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In the new epoch of Anthropocene, global freshwater resources are experiencing extensive degradation from a multitude of stressors. Consequently, freshwater ecosystems are threatened by a considerable loss of biodiversity as well as substantial decrease in adequate and secured freshwater supply for human usage, not only on local scales, but also on regional to global scales. Large scale assessments of human and ecological impacts of freshwater degradation enable an integrated freshwater management as well as complement small scale approaches. Geographic information systems (GIS) and spatial statistics (SS) have shown considerable potential in ecological and ecotoxicological research to quantify stressor impacts on humans and ecological entitles, and disentangle the relationships between drivers and ecological entities on large scales through an integrated spatial-ecological approach. However, integration of GIS and SS with ecological and ecotoxicological models are scarce and hence the large scale spatial picture of the extent and magnitude of freshwater stressors as well as their human and ecological impacts is still opaque. This Ph.D. thesis contributes novel GIS and SS tools as well as adapts and advances available spatial models and integrates them with ecological models to enable large scale human and ecological impacts identification from freshwater degradation. The main aim was to identify and quantify the effects of stressors, i.e climate change and trace metals, on the freshwater assemblage structure and trait composition, and human health, respectively, on large scales, i.e. European and Asian freshwater networks. The thesis starts with an introduction to the conceptual framework and objectives (chapter 1). It proceeds with outlining two novel open-source algorithms for quantification of the magnitude and effects of catchment scale stressors (chapter 2). The algorithms, i.e. jointly called ATRIC, automatically select an accumulation threshold for stream network extraction from digital elevation models (DEM) by assuring the highest concordance between DEM-derived and traditionally mapped stream networks. Moreover, they delineate catchments and upstream riparian corridors for given stream sampling points after snapping them to the DEM-derived stream network. ATRIC showed similar or better performance than the available comparable algorithms, and is capable of processing large scale datasets. It enables an integrated and transboundary management of freshwater resources by quantifying the magnitude of effects of catchment scale stressors. Spatially shifting temporal points (SSTP), outlined in chapter 3, estimates pooled within-time series (PTS) variograms by spatializing temporal data points and shifting them. Data were pooled by ensuring consistency of spatial structure and temporal stationarity within a time series, while pooling sufficient number of data points and increasing data density for a reliable variogram estimation. SSTP estimated PTS variograms showed higher precision than the available method. The method enables regional scale stressors quantification by filling spatial data gaps integrating temporal information in data scarce regions. In chapter 4, responses of the assumed climate-associated traits from six grouping features to 35 bioclimatic indices for five insect orders were compared, their potential for changing distribution pattern under future climate change was evaluated and the most influential climatic aspects were identified (chapter 4). Traits of temperature preference grouping feature and the insect order Ephemeroptera exhibited the strongest response to climate as well as the highest potential for changing distribution pattern, while seasonal radiation and moisture were the most influential climatic aspects that may drive a change in insect distribution pattern. The results contribute to the trait based freshwater monitoring and change prediction. In chapter 5, the concentrations of 10 trace metals in the drinking water sources were predicted and were compared with guideline values. In more than 53% of the total area of Pakistan, inhabited by more than 74 million people, the drinking water was predicted to be at risk from multiple trace metal contamination. The results inform freshwater management by identifying potential hot spots. The last chapter (6) synthesizes the results and provides a comprehensive discussion on the four studies and on their relevance for freshwater resources conservation and management.
Engineered nanoparticles are emerging pollutants. Their increasing use in commercial products suggests a similar increase of their concentrations in the environment. Studying the fate of engineered colloids in the environment is highly challenging due to the complexity of their possible interactions with the main actors present in aquatic systems. Solution chemistry is one of the most central aspects. In particular, the interactions with dissolved organic matter (DOM) and with natural colloids are still weakly understood.
The aim of this work was to further develop the dedicated analytical methods required for investigating the fate of engineered colloids in environmental media as influenced by DOM. Reviewing the literature on DOM interactions with inorganic colloids revealed that a systematic characterization of both colloids and DOM, although essential, lacks in most studies and that further investigations on the fractionation of DOM on the surface of engineered colloids is needed. Another knowledge gap concerns the effects of DOM on the dynamic structure of colloid agglomerates. For this question, analytical techniques dedicated to the characterization of agglomerates in environmental media at low concentrations are required. Such techniques should remain accurate at low concentrations, be specific, widely matrix independent and free of artefact due to sample preparation. Unfortunately, none of the currently available techniques (microscopy, light scattering based methods, separation techniques etc.) fulfills these requirements.
