Problem: Asphalt:

The great majority of asphalt used commercially is obtained from petroleum. Nonetheless, large amounts of asphalt occur in concentrated form in nature. Naturally occurring deposits of asphalt/bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things. These remains were deposited in the mud on the bottom of the ocean or lake where the organisms lived. Under the heat (above 50 °C) and pressure of burial deep in the earth, the remains were transformed into materials such as asphalt/bitumen, kerogen, or petroleum.

Besides heat, what other requirement is needed to form asphalt?
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A: pressure


Problem: In recent years light emitting diodes (LEDs) are becoming increasingly efficient leading to an extraordinary increase in the use of solid state lighting. In many situations, controlling the light emission of LEDs may be done most effectively by using the principles of nonimaging optics.
What is a form of solid state lighting?
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Answer: LEDs


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Other trees of note include the royal palm, sea grape trees in the form of shrubs on the beaches and as 5 to 7 m trees in the interior areas of the island, aloe or aloe vera (brought from the Mediterranean), the night blooming cereus, mamillaria nivosa, yellow prickly pear or barbary fig which was planted as barbed wire defences against invading British army in 1773, Mexican cactus, stapelia gigantea, golden trumpet or yellow bell which was originally from South America, bougainvillea and others.
What plant was brought to St. Barts from the Mediterranean?
A: aloe or aloe vera


Context and question: Stepper motors are a type of motor frequently used when precise rotations are required. In a stepper motor an internal rotor containing PMs or a magnetically soft rotor with salient poles is controlled by a set of external magnets that are switched electronically. A stepper motor may also be thought of as a cross between a DC electric motor and a rotary solenoid. As each coil is energized in turn, the rotor aligns itself with the magnetic field produced by the energized field winding. Unlike a synchronous motor, in its application, the stepper motor may not rotate continuously; instead, it "steps"—starts and then quickly stops again—from one position to the next as field windings are energized and de-energized in sequence. Depending on the sequence, the rotor may turn forwards or backwards, and it may change direction, stop, speed up or slow down arbitrarily at any time.
When are stepper motors most useful?
Answer: when precise rotations are required


Question: In 1957, Braunstein further demonstrated that the rudimentary devices could be used for non-radio communication across a short distance. As noted by Kroemer Braunstein".. had set up a simple optical communications link: Music emerging from a record player was used via suitable electronics to modulate the forward current of a GaAs diode. The emitted light was detected by a PbS diode some distance away. This signal was fed into an audio amplifier, and played back by a loudspeaker. Intercepting the beam stopped the music. We had a great deal of fun playing with this setup." This setup presaged the use of LEDs for optical communication applications.
Is there an answer to this question: What final device was needed to hear the signal from the initial GaAs diode?

Answer: audio amplifier


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
In 2007, two FAA whistleblowers, inspectors Charalambe "Bobby" Boutris and Douglas E. Peters, alleged that Boutris said he attempted to ground Southwest after finding cracks in the fuselage, but was prevented by supervisors he said were friendly with the airline. This was validated by a report by the Department of Transportation which found FAA managers had allowed Southwest Airlines to fly 46 airplanes in 2006 and 2007 that were overdue for safety inspections, ignoring concerns raised by inspectors. Audits of other airlines resulted in two airlines grounding hundreds of planes, causing thousands of flight cancellations. The House Transportation and Infrastructure Committee held hearings in April 2008. Jim Oberstar, former chairman of the committee said its investigation uncovered a pattern of regulatory abuse and widespread regulatory lapses, allowing 117 aircraft to be operated commercially although not in compliance with FAA safety rules. Oberstar said there was a "culture of coziness" between senior FAA officials and the airlines and "a systematic breakdown" in the FAA's culture that resulted in "malfeasance, bordering on corruption." In 2008 the FAA proposed to fine Southwest $10.2 million for failing to inspect older planes for cracks, and in 2009 Southwest and the FAA agreed that Southwest would pay a $7.5 million penalty and would adopt new safety procedures, with the fine doubling if Southwest failed to follow through.
When did two whisleblowers allege that Boutris  attempted to ground Southwest Airlines?
A:
2007