Afternoon break!

A bicycle, often called a bike (and sometimes referred to as a "pushbike", "pedal bike", "pedal cycle", or "cycle"), is a human-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A person who rides a bicycle is called a cyclist, or bicyclist.

Bicycles were introduced in the 19th century and now number about one billion worldwide, twice as many as automobiles. They are the principal means of transportation in many regions. They also provide a popular form of recreation, and have been adapted for such uses as children's toys, adult fitness, military and police applications, courier services and bicycle racing.

The basic shape and configuration of a typical upright bicycle has changed little since the first chain-driven model was developed around 1885. However, many details have been improved, especially since the advent of modern materials and computer-aided design. These have allowed for a proliferation of specialized designs for particular types of cycling.

The invention of the bicycle has had an enormous impact on society, both in terms of culture and of advancing modern industrial methods. Several components that eventually played a key role in the development of the automobile were originally invented for the bicycle, including ball bearings, pneumatic tires, chain-driven sprockets, and spoke-tensioned wheels.

Beijing ( /beɪˈdʒɪŋ/; Chinese: 北京; pinyin: Běijīng, [peɪ˨˩ t͡ɕiŋ˥]), formerly romanized as Peking ( /piːˈkɪŋ/ or /peɪˈkɪŋ/), is the capital of the People's Republic of China and one of the most populous cities in the world, with a population of 19,612,368 as of 2010. The metropolis, located in northern China, is governed as a direct-controlled municipality under the national government, with 14 urban and suburban districts and two rural counties. Beijing Municipality is surrounded by Hebei Province with the exception of neighboring Tianjin Municipality to the southeast.

Sleep is a naturally recurring state characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles. It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and is more easily reversible than being in hibernation or a coma. Sleep is a heightened anabolic state, accentuating the growth and rejuvenation of the immune, nervous, skeletal and muscular systems. It is observed in all mammals, all birds, and many reptiles, amphibians, and fish.

The purposes and mechanisms of sleep are only partially clear and are the subject of intense research. Sleep is often thought to help conserve energy, but decreases metabolism only about 5–10%. Hibernating animals need to sleep despite the hypometabolism seen in hibernation, and must return from hypothermia to euthermia in order to sleep, making sleeping "energetically expensive."

In mammals and birds, sleep is divided into two broad types: rapid eye movement (REM) and non-rapid eye movement (NREM or non-REM) sleep. Each type has a distinct set of associated physiological, neurological, and psychological features. The American Academy of Sleep Medicine (AASM) further divides NREM into three stages: N1, N2, and N3, the last of which is also called delta sleep or slow-wave sleep (SWS).

A nap is a short period of sleep, typically taken during daylight hours as an adjunct to the usual nocturnal sleep period. Naps are most often taken as a response to drowsiness during waking hours. Cultural attitudes toward napping during the work day vary; children and the elderly are often expected to nap during the day and are provided with designated periods and locations to do so, but most working adults are not and napping on the job is widely considered unacceptable. On the other hand, many cultures (especially those in hot climates) serve their largest meals at midday, with an official allowance for a nap period (siesta) afterwards before returning to work.

A siesta (Spanish pronunciation: [ˈsjesta]) is a short nap taken in the early afternoon, often after the midday meal. Such a period of sleep is a common tradition in some countries, particularly those where the weather is warm.

Since the siesta is the traditional daytime sleep of Spain, and through Spanish influence, of many Hispanic American countries and in the Philippines, the word siesta has been taken from Spanish, from the Latin hora sexta – "the sixth hour" (counting from dawn, therefore noon, hence "midday rest"). Einhard's Life of Charlemagne recounts the emperor's summertime siesta: "In summer, after his midday meal, he would eat some fruit and take another drink; then he would remove his shoes and undress completely, just as he did at night, and rest for two or three hours."

Factors explaining the geographical distribution of the modern siesta are mainly high temperatures and heavy intake of food at the midday main meal. Combined, these two factors contribute to the feeling of post-lunch drowsiness. In these countries, the heat can be unbearable in the early afternoon, making a midday break at home ideal. However, in the cold Patagonia, people have siestas too. This could indicate that siestas have a stronger relation with culture than with climate.

The original concept of a siesta seems to have been merely that of a midday break intended to allow people to spend time with their friends and family. It has been suggested that the long length of the modern siesta dates back to the Spanish Civil War, when poverty resulted in many Spaniards working multiple jobs at irregular hours, pushing back meals to later in the afternoon and evening. However, this hypothesis sounds unlikely, considering that the siesta tradition was very common in Hispanic America and other countries with Hispanic influence, much before the Spanish Civil War.^{[citation needed]}

Han Chinese or Han People (simplified Chinese: 汉族 or 汉人; traditional Chinese: 漢族 or 漢人; pinyin: hànzú or hànrén) are an ethnic group native to China and are the largest single ethnic group in the world.

Han Chinese constitute about 92% of the population of the People's Republic of China (mainland China), 98% of the population of the Republic of China (Taiwan), 74% of the population of Singapore, and about 20% of the entire global human population, making it the largest ethnic group in the world. There is considerable genetic, linguistic, cultural, and social diversity among the subgroups of the Han, mainly due to thousands of years of immigration and assimilation of various regional ethnicities and tribes within China. The Han Chinese are a subset of the Chinese nation (Zhonghua minzu). Sometimes Han and other Chinese refer to themselves as the "Descendants of the Yan and Huang Emperors" (simplified Chinese: 炎黄子孙; traditional Chinese: 炎黃子孫).

China (ⁱ/ˈtʃaɪnə/; Chinese: 中国; pinyin: Zhōngguó; see also Names of China), officially the People's Republic of China (PRC), is the world's most-populous country, with a population of over 1.3 billion. The East Asian state covers approximately 9.6 million square kilometres, and is the world's second-largest country by land area, and the third- or fourth-largest in total area, depending on the definition of total area.