The Mayan languages form a language family spoken in Mesoamerica and northern Central America. Mayan languages are spoken by at least 6 million indigenous Maya, primarily in Guatemala, Mexico, Belize and Honduras. In 1996, Guatemala formally recognized 21 Mayan languages by name, and Mexico recognizes eight more. The Mayan language family is one of the best documented and most studied in the Americas. Modern Mayan languages descend from Proto-Mayan, a language thought to have been spoken at least 5,000 years ago.

The Doppler effect (or Doppler shift), named after the Austrian physicist Christian Doppler, who proposed it in 1842 in Prague, is the change in frequency of a wave (or other periodic event) for an observer moving relative to its source. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from an observer. The received frequency is higher (compared to the emitted frequency) during the approach, it is identical at the instant of passing by, and it is lower during the recession.

Plasma is one of the four fundamental states of matter (the others being solid, liquid, and gas). Heating a gas may ionize its molecules or atoms (reducing or increasing the number of electrons in them), thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions.

Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. The extreme opposite of endemism is cosmopolitan distribution.

The expert predicted that America's gross domestic product will return to more than 3 percent yearly expansion. For example, Dow Chemical is investing $4 billion in Texas plastics production that will be operational by 2019. Such growth requires cheap oil and natural gas - and "by 2022 or so, the United States will surpass Saudi Arabia in oil output, and Russia in gas." He continued: "The big attraction is the low price of natural gas, the lowest-carbon fossil fuel, which can be produced profitably at about a third the price per unit of energy as other hydrocarbons. That is particularly attractive to chemical companies. It is the raw material for plastics, Styrofoam, tires, sealants, adhesives, films, liquid crystal screens, nylons, polyesters - nearly everything around us."