### Refine

#### Year of publication

#### Document Type

- Doctoral Thesis (268)
- Article (61)
- Working Paper (16)
- Book (15)
- Conference Proceedings (9)
- Part of Periodical (5)
- Habilitation (3)
- Other (3)
- Master's Thesis (2)
- Part of a Book (1)

#### Language

- English (384) (remove)

#### Keywords

- Stress (24)
- Fernerkundung (18)
- Hydrocortison (13)
- Modellierung (12)
- Optimierung (12)
- Cortisol (9)
- cortisol (9)
- stress (9)
- Finanzierung (7)
- Stressreaktion (7)

#### Institute

- Geographie und Geowissenschaften (79)
- Psychologie (79)
- Mathematik (46)
- Fachbereich 4 (30)
- Wirtschaftswissenschaften (25)
- Fachbereich 6 (24)
- Informatik (16)
- Anglistik (15)
- Fachbereich 1 (14)
- Rechtswissenschaft (14)

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.

Mankind has dramatically influenced the nitrogen (N) fluxes between soil, vegetation, water and atmosphere " the global N cycle. Increasing intensification of agricultural land use, caused by the growing demand for agricultural products, has had major impacts on ecosystems worldwide. Particularly nitrogenous gases such as ammonia (NH3) have increased mainly due to industrial livestock farming. Countries with high N deposition rates require a variety of deposition measurements and effective N monitoring networks to assess N loads. Due to high costs, current "conventional"-deposition measurement stations are not widespread and therefore provide only a patchy picture of the real extent of the prevailing N deposition status over large areas. One tool that allows quantification of the exposure and the effects of atmospheric N impacts on an ecosystem is the use of bioindicators. Due to their specific physiology and ecology, especially lichens and mosses are suitable to reflect the atmospheric N input at ecosystem level. The present doctoral project began by investigating the general ability of epiphytic lichens to qualify and quantify N deposition by analysing both lichens and total N and δ15N along a gradient of different N emission sources and severity. The results showed that this was a viable monitoring method, and a grid-based monitoring system with nitrophytic lichens was set up in the western part of Germany. Finally, a critical appraisal of three different monitoring techniques (lichens, mosses and tree bark) was carried out to compare them with national relevant N deposition assessment programmes. In total 1057 lichen samples, 348 tree bark samples, 153 moss samples and 24 deposition water samples, were analysed in this dissertation at different investigation scales in Germany.The study identified species-specific ability and tolerance of various epiphytic lichens to accumulate N. Samples of tree bark were also collected and N accumulation ability was detected in connection with the increased intensity of agriculture, and according to the presence of reduced N compounds (NHx) in the atmosphere. Nitrophytic lichens (Xanthoria parietina, Physcia spp.) have the strongest correlations with high agriculture-related N deposition. In addition, the main N sources were revealed with the help of δ15N values along a gradient of altitude and areas affected by different types of land use (NH3 density classes, livestock units and various deposition types). Furthermore, in the first nationwide survey of Germany to compare lichens, mosses and tree bark samples as biomonitors for N deposition, it was revealed that lichens are clearly the most meaningful monitor organisms in highly N affected regions. Additionally, the study shows that dealing with different biomonitors is a difficult task due to their variety of N responses. The specific receptor surfaces of the indicators and therefore their different strategies of N uptake are responsible for the tissue N concentration of each organism group. It was also shown that the δ15N values depend on their N origin and the specific N transformations in each organism system, so that a direct comparison between atmosphere and ecosystems is not possible.In conclusion, biomonitors, and especially epiphytic lichens may serve as possible alternatives to get a spatially representative picture of the N deposition conditions. Furthermore, bioindication with lichens is a cost-efficient alternative to physico-chemical measurements to comprehensively assess different prevailing N doses and sources of N pools on a regional scale. They can at least support on-site deposition instruments by qualification and quantification of N deposition.

The main goal of this publication is the development and application of an empirical method, which allows to forecast the transport of radionuclides in soils ad sediments. The calculations are based on data published in the literature. 10 case studies, comprising 30 time series, deal with the transport of Cs-134, Cs-137, Sr-85, Sr-90, and Ru-106. Transport in undisturbed soils and experimental systems like lysimeters and columns in laboratories are dealt with. The soils involved cover a large range of soils, e. g. podsols, cambisols (FAO), and peaty soils. Different speciations are covered, namely ions, aerosols, and fuel particles. Time series analysis centres around the Weibull-distribution. All theoretical models failed to forecast the transport of radionuclides. It can be shown that the parameters D and v, the dispersion coefficient and the advection velocity, appearing in solutions of the advection-dispersion equation (ADE), have no real physical meaning. They are just fitting parameters. The calculation of primary photon fluence rates, caused by Cs-137 in the soil, stresses the unreliability of forecasts based on theoretical models.

