Jeju Province Jeju Special Self-Governing Province, is one of the nine provinces of South Korea. The province is situated on the nation's largest island of Jeju transliterated as Cheju, Cheju Do, etc, it was known as Quelpart to Europeans and during the Japanese occupation as Saishū. The island lies in the Korea Strait, southwest of South Jeolla Province, of which it was a part before it became a separate province in 1946, its capital is Jeju City. Jeju has an independent visa policy. So all ordinary passport holders excluding those from Afghanistan, Ghana, Kosovo, Nigeria, North Korea, North Macedonia, Syria and Yemen can stay visa-free 30 days in Jeju if they require a visa for the South Korean mainland. Domestic flights from the mainland do not require identification. According to legend, three demi-gods emerged from Samsung, said to have been on the northern slopes of Mt. Halla and became the progenitors of the Jeju people who founded the Kingdom of Tamna, it has been claimed that three brothers—including Ko-hu—who were the 15th descendants of Koulla, one of the Progenitors of the Jeju people, were received by the court of Silla, at which time the name Tamna was recognized, while the official government posts of Commander and Governor were conferred by the court upon the three.
However, there is no concrete evidence of when the "Three Names" appeared nor for the exact date of when Ko-hu and his brothers were received by Silla. It may be supposed that the "Three Names" Founding Period occurred during the Three Kingdoms Period on the mainland of Korea. Taejo, founder of Goryeo, attempted to establish the same relationship between Goryeo and Tamna as Tamna had had with Silla. Tamna refused to accept this position and the Goryeo court dispatched troops to force Tamna to submit. Ko ja-gyeon, chief of Tamna, submitted to Goryeo in 938 and sent his son, Prince Mallo, to Goryeo's court as a de facto hostage. In 1105, the Goryeo court abolished the name Takna, used up to this time and, from that year on, the island was known as "Tamna-gun" and Goryeo officials were sent to handle the affairs of the island. Tamna-country was changed to Tamna-county in 1153 during the reign of King Uijong and Choi Cheok-kyeong was posted as Tamna-Myeong or Chief of Tamna. During the reign of Gojong of Goryeo, Tamna was renamed "Jeju," which means "province across the sea".
In 1271, General Kim Tong-jeong escaped with what remained of his Sambyeolcho force from Jindo and built the Hangpadu Fortress at Kwiil-chon from where they continued their fight against the combined Korean government-Mongolian army but within two years, faced by an enemy army of over 10,000 troops, the Sambyeolcho was annihilated. During the Joseon Dynasty, Jeju islanders were treated as foreigners and Jeju was considered as a place for horse breeding and exile for political prisoners. In the 17th Century, Injo of Joseon issued an edict prohibiting islanders from travelling to the Korean mainland. Jeju islanders staged several major uprisings, including the Kang Je Geom Rebellion, Bang Seong Chil Rebellion, the Lee Jae Su Rebellion. In 1910, Japan annexed Korea, including Jeju, inaugurating a period of hardship and deprivation for the islanders, many of whom were compelled to travel to the mainland or Japan for work. Residents of Jeju were active in the Korean independence movement during the period of Japanese rule.
On Jeju, the peak of resistance came in 1931–32 when haenyeo from six eastern villages launched a protest against the Japanese-controlled Divers Association. Before it was brutally crushed, the protests spread and 17,000 people participated, with over 100 arrested in Korea's largest protest movement led by women and fisheries workers. On April 3, 1948, against a background of an ongoing ideological struggle for control of Korea and a variety of grievances held by islanders against the local authorities, the many communist sympathizers on the island attacked police stations and government offices; the brutal and indiscriminate suppression of the leftist rebellion resulted in the deaths of tens of thousands of both villagers and communist radicals and the imprisonment of thousands more in internment camps. While claims have been made that the U. S. government oversaw and supported "anti-communist" activities administratively if not in the field, validation remains to be made. It is a fact the US was involved in counter-insurgence operations across Korea at this time leading up to the Korean War and UN involvement.