However, a compromise was found with hydrodynamic chromatography coupled to inductively coupled plasma mass spectrometry (HDC-ICP-MS). This method has the potential to size inorganic particles in complex media in concentration ranges below ppb and is element specific; however, its limitations were not systematically explored. In this work, the potential of this method has been further explored. The simple size separation mechanism ensures a high flexibility of the elution parameters and universal calibration can be accurately applied to particles of different compositions and surface chemistries. The most important limitations of the method are its low size resolution and the effect of the particle shape on the retention factor. The implementation of HDC coupled to single particle ICP-MS (HDC-SP-ICP-MS) offers new possibilities for the recognition of particle shape and hence the differentiation between primary particles and homoagglomerates. Therefore, this coupling technique is highly attractive for monitoring the effects of DOM on the stability of colloids in complex media. The versatility of HDC ICP MS is demonstrated by its successful applications to diverse samples. In particular, it has been used to investigate the stability of citrate stabilized silver colloids in reconstituted natural water in the presence of different types of natural organic matter. These particles were stable for at least one hour independently of the type of DOM used and the pH, in accordance with a coauthored publication addressing the stability of silver colloids in the River Rhine. Direct monitoring of DOM adsorption on colloids was not possible using UV and fluorescence detectors. Preliminary attempts to investigate the adsorption mechanism of humic acids on silver colloids using fluorescence spectroscopy suggest that fluorescent molecules are not adsorbed on silver particles. Several solutions for overcoming the encountered difficulties in the analysis of DOM interactions are proposed and the numerous perspectives offered by further developments and applications of HDC-(SP)-ICP-MS in environmental sciences are discussed in detail.
Modern agriculture is a dominant land use in Europe, although it has been associated with negative effects on biodiversity in agricultural landscapes. One species-rich insect group in agro-ecosystems is the Lepidoptera (moths and butterflies); however, the populations of a number of Lepidoptera species are currently declining. The aims of this thesis were to assess the amount and structure of field margins in agricultural landscapes, study the effects of realistic field margin input rates of agrochemicals (fertilizer and pesticides) on Lepidoptera, and provide information on moth pollination services.
In general, field margins are common semi-natural habitat elements in agro-ecosystems; however, data on the structure, size, and width of field margins is limited. An assessment in two German agricultural landscapes (4,000 ha each) demonstrated that many of the evaluated field margins were less than 3 m wide (Rhineland‐Palatinate: 85% of margin length; Brandenburg: 45% margin length). In Germany, risk mitigation measures (such as buffer zones) to reduce pesticide inputs to terrestrial non-crop habitats do not have to be established by farmers next to narrow field margins. Thus, narrow field margins receive inputs of agrochemicals, especially via overspray and spray drift. These field margins were used as a development habitat for caterpillars, but the mean abundance of caterpillars was 35 – 60% lower compared with that in meadows. Caterpillars were sensitive to realistic field margin input rates of insecticide (pyrethroid, lambda-cyhalothrin) in a field experiment as well as in laboratory experiments. Moreover, 40% fewer Hadena bicruris eggs were observed on Silene latifolia plants treated with this insecticide compared with control plants, and the flowers of these insecticide-treated plants were less likely to be pollinated by moths. In addition, realistic field margin input rates of herbicides can also affect Lepidoptera. Ranunculus acris L. plants treated with sublethal rates of a sulfonylurea herbicide were used as host plants for Mamestra brassicae L. caterpillars, which resulted in significantly lower caterpillar weights, increased time to pupation, and increased overall development time compared with caterpillars feeding on control plants. These results might have been caused by lower nutritional value of the herbicide-treated plants or increased concentrations of secondary metabolites involved in plant defense. Fertilizer applications slightly increased the caterpillar abundance in the field experiment. However, fertilizers reduce plant diversity in the long term and thus, most likely, also reduce caterpillar diversity.
