53 research outputs found

    Implications of design and data quality for the analysis of a nationwide biodiversity monitoring scheme

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    Biodiversity monitoring schemes are designed to infer trends in biodiversity over long time periods. The value of a biodiversity monitoring program depends largely on its data quality. High quality data allow to estimate temporal trends without bias and with high precision. Data quality largely depends on the initial design of the monitoring scheme, on properly conducted fieldwork, on various aspects of quality control mechanisms, and on the methods to analyse the data. In my thesis I show and discuss implications of design and data quality presenting five case studies using data from the Swiss Biodiversity Monitoring Scheme (BDM). The BDM is a long-term programme of the Swiss Federal Office for the Environment and was initiated in 2001 to monitor Switzerland’s biodiversity. The programme focuses on changes in species richness and surveys selected species groups in a systematic sampling grid all over the country. Defined and constant sampling methods are needed to allow for unbiased and precise estimations of biodiversity trends. In Chapter I, we analysed inter-observer variation of double-sampled vegetation plots. We could show that both systematic (directed) methodological errors and random variance of species counts were small. We concluded that BDM methods are adequate for detecting biodiversity trends. In the meantime this conclusion has been widely confirmed with recent data from quality control. Chapter II focuses on detectability of species that provides the link between a raw species count and true species richness. Variation in detectability between species or habitats may considerably bias trend estimates in biological studies. We therefore asked if capture-recapture methods were suitable to analyse differences in species detectability of butterflies and looked for underlying factors that may cause variation in detectability. Because the methods available at that time were not allowing the analysis of butterfly surveys over the whole season we had to restrict it to three mid-season surveys. We found that average detectability per count was 0.61 and was influenced by observer, transect and region. Individual species during one count were detected with a mean probability of 0.50. Since the study has been published in 2007 statistical methods have been substantially developed and nowadays enable detailed analyses of butterfly communities. In the study in Chapter III we demonstrated how data from the systematic BDM surveys could be used in combination with environmental variables. We tested different sets of variables for modelling plant species richness and produced species richness maps for Switzerland by predicting species richness for each kilometre square. We found that the final models performed similarly well. Average elevation was the best single variable for explaining plant species richness nationwide. Species richness maps typically showed belt-like patterns of highest richness at intermediate altitudes. We discussed different approaches for explaining such “mid-elevational peaks” of species richness. In the frame of the BDM vascular plants, butterflies and birds are surveyed on the same sites during the same years. These simultaneous studies may be considered as a major advantage of the BDM compared to the monitoring programs in other countries. In the final two chapters we therefore inferred patterns between the species groups. Chapter IV is based on data of the first iteration of surveys. We looked at the changes that had happened in surveyed species communities of plants, birds and butterflies within the period of 5 years. As a response to climate warming we expected species to shift their distribution towards higher altitudes. We used the “Community Temperature Index” (CTI) to test for differences in reaction to climate change. As expected, in the lowlands birds and butterflies tracked climate warming with an average uphill shift of 42 and 38m respectively, while plants showed a shift of only 8m. At higher elevations there was no significant CTI change in plants and butterflies. In general our results supported the idea that reactions to climate change in alpine landscapes were lowest and alpine landscapes could be safer places because of their highly varied surfaces. In the study in Chapter V we examined to what extent distribution patterns of butterfly species are shaped by interactions with their individual host plants or, alternatively, by environmental factors. Our findings indicated that butterfly - host plant interactions were not relevant in benign environments. In contrast, at the cold distribution limits there was a strong coincidence between butterfly and plant ranges. We argued that this could be evidence for butterfly species being limited by the distribution of their host plants in harsh environments and discussed the implications of the findings under climate change conditions. Finally I summarized the most important results and also included more recent experiences from other studies using BDM data and from unpublished analyses, e.g. from quality control. I concluded in discussing the strength and weaknesses of long-monitoring programmes and pointed out that they should be considered as a complementary data source and reference for experimentally orientated research

    Automated Pattern-Based Service Deployment in Programmable Networks

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    This paper presents a flexible service deployment architecture for the automated, on-demand deployment of distributed services in programmable networks. The novelty of our approach is (a) the customization of the deployment protocol by utilizing modular building blocks, namely navigation patterns, aggregation patterns, and capability functions, and (b) the definition of a corresponding service descriptor. A customizable deployment protocol has several important advantages: It supports a multitude of services, and it allows for an ad hoc optimization of the protocol according to the specific needs of a service and the current network conditions. Moreover, our architecture provides an environment for studying new patterns which aim at reducing deployment latency and bandwidth for certain services. We demonstrate how the developed architecture can be used to setup a virtual private network, and we present measurements conducted with our prototype in the PlanetLab test network. Furthermore, a comparison of a distributed pattern with a centralized pattern illustrates the performance trade-off for different deployment strategie

    04411 Abtracts Collection -- Service Management and Self-Organization in IP-based Networks

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    From 03.10.04 to 06.10.04, the Dagstuhl Seminar 04411 ``Service Management and Self-Organization in IP-based Networks\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

    Microdomain Ca2+ Activation during Exocytosis in Paramecium Cells. Superposition of Local Subplasmalemmal Calcium Store Activation by Local Ca2+ Influx

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    In Paramecium tetraurelia, polyamine-triggered exocytosis is accompanied by the activation of Ca2+-activated currents across the cell membrane (Erxleben, C., and H. Plattner. 1994. J. Cell Biol. 127:935– 945). We now show by voltage clamp and extracellular recordings that the product of current × time (As) closely parallels the number of exocytotic events. We suggest that Ca2+ mobilization from subplasmalemmal storage compartments, covering almost the entire cell surface, is a key event. In fact, after local stimulation, Ca2+ imaging with high time resolution reveals rapid, transient, local signals even when extracellular Ca2+ is quenched to or below resting intracellular Ca2+ concentration ([Ca2+]e ⩽ [Ca2+]i). Under these conditions, quenched-flow/freeze-fracture analysis shows that membrane fusion is only partially inhibited. Increasing [Ca2+]e alone, i.e., without secretagogue, causes rapid, strong cortical increase of [Ca2+]i but no exocytosis. In various cells, the ratio of maximal vs. minimal currents registered during maximal stimulation or single exocytotic events, respectively, correlate nicely with the number of Ca stores available. Since no quantal current steps could be observed, this is again compatible with the combined occurrence of Ca2+ mobilization from stores (providing close to threshold Ca2+ levels) and Ca2+ influx from the medium (which per se does not cause exocytosis). This implies that only the combination of Ca2+ flushes, primarily from internal and secondarily from external sources, can produce a signal triggering rapid, local exocytotic responses, as requested for Paramecium defense

    ERIS: revitalising an adaptive optics instrument for the VLT

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    ERIS is an instrument that will both extend and enhance the fundamental diffraction limited imaging and spectroscopy capability for the VLT. It will replace two instruments that are now being maintained beyond their operational lifetimes, combine their functionality on a single focus, provide a new wavefront sensing module that makes use of the facility Adaptive Optics System, and considerably improve their performance. The instrument will be competitive with respect to JWST in several regimes, and has outstanding potential for studies of the Galactic Center, exoplanets, and high redshift galaxies. ERIS had its final design review in 2017, and is expected to be on sky in 2020. This contribution describes the instrument concept, outlines its expected performance, and highlights where it will most excel.Comment: 12 pages, Proc SPIE 10702 "Ground-Based and Airborne Instrumentation for Astronomy VII

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