4242 research outputs found
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Integrating biological, ecological and socio-economic indicators to assess data-limited, tropical, small-scale fisheries : the case of the Colombian Pacific
Full text linkIn tropical countries Small-Scale Fisheries (SSF) contribute more than half of the total fisheries catch and provide food security, nutrition, employment and multiplier effects to local coastal economies. The multi-species and multi-gear nature of SSF demands a holistic approach for their assessment and management. Using the Colombian Pacific coast as a case study area of tropical, data-limited SSF, this thesis presents a comprehensive assessment that includes: a) the stock condition of main target species, b) the potential impacts of SSF to the biological communities and ecosystems, and (c) the socio-economic drivers of the gear choices made by small-scale fishers. A set of practical recommendations to transition towards more holistic assessments and management of tropical SSF is drawn from the results of the thesis, taking into account the regional and global contexts
Spreadable Media, Citizens, and Participatory Culture : Uses and Effects of Political Internet Memes
Full text linkInternet memes are increasingly visible in political contexts and are believed to be a tool for people to express opinions, values, and experiences in a digital public sphere. This research project was undertaken to learn more about Internet meme users by exploring the uses for Internet memes and the effects of Internet meme use in political settings. Across three studies, this dissertation thus presents an exploration of the political relevance of Internet meme use. The first study dealt with the central motives for using Internet memes, and the role that users attribute to political Internet memes. In a Delphi-method interview study with meme users (N=25), participants discussed why they seek out Internet memes. A qualitative content analysis revealed that political meme use is driven by an interplay of self-expression, social identity, and entertainment motives, and Internet memes are seen as an instrument for political engagement. To focus on the political attitudes and behaviors of meme users, the second study used an online survey (N=333) to assess the antecedents and consequences of political Internet meme use. Hierarchical regression analyses showed that the use of political Internet memes can be significantly predicted by political interest and by political meme efficacy, or the belief that memes are an efficacious political activity. Further, meme use significantly predicted higher levels of engagement in conventional and unconventional political activities, even when controlling for political interest. The third study was therefore aimed at uncovering mechanisms of possible mobilizing effects of political Internet meme use. In a controlled laboratory setting, participants (N=104) were randomly assigned into one of three conditions. Subsequent prosocial behavior tendencies were not found to differ across the conditions, although marginally significant interaction effects related to cost were found, along with a result related to a measure of selfish tendencies. Implications of the overall results and recommendations for future research are discussed
Understanding service modularity - antecedents, processes, and operationalization
Full text linkThe concept of service modularity has emerged as a promising solution to achieve a sound balance between growing customer requirements for individualization and a companya s necessity to standardize services for cost efficiency reasons. Although service modularity has been on the academic agenda for some time, not many examples of modularized service portfolios can be identified. Therefore, this dissertation aims to examine service modularity in the context of professional services by connecting the decisions made before, during, and after service modularization with a specific focus on the effect on the sales process. The enhanced understanding of the concept is expected to uncover new research gaps in service modularity, as well as promote its application in the context of professional services. Apart from its theoretical contribution, this dissertation will provide practitioners with an improved understanding with respect to what it means to offer a modular service portfolio, what needs to be done for the transformation, as well as what to expect from its completion
Analyse der ökologischen Auswirkung einer elektronischen Ersetzung von Seefrachtkonnossementen mittels Blockchain, insbesondere bezogen auf den CO2-Fußabdruck
Full text linkUm herauszufinden, wie sich die CO2-Fußabdrücke in Bezug auf den postalischen und elektronischen Versand der Konnossemente auswirken, wurde eine quantitative Analyse durchgeführt. Es wurde ein Beispielfall betrachtet, der anhand von finanzwirtschaftlichen Zahlen auf die weltweiten Emissionen hochgerechnet wurde. Dies geschah bei der analogen Abwicklung anhand der CO2-Emissionen der ein-zelnen Transportteile. Im Rahmen der Blockchain-basierten Umsetzung wurden die CO2-Fußabdruck anhand der Prozessschritte und der Transaktionsdaten der Bitcoin und von Ether beziehungsweise unter der Verwendung der CO2-Emissionen eines ausgewählten Fujitsu Servers hochgerechnet
We. The Revolution, a Review. Vive la Revolution or Death and All His Friends
No full textReview of the video game We. The Revolutio
Modeling the North Atlantic and Labrador Sea dynamics with the global high-resolution ocean model FESOM
