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  • Articles  (19)
  • Springer  (19)
  • 2000-2004  (4)
  • 1995-1999  (4)
  • 1990-1994  (11)
  • 1905-1909
  • Computer Science  (13)
  • Process Engineering, Biotechnology, Nutrition Technology  (6)
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  • Articles  (19)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 54 (2000), S. 681-685 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract New methods of determining the structural groups —COOH and —CH2— have been developed. The investigation of carboxyl groups is possible both after derivatization with p-fluorophenacylbromide and by quantitative interpretation of the Fourier transform infrared (FT IR) spectra. There exists a linear relationship between the results of these two methods that is generally valid for the analysis of all brown coal components. The maximum extinction coefficient of the symmetric stretching vibration band of the CH2 groups has been determined using model substances. This allows quantification of this structural group directly from the FT IR spectrum. The results agree with the contents of methylene groups as determined by 13C-cross polarization–magic angle spinning–nuclear magnetic resonance (13C CPMAS NMR) spectroscopy. Using these methods, the COOH and CH2 groups contained in brown coals of the North Rhine region and in their bioconversion products have been quantified.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 43 (1995), S. 1050-1055 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Two rice α-amylase isozymes, AmylA and Amy3D, were produced by secretion from genetically engineered strains of Saccharomyces cerevisiae. They have distinct differences in enzymatic characteristics that can be related to the physiology of the germinating rice seed. The rice isozymes were purified with immunoaffinity chromatography. The pH optima for amy3D (pH optimum 5.5) and Amy1A (pH optimum 4.2) correlate with the pH of the endosperm tissue at the times in rice seedling development when these isozymes are produced. Amy3D showed 10–14 times higher reactivity to oligosaccharides than Amy1A. Amy1A, on the other hand, showed higher reactivity to soluble starch and starch granules than Amy3D. These results suggest that the isozyme Amy3D, which is expressed at an early stage of germination, produces sugars from soluble starch during the early stage of seed germination and that the isozyme Amy1A works to initiate hydrolysis of the starch granules.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 68 (1993), S. 209-214 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract We investigate spike initiation and propagation in a model axon that has a slow regenerative conductance as well as the usual Hodgkin-Huxley type sodium and potassium conductances. We study the role of slow conductance in producing repetitive firing, compute the dispersion relation for an axon with an additional slow conductance, and show that under appropriate conditions such an axon can produce a traveling zone of secondary spike initiation. This study illustrates some of the complex dynamics shown by excitable membranes with fast and slow conductances.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 66 (1992), S. 381-387 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract We present a scheme for systematically reducing the number of differential equations required for biophysically realistic neuron models. The techniques are general, are designed to be applicable to a large set of such models and retain in the reduced system as high a degree of fidelity to the original system as possible. As examples, we provide reductions of the Hodgkin-Huxley system and the A-current model of Connor et al. (1977).
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 70 (1994), S. 397-405 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract. An important step in visual processing is the segregation of objects in a visual scene from one another and from the embedding background. According to current theories of visual neuroscience, the different features of a particular object are represented by cells which are spatially distributed across multiple visual areas in the brain. The segregation of an object therefore requires the unique identification and integration of the pertaining cells which have to be “bound” into one assembly coding for the object in question. Several authors have suggested that such a binding of cells could be achieved by the selective synchronization of temporally structured responses of the neurons activated by features of the same stimulus. This concept has recently gained support by the observation of stimulus-dependent oscillatory activity in the visual system of the cat, pigeon and monkey. Furthermore, experimental evidence has been found for the formation and segregation of synchronously active cell assemblies representing different stimuli in the visual field. In this study, we investigate temporally structured activity in networks with single and multiple feature domains. As a first step, we examine the formation and segregation of cell assemblies by synchronizing and desynchronizing connections within a single feature module. We then demonstrate that distributed assemblies can be appropriately bound in a network comprising three modules selective for stimulus disparity, orientation and colour, respectively. In this context, we address the principal problem of segregating assemblies representing spatially overlapping stimuli in a distributed architecture. Using synchronizing as well as desynchronizing mechanisms, our simulations demonstrate that the binding problem can be solved by temporally correlated responses of cells which are distributed across multiple feature modules.