Refine
Year of publication
- 2013 (87) (remove)
Document Type
- Bachelor Thesis (31)
- Doctoral Thesis (23)
- Part of Periodical (13)
- Master's Thesis (12)
- Diploma Thesis (3)
- Study Thesis (3)
- Conference Proceedings (1)
- Habilitation (1)
Keywords
- Pflanzenschutzmittel (3)
- Information Retrieval (2)
- Routing (2)
- Vorlesungsverzeichnis (2)
- ABox (1)
- Abduktion <Logik> (1)
- Aggregation (1)
- Agrochemikalien (1)
- Arbeitsbelastungen (1)
- Arbeitszufriedenheit (1)
- Bach (1)
- Bewertung (1)
- Biogeografie (1)
- Biomonitoring (1)
- Boden (1)
- Bodenchemie (1)
- Bodenökologie (1)
- Burn-out-Syndrom (1)
- Burnout (1)
- C++ (1)
- CIDR (1)
- Calculus (1)
- Cations (1)
- Chironomus riparius (1)
- Computational Toxicology (1)
- Compute Shader (1)
- Computergraphik (1)
- Computermodell (1)
- Computervisualistik (1)
- Cooperative Learning; Teaching Methods (1)
- Crayfish (1)
- Crayfish plague (1)
- Deduktion (1)
- Defi-Now! (1)
- Defibrillator (1)
- Differentia Scanning Calorimetry (1)
- Differential scanning calorimetry (1)
- Digitale Bibliothek (1)
- Distance Vector Routing (1)
- Distanz Vektor Routing (1)
- Distribution <Linguistik> (1)
- E-KRHyper (1)
- E-KRHyper theorem prover (1)
- Edelkrebs (1)
- Elektronische Bibliothek (1)
- Emergenz (1)
- Endokrine Regulation (1)
- Englisch (1)
- Enterprise 2.0 (1)
- Entwicklung (1)
- Environmental Risk Assessment (1)
- Erste Hilfe (1)
- Fabric Simulation (1)
- First aid (1)
- Fledermäuse (1)
- Flugbegleiter (1)
- Fluss (1)
- Fragebeantwortung (1)
- GIRT (1)
- Game Design (1)
- Gefrierpunktserniedrigung (1)
- Genetic diversity (1)
- Genetische Variabilität (1)
- Gewässer (1)
- Glasumwandlung (1)
- Glasübergang (1)
- Graphik (1)
- Grundwasser (1)
- Grundwasserfauna (1)
- Grundwasserökologie (1)
- Hyaluronan (1)
- Hyaluronsäure (1)
- Hydratation (1)
- Hydration (1)
- Individualisierung von Lernwegen (1)
- Individualized Learning (1)
- Individuelle Förderung (1)
- Informatik (1)
- Information (1)
- Information Flow Ontology (1)
- Information Visualization (1)
- Informationsverarbeitung (1)
- Informationsverlinkung (1)
- Informationsvisualisierung (1)
- Informetrie (1)
- Integrated Model (1)
- Interactive Visualizations (1)
- Interaktive Visualisierungen (1)
- Internetregulierung (1)
- Kation-Brücken (1)
- Kationen (1)
- Kognitive Linguistik (1)
- Kontiguität (1)
- Konturfindung (1)
- Konzept (1)
- Kookkurrenz (1)
- Kooperatives Lernen (1)
- Krebspest (1)
- Landwirtschaft (1)
- Lendenwirbelsäule (1)
- Limnologie (1)
- Limology (1)
- Line Space (1)
- Linespace (1)
- Linked Data Modeling (1)
- Linking of Information (1)
- Literaturrecherche (1)
- Logischer Schluss (1)
- Lookup-Algorithmen (1)
- MKS-Simulation (1)
- Magnetis (1)
- Mesofauna (1)
- Methode (1)
- Mikroorganismus (1)
- Mitarbeiterzufriedenheit (1)
- Mixture Toxicity (1)
- Museums visitors (1)
- Museumsbesucher (1)
- N-Body Simulation (1)
- N-Körper Simulation (1)
- NMR-Spektroskopie (1)
- Non-freezing water (1)
- Nuclear Magnetic R (1)
- OWL (1)
- Online-Kommunikation (1)
- Ontologie (1)
- OpenGL (1)
- OpenGL Shading Language (1)
- Operationsplanung (1)
- Organische Bodensubstanz (1)
- Pestizid (1)
- Pestizide (1)
- Phylogeographie (1)
- Plasticization; Glass transition (1)
- Plastifizieren (1)
- Plastifizierung (1)
- Politik (1)
- Polysaccharide (1)
- Polysaccharides (1)
- Power Law (1)
- Predictive Model (1)
- Programmierung (1)
- Prädikatenlogik (1)
- Präposition (1)
- RDF (1)
- Rechnernetz (1)
- Risikoabschätzung (1)
- Risikoanalyse (1)
- Risikomanagement (1)
- Route Aggregation (1)
- Routen-Aggregation (1)
- Router (1)
- Routing- und Forwarding Tabellen (1)
- Schlussfolgern (1)
- Schreibprozess (1)
- Semantic Web (1)
- Simulation (1)
- Situationales Interesse (1)
- Smartphone Applikation (1)
