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  • 1
    Electronic Resource
    Electronic Resource
    Pattern formation and morphogenesis: A reaction-diffusion model (1986)
    Springer
    Bulletin of mathematical biology 48 (1986), S. 213-228 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The problem of cellular differentiation and consequent pattern generation during embryonic development has been mathematically investigated with the help of a reaction-diffusion model. It is by now a well-recognized fact that diffusion of micromolecules (through intercellular gap junctions), which is dependent on the spatial parameter (r), serve the purpose of ‘positional information’ for differentiation. Based on this principle the present model has been constructed by coupling the Goodwin-type equations for RNA and protein synthesis with the diffusion process. The homogeneous Goodwin system can exhibit stable periodic solution if the value of the cooperativity as measured by the Hill coefficient (ρ) is greater than 8, which is not biologically realistic. In the present work it has been observed that inclusion of a negative cross-diffusion can drive the system into local instability for any value of ρ and thus a time-periodic spatial solution is possible around the unstable local equilibrium, eventually leading to a definite pattern formation. Inclusion of a negative cross-diffusion thus makes the system biologically realistic. The cross-diffusion can also give rise to a stationary wave-like dissipative structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460024
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Crystal and molecular structure of diaqua-bis-(3,5-dimethyl-1-guanyl pyrazole) nickel (II) nitrate, [Ni(C6N4H10)2(H2O)2](N03)2 (1989)
    Springer
    Journal of chemical crystallography 19 (1989), S. 71-76 
    Details
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in space groupP21/n witha=10.651(3),b=11.082(2),c=8.993(3) Å,β=106.79(3)°;R=0.064 andR w=0.074 for 3399 observed reflections (I≥3σ(I)) from 3674 measured. The structure was solved by direct methods and refined by least squares. The Ni atom of the complex is located at a center of inversion, and is surrounded by four nitrogen atoms of the two ligands in square-planar geometry. The oxygen atoms of the two centrosymmetrically related water molecules complete the coordination around the metal ion to form an elongated octahedron.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01160844
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  • 3
    Electronic Resource
    Electronic Resource
    A multivariate statistical study of copper mineralization in the central section of Mosaboni Mine, Eastern Singhbhum, India (1986)
    Springer
    Mathematical geology 18 (1986), S. 215-235 
    Details
    ISSN: 1573-8868
    Keywords: cluster analysis ; R-mode factor analysis ; copper mineralization ; Singhbhum Copper Belt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract A multivariate statistical analysis was carried out with log-transformed values of Cu, Ni, Co, Pb, Zn, Ag, Cr, Mn, Ca, and Sr in several sets of samples collected across the mineralized base metal zone in sheared soda granite, feldspathic schist, and chlorite schist from the central section of Mosaboni Mine of the famous Singhbhum Copper Belt of eastern India. Linear correlation coefficient matrices of two sets of ore samples (〉0.5% Cu)—one from levels 18 and 21 and the other from levels 25 and 28—indicate two well-defined and distinct clusters comprising Cu, Ni, Co, Pb, and Zn on one hand and Ca, Sr, and Mn on the other. Varimax-rotatedR-mode factor analysis of two above-noted sample sets, taken along with available geologic information, indicates that over 80% of the variability in data matrices for 9–10 elements can be accounted for by four distinct processes: (a) an early phase of copper mineralization which apparently replaced Mn, Ca, and Sr in the host rock; (b) a silicate-cum-oxide phase of crystallization/recrystallization of host rock; (c) remobilization of sulfide-forming ore elements (Cu, Ni, Co, Pb, and Zn); and (d) a phase of mineralization of Ag which appears to have replaced Cr, Ca and Cu. Process (c) was quantitatively most important. Factor score studies are suggestive of preferred introduction of Ni, Co, Pb, and Zn along central parts of preexisting copper-mineralized zones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00898284
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  • 4
    Electronic Resource
    Electronic Resource
    Tropospheric ozone profiles near equator and meteorological parameters (1987)
    Springer
    Journal of atmospheric chemistry 5 (1987), S. 243-253 
    Details
    ISSN: 1573-0662
    Keywords: Ozone profile ; tropospheric ; equatorial ; weather disturbances ; lightning ; water vapour incursion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract This is a study of ozone profile shapes in the 800 to 100 millibar range obtained with balloonsonde data over Trivandrum (8.5° N) during 1975–76 and possible associations of these shapes to some meteorological parameters. Whereas monotonic ozone profiles were noted with clear weather conditions, those associated with cloud cover show three basic anomalous features. Some bulges of increased values are observed in the range of 800 to 500 mb. In the 500–100 mb range, short range or localized cloud cover or passing weather disturbances are associated with fluctuation patterns in the ozone profile and an average depleted value of ozone. The fluctuations are also associated with changing wind speed and direction at these heights. Possible causative mechanisms are discussed. Lightning associated with thundestorm, producing additional CO and NO are sought to interpret the bulges at lower heights. The decrease in values as well as the fluctuation patterns are suggested as due to possible incursion of water vapour from troposphere to stratosphere in the tropical region and dynamical effects associated with it.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00114105
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  • 5
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    A multivariate statistical study of copper mineralization in the central section of Mosaboni Mine, Eastern Singhbhum, India (1986)
    Springer
    Details
    Publication Date: 1986-02-01
    Print ISSN: 1874-8961
    Electronic ISSN: 1874-8953
    Topics: Geosciences , Mathematics
    Published by Springer
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  • 6
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    Tropospheric ozone profiles near equator and meteorological parameters (1987)
    Springer
    Details
    Publication Date: 1987-09-01
    Print ISSN: 0167-7764
    Electronic ISSN: 1573-0662
    Topics: Chemistry and Pharmacology , Geosciences
    Published by Springer
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