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 70 (1994), S. 397-405 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract An important step in visual processing is the segregation of objects in a visual scene from one another and from the embedding background. According to current theories of visual neuroscience, the different features of a particular object are represented by cells which are spatially distributed across multiple visual areas in the brain. The segregation of an object therefore requires the unique identification and integration of the pertaining cells which have to be “bound” into one assembly coding for the object in question. Several authors have suggested that such a binding of cells could be achieved by the selective synchronization of temporally structured responses of the neurons activated by features of the same stimulus. This concept has recently gained support by the observation of stimulus-dependent oscillatory activity in the visual system of the cat, pigeon and monkey. Furthermore, experimental evidence has been found for the formation and segregation of synchronously active cell assemblies representing different stimuli in the visual field. In this study, we investigate temporally structured activity in networks with single and multiple feature domains. As a first step, we examine the formation and segregation of cell assemblies by synchronizing and desynchronizing connections within a single feature module. We then demonstrate that distributed assemblies can be appropriately bound in a network comprising three modules selective for stimulus disparity, orientation and colour, respectively. In this context, we address the principal problem of segregating assemblies representing spatially overlapping stimuli in a distributed architecture. Using synchronizing as well as desynchronizing mechanisms, our simulations demonstrate that the binding problem can be solved by temporally correlated responses of cells which are distributed across multiple feature modules.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of intelligent and robotic systems 29 (2000), S. 349-387 
    ISSN: 1573-0409
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Current learning approaches to computer vision have mainly focussed on low-level image processing and object recognition, while tending to ignore high-level processing such as understanding. Here we propose an approach to object recognition that facilitates the transition from recognition to understanding. The proposed approach embraces the synergistic spirit of soft computing, exploiting the global search powers of genetic programming to determine fuzzy probabilistic models. It begins by segmenting the images into regions using standard image processing approaches, which are subsequently classified using a discovered fuzzy Cartesian granule feature classifier. Understanding is made possible through the transparent and succinct nature of the discovered models. The recognition of roads in images is taken as an illustrative problem in the vision domain. The discovered fuzzy models while providing high levels of accuracy (97%), also provide understanding of the problem domain through the transparency of the learnt models. The learning step in the proposed approach is compared with other techniques such as decision trees, naïve Bayes and neural networks using a variety of performance criteria such as accuracy, understandability and efficiency.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of intelligent and robotic systems 7 (1993), S. 233-254 
    ISSN: 1573-0409
    Keywords: Quadratic half-plane ; positive quadratic space ; model and parameter mismatch ; constraint analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The stability of the PUMA-560 robot manipulator is investigated under model mismatch using PD and PID controllers. Craig's quadratic half-plane constraint analysis is applied, and conditions are found in terms of calculated position and velocity error upper bounds to guarantee the stability of the robot arm under PD control. The theory is extended to guarantee stability under PID control using the modified positive quadratic space constraint analysis. Dynamic model mismatch is assumed to result from incomplete knowledge of the link masses, centers of mass and radii of gyration. The results indicate stability regions under different percentages of individual and combined parameter mismatch in the model.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 6 (1990), S. 53-59 
    ISSN: 1476-5535
    Keywords: Bituminous coal ; Biosolubilization ; Penicillium sp. ; Surface colonization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary APenicillium sp. previously shown to grow on lignite coals degraded an air-oxidized bituminous coal (Illinois #6) to a material that was more than 80% soluble in 0.5 N NaOH. Scanning electron microscopy of the oxidized Illinois #6 revealed colonization of the surface by thePenicillium sp., production of conidia, and erosion of the coal surface. The average molecular weight (MW) of Illinois #6 degraded by the fungus and base-solubilized was approximately 1000 Da. The average MW for base-solubilized Illinois #6 that was not exposed to the fungus was 6000 Da, suggesting solubilizing mechanisms other than base catalysis. A spectrophotometric assay to quantify the microbial conversion of biosolubilized coal was developed. Standard curves were constructed based on the absorbance at 450 nm of different quantities of microbe-solubilized coal. An acid precipitation step was necessary to remove medium and/or microbial metabolites from solubilized coal to prevent overestimation of the extent of coal biosolubilization. Furthermore, the absorption spectra for different coal products varied, necessitating construction of standard curves for individual coals.
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  • 10
    ISSN: 1476-5535
    Keywords: MolluscicidalBacillus toxin ; Bacillus brevis ; Biomphalaria glabrata ; Biocontrol of snails ; Antioxidant preservation of toxin ; Secondary fermentation factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Strain SS86-4 was one of 40Bacillus brevis strains shown to be molluscicidal to the schistosomiasis snail vectorBiomphalaria glabrata. When grown in mB4 medium in 2-L fermentors, SS86-4 was molluscicidal only if fructose or phenylalanine was present in the medium. This is reminiscent of secondary fermentation factor effects, in this case an antioxidant effect. In vivo proteases also were capable of reducing molluscicidal activity. The molluscicidal toxin has an LC50 of 1 μg toxin protein ml−1 (approx. 1 p.p.m.) and may be described as a small proteinaceous, heat-stable, oxygen-sensitive entity associated with the particulate portion of the cell wall fraction ofB. brevis that is formed prior to sporulation. Initial information indicates that its HPLC signature shows major peaks at 148.37 and 163.96 s and consists of two bands of approximately 5.3 kDa and 8.7 kDa on PAGE gel.
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