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.

Ohio started the month of July with its pedal to the metal. The Buckeye State became the 34th state to adopt the 70 miles-an-hour speed limit. Drivers can now do up to 70 on more than 570 of Ohio's 1,332 miles of interstate highway. Congress repealed the 55 mph national limit in 1995. Despite predictions of calamity and carnage on the highways, the National Highway Traffic Safety Administration reported in October 1998 that "the traffic death rate dropped to a record low level in 1997". That pattern has continued since then.

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 South Shore Estuary is an estuary located along the south shore of Long Island, between the mainland and the outer barrier islands, in eastern New York state. It stretches for over 70 miles (110 km) from West Bay in Nassau County to the Shinnecock Bay in Suffolk County.