, the attitudes towards legalisation would be expected to be based on objective interests and actual policies in France and Germany would be expected to be more similar. Nor can it be explained by institutional agency, because there are no hints that states struggle with different normative traditions. Rather, political actors seek to make use of the structures that already exist to guar-antee legitimacy for their actions. If the main concern of governmental actors really is to accumulate legitimacy, as stated in the introduction, then politicians have a good starting position in the case of legalisation of illegal foreigners. Citizens" negative attitudes towards legalisation cannot be explained by imagined labour market competition; income effects play only a secondary role. The most important explanatory factor is the educational level of each individual. Objective interests do not trigger attitudes towards legalisation, but rather a basic men-tal predisposition for or against illegal immigrants who are eligible for legalisation. Politics concerning amnesties are thus not tied to an objectively given structure like the socio-economic composition of the electorate, but are open for political discretion. Attitudes on legalising illegal immigrants can be regarded as being mediated by beliefs and perceptions, which can be used by political agents or altered by political developments. However, politicians must adhere to a national frame of legitimating strategies that cannot be neglected without consequences. It was evident in the cross-country comparison of political debates that there are national systems of reference that provide patterns of interpretation. Legalisation is seen and incorporated into immigration policy in a very specific way that differs from one country to the next. In both countries investigated in this study, there are fundamental debates about which basic principles apply to legalisation and which of these should be held in higher esteem: a legal system able to work, humanitarian rights, practical considerations, etc. The results suggest that legalisation is "technicized" in France by describing it as an unusual but possible pragmatic instrument for the adjustment of the inefficient rule of law. In Germany, however, legalisation is discussed at a more normative level. Proponents of conservative immigration policies regard it as a substantial infringement on the rule of law, so that even defenders of a humanitarian solution for illegal immigrants are not able to challenge this view without significant political harm. But the arguments brought to bear in the debate on legalisation are not necessarily sound because they are not irrefutable facts, but instruments to generate legitimacy, and there are enough possibilities for arguing and persuading because socio-economic factors play a minor role. One of the most important arguments, the alleged pull effect of legalisation, has been subjected to an empirical investigation. In the political debate, it does not make any dif-ference whether this is true or not, insofar as it is not contested by incontrovertible findings. In reality, the results suggest that amnesties indeed exert a small attracting influence on illegal immigration, which has been contested by immigration friendly politicians in the French par-liament. The effect, however, is not large; therefore, some conservative politicians may put too much stress on this argument. Moreover, one can see legalisation as an instrument to restore legitimacy that has slipped away from immigration politics because of a high number of illegally residing foreigners. This aspect explains some of the peculiarities in the French debate on legalisation, e.g. the idea that the coherence of the law is secured by creating exceptional rules for legalising illegal immigrants. It has become clear that the politics of legalisation are susceptible to manipulation by introducing certain interpretations into the political debate, which become predominant and supersede other views. In this study, there are no signs of a systematic misuse of this constellation by any certain actor. However, the history of immigration policy is full of examples of symbolic politics in which a certain measure has been initiated while the actors are totally aware of its lack of effect. Legalisation has escaped this fate so far because it is a specific instrument that is the result of neglecting populist mechanisms rather than an ex-ample of a superficial measure. This result does not apply to policies concerning illegal immi-gration in general, both with regard to concealing a lack of control and flexing the state- muscles.
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.