Full text linkThe subpolar regions of the North Atlantic ocean are crucial for the global climate in terms of deep water formation, which is a major driver for the Atlantic Meridional Overturning Circulation (AMOC) that transports heat into northern latitudes and returns cold deep water masses southward. The influence of a high horizontal resolution (5-15 km) on the general circulation and hydrography in the North Atlantic is investigated using the finite element sea ice-ocean model FESOM. A stronger shift of the upper ocean circulation and water mass properties during the model spinup is found in the high-resolution model version compared to the low-resolution (ca. 1 deg) control run. In quasi-equilibrium, the high-resolution model is able to reduce typical low-resolution model biases. Especially, it exhibits a weaker salinification of the North Atlantic subpolar gyre and a reduced mixed layer depth in the Labrador Sea. However, during the spinup adjustment, initially improved high-resolution features partially reduce over time: the strength of the Atlantic overturning and the path of the North Atlantic Current are not maintained, and hence hydrographic biases known from low-resolution ocean models return in the high-resolution quasi-equilibrium state. Long baroclinic Rossby waves are identified as a potential cause for the strong upper ocean adjustment of the high-resolution model. In addition, the high-resolution model is able to represent turbulent processes on the meso- and submesoscale within the Labrador Sea interior. Mesoscale eddies transport buoyant seawater into regions of strong convection, thereby contributing significantly to restratification. In particular, ageostrophic velocities associated with baroclinic instability were found to play a crucial role on length scales on the order of O(10) km. Until now, the dynamics on such scales were rarely modeled with a realistic global high-resolution ocean model in quasi-equilibrium
Effective and Efficient Reconstruction Schemes for the Inverse Medium Problem in Scattering
Full text linkThis thesis challenges with the development of a computational framework facilitating the solution for the inverse medium problem in time-independent scattering in two- and three-dimensional setting. This includes three main application cases: the simulation of the scattered field for a given transmitter-receiver geometry; the generation of simulated data as well as the handling of real-world data; the reconstruction of the refractive index of a penetrable medium from several measured, scattered fields. We focus on an effective and efficient reconstruction algorithm. Therefore we set up a variational reconstruction scheme. The underlying paradigm is to minimize the discrepancy between the predicted data based on the reconstructed refractive index and the given data while taking into account various structural a priori information via suitable penalty terms, which are designed to promote information expected in real-world environments. Finally, the scheme relies on a primal-dual algorithm. In addition, information about the obstacle's shape and position obtained by the factorization method can be used as a priori information to increase the overall effectiveness of the scheme. An implementation is provided as MATLAB toolbox IPscatt. It is tailored to the needs of practitioners, e.g. a heuristic algorithm for an automatic, data-driven choice of the regularization parameters is available. The effectiveness and efficiency of the proposed approach are demonstrated for simulated as well as real-world data by comparisons with existing software packages
Cardiovascular physiology of the edible crab Cancer pagurus under Ocean Warming and Acidification
Full text linkRising atmospheric CO2 levels have caused warming of the atmosphere and oceans and reduced the seawater pH. Thermal tolerance of marine ectotherms was shown to be reduced in high-CO2 waters, limiting chances for survival under the combined effects of warming and acidification. An enhanced temperature sensitivity in a high-CO2 ocean has been confirmed by reduced O2 levels in the body fluids of large marine crustacea. The haemolymph O2 level is a function of oxygen supply and demand and largely influenced by the activities of ventilatory and circulatory systems. The present work highlights the impact of combined CO2 and temperature effects on the ventilatory and cardiovascular performance of the edible crab Cancer pagurus. It adds to previous mechanistic studies on the general synergistic effects of both drivers, revealing limitations in ventilatory performance and cardiac work. The relevance of these results is underlined by the non-invasive measurements on truly resting animals
Study of diversity and function of the marine key group Vis6 with cultivation-independent methods
