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It is also known as the Wenchuan earthquake (Chinese: ; pinyin: Wenchuan da dizhen; literally: "Great Wenchuan earthquake"), after the location of the earthquake's epicenter, Wenchuan County, Sichuan. The epicenter was 80 kilometres (50 mi) west-northwest of Chengdu, the provincial capital, with a focal depth of 19 km (12 mi). The earthquake was also felt in nearby countries and as far away as both Beijing and Shanghai1,500 km (930 mi) and 1,700 km (1,060 mi) awaywhere office buildings swayed with the tremor. Strong aftershocks, some exceeding magnitude 6, continued to hit the area even months after the main quake, causing new casualties and damage.

How far was it from Chengdu?
Answer: 80 kilometres
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Hydrogen is the only element that has different names for its isotopes in common use today. During the early study of radioactivity, various heavy radioactive isotopes were given their own names, but such names are no longer used, except for deuterium and tritium. The symbols D and T (instead of 2H and 3H) are sometimes used for deuterium and tritium, but the corresponding symbol for protium, P, is already in use for phosphorus and thus is not available for protium. In its nomenclatural guidelines, the International Union of Pure and Applied Chemistry allows any of D, T, 2H, and 3H to be used, although 2H and 3H are preferred.

What are the symbols used for deuterium and tritium?
Answer: D and T
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Muslim scientists contributed to advances in the sciences. They placed far greater emphasis on experiment than had the Greeks. This led to an early scientific method being developed in the Muslim world, where progress in methodology was made, beginning with the experiments of Ibn al-Haytham (Alhazen) on optics from circa 1000, in his Book of Optics. The most important development of the scientific method was the use of experiments to distinguish between competing scientific theories set within a generally empirical orientation, which began among Muslim scientists. Ibn al-Haytham is also regarded as the father of optics, especially for his empirical proof of the intromission theory of light. Some have also described Ibn al-Haytham as the "first scientist." al-Khwarzimi's invented the log base systems that are being used today, he also contributed theorems in trigonometry as well as limits. Recent studies show that it is very likely that the Medieval Muslim artists were aware of advanced decagonal quasicrystal geometry (discovered half a millennium later in the 1970s and 1980s in the West) and used it in intricate decorative tilework in the architecture.

Ibn al-Haytham wrote about his work around the year 1000, what was it?
Answer:
Book of Optics