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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 272 (1975), S. 223-226 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract By means of a level crossing experiment the hyperfine structure constants of thez 6 P 7/2-level of Eu have been determined. The results areA=-6.51(6) MHz andB= 131.2(1.0) MHz in the isotope151Eu andA=-2.84(3) MHz andB=327.5(1.5) MHz in the isotope153Eu. Experimental data on the hyperfine splitting are available now for 11 of the 12 levels of the configuration 4f 7 (8S)6s 6p of EuI. These data are compared with the theoretical interpretation given by Bordarieret al. [1] which was based on only 7A-factors andB-factors. It is shown that the agreement between theory and experiment can be improved by taking into account configuration interactions.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 17 (1975), S. 145-156 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract We first show how to formalize environments in which situations can be changed only by action, and in which a situation should be brought about that is acceptable. This leads us to the concept of a problem constellation that consists of an action system, a reaction system, a judgement system, and an initial situation. We then present a cybernetical system which we call Robbimat. It is capable of testing problem constellations, of modifying them according to the results of the tests, and of judging the final constellation. We designed Robbimat in order to have favourable problem constellations automatically generated. As an example we discuss a simple game. It constitutes a win-loss-environment the structure of which can be deduced from the payoff function. We show how Robbimat analyses such an environment, and utilizing its structure classifies the initial situation.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 157 (1975), S. 115-124 
    ISSN: 1432-0878
    Keywords: Cerebellar cortex ; Man and other mammals ; Number of cells ; Evolution of cerebellar cortex ; Quantitative analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The number of cells per unit volume was determined in the cerebellar cortex of man and 19 other mammals. The cell density (i.e. the number of cells per unit volume) decreases from mammals with a low brain weight to those with a higher brain weight. This decrease in the number of cells is found to be proportional for all three layers of the cerebellar cortex. In addition, the ratio of Purkinje cells to granule cells was determined. In contrast to the decrease of all cell types with increasing brain weight, this ratio varies remarkably among the mammals and is not correlated with brain weight. In man, this ratio is 1∶2991, while it is lower in all other mammals investigated. These differences in the ratio of Purkinje cells to granule cells and the decrease in cell density with increasing brain weight are discussed in relation to brain evolution.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 166 (1976), S. 489-496 
    ISSN: 1432-0878
    Keywords: Cerebellar cortex (Rhesus monkey, cat) ; Supraganglionic plexus ; Myelinated parallel fibers ; Regional distribution ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the cerebellar cortex of the Rhesus monkey and the cat, the supraganglionic plexus in the molecular layer exhibits regional differences. The plexus is very well developed in the vermal parts of the anterior lobe, but only poorly developed in the nodulofloccular lobe. Most of the fibers of this plexus are myelinated parallel fibers, which synapse in the typical manner with dendritic thorns of Purkinje cells. Only very few fibers of this plexus are recurrent collaterals of Purkinje cells. Their distribution throughout the cerebellar cortex does not display regional differences. These findings agree with physiological data on the disinhibition of Purkinje cells in different parts of the cerebellar cortex.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 188 (1978), S. 509-520 
    ISSN: 1432-0878
    Keywords: Cerebellar cortex (Cat) ; Postnatal development ; Myelination of efferent and afferent fiber systems ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The myelination of the cerebellar cortex of the cat was investigated in 61 cats aged from 3 hrs post partum to two and a half years. The first myelinated fibers appear at the time of birth in the central medullary ray. Before the onset of myelination, all fibers reach a critical diameter of about 1 μm. About the 14th day of life the number of oligodendrocytes in the prospective white matter increases markedly. Thereafter, the oligodendrocytes invade the inner granular layer. It therefore seems that the myelination of the cerebellar cortex proceeds from the central medullary ray towards the granular layer. At the 60th day of postnatal life, most of the afferent and efferent fiber systems are myelinated. These findings are discussed in relation to the development of function and the maturation of the electrical activity of the cerebellar circuit.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 256 (1978), S. 1150-1150 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 25 (1976), S. 621-631 
    ISSN: 1573-5060
