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A variation of the incandescent lamp did not use a hot wire filament, but instead used an arc struck on a spherical bead electrode to produce heat. The electrode then became incandescent, with the arc contributing little to the light produced. Such lamps were used for projection or illumination for scientific instruments such as microscopes. These arc lamps ran on relatively low voltages and incorporated tungsten filaments to start ionization within the envelope. They provided the intense concentrated light of an arc lamp but were easier to operate. Developed around 1915, these lamps were displaced by mercury and xenon arc lamps.
What was not a common use for this type of bulb?
A: unanswerable

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In 1849, Horne's began operations and soon became a leading Pittsburgh department store. In 1879, it opened a seven-story landmark which was the first department store in the city's downtown. In 1972, Associated Dry Goods acquired Horne's, and ADG expanded operations of Horne's to several stores in suburban malls throughout the Pittsburgh region as well as in Erie, Pennsylvania and Northeast Ohio. In December 1986, Horne's was acquired by a local investor group following ADG's acquisition by May Department Stores. By 1994, Federated Department Stores acquired the remaining ten Horne's stores and merged them with its Lazarus division, completely ceasing all operations of any store under the Horne's name.
In what city did Horne cease their operations?
A: unanswerable

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After the constitutional changes of 1974, Tito began reducing his role in the day-to-day running of the state. He continued to travel abroad and receive foreign visitors, going to Beijing in 1977 and reconciling with a Chinese leadership that had once branded him a revisionist. In turn, Chairman Hua Guofeng visited Yugoslavia in 1979. In 1978, Tito traveled to the U.S. During the visit strict security was imposed in Washington, D.C. owing to protests by anti-communist Croat, Serb and Albanian groups.
Where did Tito travel in 1977 to reconcile with Chinese leadership?
A: Beijing

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John's illness grew worse and by the time he reached Newark Castle he was unable to travel any farther; John died on the night of 18 October. Numerous – probably fictitious – accounts circulated soon after his death that he had been killed by poisoned ale, poisoned plums or a "surfeit of peaches". His body was escorted south by a company of mercenaries and he was buried in Worcester Cathedral in front of the altar of St Wulfstan. A new sarcophagus with an effigy was made for him in 1232, in which his remains now rest.
When did John die?
A:
18 October