260 research outputs found

    Friedrich Nietzsche und die Musikphilosophie des späten 19. Jahrhunderts

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    Über die Frage nach der Bedeutung der Musik, die gleichzeitig auf metaphysischer sowie auf semiotischer Ebene gestellt wurde, gibt Nietzsches Werk in mehrfacher Weise Auskunft. Zum einen versteht Nietzsche Musik als eine Art „vor-rationale“ Erfahrung, indem wir unsere Existenz im Musikmachen und Hören als vollzogene Handlung im Aktus auf eine sowohl körperliche und geistige Weise erfahren

    On the Higgs triplet extension of the Standard Model

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    In dieser Diplomarbeit untersuchen wir die Higgs Triplett Erweiterung des Standardmodells der Elementarteilchenphysik, in welcher der skalare Sektor mit einem komplexen skalaren Triplet Δ\Delta mit Hyperladung Y=2Y=2 erweitert wird. Der zusätzliche Term in der Lagrangedichte des Yukawa Sektors induziert einen Majorana Massenterm f\"ur Neutrinos. Desweiteren werden Prozesse, in denen die doppelt geladene Komponente HH^{--} des Higgs Tripletts involviert ist, untersucht. Nachdem wir die totalen Wirkungsquerschnitte der Leptonflavor verletzenden Prozesse eeγδe^- e^- \rightarrow \gamma^- \delta^- (f\"ur γ,δ=e,μ,τ\gamma, \delta = e,\mu, \tau) und des Leptonzahl verletzenden Prozesses eeWWe^- e^- \rightarrow W^- W^- ausrechnen, berechnen wir mehrere partielle Zerfallsbreiten des doppelt geladenen Skalars, n\"amlich Γ(Hμμ)\Gamma(H^{--} \rightarrow \mu^- \mu^-), Γ(Hγδ)\Gamma(H^{--} \rightarrow \gamma^- \delta^-), Γ(HWW)\Gamma(H^{--} \rightarrow W^- W^-), Γ(HWH)\Gamma(H^{--} \rightarrow W^- H^-) und Γ(HWHZ0)\Gamma(H^{--} \rightarrow W^- H^- Z^0).In this thesis we study the Higgs triplet extension of the Standard Model of particle physics where the scalar sector is extended by a complex scalar triplet Δ\Delta with hypercharge Y=2Y = 2 . The additional term in the Lagrangian of the Yukawa sector induces a Majorana mass term for neutrinos. Further on, processes involving the doubly charged component HH^{--} of the Higgs triplet are studied. After calculating the total cross sections of the lepton flavor violating process eeγδe^- e^- \rightarrow \gamma^- \delta^- (for γ,δ=e,μ,τ\gamma, \delta = e,\mu, \tau) and the lepton number violating process eeWWe^- e^- \rightarrow W^- W^-, we compute several partial decay widths of the doubly charged scalar viz. Γ(Hμμ)\Gamma(H^{--} \rightarrow \mu^- \mu^-), Γ(Hγδ)\Gamma(H^{--} \rightarrow \gamma^- \delta^-), Γ(HWW)\Gamma(H^{--} \rightarrow W^- W^-), Γ(HWH)\Gamma(H^{--} \rightarrow W^- H^-) and Γ(HWHZ0)\Gamma(H^{--} \rightarrow W^- H^- Z^0)

    Contrasting effects of mass-flowering crops on bee pollination of hedge plants at different spatial and temporal scales

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    Landscape-wide mass-flowering of oilseed rape (canola Brassica napus) can considerably affect wild bee communities and pollination success of wild plants. We aimed to assess the impact of oilseed rape on the pollination of wild plants and bee abundance during and after oilseed-rape bloom, including effects on crop-noncrop spillover at landscape and adjacent-field scales. We focused on two shrub species (hawthorn Crataegus spp., dog rose Rosa canina) and adjacent herb flowering in forest edges, connected hedges, and isolated hedges in Lower Saxony, Germany. We selected 35 landscape circles of 1 km radius, differing in the amount of oilseed rape; 18 were adjacent to oilseed rape and 17 to cereal fields, and we quantified bee density via pan traps at all sites. Adjacent oilseed rape positively affected fruit mass and seed number per fruit of simultaneously flowering hawthorn (no effect on dog rose, which flowers after the oilseed rape bloom). At the landscape scale, oilseed rape had a negative effect on bumble bee density in the hedges during flowering due to dilution of pollinators per unit area and the consequently intensified competition between oilseed rape and wild shrubs, but a positive effect after flowering when bees moved to the hedges, which still provided resources. In contrast, positive landscape-scale effects of oilseed rape were found throughout the season in forest edges, suggesting that edges support nesting activity and enhanced food resources. Our results show that oilseed rape effects on bee abundances and pollination success in seminatural habitats depend on the spatial and temporal scale considered and on the habitat type, the wild plant species, and the time of crop flowering. These scale-dependent positive and negative effects should be considered in evaluations of landscape-scale configuration and composition of crops. Food resources provided by mass-flowering crops should be most beneficial for landscape-wide enhancement of wild bee populations if seminatural habitats are available, providing (1) nesting resources and (2) continuous flowering resources during the season