The Northwest Youth League, a Korean government sponsored watchdog group made up of refugees who had fled North Korea repressed any and all "communist sympathizers" with a campaign of shooting on sight anyone entering or leaving the president's "enemy zone" and using open, armed violence and what would be labeled today as terrorist activities. This led with many other islanders being raped and tortured. Intolerance by mainland Korean officials of islanders in general at the time, government- and organization-sponsored isolation of the island and a rumored cover-up of evidence linking the rebellion's suppres
South Korea the Republic of Korea, is a country in East Asia, constituting the southern part of the Korean Peninsula and lying to the east of the Asian mainland. The name Korea is derived from Goguryeo, one of the great powers in East Asia during its time, ruling most of the Korean Peninsula, parts of the Russian Far East and Inner Mongolia, under Gwanggaeto the Great. South Korea has a predominantly mountainous terrain, it comprises an estimated 51.4 million residents distributed over 100,363 km2. Its capital and largest city is Seoul, with a population of around 10 million. Archaeology indicates that the Korean Peninsula was inhabited by early humans starting from the Lower Paleolithic period; the history of Korea begins with the foundation of Gojoseon in 2333 BCE by the mythic king Dangun, but no archaeological evidence and writing was found from this period. The Gija Joseon was purportedly founded in 11th century BCE, its existence and role has been controversial in the modern era; the written historical record on Gojoseon was first mentioned in Chinese records in the early 7th century BCE.
Following the unification of the Three Kingdoms of Korea under Unified Silla in CE 668, Korea was subsequently ruled by the Goryeo dynasty and the Joseon dynasty. It was annexed by the Empire of Japan in 1910. At the end of World War II, Korea was divided into Soviet and U. S. zones of occupations. A separate election was held in the U. S. zone in 1948 which led to the creation of the Republic of Korea, while the Democratic People's Republic of Korea was established in the Soviet zone. The United Nations at the time passed a resolution declaring the ROK to be the only lawful government in Korea; the Korean War began in June 1950. The war lasted three years and involved the U. S. China, the Soviet Union and several other nations; the border between the two nations remains the most fortified in the world. Under long-time military leader Park Chung-hee, the South Korean economy grew and the country was transformed into a G-20 major economy. Military rule ended in 1987, the country is now a presidential republic consisting of 17 administrative divisions.
South Korea is a developed country and a high-income economy, with a "very high" Human Development Index, ranking 22nd in the world. The country is considered a regional power and is the world's 11th largest economy by nominal GDP and the 12th largest by PPP as of 2010. South Korea is a global leader in the industrial and technological sectors, being the world's 5th largest exporter and 8th largest importer, its export-driven economy focuses production on electronics, ships, machinery and robotics. South Korea is a member of the ASEAN Plus mechanism, the United Nations, Uniting for Consensus, G20, the WTO and OECD and is a founding member of APEC and the East Asia Summit; the name Korea derives from the name Goryeo. The name Goryeo itself was first used by the ancient kingdom of Goguryeo in the 5th century as a shortened form of its name; the 10th-century kingdom of Goryeo succeeded Goguryeo, thus inherited its name, pronounced by the visiting Persian merchants as "Korea". The modern spelling of Korea first appeared in the late 17th century in the travel writings of the Dutch East India Company's Hendrick Hamel.
Despite the coexistence of the spellings Corea and Korea in 19th century publications, some Koreans believe that Imperial Japan, around the time of the Japanese occupation, intentionally standardised the spelling on Korea, making Japan appear first alphabetically. After Goryeo was replaced by Joseon in 1392, Joseon became the official name for the entire territory, though it was not universally accepted; the new official name has its origin in the ancient country of Gojoseon. In 1897, the Joseon dynasty changed the official name of the country from Joseon to Daehan Jeguk; the name Daehan, which means "Great Han" derives from Samhan, referring to the Three Kingdoms of Korea, not the ancient confederacies in the southern Korean Peninsula. However, the name Joseon was still used by Koreans to refer to their country, though it was no longer the official name. Under Japanese rule, the two names Han and Joseon coexisted. There were several groups who fought for independence, the most notable being the Provisional Government of the Republic of Korea.
