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排序方式: 共有161条查询结果,搜索用时 15 毫秒
111.
Costate forms of Lagena (benthonic foraminifer) have been studied in an uppermost Maastrichtian bore-hole core sequence (28 levels) from southern Sweden. Analysis of a large sample shows that consistent assignment to previously described “species” of costate Lagena is not possible. This observation is supported by multivariate analysis of five morphologic variables which indicates that there are no distinct clusters of specimens along principal component axes associated with general size, number of costae, and relationships between roundness of test/length and number of costae. Specimens with a basal ring differ from specimens with an apical spine and those with no basal structure with regard to average number of costae. They also differ from specimens with no basal structure with regard to relationships between roundness of test/length and number of costae. These characters grade into each other thus preventing them from being used as taxonomic criteria.Mean ratios of benthonic foraminifers to total benthonic and planktonic formaminifers determined individually for each level are inversely related to mean relative frequencies of costate Lagena and directly related to mean general sizes of costate Lagena. The benthonic/planktonic ratio has been suggested by other workers to represent a paleobathymetric index across a continental slope and shelf when open marine conditions prevailed. If this were so in the Danish basin at the end of the Cretaceous, costate Lagena would have been relatively less frequent and larger at shallower depths.As a result of the study, the analyzed specimens are considered as representing a single morphospecies of the costate species Lagena sulcata. Between-level variation is regarded as ecophenotypic, and within-level variation as natural biologic variation of no taxonomic significance. A total of about 1000 species of Lagena has been described in the literature which is probably many orders of magnitude too great for a genus with such a simple morphology as Lagena. A revision of the taxonomy of Lagena is, therefore, probably necessary on a wide scale. 相似文献
112.
Jonathan Rutherford 《Geoforum》2008,39(6):1871-1883
This paper focuses on the extent to which recent infrastructure-oriented urban developments in Stockholm concord with various aspects of the ‘splintering urbanism’ thesis of Graham and Marvin. This contextualisation allows us to extend their work empirically and conceptually. In the first instance, we study a particular case of the decline of a unitary networked city (in an urban context largely absent from their book). In the second instance, we develop their notion of ‘unbundling’ to capture not just core changes in the organisation of infrastructure provision, but an overarching disjunction of the established nexus between networks, planning and social welfare in the city. This disjunction operates through interlinked transformations concerning, for example, privatisation and outsourcing in network services, separation of infrastructure planning from broader urban planning, contradictions between the environmental and social mandates of infrastructure, and a (prospective) curtailment of the redistributive, social role of essential network service provision. We conclude nonetheless that this ‘destructive’ moment of unbundling has not so far been pursued by more explicitly ‘creative’ urban fragmentation strategies, due largely to the vestiges of a socio-political consensus based around redistribution and equality. In this respect, the Stockholm case pleads for a conception of ‘splintering’ as a dynamic and multi-stage process which is not only always ongoing, unstable and incomplete, but also non-linear and open to resistance/regulation. 相似文献
113.
Dan Hammarlund Ramon Aravena Lena Barnekow Bjørn Buchardt Göran Possnert 《Journal of Paleolimnology》1997,18(3):219-233
A 9000-year carbonate-rich sediment sequence from a small hard-water lake in northernmost Sweden was studied by means of multi-component stable carbon isotope analysis. Radiocarbon dating of different sediment fractions provides chronologic control and reveals a rather constant hard-water effect through time, suggesting that the lake has remained hydrologically open throughout the Holocene. Successive depletion of 13C in fine-grained calcite and carbonate shells during the early Holocene correlate with a change in catchment vegetation from pioneer herb communities to boreal forest. The vegetational change and associated soil development likely gave rise to an increased supply of 13C-depleted carbon dioxide in groundwater recharging the lake. This process is therefore believed to be the main cause of decreasing values of 13C in dissolved inorganic carbon of the lake and thereby in limnic carbonates. Strongly 13C-depleted sedimentary organic matter may be related to enhanced kinetic fractionation during photosynthetic assimilation by means of proton pumping in Characean algae. This interpretation is supported by a substantial offset between 13C of DIC as recorded by mollusc shells and 13C of fine-grained calcite. 相似文献
114.
Based on Norwegian and Swedish representative national samples, and samples from areas with large mammalian carnivores present, we investigated whether well-known predictors for approval of wolves may explain between-country differences. Swedes were in general more positive than Norwegians were, while respondents in large carnivore areas, regardless of nationality, were less positive. The profile of those who approved wolf presence was the same in all samples. The difference between the samples was greater in Sweden, indicating that the relationship between urbanized and rural areas is more polarized in Sweden compared to Norway. We suggest this to be an effect of the fact that Norway’s large carnivore and agriculture policies favor the rural population, and of a higher degree of urbanization in Sweden. We recommend future studies to look into the different power relations between people living in urban and rural areas, comparing countries with different degree of urbanization. 相似文献
115.
《Marine Policy》2016
Sweden and other European Union countries are currently carrying out extensive work aimed at improving the marine and freshwater environment. The adaptive management approaches typically used for this require the development of new policy instruments and measures when needed, but also evaluations of instruments and measures already in use or under way. This paper reports on a study of the Swedish individual transferable quota system introduced in 2009 for the pelagic fishery. The new system was motivated mainly by economic arguments and, thus, the need to get incentives right. Despite this, the design of the Swedish system weakened the intended incentive effects in several ways, compared with the foreign systems that served as models. Moreover, the information needed for future evaluations was not collected, even though the need for future evaluations had been expressed explicitly and the data needs for this could be identified at the time that the system was introduced. 相似文献
116.
