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Riyadh

Riyadh (الرياض,, ; lit. 'the Meadows') is the capital and largest city of Saudi Arabia. It is also the capital of the Riyadh Province and the centre of the Riyadh Governorate. The current form of the metropolis emerged as an offshoot of the eponymous walled town following the dismantling of its defensive fortifications in the 1950s, after which the city underwent several phases of expansion and urbanization.

It is the largest city on the Arabian Peninsula, and is situated in the center of the an-Nafud desert, on the eastern part of the Najd plateau. The city sits at an average of 600 m above sea level, and receives around 5 million tourists each year, making it the forty-ninth most visited city in the world and the 6th in the Middle East. Riyadh had a population of 7.0 million people in 2022, making it the most-populous city in Saudi Arabia, 3rd most populous in the Middle East, and the 38th most populous in Asia.

The first mention of the city by the name Riyadh was in 1590, by an Arab chronicler. In 1745, Dahham ibn Dawwas, who was from the neighboring Manfuha, seized control of the town. Dahham built a mudbrick palace and a wall around the town, and the best-known source of the name Riyadh is from this period, thought to be referring to the earlier oasis towns that predated the wall built by Ibn Dawwas. In 1744, Muhammad ibn 'Abd al-Wahhab formed an alliance with the Emir of Diriyah, Muhammad bin Saud, and they took Riyadh from Deham. However their state, now known as the First Saudi State, collapsed in 1818. Turki ibn Abdullah founded the Second Saudi State in the early 19th century and made Riyadh his capital in 1825. However, his reign over the city was disrupted by a joint Ottoman–Rashidi alliance. Finally, in the early 20th century, 'Abdulaziz ibn Saud, known in the west simply as Ibn Saud, retrieved his ancestral kingdom of Najd in 1902 and consolidated his rule by 1926 with the final Saudi conquest of Hejaz, subsequently naming his kingdom 'Saudi Arabia' in September 1932 with Riyadh as the capital. The town was the administrative center of the government until 1938, when Ibn Saud moved to the Murabba Palace. In the 1950s, the walls were dismantled and Riyadh metropolis outgrew as an offshoot of the walled town.

Riyadh is the political and administrative center of Saudi Arabia. The Consultative Assembly (also known as the Shura Council), the Council of Ministers, the King and the Supreme Judicial Council are all situated in the city. Alongside these four bodies that form the core of the legal system of Saudi Arabia, the headquarters of other major and minor governmental bodies are also located in Riyadh. The city hosts 114 foreign embassies, most of which are located in the Diplomatic Quarter in the western reaches of the city.

Riyadh also holds economic significance, as it contains the headquarters of many banks and major companies, such as the Saudi National Bank (SNB), Al-Rajhi Bank, SABIC, Almarai, STC, and Samba Financial Group. Highway 65, known locally as the King Fahd Road, runs through some of these important centers in the city, including the King Abdullah Financial District, one of the world's largest financial districts, the Faisaliyah Center and the Kingdom Center. Riyadh is one of the world's fastest-growing cities in population and is home to many expatriates.

The city is divided into 15 municipal districts, which are overseen by the Municipality of Riyadh headed by the mayor; and the Royal Commission for Riyadh, which is chaired by the Governor of the Province, Faisal bin Bandar Al Saud. As of July 2020, the mayor is Faisal bin Abdulaziz bin Mohammed bin Ayyaf Al-Muqrin. Riyadh will host Expo 2030, becoming the second Arab city to host after Dubai in 2020.

Early history
During the Pre-Islamic era, the city at the site of modern Riyadh was called Hajr (حجر), and was reportedly founded by the tribe of Banu Hanifa. Hajr served as the capital of the province of Al-Yamamah, whose governors were responsible for most of central and eastern Arabia during the Umayyad and Abbasid eras. Al-Yamamah broke away from the Abbasid Empire in 866 and the area fell under the rule of the Ukhaydhirites, who moved the capital from Hajr to nearby Al-Kharj. The city then went into a long period of decline. In the 14th century, North African traveler Ibn Battuta wrote of his visit to Hajr, describing it as "the main city of Al-Yamamah, and its name is Hajr". Ibn Battuta goes on to describe it as a city of canals and trees with most of its inhabitants belonging to the Bani Hanifa, and reports that he continued on with their leader to Mecca to perform the Hajj.

Later on, Hajr broke up into several separate settlements and estates. The most notable of these were Migrin (or Muqrin) and Mi'kal, though the name Hajr continued to appear in local folk poetry. The earliest known reference to the area by the name Riyadh comes from a 17th-century chronicler reporting on an event from the year 1590. In 1737, Deham ibn Dawwas, a refugee from neighboring Manfuha, took control of Riyadh. Ibn Dawwas built a single wall to encircle the various oasis towns in the area, making them effectively a single fortress city. The name "Riyadh", meaning "gardens" refers to these earlier oasis towns.

Commodities
The capital of Saudi Arabia, Riyadh, was initially known for its availability of water and fertile land which made it ideal for farming dates and other crops. Dates are abundant in the Middle East due to the perfect environment for the date palms. Wheat has also been a big commodity, however, there have been issues with it. There have been issues with insects and mites infesting the wheat supply in Saudi Arabia. However, a few years ago, Riyadh decided to reduce its wheat gathering. Riyadh was then designated as the capital and the layout of the city changed, focusing more on city development in the mid-1900s. As the city developed, the commodities changed slightly. Almost one-third of Saudi Arabia’s factories are located in Riyadh, producing a range of products including machinery, equipment, metallurgical goods, chemicals, construction materials, food, textiles, furniture, and numerous publications. While food is still part of Riyadh's commodities. It has developed to steer toward more urban commodities and those veered to city life.

First Saudi State
In 1750, Muhammad ibn Abd al-Wahhab formed an alliance with Muhammad ibn Saud, the ruler of the nearby town of Diriyah. Ibn Saud then set out to conquer the surrounding region with the goal of bringing it under the rule of a single Islamic state. Ibn Dawwas of Riyadh led the most determined resistance, allied with forces from Al Kharj, Al Ahsa, and the Banu Yam clan of Najran. However, Ibn Dawwas fled and Riyadh capitulated to the Saudis in 1774, ending long years of wars, and leading to the declaration of the First Saudi State, with Diriyah as its capital.