Following the surrender of Japan, in 1945, the Republic of Korea was adopted as the legal English name for the new country. Since the government only controlled the southern part of the Korean Peninsula, the informal term South Korea was coined, becoming common in the Western world. While South Koreans use Han to refer to the entire country, North Koreans and ethnic Koreans living in China and Japan use the term Joseon as the name of the country; the Korean name "Daehan Minguk" is sometimes used by South Koreans as a metonym to refer to the Korean ethnicity as a whole, rather than just the South Korean state. The history of Korea begins with the founding of Joseon in 2333 BCE by Dangun, according to Korea's foundation mythology. Gojoseon expanded until it controlled parts of Manchuria. Gija Joseon was purportedly founded in the 12th century BC, but its existence and role have been controversial in the modern era. In 108 BCE, the Han dynasty defeated Wiman Joseon and installed four commanderies in the n
Lanzarote is a Spanish island, the northernmost and easternmost of the autonomous Canary Islands in the Atlantic Ocean. It is located 125 kilometres off the north coast of Africa and 1,000 kilometres from the Iberian Peninsula. Covering 845.94 square kilometres, Lanzarote is the fourth-largest of the islands in the archipelago. With 149,183 inhabitants, it is the third most populous Canary Island, after Tenerife and Gran Canaria. Located in the centre-west of the island is Timanfaya National Park, one of its main attractions; the island was declared a biosphere reserve by UNESCO in 1993. The island's capital is Arrecife; the first recorded name for the island, given by Italian-Majorcan cartographer Angelino Dulcert, was Insula de Lanzarotus Marocelus, after the Genoese navigator Lancelotto Malocello, from which the modern name is derived. The island's name in the native language was Tyterogaka or Tytheroygaka, which may mean "one, all ochre". Lanzarote is located 11 kilometres north-east of Fuerteventura and just over 1 kilometre from Graciosa.
The dimensions of the island are 60 kilometres from north to south and 25 kilometres from west to east. Lanzarote has 213 kilometres of coastline, of which 10 kilometres are sand, 16.5 kilometres are beach, the remainder is rocky. Its landscape includes the mountain ranges of Famara in Ajaches to the south. South of the Famara massif is the El Jable desert, which separates Montañas del Fuego; the highest peak is Peñas del Chache. The "Tunnel of Atlantis", the largest underwater volcanic tunnel in the world, is part of the Cueva de los Verdes lava tube. Called the "Island of Eternal Spring", Lanzarote has a subtropical-desert climate according to the Köppen climatic classification; the small amount of precipitation is concentrated in the winter. Rainfall during summer is a rare phenomenon and several summers are dry without any precipitation. On average the island receives 16 days of precipitation between December and February. Sometimes, the hot sirocco wind prevails, causing dusty conditions across the island.
Average precipitation in June and August is less than 0.5 millimetres. It borders on a tropical climate, with winter means of 18 °C and summer means of 25 °C. Lanzarote is the northernmost and easternmost island of the Canary Islands and has a volcanic origin, it was born through fiery eruptions and has solidified lava streams as well as extravagant rock formations. The island emerged about 15 million years ago as product of the Canary hotspot; the island, along with others, emerged after the breakup of the African and the American continental plates. The greatest recorded eruptions occurred between 1730 and 1736 in the area now designated Timanfaya National Park; as of 2018, 149,183 people live on Lanzarote, an increase of 9.4% from 2006. The seat of the island government is in the capital, which has a population of 59,000. According to the census of 2006, the majority of the inhabitants are Spanish with a sizeable number of residents from other nations, notably Colombians, Moroccans and Irish.