Full text linkPhytoplankton in the ocean represents about 0.2% of all photosynthetic biomass on Earth, but is responsible for half of the global CO2 fixation. A large proportion of this produced organic matter is funneled through the microbial loop towards higher trophic levels by heterotrophic microorganisms. These have consequently a great impact on the global carbon cycle, the CO2 concentration in the atmosphere and ultimately our climate. Phytoplankton blooms are short-termed increases in phytoplankton biomass, followed by secondary blooms of heterotrophic bacteria. Taxonomic and ecological studies at the long term ecological research station Helgoland Roads, North Sea, revealed recurring patterns of bacteria on taxonomic and functional level. Members of the phylum Bacteroidetes and in particular of the class Flavobacteriia are among the major responders to phytoplankton blooms. Analyses with both cultivation and cultivation-independent techniques, based on genome sequencing and gene annotations, can reveal the role of individual groups in the degradation of phytoplankton derived organic matter. The focus of this work was the development of a culture-independent pipeline for the targeted access and the subsequent functional genome characterization of bacterial species from the environment. This pipeline combines fluorescence in situ hybridization (FISH) with fluorescence activated cell sorting (FACS) and subsequent genome sequencing. A taxon-specific FISH probe hybridizes to the target cells which are subsequently enriched by cell sorting based on the fluorescence signal. Finally, the DNA of the sorted cells is amplified and sequenced. The development of the pipeline involved an optimization of the recently developed hybridization chain reaction (HCR)-FISH method and the assessment of various cell fixatives concerning their influence on HCR-FISH signal intensity and the quality of genome sequencing and assembly. The developed pipeline was successfully applied on a planktonic seawater sample targeting the so far uncharacterized clade Vis6. This member of the Cryomorphaceae within the Flavobacteriia is recurring during spring phytoplankton blooms off the coast of Helgoland. The description of Vis6 as a novel candidate genus Candidatus Abditibacter with three species was enabled by the combination of the sequences retrieved from targeted sorting pipeline with additional data of North Sea metagenomes and abundance data based on the 16S rRNA identity of Vis6. The growth of Candidatus Abditibacter spp. is likely based on the utilization of phytoplankton-derived polysaccharides and proteins. In the future, the developed pipeline has the potential to be used on low abundance species from highly complex samples, where previous attempts with metagenomics have been unsuccessful so far
Neural correlates of decision making in quasi-realistic binary decision situations : an EEG and fMRI study
Full text linkA central aspect of daily life is decision making, often under uncertain and ill-defined conditions. This may be why there is huge and continuously growing scientific interest in human decision making. Research of decision making was dominated by mathematical and economic models at first, which led to abstract problems and decision situations, but recent years have seen a growing trend to orient research towards realistic scenarios. The relatively young branch of Naturalistic Decision Making (NDM) placed analyzing real world decision processes of experts at its very core and emphasizes the importance of recognizing the situation to come to a quick yet reliable decision. Uncertainty is a constant aspect of decision making and can be defined as a feeling of doubt that delays or impedes the decision. The aim of this study was to investigate the neural correlates of decision making under certainty and uncertainty in a quasi-realistic setting, that approached the principles of NDM as much as possible in neuroscience. Participants were presented with variations of a simple binary choice. Two types of information from different sources were presented to them: a weather forecast on the probability of rain and a picture of the sky. Based on this information the participants decided whether they would want to take an umbrella with them in a hypothetical context situation. This information varied in its conclusiveness and in its congruency, evoking either certainty or uncertainty in the decision makers, depending on their decision strategies. Each participant undertook the experiment twice; their neural activity was measured once with the EEG and once with fMRI. To account for said individual decision strategies, uncertain and certain decision making during the experiment was identified for each participant individually. This categorization was based on the congruency of the participants' choices. Multiple analyses were conducted to investigate the data, namely: statistical analyses of the behavioral data, including visualization and parameterization of decision strategies; a contrast and conjunction analysis of the fMRI data, and an additional analysis of individual voxel based activation; an ERP analysis, and a frequency analysis of the EEG data. Overall, this study has shown two things. One concerns the neural correlates of decision making: The processing of uncertain and certain decision making seems to have some differences, as addressed in the relevant literature, but seems to be mostly driven by the same fronto-parietal network. The second concerns the nature of quasi-realistic research, which seems to be possible in a laboratory context and offers much needed ecological validity, but requires attention to detail and individual variations. To properly use quasi-realistic designs, the standard procedures of analysis have to be adapted. During the analysis of the data, a number of limitations of the experimental design became apparent, mostly stemming from an initial underestimation of the participant's individually varying decision strategies. Many possible improvements and alternative approaches to design and analysis could be devised based on these realizations, which may be beneficial to future studies in this general field