The First Saudi State was destroyed by forces sent by Muhammad Ali of Egypt, acting on behalf of the Ottoman Empire. Ottoman forces razed the Saudi capital Diriyah in 1818. They had maintained a garrison at Najd. This marked the decline of the House of Saud for a short time. Turki bin Abdullah bin Muhammad became the first Amir of the Second Saudi State; the cousin of Saud bin Saud, he ruled for 19 years till 1834, leading to the consolidation of the area though they were notionally under the control of Muhammad Ali, the Viceroy of Egypt. In 1823, Turki ibn Abdallah chose Riyadh as the new capital. Following the assassination of Turki in 1834, his eldest son Faisal killed the assassin, took control of the capital, and refused to be controlled by the Viceroy of Egypt. Najd was then invaded, and Faisal was taken captive and held in Cairo. However, as Egypt became independent of the Ottoman Empire, Faisal escaped after five years of incarceration, returned to Najd, and resumed his reign, ruling until 1865 and consolidating the reign of the House of Saud.

Following the death of Faisal, there was rivalry among his sons which situation was exploited by Muhammad bin Rashid who took most of Najd, signed a treaty with the Ottomans, and also captured Hasa in 1871. In 1889, Abdul Rahman bin Faisal, the third son of Faisal again regained control over Najd and ruled till 1891, whereafter the control was regained by Muhammad bin Raschid.

Internecine struggles between Turki's grandsons led to the fall of the Second Saudi State in 1891 at the hand of the rival Al Rashid clan, which ruled from the northern city of Ha'il. The al-Masmak fort dates from that period.

Abdul Rahman bin Faisal al-Saud had sought refuge among a tribal community on the outskirts of Najd and then went to Kuwait with his family and stayed in exile. However, his son Abdul Aziz retrieved his ancestral kingdom of Najd in 1902 and consolidated his rule by 1926, and further expanded his kingdom to cover "most of the Arabian Peninsula." He named his kingdom as Saudi Arabia in September 1932 with Riyadh as the capital. King Abdul Aziz died in 1953 and his son Saud took control as per the established succession rule of father to son from the time Muhammad bin Saud had established the Saud rule in 1744. However, this established line of succession was broken when King Saud was succeeded by his brother King Faisal in 1964. In 1975, Faisal was succeeded by his brother King Khalid. In 1982, King Fahd took the reins from his brother. This new line of succession is among the sons of King Abdul Aziz who has 35 sons; this large family of Ibn Saud hold all key positions in the large kingdom.

Modern history
From the 1940s, Riyadh mushroomed from a relatively narrow, spatially isolated town into a spacious metropolis. When King Saud came to power, he made it his objective to modernize Riyadh, and began developing Annasriyyah, the royal residential district, in 1950. Following the example of American cities, new settlements and entire neighborhoods were created on grid plans, and connected by high-capacity main roads to the inner areas. The grid pattern in the city was introduced in 1953. The population growth of the town from 1974 to 1992 averaged 8.2 percent per year.

On 16 November 1983, King Khalid International Airport was officially opened by King Fahd, in memory to the late King Khalid. It remains the biggest airport in the world at nearly 300 sq miles to date.

Al-Qaeda under Osama bin Laden launched coordinated attacks on compounds in Riyadh on 12 May 2003, resulting in the deaths of 39 people. The bombings were considered to be a terrorism campaign against Western influence in Saudi Arabia.

The mayor is Prince Faisal bin Abdulaziz al-Muqrin. Al-Muqrin was appointed in 2019 by royal decree and succeeds Tariq bin Abdul Aziz Al-Faris. Riyadh is now the administrative and to a great extent the commercial hub of the Kingdom. According to the Saudi Real Estate Companion, most large companies in the country established either sole headquarters or a large office in the city. For this reason, there has been significant growth in high-rise developments in all areas of the city. Most notable among these is King Abdullah Financial District which is fast becoming the key business hub in the city. Riyadh also has the largest all-female university in the world, the Princess Nora bint Abdul Rahman University.

According to the Global Financial Centres Index, Riyadh ranked at 77 in 2016–2017. Though the rank moved up to 69 in 2018, diversification in the economy of the capital is required in order to avoid what the World Bank called a "looming poverty crisis" brought on by lingering low oil prices and rich state benefits.

Since 2017, Riyadh has been the target of missiles from Yemen. In March 2018, one person died as a result of a missile attack. The number of missiles which targeted Riyadh are a small portion of the dozens of missiles fired from Yemen at Saudi Arabia due to the Saudi Arabian-led intervention in Yemen. In April 2018, heavy gunfire was heard in Khozama; this led to rumors of a coup attempt.

A restoration of heritage buildings of historical significance was launched in Riyadh by Crown Prince Mohammed bin Salman on 13 September 2020.

Climate
Riyadh has a hot desert climate (Köppen Climate Classification BWh), with long, extremely hot summers and short, very mild winters. The average high temperature in July is 43.9 C. If not for the elevation the city was on, Riyadh would experience an even hotter climate. The city experiences very little precipitation, especially during the summer, but receives a fair amount of rain in March and April. It is also known to have dust storms during which the dust can be so thick that visibility is under 10 m. On 1 and 2 April 2015, a massive dust storm hit Riyadh, causing the suspension of classes in many schools in the area and the cancellation of hundreds of flights, both domestic and international.

City districts
Riyadh is divided into fourteen branch municipalities, in addition to the Diplomatic Quarter. Each branch municipality in turn contains several districts, amounting to over 130 in total, though some districts are divided between more than one branch municipality. The branch municipalities are Al-Shemaysi, Irqah, Al-Ma'athar, Al-Olayya, Al-Aziziyya, Al-Malaz, Al-Selayy, Nemar, Al-Neseem, Al-Shifa, Al-'Urayja, Al-Bat'ha, Al-Ha'ir, Al-Rawdha, and Al-Shimal ("the North"). Olaya District is the commercial heart of the city, with accommodation, entertainment, dining and shopping options. The Kingdom Centre, Al Faisalyah, and Al-Tahlya Street are the area's most prominent landmarks. The center of the city, Al-Bathaa and Al-Deerah, is also its oldest part.

