Einstein coefficientsEinstein coefficients are quantities describing the probability of absorption or emission of a photon by an atom or molecule. The Einstein A coefficients are related to the rate of spontaneous emission of light, and the Einstein B coefficients are related to the absorption and stimulated emission of light. Throughout this article, "light" refers to any electromagnetic radiation, not necessarily in the visible spectrum. In physics, one thinks of a spectral line from two viewpoints.
Access controlIn physical security and information security, access control (AC) is the selective restriction of access to a place or other resource, while access management describes the process. The act of accessing may mean consuming, entering, or using. Permission to access a resource is called authorization. Locks and login credentials are two analogous mechanisms of access control. Physical security Geographical access control may be enforced by personnel (e.g. border guard, bouncer, ticket checker), or with a device such as a turnstile.
Bengali languageBengali (bɛnˈɡɔːli ), generally known by its endonym Bangla (বাংলা, ˈbaŋla), is an Indo-Aryan language native to the Bengal region of South Asia. With approximately 300 million native speakers and another 50 million as second language speakers, Bengali is the sixth most spoken native language and the seventh most spoken language by the total number of speakers in the world. Bengali is the fifth most spoken Indo-European language. Bengali is the official, national, and most widely spoken language of Bangladesh, with 98% of Bangladeshis using Bengali as their first language.