The overall objective of this thesis was to gain a deeper understanding of the antecedents, processes, and manifestations of uniqueness-driven consumer behavior. To achieve this goal, five studies have been conducted in Germany and Switzerland with a total of 1048 participants across different demographic and socio-economic backgrounds. Two concepts were employed in all studies: Consumer need for uniqueness (CNFU) and general uniqueness perception (GUP). CNFU (Tian, Bearden, & Hunter, 2001), a mainly US"based consumer research concept, measures the individual need, and thus the motivation to acquire, use, and dispose consumer goods in order to develop a unique image. GUP, adapted from the two-component theory of individuality (Kampmeier, 2001), represents a global and direct measure of self-ascribed uniqueness. Study #1 looked at the interrelation of the uniqueness-driven concepts. Therefore, GUP and CNFU were employed in the study as potential psychological factors that influence and predict uniqueness-driven consumer behavior. Different behavioral measures were used: The newly developed possession of individualized products (POIP), the newly developed products for uniqueness display (PFUD), and the already established uniqueness-enhancing behaviors (UEB). Analyses showed that CNFU mediates the relationship between GUP and the behavioral measures in a German speaking setting. Thus, GUP (representing self-perception) was identified as the driver behind CNFU (representing motivation) and the actual consumer behavior. Study #2 examined further manifestations of uniqueness-driven consumer behavior. For this purpose, an extreme form of uniqueness-increasing behavior was researched: Tattooing. The influence of GUP and CNFU on tattooing behavior was investigated using a sample derived from a tattoo exhibition. To do so, a newly developed measure to determine the percentage of the body covered by tattoos was employed. It was revealed that individuals with higher GUP and CNFU levels indeed have a higher tattooing degree. Study #3 further explored the predictive possibilities and limitations of the GUP and CNFU concepts. On the one hand, study #3 specifically looked at the consumption of customized apparel products as mass customization is said to become the standard of the century (Piller & Müller, 2004). It was shown that individuals with higher CNFU levels not only purchased more customized apparel products in the last six months, but also spend more money on them. On the other hand, uniqueness-enhancing activities (UEA), such as travel to exotic places or extreme sports, were investigated by using a newly developed 30-item scale. It was revealed that CNFU partly mediates the GUP and UEA relationship, proving that CNFU indeed predicts a broad range of consumer behaviors and that GUP is the driver behind the need and the behavior. Study #4, entered a new terrain. In contrast to the previous three studies, it explored the so termed "passive" side of uniqueness-seeking in the consumer context. Individuals might feel unique because business companies treat them in a special way. Such a unique customer treatment (UCT) involves activities like customer service or customer relationship management. Study #4 investigated if individuals differ in their need for such a treatment. Hence, with the need for unique customer treatment (NFUCT) a new uniqueness-driven consumer need was introduced and its impact on customer loyalty examined. Analyses, for example, revealed that individuals with high NFUCT levels receiving a high unique customer treatment (UCT) showed the highest customer loyalty, whereas the lowest customer loyalty was found among those individuals with high NFUCT levels receiving a low unique customer treatment (UCT). Study #5 mainly examined the processes behind uniqueness-driven consumer behavior. Here, not only the psychological influences, but also situational influences were examined. This study investigated the impact of a non-personal "indirect" uniqueness manipulation on the consumption of customized apparel products by simultaneously controlling for the influence of GUP and CNFU. Therefore, two equal experimental groups were created. Afterwards, these groups either received an e-mail with a "pro-individualism" campaign or a "pro-collectivism" campaign especially developed for study #5. The conducted experiment revealed that, individuals receiving a "pro-individualism" poster campaign telling the participants that uniqueness is socially appropriate and desired were willing to spend more money on customization options compared to individuals receiving a "pro-collectivism" poster campaign. Hence, not only psychological antecedents such as GUP and CNFU influence uniqueness-driven consumer behavior, but also situational factors.
Shape optimization is of interest in many fields of application. In particular, shape optimization problems arise frequently in technological processes which are modelled by partial differential equations (PDEs). In a lot of practical circumstances, the shape under investigation is parametrized by a finite number of parameters, which, on the one hand, allows the application of standard optimization approaches, but, on the other hand, unnecessarily limits the space of reachable shapes. Shape calculus presents a way to circumvent this dilemma. However, so far shape optimization based on shape calculus is mainly performed using gradient descent methods. One reason for this is the lack of symmetry of second order shape derivatives or shape Hessians. A major difference between shape optimization and the standard PDE constrained optimization framework is the lack of a linear space structure on shape spaces. If one cannot use a linear space structure, then the next best structure is a Riemannian manifold structure, in which one works with Riemannian shape Hessians. They possess the often sought property of symmetry, characterize well-posedness of optimization problems and define sufficient optimality conditions. In general, shape Hessians are used to accelerate gradient-based shape optimization methods. This thesis deals with shape optimization problems constrained by PDEs and embeds these problems in the framework of optimization on Riemannian manifolds to provide efficient techniques for PDE constrained shape optimization problems on shape spaces. A Lagrange-Newton and a quasi-Newton technique in shape spaces for PDE constrained shape optimization problems are formulated. These techniques are based on the Hadamard-form of shape derivatives, i.e., on the form of integrals over the surface of the shape under investigation. It is often a very tedious, not to say painful, process to derive such surface expressions. Along the way, volume formulations in the form of integrals over the entire domain appear as an intermediate step. This thesis couples volume integral formulations of shape derivatives with optimization strategies on shape spaces in order to establish efficient shape algorithms reducing analytical effort and programming work. In this context, a novel shape space is proposed.