Moths such as Noctuidae and Sphingidae have been observed to act as pollinators for numerous plant species, including a number of Orchidaceae and Caryophyllaceae. Although in temperate agro-ecosystems moths are less likely to act as the main pollinators for crops, they can pollinate non-crop plants in semi-natural habitats. Currently, the role of moths as pollinators appears to be underestimated, and long-term research focusing on ecosystems is necessary to address temporal fluctuations in their abundance and community composition.
Lepidoptera represent a diverse organism group in agricultural landscapes and fulfill essential ecosystem services, such as pollination. To better protect moths and butterflies, agrochemical inputs to (narrow) field margins habitats should be reduced, for example, via risk mitigation measures and agro-environmental schemes.
This thesis addresses the problem of terrain classification in unstructured outdoor environments. Terrain classification includes the detection of obstacles and passable areas as well as the analysis of ground surfaces. A 3D laser range finder is used as primary sensor for perceiving the surroundings of the robot. First of all, a grid structure is introduced for data reduction. The chosen data representation allows for multi-sensor integration, e.g., cameras for color and texture information or further laser range finders for improved data density. Subsequently, features are computed for each terrain cell within the grid. Classification is performedrnwith a Markov random field for context-sensitivity and to compensate for sensor noise and varying data density within the grid. A Gibbs sampler is used for optimization and is parallelized on the CPU and GPU in order to achieve real-time performance. Dynamic obstacles are detected and tracked using different state-of-the-art approaches. The resulting information - where other traffic participants move and are going to move to - is used to perform inference in regions where the terrain surface is partially or completely invisible for the sensors. Algorithms are tested and validated on different autonomous robot platforms and the evaluation is carried out with human-annotated ground truth maps of millions of measurements. The terrain classification approach of this thesis proved reliable in all real-time scenarios and domains and yielded new insights. Furthermore, if combined with a path planning algorithm, it enables full autonomy for all kinds of wheeled outdoor robots in natural outdoor environments.
In this work a framework is developed that is used to create an evaluation scheme for the evaluation of text processing tools. The evaluation scheme is developed using a model-dependent software evaluation approach and the focus of the model-dependent part is the text-processing process which is derived from the Conceptual Analysis Process developed in the GLODERS project. As input data a German court document is used containing two incidents of extortion racketeering which happened in 2011 and 2012. The evaluation of six different tools shows that one tool offers great results for the given dataset when it is compared to manual results. It is able to identify and visualize relations between concepts without any additional manual work. Other tools also offer good results with minor drawbacks. The biggest drawback for some tools is the unavailability of models for the German language. They can perform automated tasks only on English documents. Nonetheless some tools can be enhanced by self-written code which allows users with development experience to apply additional methods.
Proceedings of the 9th Open German-Russian Workshop on Pattern Recognition and Image Understanding
(2015)
The Proceedings of the 9th Open German-Russian Workshop on Pattern Recognition and Image Understanding include publications (extended abstracts), that cover but are not limited to the following topics: - Mathematical Theory of Pattern Recognition, Image and Speech Processing, Analysis, Recognition and Understanding. - Cognitive Technologies, Information Technologies, Automated Systems and Software for Pattern Recognition, Image, Speech and Signal Processing, Analysis and Understanding - Databases, Knowledge Bases, and Linguistic Tools - Special-Purpose Architectures, Software and Hardware Tools - Vision and Sensor Data Interpretation for Robotics - Industrial, Medical, Multimedia and Other Applications - Algorithms, Software, Automated Systems and Information Technologies in Bioinformatics and Medical Informatics. The workshop took place from December 1st-5th, 2014, at the University of Koblenz-Landau in Koblenz, Germany.
Geographic cluster based routing in ad-hoc wireless sensor networks is a current field of research. Various algorithms to route in wireless ad-hoc networks based on position information already exist. Among them algorithms that use the traditional beaconing approach as well as algorithms that work beaconless (no information about the environment is required besides the own position and the destination). Geographic cluster based routing with guaranteed message delivery can be carried out on overlay graphs as well. Until now the required planar overlay graphs are not being constructed reactively.
