Scientific terminology informal or non-technical English, to say "strictly speaking" for "sensu stricto" and "broadly speaking" and so on is valid. Even in formal writing, there is no formal requirement to use the Latin terms rather than the vernacular. Valid reasons for using these Latin or partly Latin expressions are not points of pretentiousness; they include: A good example is the word "laser", an acronym for "Light Amplification by Stimulated Emission of Radiation", and therefore all its letters should be capitalized. However, because of frequent use, this acronym became a neologism, i.e., it has integrated into English and most other languages. Consequently,
Sound amplification by stimulated emission of radiation of direct semiconductors. The reasoning behind that comes from the fact that, due to the k-selection rule in semiconductors, interband transitions with the production of only one phonon can be only those that produce an optical phonon. However, optical phonons have a short life-time (they split into two due to anharmonicity) and therefore they add some important complications. Here we can note that even in the case of multi-stage process of acoustic phonon creation it is possible to create SASER. Examples of narrow-gap indirect semiconductors that can be used are chalcogenides PbTe, PbSe and PbS with energy gap 0.15 –