    Keywords: Hordeum vulgare ; Hordeum bulbosum ; barley ; bulbous barley grass ; interspecific hybrids ; colchicine treatments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary To produce hexaploid (or other polyploid) hybrids, diploid or tetraploid Hordeum vulgare was crossed with hexaploid or octoploid H. bulbosum, and perennial triploid hybrids between the two species were treated with colchicine. The crosses did not yield viable plants: seedset was low, the seed aborted and embryo culture was unsuccessful. The colchicine treatments geve rise to plants in which hexaploid chromosome numbers were observed. At the hexaploid level chromosomal instability occurred, resulting in chromosome elimination. The colchicine-treated triploid hybrids showed in the first years after the treatment better fertility after open flowering than untreated plants, but the level of fertility remained very low. The offspring consisted of haploid, diploid and approximately triploid plants like H. vulgare, tetraploid and approximately tetraploid plants like H. bulbosum, and plants with hybrid morphology and unstable chromosome number, which were highly sterile. Thus the crossing barrier between H. vulgare and H. bulbosum could not be broken down at higher ploidy level.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 24 (1975), S. 731-741 
    ISSN: 1573-5060
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Trisomic cytotypes were produced in dihaploid (diploid) plants of Solanum tuberosum L. Group Tuberosum, the common potato, according to two methods. Firstly, the aberrant types were selected, through chromosome counting, from parthenogenic dihaploid offspring of tetraploid-diploid crosses. In dihaploid populations from twelve tetraploid potato varieties the frequencies of aneuploids ranged from 3.5 to 11.0%. About 95% of these aneuploids had only one, and the others not more than two extra chromosomes. Secondly, the aneuploids were produced from triploid-diploid crosses. Seedset strongly depended on the crossability of the parental plant material, and the best results were obtained when the motherplants were grafted onto tomato. On avarage the three most successful cross combinations resulted in approximately 0.7 berries per pollination and 6 seeds per berry. With regard to seedsize the seed could be divided in two groups, viz, normal and small seeds. Half of the seed did not germinate or produced inviable seedlings, especially among the small seed group. About 93% of the plants was neuploid, with 25, 26 and 27 being the predominant chromosome number. It was concluded that the production of trisomics was the most successful through triploid-diploid crosses. The results were discussed with reference to the chromosomal behaviour in the meiosis in triploid plants (Lange & Wagenvoort, 1973a). It thus was possible to relate the low seedset to the distribution of chromosomes in the meiotic anaphases. On the one side this distribution resulted in a limitation of the avalability of gametes with monohaploid and near-monohaploid chromosome numbers, while on the other side the macrospores with higher chromosome numbers seemed to be inviable. Finally a crossing scheme was presented for transmitting the trisomic condition into a genetic background with better homogeneity and more homozygosity.
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  • 9
    ISSN: 1573-5060
    Keywords: Lycopersicon esculentum ; tomato ; Epitrix hirtipennis ; tobacco flea beetle ; insect resistance ; preference reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In comparisons made under typical summer conditions in the field at Davis, California, the foliage of the anthocyanin-deficient mutant af proved to be much more susceptible to attack by Epitrix hirtipennis (Melsheimer) than that of the isogenic normal line, normal cultivars, or any other tested mutant. Since a relatively uniform level of damage was observed in leaves of various ages that contacted the soil, the interaction is probably of a preference rather than antibiotic nature. A comparison with nine other anthocyaninless mutants proved that anthocyanin deficiency is not responsible for susceptibility. The severe reduction of glandular hairs and consequent lack of foliage aroma—hitherto unsuspected pleiotropic effects of af—probably account for the high susceptibility of this mutant. The evolutionary significance of the distinct foliage aromas characteristic of each tomato species is discussed.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 46 (1976), S. 217-233 
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Chromosome measurements were carried out in Hordeum vulgare, H. bulbosum, and their diploid, triploid, and tetraploid hybrids. The chromosomes were classified by using relative values, and thus karyotypes were established. For comparison of these karyotypes both relative and absolute values were used. It was concluded that differential amphiplasty occurred, whereas neutral amphiplasty could not be demonstrated. In the hybrids the relative length of the parts of the chromosomes (long arm, short arm, satellite) was not changed in comparison with these lengths in the pure species. The karyotypes of both species had considerable similarities. From comparing the mean absolute genome lengths, it was, however, concluded that in the pure species, as well as in all hybrid types, the chromosomes of H. vulgare were longer than those of H. bulbosum. In the diploid and tetraploid hybrids the mean genome lengths were shorter than those in the pure species and the triploid hybrids. The differential amphiplasty was such that the secondary constriction of chromosome 6 of H. bulbosum, did not show up in the hybrids. This could be related to the suppression of nucleolar formation in the genome of H. bulbosum, because the maximum number of nucleoli in root tip cells equalled the number of satellite chromosomes. Finally it was found that the pattern of nucleolar fusion in diploid and triploid hybrids deviated from the expectation. The results were discussed in relation to chromosomal disturbances that occurred in the hybrid tissues and that resulted in elimination of chromosomes and other effects.
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