This thesis proposes a reactive algorithm, the Beaconless Cluster Based Planarization (BCBP) algorithm, which constructs a planar overlay graph and noticeably reduces the number of messages required for that. Based on an algorithm for cluster based planarization it beaconlessly constructs a planar overlay graph in an unit disk graph (UDG). An UDG is a model for a wireless network in which every participant has the same sending radius. Evaluation of the algorithm shows it to be more efficient than the non beaconless variant. Another result of this thesis is the Beaconless LLRAP (BLLRAP) algorithm, for which planarity but not continued connectivity could be proven.
Placing questions before the material or after the material constitute different reading situations. To adapt to these reading situations, readers may apply appropriate reading strategies. Reading strategy caused by location of question has been intensively explored in the context of text comprehension. (1) However, there is still not enough knowledge about whether text plays the same role as pictures when readers apply different reading strategies. To answer this research question, three reading strategies are experimentally manipulated by displaying question before or after the blended text and picture materials: (a) Unguided processing with text and pictures and without the question. (b) Information gathering to answer the questions after the prior experience with text and pictures. (c) Comprehending text and pictures to solve the questions with the prior information of the questions. (2) Besides, it is arguable whether readers prefer text or pictures when the instructed questions are in different difficulty levels. (3) Furthermore, it is still uncertain whether students from higher school tier (Gymnasium) emphasize more on text or on pictures than students from lower school tier (Realschule). (4) Finally, it is rarely mentioned whether higher graders are more able to apply reading strategies in text processing and picture processing than lower graders.
Two experiments were undertaken to investigate the usage of text and pictures in the perspectives of task orientation, question difficulty, school and grade. For a 2x2(x2x2x2) mixed design adopting eye tracking method, participants were recruited from grade 5 (N = 72) and grade 8 (N = 72). In Experiment 1, thirty-six 5th graders were recruited from higher tier (Gymnasium) and thirty-six 5th graders were from lower tier (Realschule). In Experiment 2, thirty-six 8th graders were recruited from higher tier and thirty-six were from lower tier. They were supposed to comprehend the materials combining text and pictures and to answer the questions. A Tobii XL60 eye tracker recorded their eye movements and their answers to the questions. Eye tracking indicators were analyzed and reported, such as accumulated fixation duration, time to the first fixation and transitions between different Areas of Interest. The results reveal that students process text differently from pictures when they follow different reading strategies. (1) Consistent with Hypothesis 1, students mainly use text to construct their mental model in unguided spontaneous processing of text and pictures. They seem to mainly rely on the pictures as external representations when trying to answer questions after the prior experience with the material. They emphasize on both text and pictures when questions are presented before the material. (2) Inconsistent with Hypothesis 2, students are inclined to emphasize on text and on pictures as question difficulty increases. However, the increase of focus on pictures is more than on text when the presented question is difficult. (3) Different from Hypothesis 3, the current study discovers that higher tier students did not differ from lower tier students in text processing. Conversely, students from higher tier attend more to pictures than students from lower tier. (4) Differed from Hypothesis 4, 8th graders outperform 5th graders mainly in text processing. Only a subtle difference is found between 5th graders and 8th graders in picture processing.
To sum up, text processing differs from picture processing when applying different reading strategies. In line with the Integrative Model of Text and Picture Comprehension by Schnotz (2014), text is likely to play a major part in guiding the processing of meaning or general reading, whereas pictures are applied as external representations for information retrieval or selective reading. When question is difficulty, pictures are emphasized due to their advantages in visualizing the internal structure of information. Compared to lower tier students (poorer problem solvers), higher tier students (good problem solvers) are more capable of comprehending pictures rather than text. Eighth graders are more efficient than 5th graders in text processing rather than picture processing. It also suggests that in designing school curricula, more attention should be paid to students’ competence on picture comprehension or text-picture integration in the future.
101worker is the modular knowledge engineering component of the 101companies project. It has developed maintainability and performance problems due to growing organically, rather than following best software design practices. This thesis lays out these problems, drafts a set of requirements for refactoring the system and then describes and analyzes the resulting implementation. The solution involves collation of scattered and redundant information, setup of unit and functional test suites and incrementalization of the bus architecture of 101worker.
