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Many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 has the distinction of being the only naturally occurring fissile isotope. Uranium-238 is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor. Another fissile isotope, uranium-233, can be produced from natural thorium and is also important in nuclear technology. While uranium-238 has a small probability for spontaneous fission or even induced fission with fast neutrons, uranium-235 and to a lesser degree uranium-233 have a much higher fission cross-section for slow neutrons. In sufficient concentration, these isotopes maintain a sustained nuclear chain reaction. This generates the heat in nuclear power reactors, and produces the fissile material for nuclear weapons. Depleted uranium (238U) is used in kinetic energy penetrators and armor plating.
What is 239U?
A: unanswerable

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Besides slaves, there were a number of free people of color in the state. Most were descended from free African Americans who had migrated along with neighbors from Virginia during the 18th century. The majority were the descendants of unions in the working classes between white women, indentured servants or free, and African men, indentured, slave or free. After the Revolution, Quakers and Mennonites worked to persuade slaveholders to free their slaves. Some were inspired by their efforts and the language of the Revolution to arrange for manumission of their slaves. The number of free people of color rose markedly in the first couple of decades after the Revolution.
After the revolution Quakers and mennonited encouraged slaveholders to do what?
A: free their slaves

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Qing dynasty rule in Tibet began with their 1720 expedition to the country when they expelled the invading Dzungars. Amdo came under Qing control in 1724, and eastern Kham was incorporated into neighbouring Chinese provinces in 1728. Meanwhile, the Qing government sent resident commissioners called Ambans to Lhasa. In 1750 the Ambans and the majority of the Han Chinese and Manchus living in Lhasa were killed in a riot, and Qing troops arrived quickly and suppressed the rebels in the next year. Like the preceding Yuan dynasty, the Manchus of the Qing dynasty exerted military and administrative control of the region, while granting it a degree of political autonomy. The Qing commander publicly executed a number of supporters of the rebels and, as in 1723 and 1728, made changes in the political structure and drew up a formal organization plan. The Qing now restored the Dalai Lama as ruler, leading the governing council called Kashag, but elevated the role of Ambans to include more direct involvement in Tibetan internal affairs. At the same time the Qing took steps to counterbalance the power of the aristocracy by adding officials recruited from the clergy to key posts.
What came under Qing control in 1742?
A: unanswerable

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Within computer systems, two of many security models capable of enforcing privilege separation are access control lists (ACLs) and capability-based security. Using ACLs to confine programs has been proven to be insecure in many situations, such as if the host computer can be tricked into indirectly allowing restricted file access, an issue known as the confused deputy problem. It has also been shown that the promise of ACLs of giving access to an object to only one person can never be guaranteed in practice. Both of these problems are resolved by capabilities. This does not mean practical flaws exist in all ACL-based systems, but only that the designers of certain utilities must take responsibility to ensure that they do not introduce flaws.[citation needed]
A host computer tricked into indirectly allowing access to restricted files is known as what?
A:
the confused deputy problem