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.

Volunteer hosts went to the airport, picked up assigned students, fed them dinner, took them to the opening lecture at the Clay Center, put them in spare bedrooms for the night, then fed them breakfast this morning and will deliver the outstanding teens to buses that convey them to the mountain retreat where they undergo a month of intensive science training and outdoor fun.

Luckily, this year, enough local families volunteered to host all the brilliant youths. In the past, the number of guest homes sometimes fell short, and some of the visitors slept on cots and sleeping bags at local churches. They're adventurous teens and don't mind this makeshift camp-in but it's better if friendly hosts give them a more personal welcome for their stay.

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.

Speed skating is a competitive form of ice skating in which the competitors race each other in traveling a certain distance on skates. Types of speed skating are long track speed skating, short track speed skating, and marathon speed skating. Short track speed skating takes place on a smaller rink, normally the size of an ice hockey rink. Distances are shorter than in long track racing, with the longest Olympic race being 3000 meters. Races are usually held as knockouts, with the best two in heats of four or five qualifying for the final race, where medals are awarded. Disqualifications and falls are not uncommon. The sport originates from pack-style events held in North America and was officially sanctioned in the 1970s, becoming an Olympic sport in 1992. Although this form of speed skating is newer, it is growing faster than long track speed skating, largely because short track can be done on an ice hockey rink rather than a long-track oval.

USS Gilliam (APA-57), named for Gilliam County in Oregon, was the lead ship in the her class of attack transports serving in the United States Navy during World War II. She was launched 28 March 1944 under a Maritime Commission contract by the Consolidated Steel Corporation, Wilmington, California; sponsored by Mrs. A. O. Williams of Wilmington; acquired 31 July 1944; and commissioned 1 August 1944, Comdr. H. B. Olsen in command.