Real-time graphics applications are tending to get more realistic and approximate real world illumination gets more reasonable due to improvement of graphics hardware. Using a wide variation of algorithms and ideas, graphics processing units (GPU) can simulate complex lighting situations rendering computer generated imagery with complicated effects such as shadows, refraction and reflection of light. Particularly, reflections are an improvement of realism, because they make shiny materials, e.g. brushed metals, wet surfaces like puddles or polished floors, appear more realistic and reveal information of their properties such as roughness and reflectance. Moreover, reflections can get more complex, depending on the view: a wet surface like a street during rain for example will reflect lights depending on the distance of the viewer, resulting in more streaky reflection, which will look more stretched, if the viewer is locatedrnfarther away from the light source. This bachelor thesis aims to give an overview of the state-of-the-art in terms of rendering reflections. Understanding light is a basic need to understand reflections and therefore a physical model of light and its reflection will be covered in section 2, followed by the motivational section 2.2, that will give visual appealing examples for reflections from the real world and the media. Coming to rendering techniques, first, the main principle will be explained in section 3 followed by a short general view of a wide variety of approaches that try to generate correct reflections in section 4. This thesis will describe the implementation of three major algorithms, that produce plausible local reflections. Therefore, the developed framework is described in section 5, then three major algorithms will be covered, that are common methods in most current game and graphics engines: Screen space reflections (SSR), parallax-corrected cube mapping (PCCM) and billboard reflections (BBR). After describing their functional principle, they will be analysed of their visual quality and the possibilities of their real-time application. Finally they will be compared to each other to investigate the advantages and disadvantages over each other. In conclusion, the gained experiences will be described by summarizing advantages and disadvantages of each technique and giving suggestions for improvements. A short perspective will be given, trying to create a view of upcoming real-time rendering techniques for the creation of reflections as specular effects.
The increasing, anthropogenic demand for chemicals has created large environmental problems with repercussions for the health of the environment, especially aquatic ecosystems. As a result, the awareness of the public and decision makers on the risks from chemical pollution has increased over the past half-century, prompting a large number of studies in the field of ecological toxicology (ecotoxicology). However, the majority of ecotoxicological studies are laboratory based, and the few studies extrapolating toxicological effects in the field are limited to local and regional levels. Chemical risk assessment on large spatial scales remains largely unexplored, and therefore, the potential large-scale effects of chemicals may be overlooked.
To answer ecotoxicological questions, multidisciplinary approaches that transcend classical chemical and toxicological concepts are required. For instance, the current models for toxicity predictions - which are mainly based on the prediction of toxicity for a single compound and species - can be expanded to simultaneously predict the toxicity for different species and compounds. This can be done by integrating chemical concepts such as the physicochemical properties of the compounds with evolutionary concepts such as the similarity of species. This thesis introduces new, multidisciplinary tools for chemical risk assessments, and presents for the first time a chemical risk assessment on the continental scale.
After a brief introduction of the main concepts and objectives of the studies, this thesis starts by presenting a new method for assessing the physiological sensitivity of macroinvertebrate species to heavy metals (Chapter 2). To compare the sensitivity of species to different heavy metals, toxicity data were standardized to account for the different laboratory conditions. These rankings were not significantly different for different heavy metals, allowing the aggregation of physiological sensitivity into a single ranking.
Furthermore, the toxicological data for macroinvertebrates were used as input data to develop and validate prediction models for heavy metal toxicity, which are currently lacking for a wide array of species (Chapter 3). Apart from the toxicity data, the phylogenetic information of species (evolutionary relationships among species) and the physicochemical parameters for heavy metals were used. The constructed models had a good explanatory power for the acute sensitivity of species to heavy metals with the majority of the explained variance attributed to phylogeny. Therefore, the integration of evolutionary concepts (relatedness and similarity of species) with the chemical parameters used in ecotoxicology improved prediction models for species lacking experimental toxicity data. The ultimate goal of the prediction models developed in this thesis is to provide accurate predictions of toxicity for a wide range of species and chemicals, which is a crucial prerequisite for conducting chemical risk assessment.