Some of the main districts of Riyadh are:

 * Al-Bat'ha
 * Al-Deerah (old Riyadh)
 * Mi'kal
 * Manfuha
 * Manfuha Al-Jadidah (منفوحة الجديدة – "new Manfuha")
 * Al-'Oud
 * Al-Mansorah
 * Al-Margab
 * Salam
 * Jabrah
 * Al-Yamamah
 * 'Otayyigah
 * Al-'Olayya & Sulaymaniyyah
 * Al-'Olayya
 * Al-Sulaymaniyyah
 * Al Izdihar
 * King Fahd District
 * Al-Masif
 * Al-Murooj
 * Al-Mugharrazat
 * Al-Wurood
 * Nemar
 * Nemar
 * Dharat Nemar
 * Tuwaiq
 * Hazm
 * Deerab
 * Irqah
 * Irqah
 * Al-Khozama
 * Diplomatic Quarter
 * Al-Shemaysi
 * Al-Shemaysi
 * Eleyshah
 * Al-Badi'ah
 * Syah
 * Al-Nasriyyah
 * Umm Sleym
 * Al-Ma'athar
 * Umm Al-Hamam (East)
 * Al-Ma'athar
 * Al-Olayya
 * Al-Nakheel
 * King Saud University main campus
 * Umm Al-Hamam (East)
 * Umm Al-Hamam (West)
 * Al-Ma'athar Al-Shimali ("North Ma'athar")
 * Al-Rahmaniyya
 * Al-Muhammadiyya
 * Al-Ra'id
 * Al-Ha'ir
 * Al-Ha'ir
 * Al-Ghannamiyyah
 * Uraydh
 * Al-'Aziziyyah
 * Al Aziziyah (Riyadh)
 * Ad Dar Al Baida
 * Taybah
 * Al Mansouriyah
 * Al-Malaz
 * Al-Malaz
 * Al-Rabwah
 * Al-Rayyan
 * Jarir
 * Al-Murabba'
 * Sinaiyah Qadeem
 * Al-Shifa
 * Al-Masani'
 * Al-Shifa
 * Al-Mansuriyya
 * Al-Marwah
 * Al-Urayja
 * Al-Urayja
 * Al-Urayja Al-Wusta ("Mid-Urayja")
 * Al-Urayja (West)
 * Shubra
 * Dharat Laban
 * Hijrat Laban
 * As-Suwaidi
 * As-Suwaidi (West)
 * Dahrat Al-Badi'ah
 * Sultanah
 * Al-Shemal
 * Al-Malga
 * Al-Sahafa
 * Hittin
 * Al-Wadi
 * Al-Ghadir
 * Al-Nafil
 * Imam Muhammad ibn Saud University main campus
 * Al-Qayrawan
 * Al-Aqiq
 * Al-Arid
 * Al-Naseem
 * Al-Naseem (East)
 * Al-Naseem (West)
 * As-Salam
 * Al-Manar
 * Al-Rimayah
 * Al-Nadheem
 * Al-Rawdhah
 * Al-Rawdhah
 * Al-Qadisiyah
 * Al-M'aizliyyah
 * Al-Nahdhah
 * Gharnatah (Granada)
 * Qortubah (Cordoba)
 * Al-Andalus (Andalusia)
 * Al-Hamra
 * Al-Qouds
 * Al-Selayy
 * Al-Selayy
 * Ad Difa'
 * Al Iskan
 * Khashm Al-'Aan
 * Al-Sa'adah
 * Al-Fayha
 * Al-Manakh
 * King Abdullah Financial District
 * Diriyah (suburb of Riyadh)

Demographics

In 2022, the city had over 7 million people. The city had a population of 40,000 inhabitants in 1935 and 83,000 in 1949. The city has experienced very high rates of population growth, from 150,000 inhabitants in the 1960s to over seven million, according to the most recent sources. As of 2017, the population of Riyadh is composed of 64.19% Saudis, while non-Saudis account for 35.81% of the population. Indians are the largest minority population at 13.7%, followed by Pakistanis at 12.4%. The population is so high due to the doubled birth rates and the high economic growth. There was also an influx of immigrants.

Vernacular architecture of Old Riyadh
The old town of Riyadh within the city walls did not exceed an area of 1 km2, and therefore very few significant architectural remnants of the original walled oasis town of Riyadh exist today. The most prominent is the Masmak fort and some parts of the original wall structure with its gate which have been restored and reconstructed. There are also a number of traditional mud-brick houses within these old limits, but they are for the most part dilapidated.

Expansion outside the city walls was slow to begin with, although there were some smaller oases and settlements surrounding Riyadh. The first major construction beyond the walls was King Abdulaziz's Murabba Palace. It was constructed in 1936, completed in 1938, and a household of 800 people moved into it in 1938. The palace is now part of a bigger complex called The King Abdulaziz Historical Centre.

There are other traditional villages and towns in the area around traditional Riyadh which the urban sprawl reached and encompasses. These include Diriyah, Manfuha and Wadi Laban. Unlike in the early days of development in Riyadh during which vernacular structures were razed to the ground without consideration, there is a new-found appreciation for traditional architecture. The Saudi Commission for Tourism and National Heritage is making efforts to revitalize the historic architecture in Riyadh and other parts of the kingdom.

 * Ain Heet Cave

Ain Heet cave has an underground lake (150 meters deep) situated at the face of Mount Al Jubayl in Wadi As Sulay in a small village called Heet in Riyadh. Between Riyadh and Al Kharj road, it is one of the easily accessible caves in the area of Riyadh.

Archeological sites
The archeological sites at Riyadh which are of historical importance, in which the Municipality of Riyadh is involved, are the five old gates on the old walls of Riyadh. These are the eastern gate of Thumaira, the northern gate of Al-Suwailen, the southern gate of Dukhna, the western gate of Al-Madhbah, and the south-western gate of Shumaisi. There are also four historic palaces: Musmak Palace, Murabba Palace (palace of King Abdul Aziz), Atiqah Palace (belongs to Prince Muhammad bin Abdul Rahman) and Al Shamsiah Palace (belongs to Saud Al Kabeer).

Turaif district
The Turaif district, is another important archeological site inscribed in UNESCO World Heritage List on 31 July 2010. It was founded in the 15th century bearing an architectural style of Najdi. There are some Historic palaces and monuments in Al-Turaif district include: Salwa Palace, Saad bin Saud Palace, The Guest House and At-Turaif Bath House, and Imam Mohammad bin Saud Mosque.

Masmak Fortress
This fortress was built around 1865 under the reign of Mohammed ibn Abdullah ibn Rasheed (1289-1315 AH), the ruler of Ha'il to the north, who had wrested control of the city from the rival clan of Al Saud. In January 1902 Ibn Saud, who was at the time living in exile in Kuwait, succeeded in capturing the Masmak fortress from its Rashid garrison. The event, which restored Saudi control over Riyadh, has acquired an almost mythical status in the history of Saudi Arabia. The story of the event is often retold and has as its central theme the heroism and bravery of King Abdulaziz al-Saud. The Masmak Fortress is now a museum and is in close proximity to the Clock Tower Square, also known to English-speaking residents as Chop Chop Square, referring to the capital punishment that takes place there.