- Softwareergonomie (1)
- Spiel (1)
- Steuerung (1)
- Stoffsimulation (1)
- Streams (1)
- Stress (1)
- Stygofauna (1)
- Stygoregion (1)
- Suchmaschine (1)
- Supernetting (1)
- Support System (1)
- Säugetiere (1)
- Süßwasserhaushalt (1)
- TBox (1)
- Text Analysis (1)
- Text Mining (1)
- Textlinguistik (1)
- Theorem prover (1)
- Theorembeweiser (1)
- Torf (1)
- Umweltchemikalie (1)
- Umwelttoxikologie (1)
- Umweltwissenschaften (1)
- Unterrichtsmethoden (1)
- Usability (1)
- Videospiel (1)
- Visualisierung (1)
- Vocabulary Mapping (1)
- Wachstumsregler (1)
- Web 2.0 (1)
- Web Analytics (1)
- Wikipedia (1)
- Wirbellose (1)
- Wissensbasis (1)
- World Wide Web (1)
- Zuckmücken (1)
- agent-based simulation (1)
- agriculture (1)
- aquatic ecotoxicology (1)
- automated theorem prover (1)
- bats (1)
- biogeography (1)
- biomonitoring (1)
- burnout (1)
- by-stander effect (1)
- cation bridges (1)
- co-occurrence (1)
- cognitive linguistic approach (1)
- concept (1)
- conflicting information (1)
- contiguity (1)
- development (1)
- digital library (1)
- ecological risk management (1)
- ecosystem functions (1)
- emergence (1)
- endocrine disrupting chemicals (1)
- endokrine Regulation (1)
- english prepositions (1)
- flight attendant (1)
- freshwater ecosystem (1)
- game (1)
- governance (1)
- groundwater ecology (1)
- groundwater fauna (1)
- iSearch (1)
- information flow regulation (1)
- information processing (1)
- interaktiv (1)
- invertebrates (1)
- knowledge base (1)
- kollaboratives Schreiben (1)
- konfligierende Information (1)
- kooperatives Schreiben (1)
- landscape (1)
- life cycle test (1)
- mammals (1)
- metasearch engine (1)
- microorganisms (1)
- minimum self-contained graphs (1)
- modelling (1)
- nicht gefrierbares Wasser (1)
- norm (1)
- ontology (1)
- peat (1)
- pesticide (1)
- pesticides (1)
- plant protection products (1)
- policy modelling (1)
- probabilistic (1)
- question answering (1)
- risk assessment (1)
- search engine (1)
- situational interest (1)
- smartphone app (1)
- soil (1)
- soil organic matter (1)
- stygofauna (1)
- teaching (1)
- usability study (1)
- video game (1)
- workload (1)
- Ökologie (1)
- Ökosystem (1)
- Ökotoxologie (1)
Institute
- Fachbereich 4 (50)
- Fachbereich 7 (9)
- Zentrale Einrichtungen (8)
- Fachbereich 8 (4)
- Institut für Computervisualistik (4)
- Institut für Informatik (4)
- Institute for Web Science and Technologies (2)
- Fachbereich 5 (1)
- Institut für Germanistik (1)
- Institut für Integrierte Naturwissenschaften, Abt. Biologie (1)
The conservation of groundwater ecosystems requires an assessment and evaluation scheme that shows the state of the ecosystem. Consequently, faunal and microbial criteria are required for groundwater monitoring, in addition to physico-chemical analyses. To proof the adequacy of the application of groundwater organisms for the biological assessment of groundwater quality, an extensive sampling collection of various groundwater systems was accomplished between 2002 and 2009 in Germany. Key aspects were the examination of the indicator potential of groundwater communities towards surface-groundwater interactions and anthropogenic impacts, as well as the analysis of stygofaunal distribution patterns, as a base and reference for a faunal assessment scheme of groundwater systems. The sampling design considered local, regional, and biogeographic conditions. To test the indicator potential of groundwater organisms on a local and regional scale, groundwater systems in Nordrhein-Westfalen (NRW) and Baden-Württemberg (BW) were examined. The faunal and microbial data from unconsolidated aquifers (Erftgebiet, NRW) show the sensitivity of groundwater organisms against land use effects, e.g. extensive agriculture. Data analyses revealed positive