Performance Evaluation of Vision-Based Algorithms for MAVs

An important focus of current research in the field of Micro Aerial Vehicles (MAVs) is to increase the safety of their operation in general unstructured environments. Especially indoors, where GPS cannot be used for localization, reliable algorithms for localization and mapping of the environment are necessary in order to keep an MAV airborne safely. In this paper, we compare vision-based real-time capable methods for localization and mapping and point out their strengths and weaknesses. Additionally, we describe algorithms for state estimation, control and navigation, which use the localization and mapping results of our vision-based algorithms as input.Comment: Presented at OAGM Workshop, 2015 (arXiv:1505.01065

Depth-dependent abundance of Midas Cichlid fish ( Amphilophus spp: ) in two Nicaraguan crater lakes

The Midas Cichlid species complex (Amphilophus spp.) in Central America serves as a prominent model system to study sympatric speciation and parallel adaptive radiation, since small arrays of equivalent ecotype morphs have evolved independently in different crater lakes. While the taxonomy and evolutionary history of the different species are well resolved, little is known about basic ecological parameters of Midas Cichlid assemblages. Here, we use a line transect survey to investigate the depth-dependent abundance of Amphilophus spp. along the shores of two Nicaraguan crater lakes, Apoyo and Xiloá. We find a considerable higher density of Midas cichlids in Lake Xiloá as compared to Lake Apoyo, especially at the shallowest depth level. This might be due to the higher eutrophication level of Lake Xiloá and associated differences in food availability, and/or the presence of a greater diversity of niches in that lake. In any case, convergent forms evolved despite noticeable differences in size, age, eutrophication level, and carrying capacity. Further, our data provide abundance and density estimates for Midas Cichlid fish, which serve as baseline for future surveys of these ecosystems and are also relevant to past and future modeling of ecological speciatio

Critical Success Factors for ERP system upgrades – The Case of a German large-scale Enterprise

The aim of our study was to gain insight into the research field of critical success factors (CSFs) of enterprise resource planning (ERP) projects, especially the post-implementation phase, with specific focus on system upgrades as an essential part of this phase. Therefore, we conducted a systematic literature review in order to update the existing reviews of CSFs. On the basis of that review, we conducted a single case study within a German large-scale enterprise in the service sector. As a result, we could show that all 31 factors found in the literature review also affect the success of ERP system upgrades. Eight of the top 10 CSFs ranked as most important in the literature review also appear in the top 10 for upgrade projects. However, other factors gained or lost importance considerably in comparison to the literature review

Round robin for glass tank models : Report of the International Commission on Glass (ICG) Technical Committee 21 "Modelling of Glass Melts"

Different numerical and physical models for glass tanks were compared by a simple round robin. Most models produced qualitatively similar velocity and temperature distributions. The minimum residence time of tracers in numerical models gave similar values too, but differed to the physical scale model. An explanation for this is the different kind of batch modelling in both methods of Simulation. Especially the velocity vectors at some fixed test points showed larger deviations. In regions with steep gradients small variations in the local flow distribution can lead to large changes at fixed test points. These differences therefore should not be rated very high

Body shape differences in a pair of closely related Malawi cichlids and their hybrids: Effects of genetic variation, phenotypic plasticity, and transgressive segregation

Citation: Husemann, M., Tobler, M., McCauley, C., Ding, B., & Danley, P. D. (2017). Body shape differences in a pair of closely related Malawi cichlids and their hybrids: Effects of genetic variation, phenotypic plasticity, and transgressive segregation. Ecology and Evolution. doi:10.1002/ece3.2823Phenotypic differences may have genetic and plastic components. Here, we investigated the contributions of both for differences in body shape in two species of Lake Malawi cichlids using wild-caught specimens and a common garden experiment. We further hybridized the two species to investigate the mode of gene action influencing body shape differences and to examine the potential for transgressive segregation. We found that body shape differences between the two species observed in the field are maintained after more than 10 generations in a standardized environment. Nonetheless, both species experienced similar changes in the laboratory environment. Our hybrid cross experiment confirmed that substantial variation in body shape appears to be genetically determined. The data further suggest that the underlying mode of gene action is complex and cannot be explained by simple additive or additive-dominance models. Transgressive phenotypes were found in the hybrid generations, as hybrids occupied significantly more morphospace than both parentals combined. Further, the body shapes of transgressive individuals resemble the body shapes observed in other Lake Malawi rock-dwelling genera. Our findings indicate that body shape can respond to selection immediately, through plasticity, and over longer timescales through adaptation. In addition, our results suggest that hybridization may have played an important role in the diversification of Lake Malawi cichlids through creating new phenotypic variation. © 2017 Published by John Wiley & Sons Ltd

Possible experiment to check the reality of a nonequilibrium temperature

An experiment is proposed to check the physical reality of a nonequilibrium absolute temperature previously proposed from theoretical grounds in the framework of extended irreversible thermodynamics

