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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 54 (1986), S. 313-317 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Experiments by Schiller et al. have suggested that non-directional edge-specific simple cells are constructed from two directionally selective subunits with opposite preferred direction. This hierarchical notion was based on the fact that the responses of such units to edges moving in opposite directions are spatially displaced with respect to each other. An alternative explanation of the observed response separation is the delay between the responses of the center and surround mechanisms at the retinal level. Measurements of the response separation as a function of stimulus speed support this explanation and argues against the hierarchical notion of Schiller et al.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 53 (1986), S. 195-202 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract A theory of early visual information processing proposed by Marr and co-workers suggests that simple cortical cells may be involved in the detection of zero crossing in the retinal output. We have tested this theory by using pairs of adjacent edges (staircases stimuli) and recording from edge-specific simple cells in cat striate cortex. The zero crossing hypothesis gives rise for such stimuli to non-obvious predictions that were generally confirmed by the experiment.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 8 (1989), S. 219-226 
    ISSN: 1432-0789
    Keywords: Denitrification ; Acetylen inhibition technique ; 15N technique ; Organic residues ; Mineral fertilization ; Irrigation ; Temperate climate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Denitrification N losses can be determined by three methods. The first is by estimating the non-recovery of 15 N-labelled compounds (15N-balance method). Using this method, denitrification losses are deduced from the balance of an N budged (15N-labeled fertilizer), having accounted for transformations in soil, plant uptake, and leaching losses. The evolution of gaseous N from native soil N is not taken into account by this procedure. Studies on arable land with annual crops in the temperate zone have shown that of the fertilizer N applied, about 20–500% (10–70 kg N* ha−1) is not recovered at the end of the growth period. The second method of determining denitrification N losses is by in situ field measurement of 15 N 2 and 15 N 2 O production. Under this procedure, 15N-enriched N is applied to a plot and the denitrification N losses are determined by covering the soil. The method allows a quantitative estimate of the relative contributions to the emitted gas by both the original enriched source and the native soil N. N-evolution rates measured on arable land under a temperate climate are approximately the same order of magnitude as the N losses estimated by the non-recovery of 15 N method. The third measuring procedure is based on the acetylene inhibition phenomenon. This principle uses the inhibition of bacterial N2O reduction to N2 in the presence of acetylene (C2H2). The methoddetermines the denitrification of all NO3 −-N irrespective of its source. Measurements on classical crop production systems show maximum N losses in the temperate climate of about 20–30 kg N* ha−1 during the growth period of annual crops. A similar level of denitrification is estimated for grassland sites under the same climate. In the subtropics (mediterranean climate with hot summers and mild winters), from both intensively cultivated arable land and grassland sites, N losses may exceed 200 kg* ha−1 year−1. Without the use of irrigation the denitrification flux is negligible in spite of the high temperatures in this climate.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1076
    Keywords: Gastroenteritis ; Infants ; Rotavirus ; Adenovirus 31 ; Genome type
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An an infants' ward, gastroenteritis occurred in five children in two groups, probably by nosocomial spead of adenovirus 31 (three cases) and adenovirus 31 + rotavirus (two cases). The infants recovered well. The DNA of adenovirus 31 isolates was analysed with ten restriction endonucleases and found identical for all five strains, but different from the prototype.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 47 (1986), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The effects of several γ-aminobutyric acid (GABA)-ergic drugs on sodium-dependent high-affinity choline uptake (HACU) were investigated in the hippocampus. HACU was measured in vitro after in vivo administration of the drug to mice. HACU was inhibited by those drugs that enhance GABA transmission. The convulsant 3-mercaptopropionic acid, which decreases GABA levels, stimulated HACU. From these results and previous find ings, it appears that GABA mediates a tonic inhibitory effect on the septal-hippocampal cholinergic system.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 5 (1989), S. 0 