Kingdom Centre
Designed by the team of Ellerbe Becket and Omrania, the tower is built on 94,230 square meters of land. The Kingdom Centre is owned by a group of companies including Kingdom Holding Company, headed by Al-Waleed bin Talal, a prince of the Saudi royal family, and is the headquarters of the holding company. The project cost 2 billion Saudi Arabian Riyals and the contract was undertaken by El-Seif. The Kingdom Centre is the winner of the 2002 Emporis Skyscraper Award, selected as the "best new skyscraper of the year for design and functionality". A three-level shopping center, which also won a major design award, fills the east wing. The large opening is illuminated at night in continuously changing colors. The shopping center has a separate floor for women only to shop where men are not allowed to enter.

The Kingdom Tower has 99 stories and is the fifth tallest structure in the country, rising to 300 m. A special aspect of the tower is that it is divided into two parts in the last one-third of its height and is linked by a sky-bridge walkway, which provides extensive views of Riyadh.

Burj Rafal Hotel Kempinski
Burj Rafal, located on King Fahd Road, is the tallest skyscraper in Riyadh at 307.9 meters (1,010 feet) tall. The tower was designed and engineered by P & T Group. Construction began in 2010 and was completed in 2014. The project was considered a success, with 70% of the residential units already sold by the time the skyscraper was topped out. The tower contains 474 residential condominium units and a 349-room 5-star Kempinski hotel.

Burj Al Faisaliyah
Al Faisaliyah Centre (Arabic: برج الفيصلية) is the first skyscraper constructed in Saudi Arabia and is the third tallest building in Riyadh after the Burj Rafal and the Kingdom Centre. The golden ball that lies atop the tower is said to be inspired by a ballpoint pen, and contains a restaurant; immediately below this is an outside viewing deck. There is a shopping center with major world brands at ground level. Al Faisaliyah Centre also has a hotel on both sides of the tower while the main building is occupied by office. The Al Faisaliyah Tower has 44 stories. It was designed by Foster and Partners.

Riyadh TV Tower
The Riyadh TV Tower is a 170 meter high television tower located inside the premises of the Saudi Ministry of Information. It is a vertical cantilever structure which was built between 1978 and 1981. The first movie made in 1983 by the TV tower group and named "1,000 Nights and Night" had Mohammed Abdu and Talal Mmdah as the main characters. At that time, there were no women on TV because of religious restrictions. Three years later, Abdul Khaliq Al-Ghanim produced a TV series called "Tash Ma Tash," which earned a good reaction from audiences in Eastern Arabia. This series created a media revolution back in the 1980s.

Museums and collections
In 1999, a new central museum was built in Riyadh, at the eastern side of the King Abdul Aziz Historical Centre. The National Museum of Saudi Arabia combined several collections and pieces that had up until then been scattered over several institutions and other places in Riyadh and the Kingdom. For example, the meteorite fragment is known as the "Camel's Hump", recovered in 1966 from the Wabar site, that was on display at the King Saud University in Riyadh became the new entry piece of the National Museum of Saudi Arabia.

The Royal Saudi Air Force Museum, or Saqr Al-Jazira, is located on the East Ring Road of Riyadh between exits 10 and 11. It contains a collection of aircraft and aviation-related items used by the Royal Saudi Air Force and Saudia (Saudi Arabian Airlines).

Sports
Football is the most popular sport in Saudi Arabia. The city hosts four major football clubs, Al Hilal was established in 1957 and has won 18 championships in the Saudi Professional League. Al-Nassr club is another team in the top league that has many supporters around the kingdom. It was established in 1955, and has been named champion of the Saudi professional League 9 times. Another well-known club, Al-Shabab, was established in 1947 and holds 6 championships. There is also Al-Riyadh Club, which was established in 1954, as well as many other minor clubs.

The city also has several large stadiums such as King Fahd International Stadium with a seating capacity of 70,000. The stadium hosted the FIFA Confederations Cup three times, in the years 1992, 1995 and 1997. It also hosted the FIFA U-20 World Cup in 1989, and Prince Faisal bin Fahd Stadium (Al-Malaz Stadium) that is used mostly for football matches. The stadium has a capacity of 22,500 people.

The city's GPYW Indoor Stadium served as host arena for the 1997 Asian Basketball Championship, where Saudi Arabia's national basketball team reached the Final Four.

On 29 February 2020, the world's richest thoroughbred horse race took place at the King Abdulaziz Racetrack in Riyadh. The Saudi Cup is a new race for thoroughbreds aged four and up, to be run at weight-for-age terms over 1800m (9f). The prize money is US$20m with a prize of US$10m to the winner and prize money down to tenth place. The Saudi Cup is perfectly positioned between the Pegasus World Cup and the Dubai World Cup to attract the best horses from around the world to compete for horse racing's richest prize. Putting the Kingdom of Saudi Arabia on the international horseracing map, the Saudi Cup will also hold an undercard of international races on both dirt and the new turf course.

On 26 April 2020, Saudi Arabia entered the bidding process for the 2030 Asian Games; their main rival for this event was Doha, Qatar. On 16 December 2020, it was announced that Riyadh will host the 2034 Asian Games.

Esports in Riyadh began its journey with the city's first major tournament, the GSA E-Sports Cup, in 2018. The Saudi Esports Federation further boosted this growth by organizing the Gamers8 festival in 2022 and 2023. The 2023 edition of the festival offered the largest prize pool in the history of global competitive esports at the time, totaling $45 million. As part of the Gamers8 festival, the Riyadh Masters, a Dota 2 tournament, boasted a significant prize pool of $15 million, surpassed only by the Fortnite World Cup Finals and The International in the history of esports tournaments. Gamers8 would be replaced by the Esports World Cup in 2024, which boasts a total prize pool of over $60 million, which will be the largest prize pool in the history of global competitive esports, split among at least 20 different tournaments and a Club Championship for esports organizations.

Air
Riyadh's King Khalid International Airport (KKIA) is located 35 kilometers north of the city center. It is the city's main airport, and served over 20 million passengers in 2013. The airport will be expanded into a huge airport, with six parallel runways and three or four large passenger terminals by 2030. It will be able to serve 120 million passengers per year after 2030, and 185 million passengers per year by 2050.

Buses
The metro system will be integrated with an 85 km, three-line bus rapid transit (BRT) network.