Other populous groups include Chinese people and Indians, which constitute a large proportion of the remaining 15.6% of the population. The island has an international airport, Arrecife Airport, through which 5,438,178 passengers travelled in 2008. Tourism has been the mainstay of the island's economy for over 40 years, the only other industry being agriculture. Lanzarote is part of the province of Las Palmas, is divided into seven municipalities: Arrecife Haría San Bartolomé Teguise Tías Tinajo Yaiza There are five hundred different kinds of plants on the island, of which 17 species are endemic; these plants have adapted to the relative scarcity of water in the same way as succulents. They include the Canary Island date palm, found in damper areas of the north, the Canary Island pine and wild olive trees. Laurisilva trees, which once covered the highest parts of Risco de Famara, are found today. After winter rainfall, the vegetation comes to a colourful bloom between March; the vineyards of La Gería, Lanzarote DO wine region, are a protected area.
Single vines are planted in pits 4–5 metres wide and 2–3 metres deep, with small stone walls around each pit. This agricultural technique is designed to harvest rainfall and overnight dew and to protect the plants from the winds. There are 180 different species of lichen-forming fungi; these survive in the suitable areas like rock surfaces, promote weathering. Apart from the native bats and the mammals which accompanied humans to the island, there are few vertebrate species on Lanzarote; these include reptiles. Some interesting endemic animals are the Gallotia lizards and the blind Munidopsis polymorpha crabs found in the Jameos del Agua lagoon, formed by a volcanic eruption; the island is home to one of two surviving populations of the threatened Canarian Egyptian vulture. The official natural symbols associated with Lanzarote are Munidopsis polymorpha and Euphorbi
Mammoth Cave National Park
Mammoth Cave National Park is an American national park in central Kentucky, encompassing portions of Mammoth Cave, the longest cave system known in the world. Since the 1972 unification of Mammoth Cave with the even-longer system under Flint Ridge to the north, the official name of the system has been the Mammoth–Flint Ridge Cave System; the park was established as a national park on July 1, 1941, a World Heritage Site on October 27, 1981, an international Biosphere Reserve on September 26, 1990. The park's 52,830 acres are located in Edmonson County, with small areas extending eastward into Hart and Barren counties; the Green River runs through the park, with a tributary called the Nolin River feeding into the Green just inside the park. Mammoth Cave is the world's longest known cave system with more than 400 miles of surveyed passageways, nearly twice as long as the second-longest cave system, Mexico's Sac Actun underwater cave. Mammoth Cave developed in thick Mississippian-aged limestone strata capped by a layer of sandstone, which has made the system remarkably stable.
It is known to include more than 400 miles of passageway. Mammoth Cave National Park was established to preserve the cave system; the upper sandstone member is known as the Big Clifty Sandstone. Thin, sparse layers of limestone interspersed within the sandstones give rise to an epikarstic zone, in which tiny conduits are dissolved by the natural acidity of groundwater; the epikarstic zone concentrates local flows of runoff into high-elevation springs which emerge at the edges of ridges. The resurgent water from these springs flows on the surface before sinking underground again at elevation of the contact between the sandstone caprock and the underlying massive limestones, it is in these underlying massive limestone layers that the human-explorable caves of the region have developed. The limestone layers of the stratigraphic column beneath the Big Clifty, in increasing order of depth below the ridgetops, are the Girkin Formation, the Ste. Genevieve Limestone, the St. Louis Limestone. For example, the large Main Cave passage seen on the Historic Tour is located at the bottom of the Girkin and the top of the Ste.
Genevieve Formation. Each of the primary layers of limestone subunits. One area of cave research involves correlating the stratigraphy with the cave survey produced by explorers; this makes it possible to produce approximate three-dimensional maps of the contours of the various layer boundaries without the necessity for test wells and extracting core samples. The upper sandstone caprock is hard for water to penetrate: the exceptions are where vertical cracks occur; this protective role means that many of the older, upper passages of the cave system are dry, with no stalactites, stalagmites, or other formations which require flowing or dripping water to develop. However, the sandstone caprock layer has been dissolved and eroded at many locations within the park, such as the Frozen Niagara room; the contact between limestone and sandstone can be found by hiking from the valley bottoms to the ridgetops: as one approaches the top of a ridge, one sees the outcrops of exposed rock change in composition from limestone to sandstone at a well-defined elevation.