correlations of organic material (estimated amount of detritus, TOC) and nitrate with faunal abundance, species richness, diversity and the proportions of stygoxene species. Moreover, the bacterial abundance and diversity in the groundwater of the Erftgebiet was high compared to oligotrophic groundwater systems, indicating an effect of surface influence due to agricultural land use. The groundwater colonization in the Alb-Donau-Kreis (BW) was analyzed for regional effects (landscape, type of aquifer, hydrogeology) and local effects (comparing single wells). The results show that the fauna reflects the strength of the hydrological exchange on different spatial scales. Furthermore, the fauna reflects the interaction of regional and local conditions. Accordingly, the diversity and abundance of groundwater organisms was influenced by the high connectivity of the karst and unconsolidated alluvial aquifers, the type of land use, covering layers of soil, the age of groundwater, and the sampling depths. In general, faunal and microbial data of the Alb-Donau-Kreis are characteristic for oligotrophic, oligoalimonic groundwaters. The large scale analyses of stygofaunal distribution patterns revealed significant biogeographical differences of the communities. These community patterns of the groundwater fauna do not coincide with existing classification schemes defined for surface landscapes or freshwater systems. The largest differences between faunal surface and subsurface distribution patterns were found between the groundwater of northern and southern Germany and the foothills of the central mountain ranges - all of them regions shaped by the last ice ages.
In accordance with the faunal data assessed in groundwater, four different stygoregions were defined that are populated by distinct faunal assemblages. These are 1) the "Northern lowlands", 2) the "Central mountain ranges", 3) the "South-western mountain ranges", and 4) the "Southern mountain ranges and northern alps". The study corroborates that stygofaunal and microbial communities are an adequate tool for the qualitative assessment and monitoring of groundwater ecosystems. The best indicators to detect anthropogenic impacts on groundwater ecosystems are the faunal diversity, abundance, the proportions of stygobitic (obligate groundwater species) and stygoxene species (species not obligate for groundwater), and the bacterial abundance. The development of an ecologically based groundwater assessment and management, is crucial for the conservation of our groundwater ecosystems and thus, healthy drinking water. The defintion of "stygoregions" is an important base for the development of an assessment and reference scheme for groundwater ecosystems. The assessment of the ecological state of groundwater systems must be conducted on local scale, because the strength of the local hydrological influence determines the amount of food and oxygen as well as stygoxene animals within the aquifer, and thus shapes the local groundwater communities. Nevertheless, information of the biogeographic and regional conditions is needed as a reference for the type of species and abundances that potentially can occur in certain groundwater systems.
In dieser Studienarbeit sollen verschiedene Routing-Lookup Algorithmen aufgelistet und verglichen werden, mit denen eine Routing-Tabelle erstellt und angepasst werden kann. Dazu werden hier nur dynamische Verfahren in Betracht gezogen. Allgemein wird die Funktionsweise einer Routing-Tabelle erklärt und drei Verfahren bzw. Algorithmen analysiert und bewertet. Die Algorithmen werden anhand von Beispielen erläutert und in einem abschließenden Kapitel gegenüber gestellt. Dabei werden die Vor- und Nachteile der einzelnen Verfahren aufgelistet.
