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Dynastic cycle (traditional Chinese: 朝代循環; simplified Chinese: 朝代循环; pinyin: Cháodài Xúnhuán) is an important political theory in Chinese history. According to this theory, each dynasty of China rises to a political, cultural, and economic peak and then, because of moral corruption, declines, loses the Mandate of Heaven ...
The Oxford English Dictionary's definition of Ultradian specifies that it refers to cycles with a period shorter than a day but longer than an hour. [1] The descriptive term ultradian is used in sleep research in reference to the 90–120 minute cycling of the sleep stages during human sleep. [2]
The basic rest–activity cycle (BRAC) is a physiological arousal mechanism in humans proposed by Nathaniel Kleitman, [1] hypothesized to occur during both sleep and wakefulness. Empirically, it is an ultradian rhythm of approximately 90 minutes (80–120 minutes [ 2 ] ) characterized by different levels of excitement and rest.
The sleep cycle is an oscillation between the slow-wave and REM (paradoxical) phases of sleep. It is sometimes called the ultradian sleep cycle, sleep–dream cycle, or REM-NREM cycle, to distinguish it from the circadian alternation between sleep and wakefulness. In humans, this cycle takes 70 to 110 minutes (90 ± 20 minutes). [1]
For most of its history, China was organized into various dynastic states under the rule of hereditary monarchs.Beginning with the establishment of dynastic rule by Yu the Great c. 2070 BC, [1] and ending with the abdication of the Xuantong Emperor in AD 1912, Chinese historiography came to organize itself around the succession of monarchical dynasties.
The traditional lens for viewing Chinese history is the dynastic cycle: imperial dynasties rise and fall, and are ascribed certain achievements. Throughout pervades the narrative that Chinese civilization can be traced as an unbroken thread many thousands of years into the past , making it one of the cradles of civilization .
Zooming out from the dynastic cycle but maintaining focus on power dynamics, the following general periodization, based on the most powerful groups and the ways that power is used, has been proposed for Chinese history: [37]: 45 The aristocratic settlement state (to c. 550 BCE)
Examples include circannual or annual cycles that govern migration or reproduction cycles in many plants and animals, or the human menstrual cycle. Ultradian rhythms , which are cycles shorter than 24 hours, such as the 90-minute REM cycle , the 4-hour nasal cycle , or the 3-hour cycle of growth hormone production.