Time series archives of remotely sensed data offer many possibilities to observe and analyse dynamic environmental processes at the Earth- surface. Based on these hypertemporal archives, which offer continuous observations of vegetation indices, typically at repetition rates from one to two weeks, sets of phenological parameters or metrics can be derived. Examples of such parameters are the beginning and end of the annual growing period, as well as its length. Even though these parameters do not correspond exactly to conventional observations of phenological events, they nevertheless provide indications of the dynamic processes occurring in the biosphere. The development of robust algorithms for the derivation of phenological metrics can be challenging. Currently, such algorithms are most commonly based on digital filters or the Fourier analysis of time series. Polynomial spline models offer a useful alternative to existing methods. The possibilities of using spline models in the analytical description of time series are numerous, and their specific mathematical properties may help to avoid known problems occurring with the more common methods for deriving phenological metrics. Based on a selection of different polynomial spline models suitable for the analysis of remotely sensed time series of vegetation indices, a method to derive various phenological parameters from such time series was developed and implemented in this work. Using an example data set from an intensively used agricultural area showing highly dynamic variations in vegetation phenology, the newly developed method was verified by a comparison of the results of the spline based approach to the results of two alternative, well established methods.

The subject of this thesis is a homological approach to the splitting theory of PLS-spaces, i.e. to the question for which topologically exact short sequences 0->X->Y->Z->0 of PLS-spaces X,Y,Z the right-hand map admits a right inverse. We show that the category (PLS) of PLS-spaces and continuous linear maps is an additive category in which every morphism admits a kernel and a cokernel, i.e. it is pre-abelian. However, we also show that it is neither quasi-abelian nor semi-abelian. As a foundation for our homological constructions we show the more general result that every pre-abelian category admits a largest exact structure in the sense of Quillen. In the pre-abelian category (PLS) this exact structure consists precisely of the topologically exact short sequences of PLS-spaces. Using a construction of Ext-functors due to Yoneda, we show that one can define for each PLS-space A and every natural number k the k-th abelian-group valued covariant and contravariant Ext-functors acting on the category (PLS) of PLS-spaces, which induce for every topologically exact short sequence of PLS-spaces a long exact sequence of abelian groups and group morphisms. These functors are studied in detail and we establish a connection between the Ext-functors of PLS-spaces and the Ext-functors for LS-spaces. Through this connection we arrive at an analogue of a result for Fréchet spaces which connects the first derived functor of the projective limit with the first Ext-functor and also gives sufficient conditions for the vanishing of the higher Ext-functors. Finally, we show that Ext^k(E,F) = 0 for a k greater or equal than 1, whenever E is a closed subspace and F is a Hausdorff-quotient of the space of distributions, which generalizes a result of Wengenroth that is itself a generalization of results due to Domanski and Vogt.

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.

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.

Determining the exact position of a forest inventory plotâ€”and hence the position of the sampled treesâ€”is often hampered by a poor Global Navigation Satellite System (GNSS) signal quality beneath the forest canopy. Inaccurate geo-references hamper the performance of models that aim to retrieve useful information from spatially high remote sensing data (e.g., species classification or timber volume estimation). This restriction is even more severe on the level of individual trees. The objective of this study was to develop a post-processing strategy to improve the positional accuracy of GNSS-measured sample-plot centers and to develop a method to automatically match trees within a terrestrial sample plot to aerial detected trees. We propose a new method which uses a random forest classifier to estimate the matching probability of each terrestrial-reference and aerial detected tree pair, which gives the opportunity to assess the reliability of the results. We investigated 133 sample plots of the Third German National Forest Inventory (BWI, 2011"2012) within the German federal state of Rhineland-Palatinate. For training and objective validation, synthetic forest stands have been modeled using the Waldplaner 2.0 software. Our method has achieved an overall accuracy of 82.7% for co-registration and 89.1% for tree matching. With our method, 60% of the investigated plots could be successfully relocated. The probabilities provided by the algorithm are an objective indicator of the reliability of a specific result which could be incorporated into quantitative models to increase the performance of forest attribute estimations.

