Problem: Luminous efficacy of a light source may be defined in two ways. The radiant luminous efficacy (LER) is the ratio of the visible light flux emitted (the luminous flux) to the total power radiated over all wavelengths. The source luminous efficacy (LES) is the ratio of the visible light flux emitted (the luminous flux) to the total power input to the source, such as a lamp. Visible light is measured in lumens, a unit which is defined in part by the differing sensitivity of the human eye to different wavelengths of light. Not all wavelengths of visible electromagnetic energy are equally effective at stimulating the human eye; the luminous efficacy of radiant energy (LER) is a measure of how well the distribution of energy matches the perception of the eye. The units of luminous efficacy are "lumens per watt" (lpw). The maximum LER possible is 683 lm/W for monochromatic green light at 555 nanometers wavelength, the peak sensitivity of the human eye.
What does the acronym LER refer to?
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Answer: radiant luminous efficacy

Problem: Red is used in modern fashion much as it was used in Medieval painting; to attract the eyes of the viewer to the person who is supposed to be the center of attention. People wearing red seem to be closer than those dressed in other colors, even if they are actually the same distance away. Monarchs, wives of Presidential candidates and other celebrities often wear red to be visible from a distance in a crowd. It is also commonly worn by lifeguards and others whose job requires them to be easily found.
What older period was red used in fashion?
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Answer: unanswerable

Problem: In 1979, the committees began the redistribution of land in the Jefara plain, continuing through 1981. In May 1980, measures to redistribute and equalize wealth were implemented; anyone with over 1000 dinar in his bank account saw that extra money expropriated. The following year, the GPC announced that the government would take control of all import, export and distribution functions, with state supermarkets replacing privately owned businesses; this led to a decline in the availability of consumer goods and the development of a thriving black market.
As a result of the 1981 laws putting the government in control of commerce, what began to thrive?
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Answer:
black market