A perennial stream or perennial river is a stream or river (channel) that has continuous flow in parts of its stream bed all year round during years of normal rainfall. "Perennial" streams are contrasted with "intermittent" streams which normally cease flowing for weeks or months each year, and with "ephemeral" channels that flow only for hours or days following rainfall.

The Criminal Grand Jury of Los Angeles County attends hearings brought by the District Attorney’s Office . The objective of this jury is to determine, on the basis of evidence presented by the District Attorney’s Office, whether certain persons should be charged with crimes an d required to stand trial in Superior Court. The Criminal Grand Jury is an accusatory body and not a trial jury; therefore, the burden of proof is much lower. Specifically, the Criminal Grand Jury must decide if there is a strong suspicion the individual committed the alleged crime.

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.

Conan of Aquilonia is a collection of four linked fantasy short stories written by L. Sprague de Camp and Lin Carter featuring Robert E. Howard's seminal sword and sorcery hero Conan the Barbarian. The stories were originally published in Fantastic for August 1972, July 1973, July 1974, and February, 1975. The collected stories were intended for book publication by Lancer Books, but this edition never appeared due to Lancer's bankruptcy. The first book edition was issued in paperback by Ace Books in May 1977 and the first British edition was published by Sphere Books in October 1978.

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.