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  • Springer  (399)
  • 1985-1989  (387)
  • 1955-1959  (12)
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  • 1
    ISSN: 1476-5535
    Keywords: Aflatoxin miniassay ; Fluorescence analysis ; Aspergillus flavus ; Aspergillus parasiticus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A convenient miniassay for aflatoxin has been developed for cultures ofAspergillus flavus andA. parasiticus grown for 3–10 days in 10 ml of a coconut extract medium. The sensitivity of the assay, as measured by photofluorometry (365 nm maximum excitation; 445 nm maximum emission), is of the order of 0.01 μM (3.12 ng/ml) for aflatoxin B1 dissolved in aqueous iodine (0.26 mM). High performance liquid chromatography, monitored by fluorometric analysis of both an aflatoxin B1 standard and selected culture filtrates, confirmed the sensitivity of the assay and indicated specificity for iodine-enhanced fluorescence of aflatoxin in the coconut extract medium. Thin layer chromatography further confirmed the aflatoxin titers and the specificity for enhancement of aflatoxins B1 and G1 in culture filtrates.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 97-110 
    ISSN: 1436-3259
    Keywords: ARMA processes ; fractionally differencedARMA processes ; long memory ; spectral density ; maximum likelihood estimates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract A class of regression type estimators of the parameterd in a fractionally differencedARMA (p, q) process is introduced. This class is an extension of the estimator considered by Geweke and Porter-Hudak. In a simulation study, we compared three estimators from this class together with two approximate maximum likelihood estimators which are based on two separate approximations to the likelihood. One approximation ignores the determinant term in the likelihood and the other includes a compensating factor for the determinant. When the determinant term is included, the estimate tends to be much less biased and is in general superior to the other estimate. The approximate maximum likelihood estimator out performed, by a large margin, the regression type estimators for pureARIMA (0,d,0) processes. However, forARIMA (1,d,1) processes, a regression type estimator turned out to be the best for realizations of length 400 in 3 out of the 5 cases we tried.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Computing 38 (1987), S. 299-313 
    ISSN: 1436-5057
    Keywords: 65D05 ; 41A10 ; Interpolation ; local piecewise polynomials ; ratio slope
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Ein Satz diskreter Datenwerte über dem Intervall [a, b], der eine Funktiong (x) repräsentiert, wird stückweise durch lokal definierte kubische Polynome interpoliert. Die entstehende Interpolationsfunktion hat folgende Eigenschaften: sie ist monoton und/oder konvex und repräsentiert alle durch die Daten vorgegebenen Wendepunkte, wobei keine zusätzlichen Wendepunkte erzeugt werden. Das Approximationsverfahren wird in Form eines FORTRAN 77-Unterprogramms angegeben.
    Notes: Abstract The interpolation of a discrete set of data, on the interval [a, b], representing the functiong(x) is obtained using a local piecewise polynomial of order 3. This piecewise cubic interpolant has the following properties: monotonicity and/or convexity or turning points that are present in the data are preserved and no extraneous turning points are created. This approximation method is also presented in the form of a FORTRAN77 subroutine.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-604X
    Keywords: Mathematical model ; Laser surgery ; Optical fibres ; Tumours ; Thermal diffusion ; Multiple fibres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract A mathematical model is employed to discuss the region treated by local hyperthermia, when the source of heat is a laser whose energy is directed into the treatment region through four optical fibres ending at the corners of a square. If treatment is over a period that is substantially longer than the time for the temperature distribution to reach equilibrium, a steady state model using four point sources can be employed to obtain a general idea of the temperatures reached and the region treated for different power levels and sizes of square. For shorter times, and for more accurate estimation of the regions treated, numerical calculation on a computer is essential. The details of the calculation depend on individual cases, but we demonstrate here that such computations are possible, and present a series of typical results. A comparison is made with the results of a series of experiments on canine liver, showing that it is possible to obtain good qualitative and numerical agreement.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 18 (1986), S. 93-96 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Fire technology 23 (1987), S. 280-291 
    ISSN: 1572-8099
    Keywords: Ergonomics ; fire fighter ; physical fitness ; aerobics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract The conditions and requirements of the fire fighter and the unusual demands of fire fighting activities have received increased attention since the early 1970s. Other industries usually design physical performance requirements around the capabilities of the worker, but the fire fighter must respond to the constraints and requirements of the emergency. Recent research and its relationship to a fire fighter's physical profile are described and discussed.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 20 (1988), S. 383-393 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract This paper reports on a theoretical investigation of a novel scheme devised for a two-section single-cavity (TSSC) laser. The results of the investigation are used to demonstrate its potential as a frequency-tunable laser source. By the implementation of an appropriate electrical drive scheme the TSSC laser can be shown to exhibit a reduction in frequency chirping under direct modulation. Alternatively, by employing a different drive scheme, the device can be shown to behave as a wavelength-tunable laser. Control of the tuning range by antireflection (AR) coating of laser facets is also predicted.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 1 (1988), S. 85-92 
    ISSN: 1572-879X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Low energy He+-scattering was used to simply demonstrate that the surface of a typical fused iron ammonia synthesis catalyst is largely covered by promoter oxides of calcium and/or potassium. Complementary photoemission results indicate that atomic nitrogen is deposited in the near surface region during catalyst activation in NH3/H2-mixtures.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 127 (1986), S. 265-284 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Properties of discrete Alfvén wave modes are derived, at frequencies up to the ion-cyclotron frequency, for current-carrying plasma slabs with non-uniform densities. It is shown that the essential features of the dispersion relations can be derived by examining the dominant terms in the ‘potential’ function, when the wave equation is cast in the Schrödinger equation form. Analytical predictions for a class of mass and current density profiles are compared with numerically calculated dispersion relations and wavefields for particular profiles.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 116 (1985), S. 89-96 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Spherical accretion onto black holes at high accretion rates leads to temperatures and optical depths for which Comptonization of the emerging radiation plays an important role, altering both the plasma temperature and the emergent spectrum. In this paper the nonlocal effects of Comptonization are accounted for by numerically modeling the scattering process with Monte Carlo techniques. Calculations are performed for black hole masses ranging from 101–109 M ⊙ and are compared with the local scattering model of Ipser and Price (1983). It is found that the local scattering approximation underestimates the energy in the X-ray portion of the spectrum. Monte Carlo calculations shows that the spectrum flattens and the spectral index decreases to values about 20% below those obtained by using the local scattering approximation.
    Type of Medium: Electronic Resource
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