At one valley bottom in the southern region of the park, a massive sinkhole has developed. Known as Cedar Sink, the sinkhole features a small river entering one side and disappearing back underground at the other side. Mammoth Cave is home to a sightless albino shrimp; the National Park Service offers several cave tours to visitors. Some notable features of the cave, such as Grand Avenue, Frozen Niagara, Fat Man's Misery, can be seen on lighted tours ranging from one to six hours in length. Two tours, lit only by visitor-carried paraffin lamps, are popular alternatives to the electric-lit routes. Several "wild" tours venture away from the developed parts of the cave into muddy crawls and dusty tunnels; the Echo River Tour, one of the cave's most famous attractions, used to take visitors on a boat ride along an underground river. The tour was discontinued for environmental reasons in the early 1990s. Mammoth Cave headquarters and visitor's center is located on Mammoth Cave Parkway; the parkway connects with Kentucky Route 70 from the north and Kentucky Route 255 from the south within the park.
The story of human beings in relation to Mammoth Cave spans six thousand years. Several sets of Native American remains have been recovered from Mammoth Cave, or other nearby caves in the region, in both the 19th and 20th centuries. Most mummies found represent examples of intentional burial, with ample evidence of pre-Columbian funerary practice. An exception to purposeful burial was discovered when in 1935 the remains of an adult male were discovered under a large boulder; the boulder had shifted and settled onto the victim, a pre-Columbian miner, who had disturbed the rubble supporting it. The remains of the ancient victim were named "Lost John" and exhibited to the public into the 1970s, when they were interred in a secret location in Mammoth Cave for reasons of preservation as well as emerging political sensitivities with respect to the public display of Native American remains. Research beginning in the late 1950s led by Patty Jo Watson, of Washington University in St. Louis, has done much to illuminate the lives of the late Archaic and early Woodland peoples who explored and exploited caves in the region.
Preserved by the constant cave environment, dietary evidence yielded carbon dates enabling Watson and others to determine the age of t
Škocjan Caves is a cave system in Slovenia. Due to its exceptional significance, Škocjan Caves was entered on UNESCO’s list of natural and cultural world heritage sites in 1986. International scientific circles have thus acknowledged the importance of the caves as one of the natural treasures of planet Earth. Ranking among the most important caves in the world, Škocjan Caves represents the most significant underground phenomena both on the Karst Plateau and in Slovenia. Following independence from Yugoslavia in 1991, Slovenia committed itself to protecting the Škocjan Caves area and established Škocjan Caves Regional Park and its managing authority, the Škocjan Caves Park Public Service Agency. One of the largest known underground canyons in the world Examples of natural beauty with great aesthetic value Due to particular microclimatic conditions, a special ecosystem has developed The area has great cultural and historical significance as it has been inhabited since the prehistoric times A typical example of contact karst Škocjan Caves represents the most significant underground phenomena in both the Karst region and Slovenia.
Škocjan Caves was entered on the List of Ramsar wetlands of international importance on 18 May 1999. Together with the underground stream of the Reka River, they represent one of the longest karst underground wetlands in Europe. Explored length of caves is 6,200 m, caves have formed in 300 m thick layer of Cretaceous and Paleocene limestone; the Reka River disappears underground at Big Collapse Doline into Škocjan Caves and flows underground for 34 km surfacing near Monfalcone where it contributes one third of the flow of the Timavo River, which flows 2 kilometers from the Timavo Springs to the Adriatic Sea. The view of the big river in the rainy season, as it disappears underground at the bottom of Big Collapse Doline, 160 m below the surface, is both majestic and frightening; the exceptional volume of the underground canyon is what distinguishes Škocjan Caves from other caves and places it among the most famous underground features in the world. The river flowing through the underground canyon turns northwest before the Cerkvenik Bridge and continues its course along Hanke's Channel.