The latter was conducted for the first time on the continental scale (Chapter 4), by making use of a dataset of 4,000 sites distributed throughout 27 European countries and 91 respective river basins. Organic chemicals were likely to exert acute risks for one in seven sites analyzed, while chronic risk was prominent for almost half of the sites. The calculated risks are potentially underestimated by the limited number of chemicals that are routinely analyzed in monitoring programmes, and a series of other uncertainties related with the limit of quantification, the presence of mixtures, or the potential for sublethal effects not covered by direct toxicity.
Furthermore, chemical risk was related to agricultural and urban areas in the upstream catchments. The analysis of ecological data indicated chemical impacts on the ecological status of the river systems; however, it is difficult to discriminate the effects of chemical pollution from other stressors that river systems are exposed to. To test the hypothesis of multiple stressors, and investigate the relative importance of organic toxicants, a dataset for German streams is used in chapter 5. In that study, the risk from abiotic (habitat degradation, organic chemicals, and nutrients enrichment) and biotic stressors (invasive species) was investigated. The results indicated that more than one stressor influenced almost all sites. Stream size and ecoregions influenced the distribution of risks, e.g., the risks for habitat degradation, organic chemicals and invasive species increased with the stream size; whereas organic chemicals and nutrients were more likely to influence lowland streams. In order to successfully mitigate the effects of pollutants in river systems, co-occurrence of stressors has to be considered. Overall, to successfully apply integrated water management strategies, a framework involving multiple environmental stressors on large spatial scales is necessary. Furthermore, to properly address the current research needs in ecotoxicology, a multidisciplinary approach is necessary which integrates fields such as, toxicology, ecology, chemistry and evolutionary biology.
The mitral valve is one of the four valves in the human heart. It is located in the left heart chamber and its function is to control the blood flow from the left atrium to the left ventricle. Pathologies can lead to malfunctions of the valve so that blood can flow back to the atrium. Patients with a faulty mitral valve function may suffer from fatigue and chest pain. The functionality can be surgically restored, which is often a long and exhaustive intervention. Thorough planning is necessary to ensure a safe and effective surgery. This can be supported by creating pre-operative segmentations of the mitral valve. A post-operative analysis can determine the success of an intervention. This work will combine existing and new ideas to propose a new approach to (semi-)automatically create such valve models. The manual part can guarantee a high quality model and reliability, whereas the automatic part contributes to saving valuable labour time.
The main contributions of the automatic algorithm are an estimated semantic separation of the two leaflets of the mitral valve and an optimization process that is capable of finding a coaptation-line and -area between the leaflets. The segmentation method can perform a fully automatic segmentation of the mitral leaflets if the annulus ring is already given. The intermediate steps of this process will be integrated into a manual segmentation method so a user can guide the whole procedure. The quality of the valve models generated by the method proposed in this work will be measured by comparing them to completely manually segmented models. This will show that commonly used methods to measure the quality of a segmentation are too general and do not suffice to reflect the real quality of a model. Consequently the work at hand will introduce a set of measurements that can qualify a mitral valve segmentation in more detail and with respect to anatomical landmarks. Besides the intra-operative support for a surgeon, a segmented mitral valve provides additional benefits. The ability to patient-specifically obtain and objectively describe the valve anatomy may be the base for future medical research in this field and automation allows to process large data sets with reduced expert dependency. Further, simulation methods that use the segmented models as input may predict the outcome of a surgery.
