From 1912 to 1928, the contact number for measles in the U. S. was 12.8. If we assume that Ro is still 12.8 and that inoculation is 100% effective -- everyone inoculated obtains immunity from the disease -- what fraction of the population must be inoculated to prevent an epidemic?

Urban growth invariably feeds increased commercialization and industrialization. it requires continually expanding land areas. when urbanization rates are high, and countries do not have the institutional and managerial capacities or economic wherewithal to manage such rapid growths, they exert intense pressure on the types and nature of the resulting settlements. they contribute to the development of overcrowded slums and shanty towns without adequate essential services and necessary infrastructure.-by asit k. biswas and cecilia tortajada

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