A matrix A is called completely positive if there exists an entrywise nonnegative matrix B such that A = BB^T. These matrices can be used to obtain convex reformulations of for example nonconvex quadratic or combinatorial problems. One of the main problems with completely positive matrices is checking whether a given matrix is completely positive. This is known to be NP-hard in general. rnrnFor a given matrix completely positive matrix A, it is nontrivial to find a cp-factorization A=BB^T with nonnegative B since this factorization would provide a certificate for the matrix to be completely positive. But this factorization is not only important for the membership to the completely positive cone, it can also be used to recover the solution of the underlying quadratic or combinatorial problem. In addition, it is not a priori known how many columns are necessary to generate a cp-factorization for the given matrix. The minimal possible number of columns is called the cp-rank of A and so far it is still an open question how to derive the cp-rank for a given matrix. Some facts on completely positive matrices and the cp-rank will be given in Chapter 2. Moreover, in Chapter 6, we will see a factorization algorithm, which, for a given completely positive matrix A and a suitable starting point, computes the nonnegative factorization A=BB^T. The algorithm therefore returns a certificate for the matrix to be completely positive. As introduced in Chapter 3, the fundamental idea of the factorization algorithm is to start from an initial square factorization which is not necessarily entrywise nonnegative, and extend this factorization to a matrix for which the number of columns is greater than or equal to the cp-rank of A. Then it is the goal to transform this generated factorization into a cp-factorization. This problem can be formulated as a nonconvex feasibility problem, as shown in Section 4.1, and solved by a method which is based on alternating projections, as proven in Chapter 6. On the topic of alternating projections, a survey will be given in Chapter 5. Here we will see how to apply this technique to several types of sets like subspaces, convex sets, manifolds and semialgebraic sets. Furthermore, we will see some known facts on the convergence rate for alternating projections between these types of sets. Considering more than two sets yields the so called cyclic projections approach. Here some known facts for subspaces and convex sets will be shown. Moreover, we will see a new convergence result on cyclic projections among a sequence of manifolds in Section 5.4. In the context of cp-factorizations, a local convergence result for the introduced algorithm will be given. This result is based on the known convergence for alternating projections between semialgebraic sets. To obtain cp-facrorizations with this first method, it is necessary to solve a second order cone problem in every projection step, which is very costly. Therefore, in Section 6.2, we will see an additional heuristic extension, which improves the numerical performance of the algorithm. Extensive numerical tests in Chapter 7 will show that the factorization method is very fast in most instances. In addition, we will see how to derive a certificate for the matrix to be an element of the interior of the completely positive cone. As a further application, this method can be extended to find a symmetric nonnegative matrix factorization, where we consider an additional low-rank constraint. Here again, the method to derive factorizations for completely positive matrices can be used, albeit with some further adjustments, introduced in Section 8.1. Moreover, we will see that even for the general case of deriving a nonnegative matrix factorization for a given rectangular matrix A, the key aspects of the completely positive factorization approach can be used. To this end, it becomes necessary to extend the idea of finding a completely positive factorization such that it can be used for rectangular matrices. This yields an applicable algorithm for nonnegative matrix factorization in Section 8.2. Numerical results for this approach will suggest that the presented algorithms and techniques to obtain completely positive matrix factorizations can be extended to general nonnegative factorization problems.

The presence of sea ice leads in the sea ice cover represents a key feature in polar regions by controlling the heat exchange between the relatively warm ocean and cold atmosphere due to increased fluxes of turbulent sensible and latent heat. Sea ice leads contribute to the sea ice production and are sources for the formation of dense water which affects the ocean circulation. Atmospheric and ocean models strongly rely on observational data to describe the respective state of the sea ice since numerical models are not able to produce sea ice leads explicitly. For the Arctic, some lead datasets are available, but for the Antarctic, no such data yet exist. Our study presents a new algorithm with which leads are automatically identified in satellite thermal infrared images. A variety of lead metrics is used to distinguish between true leads and detection artefacts with the use of fuzzy logic. We evaluate the outputs and provide pixel-wise uncertainties. Our data yield daily sea ice lead maps at a resolution of 1 km2 for the winter months November– April 2002/03–2018/19 (Arctic) and April–September 2003–2019 (Antarctic), respectively. The long-term average of the lead frequency distributions show distinct features related to bathymetric structures in both hemispheres.