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  • Springer  (160)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Immunogenetics 6 (1978), S. 269-276 
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Immunofluorescence tests indicate that alloantibodies specific for mouse histocompatibility antigens H-1a, H-3a, and H-13a have been produced, using four different immunizations. Furthermore, an immunization employing donors and recipients which were H-2k at the MHC produced stronger anti-H-3a and anti-H-13a than did immunizations where donors and recipients were H-2b at the MHC.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Immunogenetics 4 (1977), S. 257-266 
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Alloantibodies specific for non-H-2 histocompatibility antigens of the mouse have been produced. Immunization (BALB/cJ×DBA/2J)F1 anti-B10.D2/n was conducted, followed by hemagglutination, immunofluorescence, and mixed hemabsorption tests on absorbed and unabsorbed sera. The results indicate that antibodies specific for H-3a and H-8a antigens are present. In addition, H-8a antigenic determinants were detected on erythrocyte membrane surfaces, as well as on cells of other body tissues.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract An experiment is described which compares the performance of a neural network to human performance on a visual task which consists of detecting a target in a background image of correlated noise. A three-layer, feed-forward, multi-layer perceptron is trained to indicate the presence or absence of a target in images also presented to human observers. The basis for the comparison between the network and the human observers is the receiver operating characteristic (ROC) curve. Network performance is comparable to human performance for this particular task.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 59 (1988), S. 257-263 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The utility of the back-propagation method in establishing suitable weights in a distributed adaptive network has been demonstrated repeatedly. Unfortunately, in many applications, the number of iterations required before convergence can be large. Modifications to the back-propagation algorithm described by Rumelhart et al. (1986) can greatly accelerate convergence. The modifications consist of three changes:1) instead of updating the network weights after each pattern is presented to the network, the network is updated only after the entire repertoire of patterns to be learned has been presented to the network, at which time the algebraic sums of all the weight changes are applied:2) instead of keeping η, the “learning rate” (i.e., the multiplier on the step size) constant, it is varied dynamically so that the algorithm utilizes a near-optimum η, as determined by the local optimization topography; and3) the momentum factor α is set to zero when, as signified by a failure of a step to reduce the total error, the information inherent in prior steps is more likely to be misleading than beneficial. Only after the network takes a useful step, i.e., one that reduces the total error, does α again assume a non-zero value. Considering the selection of weights in neural nets as a problem in classical nonlinear optimization theory, the rationale for algorithms seeking only those weights that produce the globally minimum error is reviewed and rejected.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular modeling 3 (1997), S. 338-346 
    ISSN: 0948-5023
    Keywords: Keywords: Free-Wilson-analysis ; PLS ; genetic algorithm ; CoMFA ; piritrexim analogous
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Quantitative structure-activity relationships for piritrexim and analogues acting as inhibitors of tumour cell growth have been derived. First the Free-Wilson-method was used on a homologous training set of eight derivatives. The selection of variables important for the biological activity of the compounds was carried out with different multivariate methods as multiple linear regression, the partial least squares method und a genetic algorithm. The derivation of three-dimensional structure activity relationships started with a systematic conformational analysis of all compounds. For the conformations having minimal energy and being in agreement with the crystal structure of piritrexim charges were calculated with the AM1 hamiltonian. For the superimposition of the derivatives two methods were used: maximal similarity of the common substructure or of the molecular fields. A Comparative Molecular Field Analysis with steric and electrostastic fields identified regions important for the activity of the studied compounds independent of the chosen alignment and also correctly predicted the activity of two nonhomologous compounds.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 63 (1996), S. 43-49 
    ISSN: 1090-6487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Slight changes with temperature in the director orientation at the surface of a perfect planar cholesteric liquid crystal (CLC) layer, which are precursors of a jump in the pitch of the cholesteric helix, are observed by measuring the temperature dependence of the optical transmission spectra of the layer. The observed changes in the director orientation are described in the framework of the continuum theory of CLCs, supplemented with allowance for the surface anchoring forces. In particular, the angle of deviation of the director at the surface from the alignment direction at the exact temperature of the jump in pitch is expressed in terms of the anchoring potential. The relation obtained is use to find the anchoring potential in the samples.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of experimental and theoretical physics 85 (1997), S. 285-291 
    ISSN: 1090-6509
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Hysteresis of the temperature of jumps in the cholesteric pitch in planar layers of cholesteric liquid crystals (CLCs) has been observed in the temperature dependence of the optical transmission spectra measured in a 4.8 ¼m thick specimen of a 60% chiral racemic mixture of CE6. The temperature difference for the pitch jumps during heating and cooling was equal to about 0.1°C near 40.3°C. No difference in the temperature of the pitch jumps during heating and cooling was observed for an 18 µm thick specimen. A theoretical description of this hysteresis is presented on the basis of a continuum theory of elasticity of CLCs that also takes account of the surface anchoring of the CLC. Different possible mechanisms leading to a change in the director configuration in the layer during a pitch jump and their correspondence to the jump mechanism and hysteresis which occur in the experimental specimens are discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 7 (1996), S. 109-116 
    ISSN: 1573-4846
    Keywords: ferritin ; sol-gel ; magnetism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A significant recent development in sol-gel science has been the encapsulation of biomolecules such as proteins and enzymes in optically transparent silica glasses. This paper reports on the encapsulation of an iron (Fe) storage protein, ferritin, to develop a magnetic silica glass. Native ferritin, which has a nanometer-sized microcrystalline Fe oxide core, was encapsulated in optically transparent silica glasses using the sol-gel process. Fe could be released from ferritin but could not be reconstituted into apoferritin when the protein was trapped in the pores of the glass. Transmission electron microscopy of ferritin-doped aged silica gels indicated that crystallinity of the Fe oxide core was retained upon sol-gel encapsulation. Magnetic measurements on ferritin-doped silica gels indicated the material to be paramagnetic, but not superparamagnetic.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-4846
    Keywords: sol-gel monoliths ; immobilized enzyme ; oxalate oxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Novel synthetic techniques are used for the encapsulation of the enzymes oxalate oxidase and peroxidase in stable, optically transparent porous silica glass matrices. The large enzymes are fully immobilized in the porous glass but small molecules such as oxalate ions pass readily through the pores in the glass. The enzymes catalyze the reactions leading to the formation of a colored dye product. Upon exposure of the doped glass to oxalate solutions, a colored glass is formed. The absorption spectrum of the colored product and the changes of absorbance with time are measured within the glass matrix. The sensitivity and the time-dependence of the response are discussed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 8 (1997), S. 629-634 
    ISSN: 1573-4846
    Keywords: protein encapsulation ; absorption spectroscopy ; thin films ; cytochrome c
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper considers the nature of the interactions between the sol-gel derived inorganic matrix and a specific biomolecule, cytochrome c. Optical absorption and impedance spectroscopies are used to characterize the influence of synthesis conditions on the protein’s stability and conformation within the silica matrix. In some instances, encapsulation within the sol-gel matrix provides stabilization. For example, protein denaturation is reversible and aggregation is prevented. Moreover, the drying process does not negatively affect the protein; it is possible to regenerate the aged gel state by rehydration. The flexibility of the sol-gel process enables high quality cytochrome c-doped SiO2 thin films to be prepared. These films possess the characteristic reactivity and chemical function of cytochrome c in solution.
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