Assessment of bat activity in agricultural environments and the evaluation of the risk of pesticides
(2013)
Although agriculture dominates with around 50% area much of Europe- landscape, there is virtually no information on how bats use this farmed environment for foraging. Consequently, little is known about effective conservation measures to compensate potential negative effects of agrarian management practice on the food availability for bats in this habitat. Moreover, there are currently no specific regulatory requirements to include bats in European Union risk assessments for the registration of pesticides since no information about pesticide exposure on this mammal group is available. To evaluate the potential pesticide exposure of bats via ingestion of contaminated insects, information about bat presence and activity in agricultural habitats is required. In order to examine bat activity on a landscape scale it was necessary to establish a suitable survey method. Contrary to capture methods, telemetry, and direct observations, acoustic surveys of bat activity are a logistically feasible and cost-effective way of obtaining bat activity data. However, concerns regarding the methodological designs of many acoustic surveys are expressed in the scientific literature. The reasons are the failing of addressing temporal and spatial variation in bat activity patterns and the limitations of the suitability of the used acoustic detector systems. By comparing different methods and detector systems it was found that the set up of several stationary calibrated detector systems which automatically trigger the ultrasonic recording has the highest potential to produce reliable, unbiased and comparable data sets on the relative activity of bats.
By using the proposed survey method, bat diversity and activity was recorded in different crops and semi-natural habitats in southern Rhineland-Palatinate. Simultaneously, the availability of aerial prey insects was studied by using light and sticky traps. In more than 500 sampling nights about 110,000 call sequences were acoustically recorded and almost 120,000 nocturnal insects were sampled. A total of 14 bat species were recorded, among them the locally rare and critically endangered northern bat (Eptesicus nilssonii) and the barbastelle (Barbastella barbastellum), all of them also occurring over agricultural fields. The agricultural landscape of southern Palatinate is dominated by vineyards, a habitat that was shown to be of low quality for most bat species because of the demonstrated low availability of small aerial insects. By surveying bat activity and food availably in a pair-wise design on several rain water retention ponds and neighbouring vineyards it was demonstrated that aquatic insect emergence in artificial wetlands can provide an important resource subsidy for bats. The creation of artificial wetlands would be a possibility to create important foraging habitats for bats and mitigate negative effects of management practice in the agricultural landscape.
In several other agricultural crops, however, high abundances of suitable prey insects and high bat activity levels, comparable or even higher than in the nearby forests and meadows known to be used as foraging habitats were demonstrated. Especially high bat activity levels were recorded over several fruit orchards and vegetable fields where insects were also present. Both crops are known for high pesticide inputs, and, therefore, a pesticide exposure through ingestion of contaminated insects can not be excluded. To follow the current risk assessment approach for birds and mammals pesticide residues were measured on bat-specific food items in an apple orchard following insecticide applications and bat activity was recorded in parallel. The highest residue values were measured on foliage-dwelling arthropods which may results in a reproductive risk for all bat species that, even to a small extent, include this prey group in their diet. The presence of bats in agricultural landscapes that form a majority of the land area in Europe but also on a global scale leads to exposure of bats by contaminated food and depletion of their food resources by pesticide use. So far conservation efforts for bats focussed on securing hibernation sites and the creation of artificial roost sites since especially the latter were thought to be limiting population growth. However the potential pesticide effects might be also crucial for the population persistence in agricultural landscapes of bats and need to be addressed adequately, especially in risk assessment procedures for the regulation of pesticides.