This underground channel is 3.5 km long, 10 to 60 m wide and over 140 m high. At some points, it expands into huge underground chambers; the largest of these is Martel's Chamber with a volume of 2.2 million cubic m and it is considered the largest discovered underground chamber in Europe and one of the largest in the world. The canyon of such dimensions ends with a small siphon: one that cannot deal with the enormous volume of water that pours into the cave after heavy rainfall, causing major flooding, during which water levels can rise by more than one hundred metres; the first written sources on Škocjan Caves originate in the era of Antiquity by Posidonius of Apamea and they are marked on the oldest published maps of this part of the world. The fact that the French painter Louis-François Cassas was commissioned to paint some landscape pieces proves that in the 18th century the caves were considered one of the most important natural features in the Trieste hinterland, his paintings testify that.
The Carniolan scholar Johann Weikhard von Valvasor described the sink of the Reka River and its underground flow in 1689. In order to supply Trieste with drinking water, an attempt was made to follow the underground course of the Reka River; the deep shafts in the Karst were explored as well as Škocjan Caves. The systematic exploration of Škocjan Caves began with a speleology expedition in 1884. Explorers reached the banks of Mrtvo jezero in 1890; the last major achievement was the discovery of Silent Cave in 1904, when some local men climbed the sixty-metre wall of Müller Hall. The next important event took place in nearly 100 years after the discovery of Dead Lake. Slovenian divers managed to swim through the siphon Ledeni dihnik and discovered over 200 m of new cave passages. From time immemorial, people have been attracted to the gorge where the Reka River disappears underground as well as the cave entrances; the Reka River sinks under a rocky wall. Škocjan Caves Regional Park is archaeologically rich.
A valuable archaeological find in Fly Cave indicates the influence of Greek civilization, where a cave temple was located after the end of the Bronze Age and in the Iron Age. This region was one of the most significant pilgrimage sites in Europe, three thousand years ago in the Mediterranean, where it was of important cult significance in connection with the afterlife and communication with ancestral spirits, it is difficult to establish when tourism in Škocjan Caves commenced. According to some sources, in 1819, the county councilor Matej Tominc ordered that steps be built to the bottom of Big Collapse Doline. According to other sources, the steps were only renovated. A visitors' book was introduced 1 January 1819; this date is considered the beginning of modern tourism in Škocjan Caves. In recent years, Škocjan Caves has had around 100,000 visitors per year; the first part of the Caves—Marinič Cave and Mahorčič Cave with Little Collapse Dolin
An electric light is a device that produces visible light from electric current. It is the most common form of artificial lighting and is essential to modern society, providing interior lighting for buildings and exterior light for evening and nighttime activities. In technical usage, a replaceable component that produces light from electricity is called a lamp. Lamps are called light bulbs. Lamps have a base made of ceramic, glass or plastic, which secures the lamp in the socket of a light fixture; the electrical connection to the socket may be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap. The three main categories of electric lights are incandescent lamps, which produce light by a filament heated white-hot by electric current, gas-discharge lamps, which produce light by means of an electric arc through a gas, LED lamps, which produce light by a flow of electrons across a band gap in a semiconductor. Before electric lighting became common in the early 20th century, people used candles, gas lights, oil lamps, fires.