The main charter bus company in the kingdom, known as the Saudi Public Transport Company (SAPTCO), offers trips both within the kingdom and to its neighboring countries, including Egypt (via ferries from Safaga or Nuweiba) and Arab states of the Gulf Cooperation Council.

Metro
The six line Riyadh Metro is currently under construction. The first line was expected to open by end of 2021, but is now expected to open in 2024.

Railways
Saudi Railways Organization operates two separate passenger and cargo lines between Riyadh and Dammam, passing through Hofuf and Haradh. Two future railway projects, connecting Riyadh with Jeddah and Mecca in the western region, and connecting Riyadh with Buraidah, Ha'il and Northern Saudi Arabia are underway.

Roads
The city is served by a major highway system. The main Eastern Ring Road connects the city's south and north, while the Northern Ring Road connects the city's east and west. King Fahd Road runs through the center of the city from north to south, in parallel with the East Ring Road. Makkah Road, which runs east–west across the city's center, connects eastern parts of the city with the city's main business district and the diplomatic quarters.

Media
The 170 m Riyadh TV Tower, operated by the Ministry of Information, was built between 1978 and 1981. National Saudi television channels Saudi TV1, Saudi TV2, Saudi TV Sports, Al-Ekhbariya, ART channels network operate from here. Television broadcasts are mainly in Arabic, although some radio broadcasts are in English or French. Arabic is the main language used in television and radio but radio broadcasts are also made in different languages such as Urdu, French, or English. Riyadh has four Arabic newspapers; Asharq Al-Awsat (which is owned by the city governor), Al Riyadh, Al Jazirah and Al-Watan, two English language newspapers; Saudi Gazette and Arab News, and one Malayalam language newspaper, Gulf Madhyamam. The Saudi government monitors and filters internet content. Political dissent is not tolerated in Saudi Arabia. Saudi Arabia has had strict regulations on cinema and the arts.

Development projects
In 2019, King Salman launched a plan to implement 1281 development projects in Riyadh. The project is planned to cost around US$22 billion. The main goal of the plan is to improve the infrastructure, transportation, environment and other facilities in Riyadh and the surrounding area. In the framework of Saudi Vision 2030, the plan will take care of constructing 15 housing projects, building a huge museum, establishing an environmental project, sports areas, medical cities, educational facilities, etc. This includes the establishment of 14 electricity projects, 20 sewage projects, 10 housing areas, 66 trading and industrial areas, a number of lakes covering 315,000 square meters, and advanced sports cities. Since the announcement of the Vision, Riyadh has implemented various reforms to lay the foundation for the next steps of the Vision. The Vision 2030 is done to promote tourism and is part of a bigger picture that helps push Saudi Arabia to the global front. To find out more on the plan visit:https://www.vision2030.gov.sa/en/vision-2030/story-of-transformation/ Alongside the development project and in the aim of enhancing the artistic movement of the city, 1000 pieces of art are planned to be publicly displayed in the city by the end of 2030. In the framework of Riyadh's development projects, an amount of SR 604 million has been awarded to develop and construct roads of Riyadh. On 3 July 2020, Bloomberg reported that Saudi Arabia has allocated $20 billion on the mega-project of tourism and culture in Riyadh namely, "Diriyah Gate", while facing a double economic crisis after rise in coronavirus cases.

The Ministry of Investment and the Royal Commission for Riyadh City (RCRC) announced on 13 July 2021 that they have partnered with SEK Education Group to open SEK International School Riyadh, its first campus in Saudi Arabia. The new international school will welcome students from Pre-K (age 3 years) to Grade 12 (age 17/18 years), and will become one of the few schools in Riyadh accredited to offer the International Baccalaureate (IB) Primary Years Programme (PYP), Middle Years Programme (MYP), and Diploma Programme (DP).

On july 2024 The plan to create the Sports Boulevard which will include the world's tallest sports tower was approved. This is part of a $23 billion project meant to enlarge green spcaces within the city.

Arts
The arts can create a big change in societies and Riyadh is no different. There are many Muslim Scholars who have made great improvements to the arts and literature that were from Saudi Arabia. The development of agriculture is said to have pushed the wave of the arts into Saudi Arabia. One art form that is focused on is Calligraphy as it is associated with the Quran. There is also a history of folk music and folk dancing rituals that are performed in festivals. Poem readings are also very prominent in the culture as there is a poem for almost every event (weddings, funerals, etc.).

Literacy rate
The literacy rate in 2020 was 99.36% and in 2021 it was 99.38%. The literacy rate in Saudi Arabia has improved from 2010 when it was 98.10%.

Jenadriyah
Jenadriyah is an annual festival that has been held in Riyadh. It hosts a number of cultural and traditional events, such as camel race, poetry reading and others.

Riyadh International Book Fair
It is one of the largest book fairs in the MENA region. It is usually held between March and April and it hosts a wide range of Saudi, Arab and international publishers.

Riyadh Season
In the framework of the recent Saudi endeavor to promote tourism in the country, Riyadh Season was held as part of the Saudi Seasons initiative. The season took place in October 2019 and lasted until December 2019. It hosted a wide range of sports, musical, theatrical, fashion shows, circus, and various other entertainment activities. Some of Riyadh Season events are BTS concert, Joy Convention and Joy Expo, Ice Rink, WWE Events, Arabian concerts, Egyptian Theater, League of Legends, Real Madrid Interactive Expo and Ferrari Festival.

Noor Riyadh
Noor Riyadh (Noor meaning light in Arabic) is an annual festival and one of the four major projects under the mandate of the Royal Commission for Riyadh City. It is the festival of light and art. In 2021, the festival will be launched on 18 March and will last until 3 April.

Hiba Tawaji Concert
Riyadh hosted the first all-female concert in 2017. This marks a change within the culture of Riyadh that has sparked the wave of arts to Saudi Arabia.

title: Riyadh


text:
Rhineland

The Rhineland (Rheinland; Rhénanie; Rijnland; Rhingland; Latinised name: Rhenania) is a loosely defined area of Western Germany along the Rhine, chiefly its middle section.

Term
Historically, the term "Rhinelands" refers (physically speaking) to a loosely defined region embracing the land on the banks of the Rhine, which were settled by Ripuarian and Salian Franks and became part of Frankish Austrasia. In the High Middle Ages, numerous Imperial States along the river emerged from the former stem duchy of Lotharingia, without developing any common political or cultural identity.