    Landscape configuration of crops and hedgerows drives local syrphid fly abundance

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    Summary 1. Human-dominated landscapes are characterized by a mosaic of natural and managed eco- systems, affecting arthropod communities on different spatial scales. Effective landscape man- agement for functionally important organisms suffers from little understanding of organism spillover between semi-natural habitats and adjacent crops, and of how it is affected by the surrounding landscape. 2. We examined syrphid abundance (Diptera: Syrphidae) in three types of linear semi-natural habitats, differing in connectedness to annual crops and forest [forest edges ( n = 12), forest- connected hedges ( n = 11) and isolated hedges ( n = 12)], as well as in the adjacent oilseed rape or winter wheat fields (i.e. altogether n = 70 sites in 35 landscapes). The landscape cir- cles with 1 km radius around the study sites differed in the proportion of oilseed rape (rang- ing from 0% to 35% oilseed rape) enabling us to test landscape-scale effects of oilseed rape. 3. Aphidophagous syrphids were more abundant in forest-connected hedgerows than in for- est edges (with isolated hedges being intermediate), and more abundant in crop fields adjacent to hedgerows than adjacent to forest edges, indicating spillover from semi-natural habitats to the adjacent crop fields. Aphidophagous syrphid abundance was higher in semi-natural habi- tats adjacent to oilseed rape fields than adjacent to wheat fields if the proportion of oilseed rape in the landscape was low (indicating local concentration). 4. Synthesis and applications. This study highlights the potential of hedgerows to enhance the abundances of beneficial syrphids and their spillover to adjacent crop fields, especially when they are connected with forests. We provide evidence that this local exchange is moderated by the extent of mass-flowering crops in the surrounding landscapes due to local concentration. There- fore, measurements for the improvement in local biological functioni ng should be evaluated by simultaneously investigating local and regio nal aspects of crop configurations to allow for region-specific management recommendations. Increasing the total amount of hedgerows in the agricultural matrix under moderate landscape- scale proportions of mass-flowering crops may serve best for the conservation of biodiversity and augmentation of i mportant ecosystem services such as biological control and pollination in lands capes dominated by agricultural cultivations

    Using citizen science to monitor pollination services

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    1. Pollination by insects is a vital ecosystem service and the need for its assessment is increasing in recognition and political pressure, but there are currently no large-scale systematic monitoring schemes in place to measure the direct provision of this service. 2. This study tested a protocol for using a citizen science approach to quantify pollination service provision in gardens and allotments, requiring participants to grow Vica faba L. plants and carry out some simple manipulations of the pollination environment (flowers with bees excluded, flowers hand-pollinated, or flowers left for local pollinators to visit). Volunteers assessed yield in the three treatments. 3. Eighty participants from across the U.K. successfully completed all parts of the protocol; a further 93 participants were unsuccessful but actively engaged with the project. 4. Overall, the present results suggest that pollination services for V. faba are currently not limiting in gardens or allotments in the U.K. It is possible and cost-effective to recruit volunteers to collect data on pollination deficits using this protocol. 5. The approach used in this paper, which could readily be extended to incorporate other plant species reliant on different guilds of pollinators, is feasible for adoption as a national monitoring scheme for pollination services. Key words. Bees, bumblebees, crop yield, ecosystem services, pollinator, urban, Viciafab

    Monitoring costs of result-based payments for biodiversity conservation: Will UAV-based remote sensing be the game-changer?

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    Paying landowners for conservation results rather than paying for the measures intended to provide such results is a promising approach for biodiversity conservation. However, a key roadblock for the widespread implementation of such result-based payment schemes are the frequent difficulties to monitor target species for whose presence a landowner is supposed to receive a remuneration. Until recently, the only conceivable monitoring approach would be conventional monitoring techniques, by which qualified experts investigate the presence of target species on-site. With the rise of remote sensing technologies, in particular increased capabilities and decreased costs of unmanned aerial vehicles (UAVs), technological monitoring opportunities enter the scene. We analyse the costs of monitoring an ecological target of a hypothetical result-based payments scheme and compare the monitoring cost between conventional monitoring and UAV-assisted monitoring. We identify the underlying cost structure and cost components of both monitoring approaches and use a scenario analysis to identify the influence of factors like UAV and analysis costs, area size, and monitoring frequency. We find that although conventional monitoring is the least-cost monitoring approach today, future cost developments are likely to render UAV-assisted monitoring more cost-effective

