Problem: Compact disc:

The Compact Disc is an evolution of LaserDisc technology, where a focused laser beam is used that enables the high information density required for high-quality digital audio signals. Prototypes were developed by Philips and Sony independently in the late 1970s. In 1979, Sony and Philips set up a joint task force of engineers to design a new digital audio disc. After a year of experimentation and discussion, the Red Book CD-DA standard was published in 1980. After their commercial release in 1982, compact discs and their players were extremely popular. Despite costing up to $1,000, over 400,000 CD players were sold in the United States between 1983 and 1984. The success of the compact disc has been credited to the cooperation between Philips and Sony, who came together to agree upon and develop compatible hardware. The unified design of the compact disc allowed consumers to purchase any disc or player from any company, and allowed the CD to dominate the at-home music market unchallenged.

Who created Compact Disc prototypes in the 1970s?
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A: Philips and Sony


Problem: Because the electron mobility is higher than the hole mobility for all semiconductor materials, a given bipolar n–p–n transistor tends to be swifter than an equivalent p–n–p transistor. GaAs has the highest electron mobility of the three semiconductors. It is for this reason that GaAs is used in high-frequency applications. A relatively recent FET development, the high-electron-mobility transistor (HEMT), has a heterostructure (junction between different semiconductor materials) of aluminium gallium arsenide (AlGaAs)-gallium arsenide (GaAs) which has twice the electron mobility of a GaAs-metal barrier junction. Because of their high speed and low noise, HEMTs are used in satellite receivers working at frequencies around 12 GHz. HEMTs based on gallium nitride and aluminium gallium nitride (AlGaN/GaN HEMTs) provide a still higher electron mobility and are being developed for various applications.
Where are HEMTs most commonly used?
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Answer: unanswerable


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Hunter-gatherer societies manifest significant variability, depending on climate zone/life zone, available technology and societal structure. Archaeologists examine hunter-gatherer tool kits to measure variability across different groups. Collard et al. (2005) found temperature to be the only statistically significant factor to impact hunter-gatherer tool kits. Using temperature as a proxy for risk, Collard et al.'s results suggest that environments with extreme temperatures pose a threat to hunter-gatherer systems significant enough to warrant increased variability of tools. These results support Torrence's (1989) theory that risk of failure is indeed the most important factor in determining the structure of hunter-gatherer toolkits.
What was found to be one of the many significant factors affecting hunter-gatherer tool kits?
A: unanswerable


Context and question: As part of the housing and credit booms, the number of financial agreements called mortgage-backed securities (MBS) and collateralized debt obligations (CDO), which derived their value from mortgage payments and housing prices, greatly increased. Such financial innovation enabled institutions and investors around the world to invest in the U.S. housing market. As housing prices declined, major global financial institutions that had borrowed and invested heavily in subprime MBS reported significant losses.
MBS and CDO derive their value from?
Answer: mortgage payments and housing prices


Question: Greece's post-compulsory secondary education consists of two school types: unified upper secondary schools (Γενικό Λύκειο, Genikό Lykeiό) and technical–vocational educational schools (Τεχνικά και Επαγγελματικά Εκπαιδευτήρια, "TEE"). Post-compulsory secondary education also includes vocational training institutes (Ινστιτούτα Επαγγελματικής Κατάρτισης, "IEK") which provide a formal but unclassified level of education. As they can accept both Gymnasio (lower secondary school) and Lykeio (upper secondary school) graduates, these institutes are not classified as offering a particular level of education.
Is there an answer to this question: What type of institute does secondary education also include?

Answer: vocational training


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
In 1914, Claridge's Company entered into a joint venture to produce tar-bound macadam, with materials manufactured through a subsidiary company called Clarmac Roads Ltd. Two products resulted, namely Clarmac, and Clarphalte, with the former being manufactured by Clarmac Roads and the latter by Claridge's Patent Asphalte Co., although Clarmac was more widely used.[note 1] However, the First World War impacted financially on the Clarmac Company, which entered into liquidation in 1915. The failure of Clarmac Roads Ltd had a flow-on effect to Claridge's Company, which was itself compulsorily wound up, ceasing operations in 1917, having invested a substantial amount of funds into the new venture, both at the outset, and in a subsequent attempt to save the Clarmac Company.
Which of Claridge's two tar macadams was the more successful?
A:
Clarmac