A "Rhineland" conceptualization can be traced to the period of the Holy Roman Empire from the sixteenth until the eighteenth centuries when the Empire's Imperial Estates (territories) were grouped into regional districts in charge of defence and judicial execution, known as Imperial Circles. Three of the ten circles through which the Rhine flowed referred to the river in their names: the Upper Rhenish Circle, the Electoral Rhenish Circle and the Lower Rhenish-Westphalian Circle (very roughly equivalent to the present-day German federal state of North Rhine Westphalia). In the twilight period of the Empire, after the War of the First Coalition, a short-lived Cisrhenian Republic was established (1797–1802). The term covered the whole French conquered territory west of the Rhine (German: Linkes Rheinufer), but also including a small portion of the bridgeheads on the eastern banks. After the collapse of the French empire, the regions of Jülich-Cleves-Berg and Lower Rhine were annexed to the Kingdom of Prussia. In 1822 the Prussian administration reorganized the territory as the Rhine Province (Rheinprovinz, also known as Rhenish Prussia), a tradition that continued in the naming of the current German states of Rhineland-Palatinate and North Rhine-Westphalia.

In the early 1800s, Rhinelanders settled the Missouri Rhineland, a German cultural region and wine producing area in the U.S. State of Missouri, and named it after noticing similarities in soil and topography to the Rhineland in Europe. By 1860, nearly half of all settlers in Missouri Rhineland came from Koblenz, capital of the Rhine Province.

Following the First World War, the western part of Rhineland was occupied by Entente forces, then demilitarized under the 1919 Treaty of Versailles and then the 1925 Locarno Treaties. Nazi Germany remilitarized the territory in 1936, as part of a diplomatic test of will, three years before the outbreak of the Second World War.

Geography
To the west the area stretches to the borders with Luxembourg, Belgium and the Netherlands; on the eastern side it encompasses the towns and cities along the river and the Bergisches Land area up to the Westphalian (Siegerland) and Hessian regions. Stretching down to the North Palatine Uplands in the south, this area, except for the Saarland, more or less corresponds with the modern use of the term.

The southern and eastern parts are mainly hill country (Westerwald, Hunsrück, Siebengebirge, Taunus and Eifel), cut by river valleys, principally the Middle Rhine up to Bingen (or very rarely between the confluence with the Neckar and Cologne ) and its Ahr, Moselle and Nahe tributaries. The border of the North German plain is marked by the lower Ruhr. In the south, the river cuts the Rhenish Massif.

The area encompasses the western part of the Ruhr industrial region and the Cologne Lowland. Some of the larger cities in the Rhineland are Aachen, Bonn, Cologne, Duisburg, Düsseldorf, Essen, Koblenz, Krefeld, Leverkusen, Mainz, Mönchengladbach, Mülheim an der Ruhr, Oberhausen, Remscheid, Solingen, Trier and Wuppertal.

Toponyms as well as local family names often trace back to the Frankish heritage. The lands on the western shore of the Rhine are strongly characterized by Roman influence, including viticulture. In the core territories, large parts of the population are members of the Catholic Church.

Pre-Roman
At the earliest historical period, the territories between the Ardennes and the Rhine were occupied by the Treveri, the Eburones and other Celtic tribes, who, however, were all more or less modified and influenced by their Germanic neighbors. On the East bank of the Rhine, between the Main and the Lahn, were the settlements of the Mattiaci, a branch of the Germanic Chatti, while farther to the north were the Usipetes and Tencteri.

Roman and Frankish conquests
Julius Caesar conquered the Celtic tribes on the West bank, and Augustus established numerous fortified posts on the Rhine, but the Romans never succeeded in gaining a firm footing on the East bank. As the power of the Roman empire declined the Franks pushed forward along both banks of the Rhine, and by the end of the 5th century had conquered all the lands that had formerly been under Roman influence. By the 8th century, the Frankish dominion was firmly established in western Germania and northern Gaul.

On the division of the Carolingian Empire at the Treaty of Verdun the part of the province to the east of the river fell to East Francia, while that to the west remained with the kingdom of Lotharingia.

Holy Roman Empire
By the time of Emperor Otto I (d. 973) both banks of the Rhine had become part of the Holy Roman Empire, and in 959 the Rhenish territory was divided between the duchies of Upper Lorraine, on the Mosel, and Lower Lorraine on the Meuse.

As the central power of the Holy Roman Emperor weakened, the Rhineland disintegrated into numerous small independent principalities, each with its separate vicissitudes and special chronicles. The old Lotharingian divisions became obsolete, and while the Lower Lorraine lands were referred to as the Low Countries, the name of Lorraine became restricted to the region on the upper Moselle that still bears it. After the Imperial Reform of 1500/12, the territory was part of the Lower Rhenish–Westphalian, Upper Rhenish, and Electoral Rhenish Circles. Notable Rhenish Imperial States included:
 * the ecclesiastical electorates of Cologne (without Westphalian possessions) and Trier
 * the duchies of Jülich, Cleves, and Berg, forming the United Duchies of Jülich-Cleves-Berg from 1521
 * the County of Sponheim and numerous further Imperial Counties
 * the Free Imperial Cities of Aachen and Cologne.

In spite of its dismembered condition and the sufferings it underwent at the hands of its French neighbors in various periods of warfare, the Rhenish territory prospered greatly and stood in the foremost rank of German culture and progress. Aachen was the place of coronation of the German emperors, and the ecclesiastical principalities of the Rhine played a large role in German history.

French Revolution
At the Peace of Basel in 1795, the whole of the left bank of the Rhine was taken by France. The population was about 1.6 million in numerous small states. In 1806, the Rhenish princes all joined the Confederation of the Rhine, a puppet of Napoleon. France took direct control of the Rhineland until 1814 and radically and permanently liberalized the government, society and economy. The Coalition of France's enemies made repeated efforts to retake the region, but France repelled all the attempts.

The French swept away centuries worth of outmoded restrictions and introduced unprecedented levels of efficiency. The chaos and barriers in a land divided and subdivided among many different petty principalities gave way to a rational, simplified, centralized system controlled by Paris and run by Napoleon's relatives. The most important impact came from the abolition of all feudal privileges and historic taxes, the introduction of legal reforms of the Napoleonic Code, and the reorganization of the judicial and local administrative systems. The economic integration of the Rhineland with France increased prosperity, especially in industrial production, while business accelerated with the new efficiency and lowered trade barriers. The Jews were liberated from the ghetto. There was limited resistance; most Germans welcomed the new regime, especially the urban elites, but one sour point was the hostility of the French officials toward the Roman Catholic Church, the choice of most of the residents. The reforms were permanent. Decades later workers and peasants in the Rhineland often appealed to Jacobinism to oppose unpopular government programs, while the intelligentsia demanded the maintenance of the Napoleonic Code (which stayed in effect for a century).

