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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Stochastic environmental research and risk assessment 12 (1998), S. 15-32 
    ISSN: 1436-3259
    Keywords: Key words: Kalman filtering ; groundwater modelling ; inverse methods ; uncertainty analysis ; state prediction ; parameter estimation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The popularity of applying filtering theory in the environmental and hydrological sciences passed its first climax in the 1970s. Like so many other new mathematical methods it was simply the fashion at the time. The study of groundwater systems was not immune to this fashion, but neither was it by any means a prominent area of application. The spatial-temporal characteristics of groundwater flow are customarily described by analytical or, more frequently, numerical, physics-based models. Consequently, the state-space representations associated with filtering must be of a high order, with an immediately apparent computational over-burden. And therein lies part of the reason for the but modest interest there has been in applying Kalman filtering to groundwater systems, as reviewed critically in this paper. Filtering theory may be used to address a variety of problems, such as: state estimation and reconstruction, parameter estimation (including the study of uncertainty and its propagation), combined state-parameter estimation, input estimation, estimation of the variance-covariance properties of stochastic disturbances, the design of observation networks, and the analysis of parameter identifiability. A large proportion of previous studies has dealt with the problem of parameter estimation in one form or another. This may well not remain the focus of attention in the future. Instead, filtering theory may find wider application in the context of data assimilation, that is, in reconstructing fields of flow and the migration of sub-surface contaminant plumes from relatively sparse observations.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Stochastic environmental research and risk assessment 11 (1997), S. 229-254 
    ISSN: 1436-3259
    Keywords: Model validation ; analysis of uncertainty ; model verification ; quality assurance ; system identification ; model calibration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The development and use of models for predicting exposures are increasingly common and are essential for many risk assessments of the United States Environmental Protection Agency (EPA). Exposure assessments conducted by the EPA to assist regulatory or policy decisions are often challenged to demonstrate their “scientific validity”. Model validation has thus inevitably become a major concern of both EPA officials and the regulated community, sufficiently so that the EPA's Risk Assessment Forum is considering guidance for model validation. The present paper seeks to codify the issues and extensive foregoing discussion of validation with special reference to the development and use of models for predicting the impact of novel chemicals on the environment. Its preparation has been part of the process in formulating a White Paper for the EPA's Risk Assessment Forum. Its subject matter has been drawn from a variety of fields, including ecosystem analysis, surface water quality management, the contamination of groundwaters from high-level nuclear waste, and the control of air quality. The philosophical and conceptual bases of model validation are reviewed, from which it is apparent that validation should be understood as a task of product (or tool) design, for which some form of protocol for quality assurance will ultimately be needed. The commonly used procedures and methods of model validation are also reviewed, including the analysis of uncertainty. Following a survey of past attempts at resolving the issue of model validation, we close by introducing the notion of a model having maximum relevance to the performance of a specific task, such as, for example, a predictive exposure assessment.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 38 (1982), S. 319-319 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Diploid, triploid, and gynogenetic offspring resulted from hybridizing femaleCtenopharyngodon idella with maleAristichthys nobilis.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 6 (1990), S. 29-41 
    ISSN: 1476-5535
    Keywords: Xylose ; Ethanol ; Fermentation ; NMR ; Pachysolen tannophilus ; Pichia stipitis ; Candida shehatae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The fermentation ofd-xylose byPachysolen tannophilus, Candida shehatae, andPichia stipitis has been investigated by13C-nuclear magnetic resonance spectroscopy of both whole cells and extracts. The spectra of whole cells metabolizingd-xylose with natural isotopic abundance had significant resonance signals corresponding only to xylitol, ethanol and xylose. The spectra of whole cells in the presence of [1-13C]xylose or [2-13C]xylose had resonance signals corresponding to the C-1 or C-2, respectively, of xylose, the C-1 or C-2, respectively, of xylitol, and the C-2 or C-1, respectively, of ethanol. Xylitol was metabolized only in the presence of an electron acceptor (acetone) and the only identifiable product was ethanol. The fact that the amount of ethanol was insufficient to account for the xylitol metabolized indicates that an additional fate of xylitol carbon must exist, probably carbon dioxide. The rapid metabolism of xylulose to ethanol, xylitol and arabinitol indicates that xylulose is a true intermediate and that xylitol dehydrogenase catalyzes the reduction (or oxidation) with different stereochemical specificity from that which interconverts xylitol andd-xylulose. The amino acidl-alanine was identified by the resonance position of the C-3 carbon and by enzymatic analysis of incubation mixtures containing yeast and [1-13C]xylose or [1-13C]glucose. The position of the label from both substrates and the identification of isotope also in C-1 of alamine indicates flux through the transketolase/transaldolase pathway in the metabolism. The identification of a resonance signal corresponding to the C-1 of ethanol in spectra of yeast in the presence of [1-13C]xylose and fluoroacetate (but not arsenite) indicates the existence of equilibration of some precursor of ethanol (e.g. pyruvate) with a symmetric intermediate (e.g. fumarate or succinate) under these conditions.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 64 (1977), S. 91-91 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archive of applied mechanics 23 (1955), S. 231-253 
    ISSN: 1432-0681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 46 (1958), S. 181-185 
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Empfindlichkeit kolorimetrischer Bestimmungen, die auf Herabsetzung der Extinktion durch komplexbildende Anionen beruhen, kann durch Messung der Absorptionsänderung in der organischen Phase nach Schütteln mit einem geeigneten Lösungsmittel, das heißt durch Bestimmung der durch das Anion verminderten Extrahierbarkeit, erhöht werden. Dieses Prinzip wurde auf die Bestimmung von Fluoridion angewendet.
    Abstract: Résumé La sensibilité des déterminations colorimétriques basée sur l'effet de diminution d'extinction dû à des anions donnant lieu à la formation de complexes peut être accrue par la variation de l'absorption dans la phase organique après agitation avec un solvant approprié, ce qui revient à déterminer l'effet d'empêchement d'extraction dû à l'anion. Ce principe a été appliqué au dosage de l'ion fluorure.
    Notes: Summary The sensitivity of colorimetric determinations based on reduction of extinction by complex-forming anions can be increased by measuring the change of absorbancy in the organic phase after shaking with a suitable solvent, i. e. by determining the interference of the anion with extractability. This principle has been applied to the determination of the fluoride ion.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 8 (1975), S. 155-161 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé On a étudié le comportement thermique de cinq nouveaux composés Hexakis-DMSO-Cr(III) à l'aide du “Derivatograph”. On discute la stabilité thermique et la composition de ces complexes.
    Abstract: Zusammenfassung Das thermische Verhalten von fünf neuen Hexakis-DMSO-Cr(III)-Verbindungen wurde mit dem Derivatograph untersucht. Die Hitzebeständigkeit und Zusammensetzung dieser Komplexe wurden erörtert.
    Notes: Abstract The thermal behaviours of five new hexakis-DMSO-Cr(III) compounds were investigated by means of the Derivatograph. The composition of these complexes are discussed.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 32 (1997), S. 937-940 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Thin-film copper indium diselenide was prepared by selenization of copper indium oxide deposited by spray pyrolysis of an aqueous solution containing copper and indium salts. The degree of reproducibility in thickness, composition and electrical parameters was found to be good. The electrical parameters could be controlled and tuned for photovoltaic applications reproducibly by means of this cost-efficient fabrication technique.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 45 (1958), S. 162-162 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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