    Kinetic Parameter Estimation of Solvent Free ReactionsMonitored by 13C NMR Spectroscopy. A Case Study: Mono andDi-(hydroxy)ethylation of Aniline with EthyleneCarbonate

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    The kinetics of solvent-free reactions can be followed in situ by 13C NMR spectroscopy, provided that the reaction mixture can be maintained liquid at the monitoring temperature. The pros and cons of the technique and the correct translation of the signal intensities into concentrations are discussed. A good model for this investigation is the reaction of ethylene carbonate (1) with aniline (2): at 140 °C, two alkylation products of N-mono- and N,N-bis-(2-hydroxy)ethylation of aniline form (compounds 3 and 4, respectively). The overall reaction occurs with heavy volume shrinking, so that the physical as well as the chemical features evolve during the course of the process. The chemical evolution is described by the kinetic constants k1 and k2 of the two N-alkylation steps, the physical evolution by the time dependent activity coefficients α(t). Two complementary procedures are utilized for the determination of these parameters

    Seasonal complementary in pollinators of soft-fruit crops

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    Understanding the relative contributions of wild and managed pollinators, and the functional contributions made by a diverse pollinator community, is essential to the maintenance of yields in the 75% of our crops that benefit from insect pollination. We describe a field study and pollinator exclusion experiments conducted on two soft-fruit crops in a system with both wild and managed pollinators. We test whether fruit quality and quantity is limited by pollination, and whether different pollinating insects respond differently to varying weather conditions. Both strawberries and raspberries produced fewer marketable fruits when insects were excluded, demonstrating dependence on insect pollinators. Raspberries had a short flowering season which coincided with peak abundance of bees, and attracted many bees per flower. In contrast, strawberries had a much longer flowering season and appeared to be much less attractive to pollinators, so that ensuring adequate pollination is likely to be more challenging. The proportion of high-quality strawberries was positively related to pollinator abundance, suggesting that yield was limited by inadequate pollination on some farms. The relative abundance of different pollinator taxa visiting strawberries changed markedly through the season, demonstrating seasonal complementarity. Insect visitors responded differently to changing weather conditions suggesting that diversity can reduce the risk of pollination service shortfalls. For example, flies visited the crop flowers in poor weather and at the end of the flowering season when other pollinators were scarce, and so may provide a unique functional contribution. Understanding how differences between pollinator groups can enhance pollination services to crops strengthens the case for multiple species management. We provide evidence for the link between increased diversity and function in real crop systems, highlighting the risks of replacing all pollinators with managed alternatives

    Disentangling the contributions of dispersal limitation, ecological drift, and ecological filtering to wild bee community assembly

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    The species composition within communities is highly dependent on the rate of species immigration and whether immigrating species possess the functional traits required by the prevailing environmental conditions. Once established, random fluctuations in birth and death rates may reduce the diversity of ecologically equivalent species if local populations are not replenished by immigrating individuals. Consequently, three key processes drive community assembly: dispersal limitation, ecological filtering, and ecological drift. However, disentangling the relative contribution of these processes remains a challenge in community ecology. We used a binomial generalized linear mixed model to test whether the occurrences of solitary bees within 46 communities in southeast Norway were driven by (1) dispersal limitation, that is, the geographic distance to the nearest site where conspecifics occurred; (2) ecological filtering, that is, if forb species richness selected for non-Ericaceae-affiliated species; and (3) ecological drift, that is, if small, isolated communities were dominated by regionally common species. The regression slopes from the model for each potential driver of community composition were compared with those expected under a null model, in which species were treated as ecologically equivalent. Both dispersal limitation and ecological filtering influenced the probability of species occurring within communities. The occurrence of species decreased with elevation, and this relationship depended on the relative commonness of species and their floral preferences. For non-Ericaceae-affiliated species, the patterns of occurrence mirrored that expected under the null (neutral) model, resulting in the same patterns as would be expected under ecological drift. In contrast, the response of Ericaceae-affiliated species differed from what would be expected from the null model. Our results also indicate that processes leading to neutral dynamics in species compositions drive a large part of the gradient in species richness in Norwegian bee communities. These processes seem related to sampling effects so that large and interconnected communities have a higher probability of including regionally rare species than small, isolated communities. Our results suggest that targeting habitats—where the influence of ecological filtering is expected to be greater than that of neutral dynamics—can increase the success of habitat management plans aimed at promoting rare species
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