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991.
Breeding bird communities in Berlin were investigated at five study sites, which represent an structural urban-rural gradient,
from densely built-up areas with sealed ground to green areas such as large parks. In this paper, we tested the Hasse Diagram
Technique (HDT), an approach belonging to partial order theory, for its appropriateness to extract information about changes
in species composition from our data set. As expected, the overall number of bird species was positively correlated with the
urban-rural gradient, increasing from 12 found in the city center to 28 in an urban park. By HDT analysis, four different
sub-groups of birds could be identified, contributing differentially to the increase in species number: (1) ubiquists, i.e.,
species found at each study site, (2) a sub-group, the species’ number of which was positively correlated with the urban-rural
gradient, increasing with increasingly green areas, (3) a sub-group, the species’ number of which was negatively correlated
with the urban-rural gradient, decreasing with a declining density of buildings, and (4) species, the distribution of which
did not show any correlation with the urban-rural gradient. The results show that HDT is a suitable tool for formalized analysis
of the pattern of species’ communities along an environmental gradient. 相似文献
992.
993.
Abstract The results of a 1986 survey of 185 biotechnology faculty in the land-grant colleges of agriculture are presented. Comparisons are made to a previous survey of biotechnology faculty in nonagricultural research universities. The survey investigates issues raised by industrial involvement in university biotechnology research and the impact of the new biosciences on the agricultural colleges. It was found that college of agriculture biotechnologists have more recently received their highest degrees, show more industrial involvement, and are more positive about the possible benefits of that involvement than their nonagricultural university counterparts. Industrial funding proved to be a significant exogenous variable affecting the activities and attitudes of agricultural college biotechnology faculty. Those with higher levels of industrial funding appear to have lower university productivity. 相似文献
994.
Vladimir B. Bokov 《Journal of the Royal Statistical Society. Series A, (Statistics in Society)》2007,170(3):735-758
Summary. In process characterization the quality of information that is obtained depends directly on the quality of process model. The current quality revolution is now providing a strong stimulus for rethinking and re-evaluating many statistical ideas. Among these are the role of theoretic knowledge and data in statistical inference and some issues in theoretic–empirical modelling. With this concern the paper takes a broad, pragmatic view of statistical inference to include all aspects of model formulation. The estimation of model parameters traditionally assumes that a model has a prespecified known form and takes no account of possible uncertainty regarding model structure. But in practice model structural uncertainty is a fact of life and is likely to be more serious than other sources of uncertainty which have received far more attention. This is true whether the model is specified on subject-matter grounds or when a model is formulated, fitted and checked on the same data set in an iterative interactive way. For that reason novel modelling techniques have been fashioned for reducing model uncertainty. Using available knowledge for theoretic model elaboration the techniques that have been created approximate the exact unknown process model concurrently by accessible theoretic and polynomial empirical functions. The paper examines the effects of uncertainty for hybrid theoretic–empirical models and, for reducing uncertainty, additive and multiplicative methods of model formulation are fashioned. Such modelling techniques have been successfully applied to perfect a steady flow model for an air gauge sensor. Validation of the models elaborated has revealed that the multiplicative modelling approach allows us to attain a satisfactory model with small discrepancy from empirical evidence. 相似文献
995.
996.
Cities as environments 总被引:4,自引:3,他引:1
997.
998.
A suitable parity for exchange rate fixing can be derived from an analysis of the equilibrium exchange rate. As the equilibrium
exchange rates of the new EU 5 countries, the Czech Republic, Hungary, Poland, Slovenia, and the Slovak Republic, tend to
exhibit appreciation trends, credibility of the potential commitment to fixed exchange rate parity with respect to the euro
can be undermined. In order to investigate this issue, we estimate a behavioral model of real exchange rates for EU 5 countries
and derive the respective equilibrium real exchange rates. Using the linear-quadratic filter we estimate permanent equilibrium
exchange rates and their stationary points. We find that as of 2004 fixing of the national currencies to the euro should not
be undermined by further significant trend appreciation in the equilibrium exchange rates of the EU 5 countries, in aggregate. 相似文献
999.
1000.