Taxonomy and Systematics of Spiny-Backed Treefrogs, Genus Osteocephalus (Amphibia: Anura: Hylidae)
(2015)
The pan-Amazonian treefrog genus Ostecephalus is poorly understood both on a taxonomic and phylogenetic level. The status of several frogs already or not yet referred to the genus is unclear and the relationships among the genus and with respect to related genera is not understood. In this work O. cabrerai (Cochran and Goin, 1970) from Colombia and Peru is redescribed and O. festae (Peracca, 1904) from the foothills of the Andes in Ecuador is revalidated. Hyla inframaculata Boulenger, 1882, from the lower Amazon in Brazil, is reallocated to Osteocephalus and O. elkejungingerae (Henle, 1981) from the Andean foothills in Peru is shown to be a synonym of Hyla mimetica (Melin, 1941), the valid name being O. mimeticus. Hyla vilarsi Melin, 1941 is considered a valid species in the genus Osteocephalus and revalidated from the synonymies of several other frogs. Three new species, O. castaneicola from northern Bolivia and southern Peru, O. duellmani from a sub-Andean mountain range in southern Ecuador, and O. camufatus from central Amazonian Brazil, are described. A phylogenetic analysis based on up to nine mitochondrial genes and one nuclear one reveals the paraphyly of the genus as previously understood with respect to the genus Tepuihyla. A new taxonomy is proposed, securing the monophyly of Osteocephalus and Tepuihyla by rearranging and redefining the content of both genera. A new genus, Dryaderces, is erected for the sister group of Osteocephalus. The colouration of newly metamorphosed individuals is proposed as a morphological synapomorphy for Osteocephalus. Five monophyletic species groups within Osteocephalus are recognized, three species of Osteocephalus (O. germani, O.rnphasmatus, O. vilmae) and three species of Tepuihyla (T. celsae, T. galani, T. talbergae) synonymized and three species (Hyla helenae to Osteocephalus, O.rnexophthalmus to Tepuihyla and O. pearsoni to Dryaderces gen. n.) reallocated. Furthermore, nine putative new species are flagged (an increase to 138% of the current diversity), an indication that species numbers are largely underestimated, with most hidden diversity centred on widespread and polymorphic nominal species. The evolutionary origin of breeding strategies within Osteocephalus is discussed in the light of this new phylogeny and a novel type of amplexus (gular amplexus) is described.
Aquatic macrophytes can contribute to the retention of organic contaminants in streams, whereas knowledge on the dynamics and the interaction of the determining processes is very limited. The objective of the present study was thus to assess how aquatic macrophytes influence the distribution and the fate of organic contaminants in small vegetated streams. In a first study that was performed in vegetated stream mesocosms, the peak reductions of five compounds were significantly higher in four vegetated stream mesocosms compared to a stream mesocosm without vegetation. Compound specific sorption to macrophytes was determined, the mass retention in the vegetated streams, however, did not explain the relationship between the mitigation of contaminant peaks and macrophyte coverage. A subsequent mesocosm study revealed that the mitigation of peak concentrations in the stream mesocosms was governed by two fundamentally different processes: dispersion and sorption. Again, the reductions of the peak concentrations of three different compounds were in the same order of magnitude in a sparsely and a densely vegetated stream mesocosm, respectively, but higher compared to an unvegetated stream mesocosm. The mitigation of the peak reduction in the sparsely vegetated stream mesocosm was found to be fostered by longitudinal dispersion as a result of the spatial distribution of the macrophytes in the aqueous phase. The peak reduction attributable to longitudinal dispersion was, however, reduced in the densely vegetated stream mesocosm, which was compensated by compound-specific but time-limited and reversible sorption to macrophytes. The observations on the reversibility of sorption processes were subsequently confirmed by laboratory experiments. The experiments revealed that sorption to macrophytes lead to compound specific elimination from the aqueous phase during the presence of transient contaminant peaks in streams. After all, these sorption processes were found to be fully reversible, which results in the release of the primarily adsorbed compounds, once the concentrations in the aqueous phase starts to decrease. Nevertheless, the results of the present thesis demonstrate that the processes governing the mitigation of contaminant loads in streams are fundamentally different to those already described for non-flowing systems. In addition, the present thesis provides knowledge on how the interaction of macrophyte-induced processes in streams contributes to mitigate loads of organic contaminants and the related risk for aquatic environments.
This research examines information audit methodologies and information capturing methods for enterprise social software which are an elementary part of the audit process. Information auditing is lacking of a standardized definition and methodology because the scope of the audit process is diversified and dependent on the organization undertaking the audit. The benefits of information auditing and potential challenges of Enterprise 2.0 the audit can overcome are comprehensive and provide a major incentive for managers to conduct an audit. Information asset registers as a starting point for information auditing are not specifically focusing on social software assets. Therefore this research pro-ject combines asset registers from different areas to create a new register suitable for the requirements of Enterprise 2.0. The necssary adaptations caused by the new character of the assets are minor. The case study applying the asset register for the first time however reveals several problematic areas for information auditors completing the register. Rounding up the thesis a template is developed for setting up new work spaces on enterprise social software systems with appropriate metadata taking into account the meaningful metadata discovered in the asset register.