NitrogenNitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element bond to form N2, a colorless and odorless diatomic gas. N2 forms about 78% of Earth's atmosphere, making it the most abundant uncombined element in air.
Cold seepA cold seep (sometimes called a cold vent) is an area of the ocean floor where hydrogen sulfide, methane and other hydrocarbon-rich fluid seepage occurs, often in the form of a brine pool. Cold does not mean that the temperature of the seepage is lower than that of the surrounding sea water. On the contrary, its temperature is often slightly higher. The "cold" is relative to the very warm (at least ) conditions of a hydrothermal vent. Cold seeps constitute a biome supporting several endemic species.
Assimilation (phonology)Assimilation is a sound change in which some phonemes (typically consonants or vowels) change to become more similar to other nearby sounds. A common type of phonological process across languages, assimilation can occur either within a word or between words. It occurs in normal speech but becomes more common in more rapid speech. In some cases, assimilation causes the sound spoken to differ from the normal pronunciation in isolation, such as the prefix in- of English input pronounced with phonetic [m] rather than [n].
I-mutationI-mutation (also known as umlaut, front mutation, i-umlaut, i/j-mutation or i/j-umlaut) is a type of sound change in which a back vowel is fronted or a front vowel is raised if the following syllable contains i, ī or j (a voiced palatal approximant, sometimes called yod, the sound of English in yes). It is a category of regressive metaphony, or vowel harmony. The term is usually used by scholars of the Germanic languages: it is particularly important in the history of the Germanic languages because inflectional suffixes with an /i/ or /j/ led to many vowel alternations that are still important in the morphology of the languages.
EoceneThe Eocene (ˈiːəsiːn,_ˈiːoʊ- ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name Eocene comes from the Ancient Greek ἠώς (ēṓs, "dawn") and καινός (kainós, "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch. The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch.
