Diffusion 35 Diffusion of innovations 34 Congresses 16 Pollution 13 Air 12 Atmospheric diffusion 12 Mathematical models 9 Technological innovations 9 Culture diffusion 7 Diffusion processes 7 Economic aspects 6 Heat 6 Aerosols 4 Meteorological aspects 4 Technology transfer 4 Transmission 4 Agricultural innovations 3 Economic development 3 Environmental aspects 3 Fluid dynamics 3 History 3 Mass transfer 3 Social change 3 Solids 3 Transport theory 3 Turbulent diffusion (Meteorology) 3 Civilization 2 Copper 2 Diffusion rate 2 Gases 2