Granites, among them three generations of microline-rich granites, intruded repeatedly between 1600 and 900 Ma in the South-western Swedish Gneiss Complex. The deformed and metamorphosed Gösta and Sundsta granites are medium-grained, pale greyish red rocks belonging to the oldest generation of microclinerich granites.Biotite dominates over hornblende. Allanite, titanite, apatite and zircon are important accessory minerals. The granites are metaluminous and syeno- to monzogranitic in composition. SiO2 varies between 70.4 and 78.7% and K2O/Na2O between 0.86 and 2.32. Na and K are poorly correlated with the other major elements. The rocks are low in MgO (< 0.9%) and FeO (< 3.6%). They are characterized by high Rb/Sr, Ba/Sr and Ba/Rb ratios. The ratio Nb/Ta is almost constant ( 12) and the ratio Al/Ga decreases slightly with increasing SiO2 content. The Gösta granite has small, negative Eu anomalies, differentiated light and almost flat heavy rare earth element patterns. It intruded into continental crust approximately 1560 Ma ago. It is argued that the granites formed from continental rocks by pseudoeutectic partial melting at a fairly shallow depth. The source is older than the dominant country rock. 相似文献
117.
Nowadays, Global Geopotential Models (GGMs) are used as a routine stage in the procedures to compute a gravimetric geoid.
The GGMs based geoidal height also can be used for GPS/levelling and navigation purposes in developing countries which do
not have accurate gravimetric geoid models. Also, the GGM based gravity anomaly including the digital elevation model can
be used in evaluation and outlier detections schemes of the ground gravity anomaly data. Further, the deflection of vertical
and gravity gradients components from the GGMs can be used for different geodetic and geophysical interpretation purposes.
However, still a complete and user-friendly software package is not available for universities and geosciences communities.
In this article, first we review the procedure for determination of the basic gravity field and gradient components from the
GGMs, then general MATLAB based software is presented and applied as a sample case study for determination of gravity components
based on the most recent EIGEN-GL04C GRACE model in Sweden.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
118.
This study evaluates the potential of using chironomid assemblages to estimate past temperature changes by comparing chironomid-inferred temperatures to meteorological data for the last 87 years. This comparison is made using high-resolution (i.e., sub-decadally resolved) short cores of four lakes along a gradient of altitude (Lake Njulla, 999 m a.s.l., Lake 850, 850 m a.s.l., Lake Alanen Laanijavri, 365 m a.s.l. and Lake Vuoskkujavri, 348 m a.s.l.), vegetation (pine forest to alpine tundra vegetation) and temperature (mean July temperature of 12.4 to 8.1°C). Patterns of chironomid-inferred changes in mean July air temperature were highly comparable to changes in the meteorological data. Moreover, instrumental data were almost always within the specific errors of the quantitative estimates using chironomids. These results indicate that chironomids can be used as a powerful tool to reconstruct temperatures and that chironomids are sensitive enough to record temperature changes of low magnitude such as those recorded during the Holocene. Although this relationship between temperature and chironomid community is strong for the last 87 years, we cannot assume that other environmental factors such as organic matter, changes of lake water depth or oxygen availability were not more significant over longer temporal scales of the Holocene, or longer. 相似文献
119.
Hydrogeologic studies are commonly data-intense. In particular, estimations of hydraulic properties of hard rock often require
large amounts of data. In many countries, large quantities of hydrogeologic data have been collected and archived over the
years. Therefore, the use of existing data may provide a cost-efficient alternative to collecting new data in early stages
of hydrogeologic studies, although the available data may be considered imprecise. Initially, however, the potential usefulness,
i.e., the expected accuracy, of the available data in each specific case must be carefully examined. This study investigates
the possibilities of obtaining estimates of transmissivity from hard-rock air-lift data in Sweden within an order of magnitude
of results obtained from high-quality injection-test data. The expected accuracy of the results was examined analytically
and by means of statistical methods. The results were also evaluated by comparison with injection-test data. The results indicate
that air-lift data produce estimates of transmissivity within an order of magnitude compared to injection-test data in the
studied examples. The study also shows that partial penetration and hydrofracturing may only affect the estimations approximately
half an order of magnitude. Thus, existing data may provide a cost-efficient alternative to collection of new data in early
stages of hydrogeologic studies.
Received, January 1998 Revised, November 1998, December 1998 Accepted, December 1998 相似文献
120.
Spatial variability in surface sediment composition characterised by near-infrared (NIR) reflectance spectroscopy 总被引:1,自引:0,他引:1
Tom Korsman Mats B. Nilsson Karin Landgren Ingemar Renberg 《Journal of Paleolimnology》1999,21(1):61-71
Near-infrared (NIR) spectral data were obtained from 165 surface sediment samples from a northern Swedish humic, mesotrophic lake (0.5 km2). The NIR spectra, together with data on water depth and loss-on-ignition (LOI), allow an evaluation of the source of spatial variance in sediment characteristics. The results show that water depth and organic matter (LOI) account for 20 and 16%, respectively, of the variance in the NIR-absorbance data. More importantly, the spatial variance in the spectral data suggest that NIR analysis of lake sediments mainly reflect sediment properties that cannot simply be explained by depth or amount of organic matter. The influence of inlets and land-use (e.g. clear-cutting) on sediment characteristics was more pronounced in the spectral data than would be expected from the LOI data. This is explained by differences in the chemical composition of the organic matter, as revealed by NIR spectroscopy, rather than in the amount of organic matter or depth-related sedimentation properties (e.g. particle size or density). This initial attempt to characterise sediment properties using NIR suggests that NIR analysis might become a valuable complementary tool to traditional sediment characterisation. 相似文献