English prepositions take only a small proportion of the language but play a substantial role. Although prepositions are of course also frequently used in English textbooks for secondary school, students fail to incidentally acquire them and often show low achievements in using prepositions correctly. The strategy commonly employed by language instructors is teaching the multiple senses of prepositions by rote which fails to help the students to draw links between the different meanings in usage. New findings in Cognitive Linguistics (CL) suggest a different approach to teaching prepositions and thus might have a strong impact on the methodologies of foreign language teaching and learning on the aspects of meaningful learning. Based on the Theory of Domains (Langacker, 1987), the notions of image schemas (Johnson, 1987) as well as the Conceptual Metaphor Theory (Lakoff & Johnson, 1980), the present study developed a CL-inspired approach to teaching prepositions, which was compared to the traditional teaching method by an empirical study conducted in a German school setting. Referring to the participants from the higher track and the medium track, who are at different proficiency levels, the results indicate that the CL-inspired teaching approach improved students" performance significantly more than the traditional approach in all the cases for the higher track and in some cases for the medium track. Thus, these findings open up a new perspective of the CL-inspired meaningful learning approach on language teaching. In addition, the CL-inspired approach demonstrates the unification of the integrated model of text and picture comprehension (the ITPC model) in integrating the new knowledge with related prior knowledge in the cognitive structure. According to the learning procedure of the ITPC model, the image schema as visual image is first perceived through the sensory register, then is processed in the working memory by conceptual metaphor, and finally it is integrated with cognitive schemata in the long term memory. Moreover, deep-seated factors, such as transfer of mother tongue, the difficulty of teaching materials, and the influence of prior knowledge, have strong effects on the acquisition of English prepositions.
Augmented Reality (AR) is getting more and more popular. To augment information into the field of vision of the user using HMDs, e.g. front shields of a car, glasses, displays of a smartphone or tablets are the main use of AR technology. It is necessary to get the position and orientation (pose) of the camera in space to augment correctly.
Nowadays, this is solved with artificial markers. These known markers are placed in the room and the system is taught to this set up. The next step is to get rid of these artificial markers. If we are calculating the pose without such markers we are talking about marker-less tracking. Instead of artificial markers we will use natural objects in the real world as reference points to calculate the pose. Thus, this approach can be used flexibly and dynamically. We are no longer dependent on artificial markers but we need much more knowledge about the scenery to find the pose. This is compensated by technical actions and/or the user himself. However, both solutions are neither comfortable nor efficient for the usage of such a system. This is why marker-less 3D tracking is still a big field of research.
This sets the starting point for the bachelor thesis. In this thesis an approach is proposed that needs only a quantity of 2D Feature from a given camera image and a quantity of 3D Feature of an object to find the initial Pose. With this approach, we got rid of the technical and user assistance. 2D and 3D Features can be detected in any way you like.
The main idea of this approach is to build six correspondences between these quantities. With those we are able to estimate the pose. Each 3D Feature is mapped with the estimated pose onto image coordinates, whereby the estimated pose can be evaluated. Each distance is measured between the mapped 3D Feature and the associated 2D Feature. Each correspondency is evaluated and the results are summed up to evaluate the whole pose. The lower this summed up value is, the better the pose. It has been shown to have a correct pose with a value around ten pixels.
Due to lots of possibilities to build six correspondences between the quantities, it is necessary to optimize the building process. For the optimization we will use a genetic algorithm.
During the test case the system worked quite reliably. The hit rate was around 90% with a runtime of approximately twelve minutes. Without optimization it can take easily some years.
Die vorliegende Arbeit behandelt die Entwicklung einer Simulationsumgebung zur Darstellung von Objekten im Weltraum und ihrer gravitativen Wechselwirkung zu einander.
Vorab werden in Kapitel 1 Motivation und Zielsetzung der Arbeit erläutert, des Weiteren werden die verwendeten Werkzeuge benannt. Die nötigen astronomischen Grundlagen werden in Form von Begriffserklärungen und der Vorstellung der dieser Arbeit zugrunde liegenden physikalischen Gesetze in Kapitel 2 beschrieben.
Kapitel 3 befasst sich mit dem Aufbau der einzelnen Klassen. Hier wird insbesondere auf die Berechnung der Positionen und Geschwindigkeiten der simulierten Himmelskörper und den Aufbau und die Funktionsweise der verwendeten Elemente der Graphikengine Ogre3D eingegangen.
Im Kapitel 4 wird der Einsatz des Werkzeugs 3ds Max zur Erstellung der Geometrieobjekte und Materialien erläutert.