Homogenisieren von Glas durch Rühren Grundlagen und Modellversuche

In einer kurzen Übersicht werden die allgemeinen Homogenisierungsmechanismen wie Schlierendeformation und Diffusion auf den Spezialfall des Rührens bezogen dargestellt. Es werden dabei einige wesentliche Literaturstehen ausgewertet und ergänzend miteinander verglichen. Für das Rühren unter Durchsatz wird auf die Problematik der Verknüpfung des Verweilzeitverhaltens und der zur Homogenisierung nötigen Geschwindigkeitsgradienten eingegangen. Nach dieser theoretischen Darstellung der grundsätzlichen Problematik werden Möglichkeiten der labormäßigen Unterstützung von Rührerverbesserungen durch physikalische Modelle aufgezeigt. Einer kurzen Übersicht über bisherige experimentelle Verfahrensweisen auf diesem Gebiet folgt die Darstellung der vom Autor angewendeten Methode. Bei diesem Verfahren wird in den Zulauf des Modellrühraggregates ein definiertes Volumen elektrisch leitfähig gemachter Modellflüssigkeit eindosiert. Der danach im Auslauf registrierte zeitliche Verlauf der elektrischen Leitfähigkeit gibt Informationen über die Mischwirkung und den Mischmechanismus des untersuchten Rühraggregates. An Hand eines Beispiels einer einfachen Rührarmform wird gezeigt, wie die in der Versuchsapparatur gemessenen Parameter bei der optimalen Dimensionierung des Rührarms helfen können

Teaching an Old Jaw New Tricks: Diet-Induced Plasticity in a Model Organism, from Weaning to Adulthood

Many organisms exhibit a decrease in the ability to modify their phenotypes in response to shifts in environmental conditions as they mature. Such age-dependent plasticity has important implications in a variety of evolutionary and ecological contexts, particularly with respect to understanding adaptive responses to heterogeneous environments. In this study we used experimental diet manipulation to examine the life-history trajectory of plasticity in the feeding complex of a model organism, the white rabbit (Oryctolagus cuniculus). We demonstrate that, contrary to expectations derived from previous cross-sectional studies of skeletal plasticity, the jaws of weanlings and young adults exhibit similar increases in relative bone cross-sectional areas in response to the introduction of mechanically challenging foods into their diets. Furthermore, we present evidence that sensitivity to loading patterns persists well into adulthood in some regions of the masticatory apparatus in rabbits, indicating that there is an extended window of opportunity to respond to changes in dietary properties during an animal\u27s life span. We conclude that certain aspects of the facial skeleton of rabbits, and perhaps mammals in general, are sensitive to environmental stimuli long after skeletal maturity is achieved, highlighting the importance of plasticity as a source of adaptive variation at later life-history stages

Convergence of gut microbiotas in the adaptive radiations of African cichlid fishes

Ecoevolutionary dynamics of the gut microbiota at the macroscale level, that is, in across-species comparisons, are largely driven by ecological variables and host genotype. The repeated explosive radiations of African cichlid fishes in distinct lakes, following a dietary diversification in a context of reduced genetic diversity, provide a natural setup to explore convergence, divergence and repeatability in patterns of microbiota dynamics as a function of the host diet, phylogeny and environment. Here we characterized by 16S rRNA amplicon sequencing the gut microbiota of 29 cichlid species from two distinct lakes/radiations (Tanganyika and Barombi Mbo) and across a broad dietary and phylogenetic range. Within each lake, a significant deviation between a carnivorous and herbivorous lifestyle was found. Herbivore species were characterized by an increased bacterial taxonomic and functional diversity and converged in key compositional and functional community aspects. Despite a significant lake effect on the microbiota structure, this process has occurred with remarkable parallels in the two lakes. A metabolic signature most likely explains this trend, as indicated by a significant enrichment in herbivores/omnivores of bacterial taxa and functions associated with fiber degradation and detoxification of plant chemical compounds. Overall, compositional and functional aspects of the gut microbiota individually and altogether validate and predict main cichlid dietary habits, suggesting a fundamental role of gut bacteria in cichlid niche expansion and adaptation

The Evolution of Functionally Redundant Species; Evidence from Beetles

While species fulfill many different roles in ecosystems, it has been suggested that numerous species might actually share the same function in a near neutral way. So-far, however, it is unclear whether such functional redundancy really exists. We scrutinize this question using extensive data on the world’s 4168 species of diving beetles. We show that across the globe these animals have evolved towards a small number of regularly-spaced body sizes, and that locally co-existing species are either very similar in size or differ by at least 35%. Surprisingly, intermediate size differences (10–20%) are rare. As body-size strongly reflects functional aspects such as the food that these generalist predators can eat, these beetles thus form relatively distinct groups of functional look-a-likes. The striking global regularity of these patterns support the idea that a self-organizing process drives such species-rich groups to self-organize evolutionary into clusters where functional redundancy ensures resilience through an insurance effect