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  • Springer  (6)
  • 1995-1999  (6)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Environmental geology 30 (1997), S. 189-197 
    ISSN: 1432-0495
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The objectives of the interdisciplinary pilot project "Development of a municipal environmental information system" in Hannover encompassed the development, modification and improvement of data acquisition methods and methods for describing the environment on the basis of this data, as well as methods for evaluating the data as a basis for measures affecting the environment taken by the community. The subproject "Urban Soils" had the following two main objectives: (i) development of a data acquisition method for soils in municipal areas and a method for evaluating this data, and (ii) development of methods for making this information available to local government in the form of a "soil information system" for urban areas. To achieve these objectives, the following work was carried out: (1) a factor analysis to determine which factors affect the soil in an urban area; (2) study of methods for mapping soils in cities; (3) development of a concept for a soil information system; and (4) evaluation of environmental problems of the municipality using the soil information system. Data acquisition was done in two steps: First, soil-relevant data was selected, standardized, digitized and stored in an alphanumeric and a graphic database for a factor analysis. By intersection of the eight information levels, the factors affecting the soil were determined for the city of Hannover (200 km2). To test the hypothesis that the results for one site can be transferred to another site with the same combination of factors, 43 test sites typical of urban land use were selected. These test sites were mapped in a way to fulfill geostatistical requirements; physical and chemical analyses of the soils were made. A prognosis of soil distribution and properties was made on the basis of the factor analysis. and compared with the actual conditions. Concurrent with the pedological research, a prototype soil information system was developed. The system consists of databases, a methodbase, a geometrical tool, and a control system. Alphanumeric data is stored in a relational database, the geometric data in ISAM files. Methods for determining soil parameter values were selected and tested for their applicability. Using the pedological data and the soil information system, information can be obtained about soil conditions in Hannover as well as about soil processes (e.g. infiltration rates) and interaction with the atmosphere, hydrosphere, etc. This information can be obtained in the form of thematic maps and statistical representations, which can be used by decision-makers at the municipal level.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 79 (1998), S. 15-27 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract. A nonlinear analysis of the underlying dynamics of a biomedical time series is proposed by means of a multi-dimensional testing of nonlinear Markovian hypotheses in the observed time series. The observed dynamics of the original N-dimensional biomedical time series is tested against a hierarchy of null hypotheses corresponding to N-dimensional nonlinear Markov processes of increasing order, whose conditional probability densities are estimated using neural networks. For each of the N time series, a measure based on higher order cumulants quantifies the independence between the past of the N-dimensional time series, and its value r steps ahead. This cumulant-based measure is used as a discriminating statistic for testing the null hypotheses. Experiments performed on artificial and real world examples, including autoregressive models, noisy chaos, and nonchaotic nonlinear processes, show the effectiveness of the proposed approach in modeling multivariate systems, predicting multidimensional time series, and characterizing the structure of biological systems. Electroencephalogram (EEG) time series and heart rate variability trends are tested as biomedical signal examples.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1420-9071
    Keywords: Dimethylbenz[a]anthracene ; estradiol ; phenobarbital ; melatonin ; 6-sulfatoxymelatonin ; hepatic metabolism ; urinary excretion ; cancer etiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The protective function of the pineal hormone melatonin in the etiology of cancer and carcinogenic activation is increasingly well-established. Low melatonin levels seem to parallel cancer growth. The question arises as to which factors cause the depression of melatonin levels and what the direct effects are. Melatonin is known to be metabolized in the liver by hydroxylation and subsequent conjugation yielding 6-sulfatoxymelatonin as a main product. Nevertheless, the microsomal monoxygenases catalyzing the first step have been poorly investigated. To further characterize these enzymes, typical inducers of three different sub-classes, namely phenobarbital, 7,12-dimethylbenz[a]anthracene, and 17β-estradiol, were administered to female Fischer rats. Circadian urinary excretion patterns of melatonin and 6-sulfatoxymelatonin were determined over a 24-hour period on the third (second) day of induction. Liver homogenates were used to monitor the in vitro conversion of melatonin or 6-hydroxymelatonin to 6-sulfatoxymelatonin. Results of both approaches showed the microsomal monoxygenases catalyzing the 6-hydroxylation of melatonin to be strongly inducible by phenobarbital and to a lesser degree by the polyaromatic hydrocarbon 7,12-dimethylbenz[a]anthracene. The dramatic depletion of circulating melatonin as a result of these induction patterns and its possible implications for oncogenesis are discussed.
    Type of Medium: Electronic Resource
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  • 4
  • 5
    Publication Date: 1998-08-10
    Print ISSN: 0340-1200
    Electronic ISSN: 1432-0770
    Topics: Biology , Computer Science , Physics
    Published by Springer
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  • 6
    Publication Date: 1997-04-16
    Print ISSN: 0943-0105
    Electronic ISSN: 1432-0495
    Topics: Geosciences
    Published by Springer
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