Abschließend wird in Kapitel 5 ein Fazit gezogen und mögliche zukünftige Erweiterungen erwogen.
This habilitation thesis deals with the effects of toxicants on freshwater ecosystems and considers different toxicant classes (pesticides, organic toxicants, salinity) and biotic endpoints (taxonomic community structure, trait community structure, ecosystem functions).
The thesis comprises 12 peer-reviewed international publications on these topics. All of the related studies rely on mesocosm or field investigations, or the analysis of field biomonitoring or chemical monitoring data. Publications I and II are devoted to passive sampling of a neonicotinoid insecticide and polycyclic aromatic hydrocarbons (PAHs), respectively. They show that biofouling and a diffusion-limiting membrane can reduce the sampling rate of the pulsed insecticide exposure and that receiving phases of different thicknesses can be used to assess the kinetic regime during field deployment of passive samplers. Publications III to VI mainly focus on trait-based approaches to reveal toxicant effects on invertebrates in streams. An overview on the framework and several applications of a trait-based approach to detect effects of pesticides (SPEARpesticides index) are given in publication III. Publication IV describes the development of a trait database for South-East Australian stream invertebrates and its successful application in the adaptation of SPEARpesticides as well as the development of a salinity index. Moreover, a conceptual model for the future development of trait-based biomonitoring indices is proposed. Publication V reports a mesocom study on the effects of a neonicotinoid insecticide on field-realistic invertebrate communities. The insecticide had long-term effects on the invertebrate communities, which were only detected when grouping the taxa according to their life-history traits. A comprehensive field study employing different pesticide sampling methods including passive sampling and biomonitoring of the invertebrate and microbial communities is presented in publication VI. The study did not find pesticide-induced changes in the microbial communities, but detected adverse effects of current-use pesticides on the invertebrate communities using the trait-based SPEARpesticides index. This index is also applied in a meta-analysis on thresholds for the effects of pesticides on invertebrate communities in publication VII. It is shown that there is a similar dose-response relationship between SPEARpesticides and pesticide toxicity over different biogeographical regions and continents. In addition, the thresholds for effects of pesticides are lower than derived from most mesocosm studies and than considered in regulatory pesticide risk assessment. The publications VIII to X use statistical data analysis approaches to examine effects of toxicants in freshwater ecosystems. Using governmental monitoring data on 331 organic toxicants monitored monthly in 4 rivers over 11 years, publication VIII finds that organic toxicants frequently occurred in concentrations envisaging acute toxic effects on invertebrates and algae even in large rivers. Insecticides and herbicides were the chemical groups mainly contributing to the ecotoxicological risk. Publication IX introduces a novel statistical method based on a similarity index to estimate thresholds for the effects of toxicants or other stressors on ecological communities. The application of the method for deriving thresholds for salinity, heavy metals and pesticides in streams is presented in three case studies. Publication X tackles the question of interactive effects between different toxicants using data from a field study on stream invertebrates in 24 sites of South-East Australia. Both salinity and pesticides exhibited statistically significant effects on the invertebrate communities, but no interaction between the stressors was found. Moreover, salinity acted on a higher taxonomical level than pesticides suggesting evolutionary adaptation of stream invertebrates compared to pesticide stress. Publications XI and XII concentrate on the effects of toxicants on biodiversity, ecosystem functions and ecosystem services, with publication XI summarising different studies related to the ecological risk assessment for these endpoints. A field study on the effects of pesticides and salinity on the ecosystem functions of allochthonous organic matter decomposition, gross primary production and ecosystem respiration is presented in publication XII. Both pesticides and salinity reduced the breakdown of allochthonous organic matter, whereas no effects on the other ecosystem functions were detected. A chapter following these publications synoptically discusses all studies of this habilitation thesis and draws general conclusions. It is stressed that in order to advance the understanding of effects of toxicants on freshwater ecosystems more ecological realism is needed in ecotoxicological approaches and that the spatiotemporal extent of toxicant effects needs more scrutiny.
