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  • 1
    Electronic Resource
    Electronic Resource
    The abdominal motor system of the crayfish, Cherax destructor. II. Morphology and physiology of the deep extensor motor neurons (1998)
    Springer
    Journal of comparative physiology 183 (1998), S. 603-619 
    Details
    ISSN: 1432-1351
    Keywords: Key words Abdominal extensor motor neurons ; Morphology ; Physiology ; Stretch receptors ; Crayfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Two opposing muscle systems underlie abdominal contractions during escape swimming in crayfish. In this study we used extracellular and intracellular stimulation, recording and dye-filling to systematically identify each of the five deep extensor excitors and single inhibitor of the crayfish, Cherax destructor. Functional associations of each neuron were characterised by recording its responses to sensory and abdominal cord inputs, its extensor muscle innervation pattern, and its relationships with other neurons. Each excitor receives excitatory input from the tonic abdominal stretch receptors and the largest neuron also receives input from the phasic stretch receptor. The two largest excitors innervate the muscle bundle containing the fastest fibres and may be electronically coupled. The smaller neurons may also be electronically coupled and innervate the remaining deep extensor fibres which display dynamic characteristics from fast to medium-fast. The inhibitor does not receive input from the stretch receptors, but is strongly excited by tactile afferents. The implications of these findings for the current models of the control of abdominal tailflips and swimming are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050285
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  • 2
    Electronic Resource
    Electronic Resource
    The abdominal motor system of the crayfish, Cherax destructor. I. Morphology and physiology of the superficial extensor motor neurons (1998)
    Springer
    Journal of comparative physiology 183 (1998), S. 583-601 
    Details
    ISSN: 1432-1351
    Keywords: Key words Abdominal extensor motor neurons ; Morphology ; Physiology ; Stretch receptors ; Crayfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Using extracellular and intracellular stimulation, recording and dye-filling, we identified and studied the superficial extensor motor neurons of the crayfish, Cherax destructor. Functional associations of each neuron were characterised by recording its responses to sensory and abdominal cord inputs, its extensor muscle innervation pattern and its relationships with other neurons. Two clear associations were found among the six neurons of each segment. A medium-sized excitor (no. 3), that innervates a substantial percentage of extensor muscle fibres, and the largest excitor (no. 6), recruited during peak, excitation, were inhibited by input from unknown interneurons that excited the common inhibitor (no. 5). Likewise, these excitors received excitatory input when the inhibitor was silent. Another medium-sized neuron (no. 4) that innervates many muscle fibres was co-active with one of the small excitors (no. 2). The two medium-sized neurons were never active at the same time, and these two groupings may be determined by pre-motor interneurons. The implications of these findings for our understanding of motor control in this system are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050284
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  • 3
    Electronic Resource
    Electronic Resource
    Rural land use and agricultural production in Dinokana Village, Bophuthatswana (1990)
    Springer
    GeoJournal 22 (1990), S. 335-343 
    Details
    ISSN: 1572-9893
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography
    Notes: Abstract In recent years geographers have researched the problems of many rural areas of the third world. However, analysis of rural and agricultural development in the Bantustans of South Africa has been conspicuously absent. Although mythically ‘independent’, the Bantustans have their own Departments of Agriculture, as well as parastatal bodies, which develop and implement agricultural policies. This paper examines agricultural policy in the Bophuthatswana Bantustans, which is largely based on increasing food production for ‘national’ self-sufficiency through the establishment of agricultural development projects. The effects of the implementation of this programme on a specific rural community, the village of Dinokana, are discussed. Two irrigation based projects were implemented in Dinokana in the early 1980's. The project planners did not seem to be concerned about the existence of an ‘indigenous’ irrigation system which had been the foundation for agricultural development at Dinokana for several decades, and which could have been revived and upgraded. This suggests that there is a need for agricultural planners to have a detailed historial knowledge of local African agriculture. Geographers could play a valuable role here, by uncovering the dynamics of past systems of African agricultural production, in particular focusing on patterns of rural resource management.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192833
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  • 4
    Electronic Resource
    Electronic Resource
    Rural land use and agricultural production in Dinokana Village, Bophuthatswana (1990)
    Springer
    GeoJournal 22 (1990), S. 335-343 
    Details
    ISSN: 1572-9893
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography
    Notes: Abstract In recent years geographers have researched the problems of many rural areas of the third world. However, analysis of rural and agricultural development in the Bantustans of South Africa has been conspicuously absent. Although mythically ‘independent’, the Bantustans have their own Departments of Agriculture, as well as parastatal bodies, which develop and implement agricultural policies. This paper examines agricultural policy in the Bophuthatswana Bantustans, which is largely based on increasing food production for ‘national’ self-sufficiency through the establishment of agricultural development projects. The effects of the implementation of this programme on a specific rural community, the village of Dinokana, are discussed. Two irrigation based projects were implemented in Dinokana in the early 1980's. The project planners did not seem to be concerned about the existence of an ‘indigenous’ irrigation system which had been the foundation for agricultural development at Dinokana for several decades, and which could have been revived and upgraded. This suggests that there is a need for agricultural planners to have a detailed historial knowledge of local African agriculture. Geographers could play a valuable role here, by uncovering the dynamics of past systems of African agricultural production, in particular focusing on patterns of rural resource management.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711346