Digitalization primarily takes place in and through organizations. Despite this prominent role, however, the importance of organizational structure-building processes in the digital transformation is still underexposed in discourse. The fact that ongoing digitalization is linked to an established phenomenon and its own logic, is regularly not addressed due to the attraction potential of the semantics of the digital revolution. Digital revolution and the reordering of societal relationships, though, manifest themselves primarily in processes of reorganization. Structural automation processes in the ongoing digital transformation are limiting the scope for action, necessitating forms of structural structurelessness in organizations that cultivate opportunities for chance. Since organizations realize their operations as a dual of structure and individual, and the principle of organization is therefore based on the complementarity of structural formality and unpredictable informality. The paper discusses the topicality of the classical form of modern organization in the digital age and reflects on approaches to a contemporary design of spaces of opportunity. The reflexive handling of future openness is the central task of management and leadership in order to enable variation and innovation in organizations.
Geographic ranges of species and their determinants are of great interest in the field of biogeography and are often studied in terms of the species" ecological niches. In this context, the range of a species is defined by the accessibility of an area, abiotic factors and biotic interactions, which affect a species" distributions with different intensities across spatial scales. Parapatry describes a distributional pattern in which the ranges of two species meet along sharp range limits with narrow contact zones. Such parapatric range limits are determined by changing abiotic conditions along sharp environmental gradients or can result from interspecific resource competition. However, it has been shown that often the interplay of abiotic conditions and species interactions determine parapatry. The geographic ranges of the land salamanders, Salamandra salamandra and S. atra, narrowly overlap in the European Alps with only few syntopic localities and to date, the cause of parapatry is unknown. The goal of this thesis was thus to identify the importance of abiotic and biotic factors for their parapatric range limits at different spatial scales. On a broad spatial scale, the role of climate for the parapatric range limits of the species was investigated within three contact zones in Switzerland. Climatic conditions at species" records were analysed and species distribution modelling techniques were used to explore the species" climatic niches and to quantify the interspecific niche overlap. Furthermore, it was tested whether the parapatric range limit coincides with a strong climatic gradient. The results revealed distinct niches for the species as well as the presence of strong climatic gradients which could explain the parapatric range limits of the species. Yet, there was a moderate interspecific niche overlap in all contact zones indicating that the species may co-occur and interact with each other in areas where they both find adequate conditions. Comparison among contact zones revealed geographic variation in the species" niches as well as in the climatic conditions at their records suggesting that the species can occur in a much wider range of conditions than they actually do. These findings imply that climate represents a main factor for the species" parapatric range limits. Yet, interspecific niche overlap and the geographic variation provide indirect evidence that interspecific interaction may also affect their spatial distribution. To test whether competition restricts the species" ranges on the habitat scale and to understand local syntopic co-occurrence of the salamanders within their contact zones, site-occupancy modelling was used. This approach allowed to find the habitat predictors that best explain the species" local distribution. While the slope of the site positively affected the occupancy probability of S. salamandra, no tested predictor explained that of S. atra. Also, there was no effect of the occurrence of one species on the occupancy probability of the other providing no evidence for competition. Should competition occur, it does not lead to spatial segregation of the species on this scale. Because biotic interactions most significantly affect the ranges of species on small spatial scales, the microhabitat conditions at locations of the species within syntopic contact zones were compared and a null model analysis was applied to determine their niche overlap. Resource selection probability function models were used to assess those attributes that affect the species" habitat selections. The results revealed species-specific microhabitat preferences related to leaf litter cover, tree number and that the species were active at different temperatures as well as times of the day. The high degree of diurnal activity of S. atra may be due to its preference of forest floor microhabitats that long remain suitable during daytime. Besides, there was a great niche overlap for shelters indicating that the species may compete for this resource. Differential habitat selection and the use of the available shelters at different times of the day may minimize species interactions and allow their local co-occurrence within contact zones. To identify whether the potential infection with the pathogenic chytrid fungus could serve as an alternative biotic explanation for the range margins of S. atra, several populations throughout its range were screened for infection. Since the occurrence of this pathogen was detected mostly at lower altitudes of the Alps, it may confine the range of S. atra to higher elevations. Because chytrid was not detected in any of the samples, the pathogen unlikely plays a role in determining its range limits. Overall, these findings underline the complexity of mechanisms that determine the range margins of parapatric species and provide an important basis for subsequent studies regarding the determinants of the parapatric distribution of the two salamander species.
Representation Learning techniques play a crucial role in a wide variety of Deep Learning applications. From Language Generation to Link Prediction on Graphs, learned numerical vector representations often build the foundation for numerous downstream tasks.
In Natural Language Processing, word embeddings are contextualized and depend on their current context. This useful property reflects how words can have different meanings based on their neighboring words.
In Knowledge Graph Embedding (KGE) approaches, static vector representations are still the dominant approach. While this is sufficient for applications where the underlying Knowledge Graph (KG) mainly stores static information, it becomes a disadvantage when dynamic entity behavior needs to be modelled.