Prussian influence
A Prussian influence began on a small scale in 1609 by the occupation of the Duchy of Cleves. A century later, Upper Guelders and Moers also became Prussian. The Congress of Vienna expelled the French and assigned the whole of the lower Rhenish districts to Prussia, who left them in undisturbed possession of the liberal institutions to which they had become accustomed under the French. The Rhine Province remained part of Prussia after Germany was unified in 1871.

1918–1945
The occupation of the Rhineland took place following the Armistice with Germany of 11 November 1918. The occupying armies consisted of American, Belgian, British and French forces. Under the Treaty of Versailles, German troops were banned from all territory west of the Rhine and within 50 kilometers east of the Rhine.

In 1920, under massive French pressure, the Saar was separated from the Rhine Province and administered by the League of Nations until a plebiscite in 1935, when the region was returned to Germany. At the same time, in 1920, the districts of Eupen and Malmedy were transferred to Belgium (see German-Speaking Community of Belgium).

In January 1923, in response to Germany's failure to meet its reparations obligations, French and Belgian troops occupied the Ruhr district, strictly controlling all important industrial areas. The Germans responded with passive resistance, which led to hyperinflation, and the French gained very little of the reparations they wanted. French troops left the Ruhr in August 1925.

The occupation of the remainder of the Rhineland ended on 30 June 1930.

On 7 March 1936, in violation of the Treaty of Versailles, German troops marched into the Rhineland and other regions along the Rhine. German territory west of the Rhine had been off-limits to the German military.

In 1945, the Rhineland was the scene of major fighting as the Allied forces overwhelmed the German defenders.

Post-1946
In 1946, the Rhineland was divided into the newly founded states of Hesse, North Rhine-Westphalia, and Rhineland-Palatinate. North Rhine-Westphalia is one of the prime German industrial areas, containing significant mineral deposits (coal, lead, lignite, magnesium, oil, and uranium) and water transport. In Rhineland-Palatinate agriculture is more important, including the vineyards in the Ahr, Mittelrhein, and Mosel regions.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Rhineland


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Mendel University in Brno

Mendel University in Brno (Mendelova univerzita v Brně) is located in Brno, Czech Republic. It was founded on 24 July 1919 on the basis of the former Tábor Academy. It now consists of five faculties and one institute - the Faculty of AgriSciences, Faculty of Forestry and Wood Technology, Faculty of Business and Economics, Faculty of Horticulture, Faculty of Regional Development and International Studies and Institute of Lifelong Education. It is named since 1994 after Gregor Johann Mendel, the botanist and "father of genetics", who was active in this city during his lifetime.

In June 2020, the university was included in the QS World University Rankings top 1,000 for the first time, placed #701-750.

History
Established on July 24, 1919, the university initially known as the University of Agriculture is the oldest agricultural school in Czechoslovakia. Renamed in the mid-1990s to honor Gregor Johann Mendel, reflecting its strong heritage in the agricultural sciences. It began with programs in forestry and economics and has since expanded to include several specialized faculties and research institutes.

In 2010, it adopted the name Mendel University in Brno. The establishment of CEITEC MENDELU in 2011 integrated the university into the Central European Institute of Technology, enhancing its research capabilities.

Scientific research tasks
The resolution of scientific research tasks is based on the long-term forecast and scientific orientation of the university and its faculties, covering the fields of agricultural, forestry, biological, economic, and technical sciences. It involves an open range of research activities, implemented in institutional research, competitive grant agency procedures, research centers, and international scientific research programs. The research program at MENDELU in Brno generally follows current trends in the development of basic scientific disciplines, especially biology and their applications in agricultural, forestry, horticultural, and economic sciences.

In practical implementation, it involves targeted management of biological processes, efficient utilization of non-renewable and creation of renewable natural resources in the development of sustainable, multifunctional agriculture and agribusiness. Emphasis is placed on the quality and safety of agricultural products in general, and food in particular. In the context of the conclusions of the EU Common Agricultural Policy, the university prioritizes topics related to multifunctional agriculture and forestry, the significance of their production and non-production functions in shaping the landscape and rural development."

Faculties

 * Faculty of AgriSciences
 * Department of Plant Biology
 * Department of Applied and Landscape Ecology
 * Department of Agrosystems and Bioclimatology
 * Department of Crop Science, Plant Breeding and Plant Medicine
 * Department of Agrochemistry, Soil Science, Microbiology and Plant Nutrition
 * Department of Animal Nutrition and Forage Production
 * Department of Animal Morphology, Physiology and Genetics
 * Department of Zoology, Fisheries, Hydrobiology and Apiculture
 * Department of Molecular Biology and Radiobiology
 * Department of Agriculture, Food and Environmental Engineering
 * Department of Engineering and Automobile Transport
 * Department of Food Technology
 * Department of Animal Breeding
 * Department of Chemistry and Biochemistry
 * Department of Physical Training

 * Faculty of Forestry and Wood Technology
 * Department of Forest Management and Applied Geoinformatics
 * Department of Geology and Pedology
 * Department of Mathematics
 * Department of Forest Botany, Dendrology and Geobiocoenology
 * Department of Forest and Wood Products Economics and Policy
 * Department of Landscape Management
 * Department of Forest and Forest Products Technology
 * Department of Forest Protection and Wildlife Management
 * Department of Silviculture
 * Department of Wood Processing
 * Department of Furniture, Design and Habitat
 * Department of Wood Science
 * Institute of Forest Ecology

 * Faculty of Business and Economics
 * Department of Economics
 * Department of Business Economics
 * Department of Management
 * Department of Statistics and Operational Analysis
 * Department of Accounting and Taxation
 * Department of Marketing and Trade
 * Department of Informatics
 * Department of Law
 * Department of Finance
 * Department of Social Sciences

 * Faculty of Horticulture in Lednice
 * Department of Fruit Growing
 * Department of Horticultural Machinery
 * Department of Vegetable Growing and Floriculture
 * Department of Breeding and Propagation of Horticultural Plants
 * Department of Post-harvest Technology of Horticultural Products
 * Department of Viticulture and Viniculture
 * Department of Garden and Landscape Architecture
 * Department of Planting Design and Maintenance
 * Department of Landscape Planning
 * The Mendeleum - Institute of Genetics and Plant Breeding

 * Institute of Lifelong Learning
 * Faculty of Regional Development and International Studies

