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  • 1
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 24 (1991), S. 893-909 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A method for calculating the flux at the sample position and the resolution function based on the general description of synchrotron X-ray beamlines in position–angle–wavelength space has been developed. A mathematical formulation is presented, in which source, transmission function for the slits and acceptance windows of the monochromator crystals are approximated by Gaussian functions. These approximations allow all of the algebra in connection with combining the different contributions to be done analytically. When the beam passes the various components of the beamline, such as flight paths, monochromators and mirrors, it results in coordinate transformations in parameter space. By inserting the transformations in the intensity distribution of the source, transmission functions of the slits and acceptance windows of the monochromators, these are transformed to the position of the sample. Their product gives the intensity distribution at this position and from this the resolution function in reciprocal space is calculated. The resolution of the detector is easily included by a convolution. The transmissions of the slits and the acceptance windows of the monochromator crystals have been normalized to give the same integrated transmission and reflectivities as the functions they approximate. Therefore the flux at the sample position can be calculated by multiplication of the brilliance of the source and the result obtained from an integration of the distribution over the two position parameters, the two angle parameters and the wavelength. The theory has been applied to an example and gives reasonable results for sample intensity and resolution function.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 24 (1991), S. 541-548 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Two methods for performing indirect Fourier transformation of small-angle scattering data have been introduced by Glatter [J. Appl. Cryst. (1977), 10, 415–421] and Moore [J. Appl. Cryst. (1980), 13, 168–175]. These two methods are here compared to one using maximum entropy. The methods have been applied to simulated as well as experimental scattering data. The comparison of the three methods for the simulated data shows that the maximum-entropy method and the method of Glatter give similar results, which agree well with the original distributions. The method of Moore occasionally gives results which have artificial oscillations.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 353 (1991), S. 733-735 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The semiclassical theory of Balian and Bloch4 was extended and applied to idealized spherical sodium droplets with somewhat diffuse potential walls6. A quantum beat was found in the shell structure, with a pronounced minimum being predicted around size N - 1,000. The semiclassical results were ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Intensive care medicine 17 (1991), S. 372-372 
    ISSN: 1432-1238
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1238
    Keywords: Minitracheotomy ; Intensive care ; Indication ; Complication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Patients with imminent respiratory failure due to sputum retention were assessed for minitracheotomy (MT). MT was considered potentially useful in 79 patients but only attempted in 73, 54 men and 19 women, aged 23–81 years (median 65 years). Insertion of the cannula failed in 4 cases. Sputum retention and atelectasis were successfully treated in 87% (N=60). Treatment by MT in medical and neurological patients seems as effective as in surgical patients (success rate 81% versus 90%). The frequency of complications was 16%. Most complications were insignificant and occurred during cannulation, but a few severe complications were seen. To minimize the number of these it is essential that MT is done only by doctors who are familiar with the procedure. MT can be recommended for treatment of sputum retention and atelectasis in surgical and medical/neurological intensive care patients with preserved cough function.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 131 (1991), S. 287-291 
    ISSN: 1573-5036
    Keywords: Glycine max L. ; Heterodera glycines Ichinche ; Lolium multiflorum Lam. ; Secale cereale L. ; Triticum aestivum L. ; Tylenchorhynchus claytoni (Kofoid and White) Chitwood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rye (Secale cereale L.), wheat (Triticum aestivum L.), and annual ryegrass (Lolium multiflorum Lam.) are commonly double cropped with soybean (Glycine max L.). Recent greenhouse studies have shown variability in plant-parasitic nematode response to cool season grass species and cultivars. However, subsequent soybean performance was not affected by previous annual ryegrass cultivar in the green-house. The objective of this research was to determine whether winter cover crop species or cultivars affected nematode populations and subsequent performance of soybean in teh field. Four cultivars of annual ryegrass, wheat, and rye, and a fallow control were seeded on a Suffolk sandy loam (fine-loamy, siliceous, thermic Typic Hapuldult) soil in each of three years. Nematode-susceptible soybeans were seeded following forage removal. Soil samples for nematode counts were taken immediately before soybean harvest each year. In another experiment, one cultivar each of annual ryegrass, wheat, and rye, and a fallow control were followed by three soybean cultivars selected for differing nematode susceptibility. Grass cultivars did not affect nematode populations under succedding soybean. The only nematodes affected by grass species in either experiment were Pratylenchus spp., Heterodera glycines Ichinohe, and Tylenchorhynchus claytoni (Kofoid and White) Chitwood. Nematode population means were usually low following ryegrass and high following the fallow control. High soybean yields followed the fallow control, and low soybean yields followed annual ryegrass.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1434-6079
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The double-differential cross sections (DDCS) for ejection of electrons from helium by bare ions of H, He, C, and 0 of 1.00 and 1.84 MeV amu−1 energy have been studied experimentally and theoretically. Two-centre effects resulting from the simultaneous projectile and residual target fields are found to be important in the DDCS.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1434-6079
    Keywords: 36.40 ; 35.20.Wg ; 03.65.-w
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements of the mass abundance spectra of sodium clusters containing up to 600 atoms are presented. The clusters are produced in a seeded supersonic expansion of Ar or Kr gas, and the spectra are obtained by a time-of-flight technique. The sawtooth features in the spectra are interpreted as evidence of a regular spherical shell structure with magic numbers,N 0, scaling approximately with the cube root of the number of sodium atoms. Altogether twelve shell closings are observed,N 0=2, 8, 20, 40, 58, 92, 138, 196, 260, 344, 440 and 558. There is also a pronounced odd-even staggering all the way up toN=70. The experimentally observed intensity changes for the clusters around the magic numbers are discussed in terms of the electronic free energy,F(N), calculated at finite temperature, and the second differences of the free energy Δ2 F(N)=F(N−1)−2F(N)+F(N+1). The processes behind the non-uniform abundance distributions, and the thermodynamics of finite electron systems with non-uniform level spacings are discussed on this basis.
    Type of Medium: Electronic Resource
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