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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of mathematical biology 47 (1985), S. 35-52 
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The present study deals with the effect of externally-imposed body accelerations on blood flow in arteries. Body accelerations may be caused deliberately, for example making the subjecs lie down on vibrating tables: or unintentionally during travel in road vehicles, aircraft or spacecraft. A mathematical model of flow in single arteries subject to a pulsating pressure gradient as well as body acceleration is presented. The resulting equations are solved by using the technique of Laplace transforms. Computational results are presented for the effects of body accelerations on flow variables namely flow rate, velocity of flow, acceleration and shear stress corresponding to typical arteries of human subjects.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of biological physics 10 (1982), S. 179-186 
    ISSN: 1573-0689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract When a human being experiences a sudden velocity change, the blood flow is disturbed. A theoretical analysis to predict the effects of sudden velocity changes on blood flow in large arteries is presented. The situations is modelled as a one-dimensional flow problem in a viscoelastic tube where the fluid viscosity convective term in the equation of motion and nonlinearity in the elastic modulus of the tube wall are neglected. The governing equations of the model are solved by Laplace transformation. The computed results show that relatively high blood pressures, capable of harming circulation, are produced even by relatively moderate velocity jumps.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of mathematical biology 39 (1977), S. 385-390 
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We report here an analysis of pumping of blood by means of a non-invasive circulatory-assist device using the principle of Magnetohydrodynamics. This study shows that such a pump would require the application of a slowly moving axial magnetic field of strength of about 108 amp turns/m (approximately 106 oersteds). The results indicate that the temperature rise on account of induced currents is within permissible range.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of mathematical biology 46 (1984), S. 937-949 
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The present study deals with the effect of a single cycle of body accelerations on blood flow in arteries. Such body accelerations are usually caused unintentionally, for example during travel in road vehicles, aircraft or spacecraft. A mathematical model of flow in single arteries subject to a pulsating pressure gradient due to the normal heart action as well as body acceleration expressible in terms of unit functions is presented. The body acceleration is such that it builds up from zero to a maximum value at a uniform rate, remains constant at the maximum value for some time, and thereafter reduces to zero at a uniform rate. The resulting equations are solved by using the technique of Laplace transforms. Computational results are presented for the effects of body accelerations on flow variables namely flow rate, velocity of flow, acceleration and shear stress corresponding to blood flow in the human aorta.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 44 (1976), S. 193-200 
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Distribution patterns of nitrate in field are studied in twelve treatments comprising of different N splits and irrigation schedules, after the harvest of wheat. Total amount of irrigation and nitrogen application were kept same for each treatment. The curves show that heavy irrigation at greater intervals can result in larger amount of unutilised NO3 −-N, which will eventually be lost beyond potential rooting zone. As irrigation becomes lighter and frequent, nitrates travel slowly and thus remain for more time within the reach of roots and are lost to a less extent. When whole of the nitrogen is applied in one lot, considerably more NO3 −-N is lost under all the irrigation schedules. As the number of splits are increased, susceptibility of nitrate nitrogen for leaching decreases to a greater extent under lighter and more frequent irrigation schedule than the other. Besides N-splitting and irrigation criteria, efficiency and depth of rooting system of plants seems to play a major role in defining nitrate leaching patterns towards unsaturated zone.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 47 (1977), S. 585-591 
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Distribution of nitrates in soil profiles under eight different crop rotations was studied after the harvest of various constituent crops. Nitrate distribution patterns at different dates reveal that maximum leaching loss of nitrates occurs from rotations consisting of heavily fertilized shallow rooted crops like potato. Wheat and maize, in a rotation reduce nitrate leaching to deeper soil layers because of their deep and extensive rooting systems. In rainy season, when maximum movement of nitrates occurs in the profile, raising of deep rooted crops like maize leaves for leaching only a small amount of nitrates as compared to crops like groundnut and soybean with shallow rooting systems and low N-requirement. Summer season crops like moong, cowpeas and maize (fodder), do not alter nitrate distribution patterns, unless a large amount of nitrates is present in the profile prior to their sowing.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In previous work, the yield of phosphorus in plants grown in the greenhouse on 36 alkaline soils was correlated significantly with the organic phosphorus mineralized during incubation of the soils in the laboratory, independently of the labile inorganic phosphorus. In this investigation, the same soils were used to test the hypothesis that the apparent organic-phosphorus effect observed previously was an indirect effect of CO2 evolved from soil organic matter in increasing the susceptibility of the inorganic phosphorus to uptake by plants. The hypothesis was tested on the basis of measurements of CO2 evolved and organic phosphorus mineralized concurrently during incubation of the soils in the laboratory. Statistical tests showed that the yield of phosphorus in the plants was correlated significantly with the organic phosphorus mineralized, independently of correlations with CO2 evolved and labile inorganic phosphorus; the yield of phosphorus in plants, however, was not correlated significantly with CO2 evolved, independently of correlations with organic phosphorus mineralized and labile inorganic phosphorus. The results thus provide no justification for discarding the organic-phosphorus theory and for substituting the CO2 theory in its place.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 45 (1976), S. 145-150 
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Effect of iron on zinc absorption by rice (Oryza sativa L. variety Jaya) seedlings and its translocation within the plant was studied in a nutrient solution culture using Zn65. Zinc absorption increased with zinc application, but decreased with increasing concentrations of iron in the nutrient medium. Total zinc uptake decreased to 85 per cent by increasing concentration of iron from 0 to 60 μM. Per cent reduction in zinc uptake was more at lower levels of zinc in the nutrient solution. The inhibitory action of iron on zinc absorption was ‘non-competitive’. Translocation of zinc decreased with increasing levels of iron from 0 to 20 μM. re]19750219
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 46 (1977), S. 329-336 
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Zinc adsorption was studied in suspensions of six soils of different physicochemical characteristics in dilute ZnSO4 solutions. At low concentrations, Zn2+ adsorption was described by the Langmuir adsorption equation. The calculated Langmuir adsorption maxima were related positively to clay and carbonate content and negatively with organic matter content of soils. Multiple regression analysis revealed that zinc adsorption maxima can be predicted with good precision from information in soil survey reports. When the added Zn2+ exceeded the adsorption maximum, the solid phase of zinc controlling its concentration in solution was either zinc hydroxide or carbonate so long as soil carbonates were present. The values of zinc potential also indicated that soils retain Zn2+ more strongly than Zn(OH)2 or carbonate.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 49 (1978), S. 633-639 
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Soil nitrate profiles under seven treatments of an experiment on intercropping in row crops were studied at sowing and the after harvesting of different crops. The estimates of NO3 −−N in these profiles indicate that intercropping in the row crops grown during the rainy season considerably reduced leaching loss of nitrates. Where the main crop receives the recommended fertilizer amount and the intercrop a small additional application, intercropping greatly reduced the amount of unutilized nitrates and hence their leaching beyong root zone.
    Type of Medium: Electronic Resource
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