English chemist Humphry Davy developed the first incandescent light in 1802, followed by the first practical electric arc light in 1806. By the 1870s, Davy's arc lamp had been commercialized, was used to light many public spaces. Efforts by Swan and Edison led to commercial incandescent light bulbs becoming available in the 1880s, by the early twentieth century these had replaced arc lamps; the energy efficiency of electric lighting has increased radically since the first demonstration of arc lamps and the incandescent light bulb of the 19th century. Modern electric light sources come in a profusion of types and sizes adapted to many applications. Most modern electric lighting is powered by centrally generated electric power, but lighting may be powered by mobile or standby electric generators or battery systems. Battery-powered light is reserved for when and where stationary lights fail in the form of flashlights, electric lanterns, in vehicles. Types of electric lighting include: Incandescent light bulb, a heated filament inside a glass envelope Halogen lamps are incandescent lamps that use a fused quartz envelope filled with halogen gas LED lamp, a solid-state lamp that uses light-emitting diodes as the source of light Arc lamp Xenon arc lamp Mercury-xenon arc lamp Ultra-high-performance lamp, an ultra-high-pressure mercury-vapor arc lamp for use in movie projectors Metal-halide lamp Gas-discharge lamp, a light source that generates light by sending an electric discharge through an ionized gas Fluorescent lamp Compact fluorescent lamp, a fluorescent lamp designed to replace an incandescent lamp Neon lamp Mercury-vapor lamp Sodium-vapor lamp Sulfur lamp Electrodeless lamp, a gas discharge lamp in which the power is transferred from outside the bulb to inside via electromagnetic fieldsDifferent types of lights have vastly differing efficacies and color of light.
*Color temperature is defined as the temperature of a black body emitting a similar spectrum. The most efficient source of electric light is the low-pressure sodium lamp, it produces, for all practical purposes, a monochromatic orange-yellow light, which gives a monochromatic perception of any illuminated scene. For this reason, it is reserved for outdoor public lighting applications. Low-pressure sodium lights are favoured for public lighting by astronomers, since the light pollution that they generate can be filtered, contrary to broadband or continuous spectra; the modern incandescent light bulb, with a coiled filament of tungsten, commercialized in the 1920s, developed from the carbon filament lamp introduced about 1880. As well as bulbs for normal illumination, there is a wide range, including low voltage, low-power types used as components in equipment, but now displaced by LEDs Incandescent bulbs are being phased out in many countries due to their low energy efficiency. Less than 3% of the input energy is converted into usable light.
Nearly all of the input energy ends up as heat that, in warm climates, must be removed from the building by ventilation or air conditioning resulting in more energy consumption. In colder climates where heating and lighting is required during the cold and dark winter months, the heat byproduct has at least some value. Halogen lamps are much smaller than standard incandescent lamps, because for successful operation a bulb temperature over 200 °C is necessary. For this reason, most have a bulb of fused aluminosilicate glass; this is sealed inside an additional layer of glass. The outer glass is a safety precaution, to reduce ultraviolet emission and to contain hot glass shards should the inner envelope explode during operation. Oily residue from fingerprints may cause a hot quartz envelope to shatter due to excessive heat buildup at the contamination site; the risk of burns or fire is greater with bare bulbs, leading to their prohibition in some places, unless enclosed by the luminaire. Those designed for 12- or 24-volt operation have compact filaments, useful for good optical control.
They have higher efficacies and better lives than non-halogen types. The light output remains constant throughout their life. Fluorescent lamps consist of a glass tube that contains argon under low pressure. Electricity flowing through the tube causes the gases to give off ultraviolet energy; the inside of the tubes are coated with phosphors that give off visible light when struck by ultraviolet photons. They have much higher efficiency than incandescent lamps. For the same amount of light generated, they typic
The Tang dynasty or the Tang Empire was an imperial dynasty of China spanning the 7th to 10th centuries. It was followed by the Five Dynasties and Ten Kingdoms period. Historians regard the Tang as a high point in Chinese civilization, a golden age of cosmopolitan culture. Tang territory, acquired through the military campaigns of its early rulers, rivaled that of the Han dynasty; the Tang capital at Chang'an was the most populous city in the world in its day. The Lǐ family founded the dynasty, seizing power during the collapse of the Sui Empire; the dynasty was interrupted when Empress Wu Zetian seized the throne, proclaiming the Second Zhou dynasty and becoming the only Chinese empress regnant. In two censuses of the 7th and 8th centuries, the Tang records estimated the population by number of registered households at about 50 million people, yet when the central government was breaking down and unable to compile an accurate census of the population in the 9th century, it is estimated that the population had grown by to about 80 million people.