This study investigates crowdfunding, a new form of financing projects. In the past years more and more crowdfunding platforms emerged. The main question is if crowdfunding is able to compete with the traditional types of financing social projects. The history and development of crowdfunding is presented in this paper. The different crowdfunding models are explained. An overview of German crowd funding platforms is presented. Based on successful social crowdfunding projects a list of key success factors is listed and described. In a case study a concept for financing a social project through crowdfunding is developed upon the previous studies.
Worldwide one third to one half of the freshwater crayfish species are threatened with population decline or extinction. Besides habitat deterioration, pollution, and other man-made environmental changes, invasive species and pathogens are major threats to the survival of European crayfish species. Freshwater crayfish are the largest freshwater invertebrates and strongly influence the structure of food webs. The disappearance of crayfish from a water body may change the food web and could have dramatic consequences for an ecosystem.rnOne goal in modern species conservation strategies is the conservation of genetic diversity, since genetic diversity is an advantage for the long-term survival of a species. The main aim of my thesis was to reveal the genetic structure and to identify genetic hotspots of the endangered noble crayfish (Astacus astacus) throughout Europe (part 1 of my thesis). Since the most significant threat to biodiversity of European crayfish species is the crayfish plague pathogen Aphanomyces astaci I studied new aspects in the distribution of A. astaci (part two of my thesis). The results serve as a basis for future conservation programs for freshwater crayfish. In the first part of my thesis I conducted a phylogeographic analysis of noble crayfish using mitochondrial DNA and nuclear microsatellite data. With these methods I aimed to identify its genetic hotspots and to reconstruct the recolonization history of central Europe by this species. I detected high genetic diversities in southestern Europe indicating that noble crayfish outlasted the cold climate phases during the Pleistocene in this region (Appendix 1). Because of the high genetic diversity found there, southeastern Europe is of particular importance for the conservation of noble crayfish. The mitochondrial DNA analysis points to a bifurcated colonization process from the eastern Black Sea basin to a) the North Sea and to b) the Baltic Sea basin (Appendix 2). A second independent refugium that was localized on the Western Balkans did not contribute to the colonization of central Europe. Furthermore, I found that the natural genetic structure is dissolved, probably due to the high human impact on the distribution of noble crayfish (e.g. artificial translocation). In the second part of this thesis using real-time PCR I identified calico crayfish (Orconectes immunis) as the fourth North American crayfish species to be carrier of the agent of the crayfish plague (Appendix 3). Furthermore I detected the crayfish plague pathogen in American spiny-cheek crayfish (Orconectes limosus) and native narrow-clawed crayfish (Astacus leptodactylus) in the lower Danube in Romania (Appendix 4). The distribution of infected spiny-cheek crayfish poses a threat to the native biodiversity in southeastern Europe and shows the high invasion potential of this crayfish species. Moreover, I found that even the native narrow-clawed crayfish in the Danube Delta, about 970 km downstream of the current invasion front of American crayfish, is a carrier of A. astaci (Appendix 5). This finding is of high importance, as the native species do not seem to suffer from the infection. In Appendix 6 I elucidate demonstrate that the absence of the crayfish plague agent is the most likely explanation for the coexistence of populations of European and American crayfish in central Europe. In my thesis I show that the common assumption that all North American crayfish are carrier of A. astaci and that all native crayfish species die when infected with A. astaci does not hold true. The studies presented in my thesis reveal new aspects that are crucial for native crayfish conservation: 1) The genetic diversity of noble crayfish is highest in southeastern Europe where noble crayfish outlasted the last glacial maximum in at least two different refugia. 2) Not all American crayfish populations are carrier of A. astaci and 3) not all Europen crayish populations die shortly after being infected with the crayfish plague pathogen.rnTo conserve native crayfish species and their (genetic) diversity in the long term, further introductions of American crayfish into European waters must be avoided. However, the introduction will only decrease if the commercial trade with non-indigenous crayfish species is prohibited.
Infinite worlds
(2013)
This work is concerned with creating a 2D action-adventure with roleplay elements. It provides an overview over various tasks of the implementation. First, the game idea and the used gamemechanism are verified and a definfinition of requirements is created. After introducing the used framework, the software engineering concept for realization is presented. The implementation of control components, game editor, sound and graphics is shown. The graphical implementation pays special attention to the abstraction of light and shadow into the 2D game world.