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  • 5
    Electronic Resource
    Electronic Resource
    Dimensions of drought: South African case studies (1993)
    Springer
    GeoJournal 30 (1993), S. 93-98 
    Details
    ISSN: 1572-9893
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography
    Notes: Abstract The recent drought in southern Africa has underscored the need for detailed analysis of the phenomenon. While geographers have researched the causes and impacts of drought in many African contexts, South Africa and in particular its Bantustans have not received sufficient similar attention. This paper outlines firstly the dimensions of drought in South Africa, including the biophysical and socio-economic factors. Issues such as land-use management, drought planning and relief are interrogated in the South African context. The final section of the paper highlights these debates with specific reference to case studies of past and present drought initiatives in South Africa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807832
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  • 6
    Electronic Resource
    Electronic Resource
    Two dimensional linear stability of premixed laminar flames under zero gravity (1993)
    Springer
    Flow, turbulence and combustion 51 (1993), S. 687-711 
    Details
    ISSN: 1573-1987
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper reports on the numerical study of the linear stability of laminar premixed flames under zero gravity. The study specifically addresses the dependence of stability on finite rate chemistry with low activation energy and variable thermodynamic and transport properties. The calculations show that activation energy and details of chemistry play a minor role in altering the linear neutral stability results from asymptotic analysis. Variable specific heat makes a marginal change to the stability. Variable transport properties on the other hand tend to substantially enhance the stability from critical wave number of about 0.5 to 0.20. Also, it appears that the effects of variable properties tend to nullify the effects of non-unity Lewis number. When the Lewis number of a single species is different from unity, as will happen in a hydrogen-air premixed flame, the stability results remain close to that of unity Lewis number.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00849273
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  • 7
    Electronic Resource
    Electronic Resource
    Investigation of chemically reacting and radiating supersonic flow in channels (1993)
    Springer
    Flow, turbulence and combustion 50 (1993), S. 43-68 
    Details
    ISSN: 1573-1987
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The two-dimensional time dependent Navier-Stokes equations are used to investigate supersonic flows undergoing finite rate chemical reaction and radiation interaction for a hydrogen-air system. The explicit multi-stage finite volume technique of Jameson is used to advance the governing equations in time until convergence is achieved. The chemistry source term in the species equation is treated implicitly to alleviate the stiffness associated with fast reactions. The multidimensional radiative transfer equations for a nongray model are provided for general configuration, and then reduced for a planar geometry. Both pseudo-gray and nongray models are used to represent the absorption-emission characteristics of the participating species. The supersonic inviscid and viscous, nonreacting flows are solved by employing the finite volume technique of Jameson and the unsplit finite difference scheme of MacCormack to determine a convenient numerical procedure for the present study. The specific problem considered is of the flow in a channel with a 10° compression-expansion ramp. The calculated results are compared with the results of an upwind scheme and no significant differences are noted. The problem of chemically reacting and radiating flows are solved for the flow of premixed hydrogen-air through a channel with parallel boundaries, and a channel with a compression corner. Results obtained for specific conditions indicate that the radiative interaction can have a significant influence on the entire flowfield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01086452
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  • 8
    Electronic Resource
    Electronic Resource
    The brachistochrone with acceleration: A running track (1971)
    Springer
    Journal of optimization theory and applications 7 (1971), S. 444-449 
    Details
    ISSN: 1573-2878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The equations for the brachistochrone of a self-accelerating particle are found by solving a problem in the calculus of variations with a constraint and a free end condition then applied to find the shape of a running track.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00931980
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  • 9
    Electronic Resource
    Electronic Resource
    Measurements of tropospheric OH concentrations: A comparison of field data with model predictions (1987)
    Springer
    Journal of atmospheric chemistry 5 (1987), S. 185-216 
    Details
    ISSN: 1573-0662
    Keywords: OH-radicals ; troposphere ; long path absorption spectroscopy ; sensitivity study ; formaldehyde ; measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Using long path UV absorption spectroscopy we have measured OH concentrations close to the earth's surface. The OH values observed at two locations in Germany during 1980 through 1983 range from 0.7×106 to 3.2×106 cm-3. Simultaneously we measured the concentrations of O3, H2O, NO, NO2, CH4, CO, and the light non methane hydrocarbons. We also determined the photolysis rates of O3 and NO2. This allows calculations of OH using a zero dimensional time depdendent model. The modelled OH concentrations significantly exceed the measured values for low NO x concentrations. It is argued that additional, so far unidentified. HO x loss reactions must be responsible for that discrepancy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048859
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  • 10
    Electronic Resource
    Electronic Resource
    Über die Absorption von Kupfer bei der Verdauung künstlich mit Kupfer gefärbter Gemüse (1926)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 68 (1926), S. 127-127 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02423353
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