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. Increasing the ploughing depth and ploughing in grassland has been common in Germany during the past 20 years. Incubation studies were conducted with topsoils from luvisols and gleysols at different times after change of management in order to assess its influence on nitrogen mineralization and its kinetic parameters.The results show that deep ploughing slows the mineralization of nitrogen. The difference between earlier (1967–72) and more recently (1980–82) deepened topsoil has become smaller after a further three years of cultivation, however. The preceding crops (wheat or sugar beet), the amount of N fertilizer as well as clay and nitrogen contents cause a variation in N mineralization. The results indicate a continuing approach of an‘equilibrium’organic matter and nitrogen content. The enrichment capacity of intensively managed soils may be replenished within 10 years.Gleysols formerly under grass mineralize more nitrogen than‘traditionally’ploughed soils, even 27 years after the ploughing-in. While nitrogen from easily decomposable materials decreases within the first 10 years, the resistant fraction is a long-lasting determinant for N mineralization. Both processes need to be considered when applying fertilizer to minimize nitrate leaching.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 103 (1989), S. 0 
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: For maximizing genetic gains, with given resources, plant breeders generally conduct large but un- or inadequately-replicated field trials especially during early generation evaluations and population improvement programmes. Checks arc often used to improve the precision of test plot comparisons. Adjustments by moving or weighted means etc. arc, however, empirical or based on assumptions too difficult to verify. An alternative stochastically best linear unbiased optimal locally weighted method of spatial prediction of micro-environmental heterogeneity indices of treatment plots was examined. Two checks used in an unreplicated evaluation of 1560 test lines of winter wheat expressed the micro-environmental variation in similar ways. About 46, 38 and 16 percent of the total variation in yield was a simple row and column effects, spatially dependent, and random errors, respectively. Optimal weights derived to simulate the micro-environmental heterogeneity indices were sensitive to the position of the test plot and thus provided a better local control. The model was validated, and prediction standard deviations of simulations computed.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1246
    Keywords: Psychophysics ; Frequency weighting ; Whole-body vibration ; Noise ; Combined effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Nine healthy sitting males evaluated the intensity of vertical whole-body vibration (WBV) in z-axis at four frequencies (F1 = 0.63 Hz, F2 = 1.25 Hz, F3 = 2.5 Hz, F4 = 5 Hz) and two intensities (11 = 1 ms−2 rms, 12 = 2 ms−2 rms) by cross-modality matching (CMM). The subjects were simultaneously exposed to low-frequency noise at two levels (L1 = 65 dBA, L2 = 86 dBA). L1 and L2 were context conditions which did not have to be evaluated by CMM. The results indicate a flat response between F2 and F3; the sensitivity increases towards F1. Different exponents of Stevens' power law for the frequencies of WBV contradict the frequency range tested to be a sensory continuum. L2 caused practically significantly stronger sensations of the WBV-intensity from F1 to F3 (I1) and at F2 (I2). No synergistic effect of noise and WBV was shown at F3I2. Weighting factors were calculated for all exposure conditions using Stevens' power law. The weighting of F2 and F3 contradicts that of the International Standard ISO 2631-1985 (E). The results enable recommendations for the frequency weighting of WBV between 0.63 and 1 Hz, as well as for the equivalence of noise and WBV with combined exposure.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1619-7089
    Keywords: Cirrhotic ; hydrothorax ; diaphragmatic defect ; 99mTc-HSA scintigraphy ; intraperitoneal injection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 64-year-old man presented with a massive rightsided hydrothorax associated with cirrhosis of the liver. There was no clinical evidence of ascites nor other underlying disease. The usual complementary tests failed to demonstrate any causative abnormality. Chest and abdominal scintigraphy after intraperitoneal injection of 99mTc-human serum albumin disclosed early filling of the pleural space by the radiopharmaceutical and suggested a diaphragmatic defect as the cause for this rare association.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Antifoam agents, such as polyoxyalkylene glycol-oleic acid condensates, increase cell permeability in Saccharomyces uvarum, but decrease cell permeability in Kluyveromyces bulgaricus. In S. uvarum it was found that the increase in cell permeability is related to a significantly higher level of total sterols. In K. bulgaricus, in which a decrease of permeability was observed, the overall level of sterols is lower. Determination of the sterol derivatives showed that in S. uvarum the content of all sterols identified was increased; in K. bulgaricus only the ergosterol content was increased. The difference in behaviour of the two yeasts grown in the presence of antifoam agents could be attributed to an effect of these agents on sterol biosynthesis.
    Type of Medium: Electronic Resource
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