Onderzoekingen over een virusremstof voorkomend in Dianthus cariophyllus L. : werkingsspectrum, remmingsmechanisme en aard

An inhibitor of carnation proved to inhibit 14 very different viruses when tested on a range of 20 plant species. No viruses insensitive to the inhibitor were encountered. The degree of inhibition was for all viruses dependent on the plant species used as a test plant. The investigated plants could be distinguished into species very sensitive and hardly sensitive to inhibitor. The hardly sensitive ones all belonged to the order Centrospermae. The differences in sensitivity were quantitative and qualitative. The influence on contamination was expressed as a percentage activity. A decrease in the inhibitor's concentration hiw a stronger effect on the percentage activity than an increase in virus concentration of the same order.For various reasons it was considered improbable that inhibition would result from a reaction between virus and inhibitor in a liquid medium. Their mutual independence in vitro could be confirmed by ultracentrifuging sap from carnations with mosaic disease. The feasibility was also established of inhibitor acting through the test plant.Both infectious ribonucleic acid (RNA) of tobacco mosaic virus and the intact virus on Nicotiana glutinosa were inhibited by carnation inhibitor. The inhibition was shown not to result from an interaction between the inhibitor and the proteinaceous exterior of the virus.The virus-inhibiting activity of the inhibitor was finally interpreted on the basis of the 'receptor theory' of viral infection as a blocking of the sites near the leaf surface necessary for successful viral infection.By ultracentrifuging the molecular weight of the inhibitor could be estimated as at least 10.000. The inhibitor could also be isolated and some of its physical and chemical qualities could be established

Neighborhood self management :a study of the role of local communities in the revitalization of metropolitan areas

Traditionally observers of the urban scene have held that by unilaterally shifting the balance between central and local control over urban management, conditions within cities could be improved. More recently a theoretical synthesis has been advanced which advocates the decentralization of some urban functions to the neighborhood level and the centralization of others to a metropolitan wide authority. Adherents of this latter position hold that healthy cities operate best on the principle of a “federation of neighborhoods”. Following a review of the construction of modern society, this thesis considers the theoretical benefits of dividing responsibility for four categories of urban functions between local and central authorities. The ideal theoretical division of various environmental, economic, social and political functions has subsequently been tested against an implemented form of neighborhood self management in Jerusalem. The results of this comparison confirm that properly constituted neighborhood authorities can indeed deliver human services more effectively and with considerable financial savings. It has also become apparent that social cohesion is enhanced by recognizing and legitimizing local communities. The Jerusalem experience further reveals that a strong metropolitan wide authority is crucial in securing the judicious use of natural resources and preventing environmental degradation, thereby ensuring long-term economic well being. The considered balancing of urban functions between central and local control would benefit metropolitan areas worldwide, particularly those considering a comprehensive revitalization.Applied Science, Faculty ofCommunity and Regional Planning (SCARP), School ofGraduat