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211.
Dieter Lorenz-Petzold 《Astrophysics and Space Science》1984,106(2):409-413
We discuss the Brans-Dicke-Bianchi type-VIIh field equations. Exact solutions are given for the vacuum case as well as for the stiff matter case. The derived solutions are the generalizations of the GRT-solutions first given by Doroshkevichet al. (1973) and Lukash (1974a). In addition we present a new BDT-stiff matter solution which has no analogy in the GRT. 相似文献
212.
Reference Minerals for the Microanalysis of Light Elements 总被引:2,自引:0,他引:2
M. Darby Dyar Michael Wiedenbeck David Robertson Laura R. Cross Jeremy S. Delaney Kurt Ferguson Carl A. Francis Edward S. Grew Charles V. Guidotti Richard L. Hervig John M. Hughes John Husler William Leeman Anne V. McGuire Dieter Rhede Heike Rothe Rick L. Paul Ian Richards Martin Yates 《Geostandards and Geoanalytical Research》2001,25(2-3):441-463
The quantitative determination of light element concentrations in geological specimens represents a major analytical challenge as the electron probe is generally not suited to this task. With the development of new in situ analytical techniques, and in particular the increasing use of secondary ion mass spectrometry, the routine determination of Li, Be and B contents has become a realistic goal. However, a major obstacle to the development of this research field is the critical dependence of SIMS on the availability of well characterized, homogeneous reference materials that are closely matched in matrix (composition and structure) to the sample being studied. Here we report the first results from a suite of large, gem crystals which cover a broad spectrum of minerals in which light elements are major constituents. We have characterized these materials using both in situ and wet chemical techniques. The samples described here are intended for distribution to geochemical laboratories active in the study of light elements. Further work is needed before reference values for these materials can be finalized, but the availability of this suite of materials represents a major step toward the routine analysis of the light element contents of geological specimens. 相似文献
213.
Christoph Schlumpf Claudia Pahl-Wostl Andreas Schönborn Carlo C. Jaeger Dieter Imboden 《Climatic change》2001,51(2):199-241
Participatory Integrated Assessement (IA) methods complement analytical methods like IA-modeling in their explicit inclusion of stakeholders and decision-makers in the assessment. Integrated Assessment is perceived as a process of social learning involving scientists, stakeholders, policymakers and the society at large. We introduce a new approach to provide expert knowledge for participatory integrated assessments of regional climate change: `Interactive Citizen's Information Tools' (ICITs). ICITs provide citizens with expert knowledge about causes of climate change, potential impacts, and policy options to address anthropogenic climate change. In this paper we discuss the development and application of IMPACTS in IA-focus groups in Switzerland. IMPACTS is based on user-friendly hypermedia technologies and allows citizens to get informed on a broad range of potential climate change impacts – with an emphasison prevailing uncertainties. IA-focus groups are deliberative group discussions that make use of computer tools to support the discussion and assessment. The goal of IA-focus groups is to elicit how informed citizens judge the risks of anthropogenic climate change. Experiences with IMPACTS showed that the combination of focus groups with ICITs is a feasible and promising approach for a participatory IA of regional climate change, in particular, and of complex environmental issues, in general. 相似文献
214.
Annett Bartsch Martin Gude Christer Jonasson & Dieter Scherer 《Geografiska Annaler: Series A, Physical Geography》2002,84(3&4):171-178
Sediment transport processes in the Kärkevagge are investigated concerning their spatial and temporal characteristics due to long–term monitoring. Within this study remote sensing techniques and GIS modelling in connection with geomorphic mapping are applied for identification and characterization of geomorphic process units. Relationships between geomorphometric parameters and slope processes like solifluction, talus creep and rockfall have been analysed. Multitemporal Landsat–TM5 scenes are used as source for landcover characteristics (Normalized Difference Vegetation Index) after preprocessing involving orthorectification and topographic normalization in order to remove possible terrain–induced effects. Additionally, a digital elevation model with a resolution of 20 m for the Kärkevagge catchment is developed and parameters like slope gradient, slope aspect and profile curvature are extracted as input for the analysis of the sediment transport system. The combination of landcover information, geomorphometrical and topological features allows the definition of areas for single process activities. They show specific sediment displacement characteristics depending on material conditions, topological and geometrical features. Geomorphic process units, which show a homogenous composition, are extracted from these available layers. 相似文献
215.
Martin Gude Gerhard Daut Susanne Dietrich Roland Mäusbacher Christer Jonasson Annett Bartsch & Dieter Scherer 《Geografiska Annaler: Series A, Physical Geography》2002,84(3&4):205-212
The analysis of Holocene geomorphic process activity demands long–term data sets, which are available for the Kärkevagge catchment due to 50 years of intensive geomorphologic field studies. This data set is used in combination with additional field measurements, remote sensing and digital elevation model (DEM) analysis to provide input data for modelling Holocene valley development. On the basis of this information, geomorphic process units (GPUs) are defined by means of GIS modelling. These units represent areas of homogeneous process composition that transfer sediments. Since the data base enables the quantification of single processes, the interaction of processes within the units can also be quantified. Applying this concept permits calculation of recent sediment transfer rates and hence leads to a better understanding of actual geomorphic landscape development activity. To extrapolate these data in time and space the process–related sediments in the valley are analysed for depth and total volume, primarily using geophysical methods. In this fashion the validity of measured process rates is evaluated for the Holocene time scale. Results from this analysis are exemplified in a cross–profile showing some of the principal sediment units in the valley. For example, the measured modern rates on a slush torrent debris fan seem to represent the Holocene mean rate. This approach should also be suitable for revealing Holocene geomorphic landscape development in terms of climate change. 相似文献
216.
Dieter Mueller-Dombois Dr. 《GeoJournal》1992,28(2):293-296
Island ecosystems are formed from the same generic building blocks as continental ecosystems. These can be reduced to five: (1) the terrestrial habitat (soil-parent material and topography), (2) the regional and local climate, (3) the regional biota with differential restrictions of accessibility, (4) the ecological roles assumed by the species including their potential for adaptation, and (5) the overriding dimensions of space and time. Unique to island ecosystems are various limitations that can lead to a peculiar ecology. These do not relate to the first two abiotic components mentioned above, but to the biotic components (3) and (4) and their interaction with space and time. Accessibility of species to the island habitat is a primary limitation that prevents many species of the regional biota from becoming established. This in turn results in further restrictions in the ecological types of species coming together. Limited space puts restrictions on population sizes, and time, together with isolation, is setting limits on the evolution of diversity. The paper gives examples by comparing vegetation processes in the Krakatau islands with those in Hawaii. 相似文献
217.
Dieter Kelletat Dr. 《GeoJournal》1991,24(1):77-85
The Palau islands' (Western Carolines, Micronesia) main trends of coastal evolution comprise: rise and submergence of a mid-ocean ridge; four reef building phases (Miocene to Holocene); tilting and uplift; karstification into tropical cockpit karst forms. Extensive mangrove tidal flats are also developed. Their sediments as well as the well developed bioerosive notches on the rock islands indicate a remarkable stability in an area of seismic activity and active subduction. 相似文献
218.
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220.
Dieter Richter 《International Journal of Earth Sciences》1959,46(2):413-420
Ohne Zusammenfassung 相似文献