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Surface temperature measurement of flame spread using thermographic phosphors

A technique based on remote measurements of surface temperature in connection to fires is presented. Pulsed ultraviolet laser radiation at 266 nm and 7 ns duration was used to excite a thermographic phosphor, Mg4FGeO6: Mn, which was adapted on the surface of the investigated material. The laser-induced emission from the phosphor was recorded. A calibration of the phosphorescence lifetime and spect

Human conceptions of the rise and fall of civilizations

SETI, our hopes or fears of a future contact with ETI, is a modern expression of an unending human obsession with the rise and fall of civilizations. People across the globe from our earliest sources to our contemporary culture have tried to understand the beginning and end of history, the creation and the doom. Factor L of the Drake Equation could in other words be understood in a longer historic