Problem: According to figures published in 2006 in the journal "Demoskop Weekly" research deputy director of Research Center for Sociological Research of the Ministry of Education and Science (Russia) Arefyev A. L., the Russian language is gradually losing its position in the world in general, and in Russia in particular. In 2012, A. L. Arefyev published a new study "Russian language at the turn of the 20th-21st centuries", in which he confirmed his conclusion about the trend of further weakening of the Russian language in all regions of the world (findings published in 2013 in the journal "Demoskop Weekly"). In the countries of the former Soviet Union the Russian language is gradually being replaced by local languages. Currently the number speakers of Russian language in the world depends on the number of Russians in the world (as the main sources distribution Russian language) and total population Russia (where Russian is an official language).
What does Arefyev say is happening to Russian?
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Answer: In the countries of the former Soviet Union the Russian language is gradually being replaced by local languages.


Problem: This is a consequence of Lorentz reciprocity. For an antenna element  not connected to anything (open circuited) one can write . But for an element  which is short circuited, a current is generated across that short but no voltage is allowed, so the corresponding . This is the case, for instance, with the so-called parasitic elements of a Yagi-Uda antenna where the solid rod can be viewed as a dipole antenna shorted across its feedpoint. Parasitic elements are unpowered elements that absorb and reradiate RF energy according to the induced current calculated using such a system of equations.
What antenna can the solid rod be viewed as a dipole antenna?
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Answer: Yagi-Uda


Problem: Despite the tribute and a negotiation between Laoshang Chanyu (r. 174–160 BC) and Emperor Wen (r. 180–157 BC) to reopen border markets, many of the Chanyu's Xiongnu subordinates chose not to obey the treaty and periodically raided Han territories south of the Great Wall for additional goods. In a court conference assembled by Emperor Wu (r. 141–87 BC) in 135 BC, the majority consensus of the ministers was to retain the heqin agreement. Emperor Wu accepted this, despite continuing Xiongnu raids. However, a court conference the following year convinced the majority that a limited engagement at Mayi involving the assassination of the Chanyu would throw the Xiongnu realm into chaos and benefit the Han. When this plot failed in 133 BC, Emperor Wu launched a series of massive military invasions into Xiongnu territory. Chinese armies captured one stronghold after another and established agricultural colonies to strengthen their hold. The assault culminated in 119 BC at the Battle of Mobei, where the Han commanders Huo Qubing (d. 117 BC) and Wei Qing (d. 106 BC) forced the Xiongnu court to flee north of the Gobi Desert.
In what year did Emperor Wu begin a series of attacks in Xiongnu territories?
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Answer:
133 BC