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991.
Peter Roberts 《The Geographical journal》2004,170(2):126-134
Sustainable economic development strategies promote mutually-beneficial environmental, social and economic progress. Such strategies now form an essential basis for local and regional development. Various models of sustainable economic and environmental industry development have been introduced in recent years, some of which have proved to be of particular value. The theory and practice of sustainable economic development has made rapid progress, and this approach to local and regional development is now generally accepted as offering the opportunity to solve a range of environmental and economic problems and to promote new economic activities that can generate jobs in socially excluded communities. 相似文献
992.
This RAS discussion meeting was arranged with the idea of bringing together solar physicists and magnetospheric physicists, so as to understand better how the two disciplines approach waves, and ultimately to learn from each other. V M Nakariakov, B Roberts and A N Wright report. 相似文献
993.
Phase variations of GPS receiving antennas are a significant error component in precise GPS applications. A calibration procedure
has been developed by Geo++ and the Institut für Erdmessung, which directly determines absolute phase center variations (PCVs)
without any multipath influence by field measurements. The precision and resolution of the procedure allows the determination
of reliable azimuthal variations. PCV may affect long-term static GPS differently than real-time GPS, depending on the applications.
At the same time, different antenna types are involved. Less investigations have been done on absolute PCV of rover antennas
than on geodetic antennas which, however, becomes more important due to the mixed antenna situation in GPS reference networks
and RTK networks. The concepts of the absolute PCV field calibration are summarized and emphasis is placed on a variety of
absolute PCV patterns of geodetic and rover antennas.
Electronic Publication 相似文献
994.
The pelagic ciliate communities from 58 north German lakes differing in their origin (natural lakes and artificial ponds), morphology (from shallow ponds with a maximum depth of below 0.5 m to relatively deep lakes with a maximum depth of more than 10 m, surface areas from below 10 ha to more than 100 ha), trophic state (from mesotrophic to hypertrophic) and salinity (freshwater lakes and brackish water lakes) are described and compared at species level. Each lake was comprehensively sampled quarterly in the years 1996 and 1997, respectively. Applying a quantitative protargol stain, about 140 ciliate species could be identified and quantified in all investigated lakes. 35 species, mainly members of the Prostomatida and Oligotrichida, were found commonly in all types of lakes at all seasons and dominated the pelagic ciliate communities. 3 species were common in freshwaters, but never occurred in brackish lakes. In the brackish waters a mixture of common freshwater species and marine species was found with 13 species exclusively occurring in brackish waters. Lowest ciliate cell numbers were observed for deep freshwater lakes, highest cell numbers were determined for brackish waters. Highest species richness was found in artificial peat ponds with an average of 24 pelagic ciliate species in spring samples. The range of occurrence for the identified species was wide for most common species. However, the influence of some environmental factors could be enlightened. 相似文献
995.
Richard Weaver Andrew P. Roberts Andrew J. Barker 《Earth and Planetary Science Letters》2002,200(3-4):371-386
Paleomagnetic, rock magnetic, and sedimentary micro-textural data from an early Miocene mudstone sequence exposed in Okhta River, Sakhalin, Russia, indicate the presence of pyrrhotite and magnetite at different stratigraphic levels. Sites that contain only magnetite have a reversed polarity characteristic remanent magnetization (ChRM) with a low-coercivity overprint, which coincides with the present-day geomagnetic field direction. Pyrrhotite-bearing sites have stable normal polarity ChRMs that are significantly different from the present-day field direction. After correction for bedding tilt, the ChRM data fail a reversals test. However, the normal polarity pyrrhotite ChRM directions become antipodal to the tilt-corrected magnetite ChRM directions and are consistent with the expected geocentric axial dipole field direction at the site latitude after 40% partial unfolding. These data suggest that the pyrrhotite magnetization was acquired during folding and after lock-in of the magnetite remanences. Electron microscope observations of polished sections indicate that fluid-associated halos surround iron sulphide nodules. Pyrrhotite is present in randomly oriented laths in and around the nodules, and the nodules do not appear to have been deformed by sediment compaction. This observation is consistent with a late diagenetic origin of pyrrhotite. Documentation of a late diagenetic magnetization in pyrrhotite-bearing sediments here, and in recent studies of greigite-bearing sediments, suggests that care should be taken to preclude a late origin of magnetic iron sulphides before using such sediments for geomagnetic studies where it is usually crucial to establish a syn-depositional magnetization. 相似文献
996.
The physical similarities among mine spoils may be strongly influenced by the geologic source of the spoils where overburden
is produced from areas of simple geologic structure. Textures and bulk densities are influenced by the methods of handling
the materials during mining and disposal operations. Where these influences are the same in more than one mining site, surface
hydrology and erosion parameters are often similar. A specific tailing deposit may be highly variable with respect to the
physical and chemical characteristics produced by methods of ore treatment and concentration. This variability makes it difficult
to classify tailings based on surface hydrology and erosion.
Hydrologic characteristics of spoil deposits as related to future successful rehabilitation may be improved by (1) conducting
mining activities to permit identification and segregation of favorable overburden strata for use in revegetation, (2) reconstituting
soil for optimum plant growth, (3) shaping spoils to be compatible with surrounding topography, (4) mulching with organic
materials, and (5) avoiding or ameliorating compaction of the soil-spoil surface.
Mr. Burton is currently hydrologist with the Bureau of Land Management in Lewiston, Montana, U.S.A. 相似文献
997.
998.
999.
P. Armstrong P. M. Chadwick P. J. Cottle J. E. Dickinson M. R. Dickinson N. A. Dipper S. E. Hilton W. Hogg J. Holder T. R. Kendall T. J. L. McComb C. M. Moore K. J. Orford S. M. Rayner I. D. Roberts M. D. Roberts M. Robertshaw S. E. Shaw K. Tindale S. P. Tummey K. E. Turver 《Experimental Astronomy》1999,9(2):51-80
1000.
Melanie J. Leng Neil Roberts Jane M. Reed Hilary J. Sloane 《Journal of Paleolimnology》1999,22(2):187-204
The Konya plain in south central Anatolia, Turkey, which is now largely dry, was occupied around the time of the Last Glacial Maximum by a fresh-oligosaline lake covering more than 4000 km2. Sediment cores from three residual water bodies (Pinarbai, Akgöl and Süleymanhaci) within the larger Pleistocene lake basin, have been analysed using a multidisciplinary approach. The sediment sequences are dated as spanning the last 50 Ka years, although breaks in sedimentation mean that there is only partial chronological overlap between them. Carbon and oxygen isotope analyses on lacustrine carbonate from the three cores give contrasting isotope profiles which reflect the different ages and independent hydrological behaviour of different sub-basins through the late Quaternary. Distinguishing changes that are regional from local effects is aided by modern isotope hydrology studies and by comparing the carbonate 13C and 18O values to diatom and other analyses undertaken on the same cores. 相似文献