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.

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 Vikings were seafaring north Germanic people who raided, traded, explored, and settled in wide areas of Europe, Asia, and the North Atlantic islands from the late 8th to the mid-11th centuries. The Vikings employed wooden longships with wide, shallow-draft hulls, allowing navigation in rough seas or in shallow river waters. The ships could be landed on beaches, and their light weight enabled them to be hauled over portages. These versatile ships allowed the Vikings to travel as far east as Constantinople and the Volga River in Russia, as far west as Iceland, Greenland, and Newfoundland, and as far south as Nekor. This period of Viking expansion, known as the Viking Age, constitutes an important element of the medieval history of Scandinavia, Great Britain, Ireland, Russia, and the rest of Europe.

The Urnero (Leptodactylus latinasus) is a species of frog in the Leptodactylidae family. It is found in Argentina, Bolivia, Brazil, Paraguay, and Uruguay. Its natural habitats are subtropical or tropical moist shrub land, subtropical or tropical dry lowland grassland, subtropical or tropical seasonally wet or flooded lowland grassland, freshwater marshes, intermittent freshwater marshes, pastureland, rural gardens, and ponds.

The Los Angeles County Tobacco Control Program (TCP) is part of the Division of Chronic Disease Prevention and Health Promotion in the Department of Health Services. It was established as a result of the tobacco tax initiative of 1988, Proposition 99/AB75, in December of 1989. The goal of TCP is to establish policies, health services, public education, and media conditions that support the reduction of tobacco use in Los Angeles County and the associated disease, disability, and mortality.