With its large population base, the dynasty was able to raise professional and conscripted armies of hundreds of thousands of troops to contend with nomadic powers in dominating Inner Asia and the lucrative trade-routes along the Silk Road. Various kingdoms and states paid tribute to the Tang court, while the Tang conquered or subdued several regions which it indirectly controlled through a protectorate system. Besides political hegemony, the Tang exerted a powerful cultural influence over neighboring East Asian states such as those in Japan and Korea; the Tang dynasty was a period of progress and stability in the first half of the dynasty's rule, until the An Lushan Rebellion and the decline of central authority in the half of the dynasty. Like the previous Sui dynasty, the Tang dynasty maintained a civil-service system by recruiting scholar-officials through standardized examinations and recommendations to office; the rise of regional military governors known as jiedushi during the 9th century undermined this civil order.
Chinese culture further matured during the Tang era. Two of China's most famous poets, Li Bai and Du Fu, belonged to this age, as did many famous painters such as Han Gan, Zhang Xuan, Zhou Fang. Scholars of this period compiled a rich variety of historical literature, as well as encyclopedias and geographical works; the adoption of the title Tängri Qaghan by the Tang Emperor Taizong in addition to his title as emperor was eastern Asia's first "simultaneous kingship". Many notable innovations occurred including the development of woodblock printing. Buddhism became a major influence with native Chinese sects gaining prominence. However, in the 840s the Emperor Wuzong of Tang enacted policies to persecute Buddhism, which subsequently declined in influence. Although the dynasty and central government had gone into decline by the 9th century and culture continued to flourish; the weakened central government withdrew from managing the economy, but the country's mercantile affairs stayed intact and commercial trade continued to thrive regardless.
However, agrarian rebellions in the latter half of the 9th century resulted in damaging atrocities such as the Guangzhou massacre of 878–879. The Li family belonged to the northwest military aristocracy prevalent during the Sui dynasty and claimed to be paternally descended from the Daoist founder, Laozi the Han dynasty General Li Guang and Western Liang ruler Li Gao; this family was known as the Longxi Li lineage. The Tang Emperors had Xianbei maternal ancestry, from Emperor Gaozu of Tang's Xianbei mother, Duchess Dugu. Li Yuan was Duke of Tang and governor of Taiyuan, modern Shanxi, during the Sui dynasty's collapse, caused in part by the Sui failure to conquer the northern part of the Korean peninsula during the Goguryeo–Sui War, he had prestige and military experience, was a first cousin of Emperor Yang of Sui. Li Yuan rose in rebellion in 617, along with his son and his militant daughter Princess Pingyang, who raised and commanded her own troops. In winter 617, Li Yuan occupied Chang'an, relegated Emperor Yang to the position of Taishang Huang or retired emperor, acted as regent to the puppet child-emperor, Yang You.
On the news of Emperor Yang's murder by General Yuwen Huaji on June 18, 618, Li Yuan declared himself the emperor of a new dynasty, the Tang. Li Yuan, known as Emperor Gaozu of Tang, ruled until 626, when he was forcefully deposed by his son Li Shimin, the Prince of Qin. Li Shimin had commanded troops since the age of 18, had prowess with bow and arrow and lance and was known for his effective cavalry charges. Fighting a numerically superior army, he defeated Dou Jiande at Luoyang in the Battle of Hulao on May 28, 621. In a violent elimination of royal family due to fear of assassination, Li Shimin ambushed and killed two of his brothers, Li Yuanji and Crown prince Li Jiancheng, in the Xuanwu Gate Incident on July 2, 626. Shortly thereafter, his father abdicated in his favor and Li Shimin ascended the throne, he is conventionally known by his temple name Taizong. Although killing two brothers and deposing his father contradicted the Confucian value of filial piety, Taizong showed himself to be a capable leader who listened to the advice of the wisest members of his council.
In 628, Emperor Taizong held a Buddhist memorial service for the casualties of war, in 629 he ha