To address this issue, KGE approaches would need to model dynamic entities by incorporating situational and sequential context into the vector representations of entities. Analogous to contextualised word embeddings, this would allow entity embeddings to change depending on their history and current situational factors.
Therefore, this thesis provides a description of how to transform static KGE approaches to contextualised dynamic approaches and how the specific characteristics of different dynamic scenarios are need to be taken into consideration.
As a starting point, we conduct empirical studies that attempt to integrate sequential and situational context into static KG embeddings and investigate the limitations of the different approaches. In a second step, the identified limitations serve as guidance for developing a framework that enables KG embeddings to become truly dynamic, taking into account both the current situation and the past interactions of an entity. The two main contributions in this step are the introduction of the temporally contextualized Knowledge Graph formalism and the corresponding RETRA framework which realizes the contextualisation of entity embeddings.
Finally, we demonstrate how situational contextualisation can be realized even in static environments, where all object entities are passive at all times.
For this, we introduce a novel task that requires the combination of multiple context modalities and their integration with a KG based view on entity behavior.
Avoiding aerial microfibre contamination of environmental samples is essential for reliable analyses when it comes to the detection of ubiquitous microplastics. Almost all laboratories have contamination problems which are largely unavoidable without investments in clean-air devices. Therefore, our study supplies an approach to assess background microfibre contamination of samples in the laboratory under particle-free air conditions. We tested aerial contamination of samples indoor, in a mobile laboratory, within a laboratory fume hood and on a clean bench with particles filtration during the examining process of a fish. The used clean bench reduced aerial microfibre contamination in our laboratory by 96.5%. This highlights the value of suitable clean-air devices for valid microplastic pollution data. Our results indicate, that pollution levels by microfibres have been overestimated and actual pollution levels may be many times lower. Accordingly, such clean-air devices are recommended for microplastic laboratory applications in future research work to significantly lower error rates.
In a first step, this paper analyses the emergence of the UN Sustainable Development Goals (SDGs) as new global development framework with regard to key actors, social learning cycles, innovation platforms, fundamental policy changes and transition dynamics towards sustainability. In a second step, it traces the convolution of social, political and environmental dimensions, social power relations and governance paradigms embedded in the drafting process and final framework of the water related SDG 6. This research concludes that the SDGs induced important paradigm and policy changes in addition to rearranging existing power relations.
This literature review was conducted to identify important wetlands in the Greater Accra Region and to illustrate dominant research trends, prevailing perspectives and corresponding research gaps. Six wetlands systems were identified as most significant lagoon systems, namely the Densu Delta, Sakumo, Muni-Pomadze, Keta, Korle and Songor Lagoons. Research foci for each of the respective wetlands were extrapolated and summarized in a category system. The frequency of different categories illustrates that natural science’s perspectives dominate, as most of Accra’s lagoons have been studied with regard to their ecological, physical and chemical properties. The development of research interest over time and focus on ecological baseline conditions are related to the designation of Ramsar Sites and orientation of national policies towards environmental protection. A research gap was identified, as studies link their findings to human activities but neglect the connection between governance variables and environmental developments. It is suggested to expand the natural science’s perspective on Accra’s wetlands to account for social and political aspects in order to develop a holistic and more sustainable management strategy.
In the context of accelerated global socio-environmental change, the Water-Energy-Food Nexus has received increasing attention within science and international politics by promoting integrated resource governance. This study explores the scientific nexus debates from a discourse analytical perspective to reveal knowledge and power relations as well as geographical settings of nexus research. We also investigate approaches to socio-nature relations that influence nexus research and subsequent political implications. Our findings suggest that the leading nexus discourse is dominated by natural scientific perspectives and a neo-Malthusian framing of environmental challenges. Accordingly, the promoted cross-sectoral nexus approach to resource governance emphasizes efficiency, security, future sustainability, and poverty reduction. Water, energy, and food are conceived as global trade goods that require close monitoring, management and control, to be achieved via quantitative assessments and technological interventions. Within the less visible discourse, social scientific perspectives engage with the social, political, and normative elements of the Water-Energy-Food Nexus. These perspectives criticize the dominant nexus representation for itsmanagerial, neoliberal, and utilitarian approach to resource governance. The managerial framing is critiqued for masking power relations and social inequalities, while alternative framings acknowledge the political nature of resource governance and socio-nature relations. The spatial dimensions of the nexus debate are also discussed. Notably, the nexus is largely shaped by western knowledge, yet applied mainly in specific regions of the Global South. In order for the nexus to achieve integrative solutions for sustainability, the debate needs to overcome its current discursive and spatial separations. To this end, we need to engage more closely with alternative nexus discourses, embrace epistemic pluralism and encourage multi-perspective debates about the socio-nature relations we actually intend to promote.