Das Projekt "Ground-truthing magnetic recording in meteorites" wird vom Umweltbundesamt gefördert und von Ludwig-Maximilians-Universität München, Department für Geo- und Umweltwissenschaften, Sektion Geophysik durchgeführt. Whether primordial bodies in the solar system possessed internally-generated dynamos is a fundamental constraint to understand the dynamics and timing of early planetary formation. Paleointensity studies on several meteorites reveal that their host planets possessed magnetic fields within an order-of magnitude of the present Earths field. Interpretation of paleointensity data relies heavily on fundamental knowledge of the magnetic properties of the magnetic carriers, such as the single to multidomain size threshold or how the saturation magnetization varies as a function of grain size, yet very little knowledge exists about these key parameters for some of the main magnetic recorders in meteorites: the iron-nickel alloys. Moreover, most meteorites have experienced some amount of shock during their histories, yet the consequence of even very small stresses on paleointensity data is poorly known.We wish to fill these gaps by magnetically characterizing Fe-Ni alloys as a function of grain size and by determining how absolute and relative paleointensity data are biased by strain levels lower than those petrologically observable (less than 4-5 GPa). For example, our preliminary work shows that an imposed stress of 0.6 GPa will reduce absolute paleointensity estimates by 46Prozent for single domain magnetite-bearing rocks. In general, paleointensity determinations possess inherent disadvantages regarding measurement precision and the inordinate amount of human time investment. We intend to overcome these limitations by extending and improving our fully automated magnetic workstation known as the SushiBar.
Das Projekt "Relating genetic variation and stability of forest genetic resources: A metapopulation approach" wird vom Umweltbundesamt gefördert und von Georg-August-niversität Göttingen, Büsgen-Institut, Abteilung Forstgenetik und Forstpflanzenzüchtung durchgeführt. Forest gene conservation efforts aim to maintain the genetic diversity that enables a species to persist under variable environmental conditions. Due to the dynamics and spatial structuring inherent in populations conserved in situ and ex situ, resource managers must be aware of relationships between the distribution of genetic variation and resource stability and how these are affected by determinants of population dynamics. During the current initial grant period, emphasis has been shifted away from the previous more conceptual approach towards a more practice-oriented investigation of the measurement of genetic variation and its role in the persistence of forest genetic resources, many of which are divided into more or less isolated subpopulations that together form a metapopulation. The objective of this renewal proposal is thus to analyze and develop descriptors of genetic variation suitable for revealing relationships between genetic variation and stability of forest genetic resources using a metapopulation approach. The work schedule comprises further development of our stochastic metapopulation model, analysis and development of descriptors of metapopulation stability and genetic variation, investigation of the effects of various determinants of population dynamics on genetic variation and metapopulation stability, interpretation of descriptors in special cases of the metapopulation model, and formulation of recommendations for the design and monitoring of conservation measures. Software and a Workshop will aid in the dissemination of our results.
Das Projekt "Transgenic strawberries and their wild relatives - a potential model for extinction by hybridisation" wird vom Umweltbundesamt gefördert und von Universität Basel, Botanisches Institut, Abteilung Pflanzenökologie durchgeführt. Do genetically modified strawberries pose a threat to wild varieties? Do genetically modified strawberries pose a threat to wild varieties? Strawberries are an important niche product in Switzerland. Breeders are experimenting with genetic engineering methods to enhance the marketability of this product. There are risks inherent in this approach since the transfer of modified genes to wild strawberries could endanger the continued existence of the wild varieties. Background Transgenic varieties of strawberry with higher yields and enhanced root development already exist. The first release trials have already begun in Italy. However, if transgenic varieties of strawberry cross-breed with wild ones, there may be negative effects. The hybrids produced in this way are often sterile, yet by back-crossing with wild types or by producing prolific numbers of offshoots they can penetrate the native flora and displace it. Objectives This project has two basic goals. First, it seeks to assess the extent to which transgenic strawberries are capable of cross-breeding with their wild relatives. Second, it seeks to investigate the possible ecological impact of such crossbreeding under various environmental conditions in order to assess the risks associated with cultivating transgenic strawberries in the open. Methods Greenhouse experiments with honey bees, the most important pollinators of strawberries, will be carried out to show whether and how efficiently natural pollination occurs between transgenic and wild strawberries. Genetic methods will be used to determine how frequently foreign pollination between cultivated and wild strawberries has already occurred in the open in the past. The possible ecological implications of this will be quantified using life history data such as growth and competitive pressure. In these experiments, transgenic and artificially cross-bred strawberries from the laboratory will be planted in various soils. Significance The cultivation of transgenic plants is associated with potential risks for their wild relatives. Scientists have warned that the latter could become extinct as a result of undesirable cross-breeding. However, to date the true extent of these risks has barely been investigated. This project aims to close this gap by generating basic data with transgenic and wild strawberries as model organisms. These data could ultimately be relevant for other related crop plants such as apple trees or cherry trees.
Das Projekt "Quantification of ice content in mountain permafrost based on geophysical data and simulated annealing" wird vom Umweltbundesamt gefördert und von University of Fribourg, Geosciences Departement, Geography Unit durchgeführt. Current and future global warming will cause the degradation of mountain permafrost, which may strongly influence the stability of permafrost slopes or rock walls with potentially hazardous consequences. Due to the strong heterogeneity of both the thermal regime and the ground composition of mountain permafrost, its response to atmospheric forcing can however be highly variable for different landforms and within short distances. The spatial distribution of ice and liquid water is important for determining the sensitivity of a specific permafrost occurrence to climate change because of their large influence on the pace of temperature changes (by effects of latent heat) and their importance for geotechnical properties of the ground. Detailed knowledge of the material properties and internal structures of frozen ground is therefore an important prerequisite to determine the sensitivity of permafrost to climate change. Except for the active layer ice and water contents and their temporal and spatial variability usually cannot be measured directly. Geophysical methods are sensitive for the ice and liquid water content in the ground. With the proposed collaboration, two similar but complementary approaches to quantify the composition of the ground based on 2D sections of geophysical data will be combined for an improved determination of ice and water contents in permafrost regions. The so-called 4-phase model (4PM) is based on two simple petrophysical relationships for electrical resistivity and seismic velocity and estimates volumetric fractions of ice, water, and air within the pore volume of a rock matrix by jointly using complementary data sets from electric and seismic measurements. Due to inherent ambiguities in the model it is still restricted to specific cases and often allows only a rough estimation of the phase fractions. Major drawbacks of the current 4PM comprise the unsatisfactory discrimination between rock and ice and its under-determinedness, requiring the prescription of the porosity and further parameters. The so-called RSANN model (developed and used by the host institution) uses the technique of simulated annealing (a Monte-Carlo-type stochastic simulation approach) as an optimization tool for the integration of electrical resistivity and P-wave velocity to derive 2D sections of porosity, water saturation and volumetric water content. The simulated annealing technique allows - due to its iterative procedure - more parameters to be predicted instead of being prescribed as in the 4PM. The objective of the proposed collaboration is to combine the advantages of the two algorithms (4PM and RSANN) to overcome the shortcomings of the 4PM in order to improve the reliability of the determined ice and liquid water contents. (...)