=== Bachelor programs of the Faculty of Regional Development and International Studies ===
 * Regional Development (in Czech)
 * Regional Development (in English, study is paid)
 * International Territorial Studies (in Czech)
 * International Territorial Studies (in English study is paid)

=== Master programs of the Faculty of Regional Development and International Studies ===
 * Regional Development (in Czech)
 * Regional Development (in English, study is paid)
 * International Territorial Studies (in Czech)
 * International Territorial Studies (in English study is paid)

title: Mendel University in Brno


text:
Latvian Gambit

The Latvian Gambit (or Greco Countergambit) is a chess opening characterised by the moves:

 * 1. e4 e5
 * 2. Nf3 f5

It is one of the oldest chess openings, having been analysed in the 16th century by Giulio Cesare Polerio and then the 17th century by Gioachino Greco, after whom it is sometimes named. The opening has the appearance of a King's Gambit with. It is an aggressive but objectively dubious opening for Black which often leads to wild and tricky positions. FIDE Master Dennis Monokroussos even goes so far as to describe it as "possibly the worst opening in chess". While Paul van der Sterren observes: "What is required to play the Latvian Gambit with any degree of success is a sharp eye for tactics and a mental attitude of total contempt for whatever theory has to say about it."

The Latvian is, and has always been, uncommon in top-level play, but some correspondence players are devotees.

The ECO code for the Latvian Gambit is C40 (King's Knight Opening).

History
The opening was originally known as the Greco Countergambit, and some modern writers still refer to it as such. That name recognised the Italian player Gioachino Greco (1600–1634), who contributed to the early theory of the opening. In 19th century German chess literature, the opening was often referred to as "Gambit in der Rückhand" ("backhand gambit"), i.e. gambit played by Black. (The terms "Vorhand" and "Rückhand" were used before the standard that White moves first was adopted in the mid-19th century).

The name Latvian Gambit is a tribute to several Latvian players who analysed it, Kārlis Bētiņš being the most prominent among them. The Austrian master Albert Becker once published an article that Bētiņš judged to be dismissive about the Latvian Gambit. In response, Bētiņš published and analysed one of his own games in order to defend the gambit: Ilyin-Zhenevsky vs K Bētiņš, 1921.

According to most, the opening's only advantage is its ostensible novelty value, since, irrespective of what level you play at, the chances of your opponent even knowing this opening, let alone knowing the best lines for White, are low. However, it has been used by Boris Spassky and Mikhail Chigorin, amongst many others; albeit, usually in casual play. Most notably, even Bobby Fischer and José Raúl Capablanca have lost to it. Sweden's Jonny Hector is one of the few grandmasters to play it in serious competition; he has argued that it is not as bad as its reputation and that even with best play White's advantage is not large.

3.Nxe5 (Main line)
White's 3.Nxe5 is considered the main line against the Latvian. After the usual 3...Qf6, the traditional main line has been 4.d4 d6 5.Nc4 fxe4, however recently the immediate 4.Nc4 (the Leonhardt Variation) has become popular.

3...Qf6 4.Nc4
4.Nc4 has the advantage of allowing White to open the with d3, for example 4...fxe4 5.Nc3 Qg6?! 6.d3 exd3? 7.Bxd3 Qxg2? and now White is winning after 8.Qh5+ Kd8 (or 8...g6 9.Qe5+ and 10.Be4) 9.Be4. If 6... Bb4, however, White must be careful following the same line, e.g. 7.Bd2 exd3 8.Bxd3 Qxg2 9.Qh5+ Kd8 10.Be4 Nf6! because now if White plays Bg5, which would be necessary to win the queen in the earlier line, then ...Bxc3+ wins for Black. The main line continues 5...Qf7 6.Ne3! Black usually responds with 6...c6!?, when White can either accept the pawn sacrifice with 7.Nxe4 d5 8.Ng5 Qf6 9.Nf3, or decline it with the more popular 7.d3 exd3 8.Bxd3 d5 9.0-0. The latter variation has been deeply analysed; the British grandmaster Anthony Kosten analyses one line to move 32. One line discussed by IM Jeremy Silman is 9...Bc5 10.Na4 Bd6 11.c4 d4 12.Nc2 c5 13.b4 Ne7 14.Nxc5 Bxc5 15.bxc5 Nbc6 16.Bb2 0–0 17.Nxd4 Nxd4 18.Bxd4 Bf5 19.Bxf5 Nxf5 20.Be3 Qxc4 21.Qb3 Nxe3!? 22.fxe3 Rxf1+ 23.Rxf1 Qxb3 24.axb3 Rc8 25.Rf5 and now 25...Rd8 or 25...Rc6 gives Black an excellent chance to draw the pawn-down endgame. Silman later argued that 10.b4!! and now 10...Bxb4 11.Ncxd5 cxd5 12.Nxd5 or 10...Bd6 11.Re1! Ne7 12.Nexd5 cxd5 13.Nb5 is close to winning for White, and that the "old, discredited" 9...Bd6 (rather than 9...Bc5) might be Black's best try, though still insufficient for.

3...Qf6 4.d4
A possible continuation after 4.d4 is 4...d6 5.Nc4 fxe4 6.Nc3 Qg6 7.f3 exf3 8.Qxf3 Nf6 9.Bd3 Qg4 10.Qe3+ Qe6 11.0-0 Qxe3+ 12.Bxe3 Be7 13.Rae1 0-0. White is better here, but Black has chances due to White's misplaced king and weak light squares.

3...Nc6
Also possible is the eccentric 3...Nc6?!, against which John Nunn recommends 4.d4, preferring principled opening play to the unclear tactics resulting from 4.Qh5+. After 4.d4, if 4...Qh4? (Kosten's original recommendation) 5.Nf3! Qxe4+ 6.Be2 leaves Black with a lost position. After 4.d4, Kosten analyses 4...Qf6!? 5.Nc3 Bb4 6.exf5! Nxe5 7.Qe2.

Instead of 4.d4, Kosten says that White can accept the proffered rook with 4.Qh5+ g6 5.Nxg6 Nf6 6.Qh3 hxg6 7.Qxh8 Qe7 (7...fxe4? 8.d4! is strong) 8.d3! (Stefan Bücker gives an alternative 8.Nc3! Nb4 9.d3 as also winning for White) 8...fxe4 9.Be3 d5 10.Bc5! Qxc5 11.Qxf6 Bf5 12.dxe4 Nd4 13.exf5! Nxc2+ 14.Kd1 Nxa1 15.Bd3 Qd6 16.Re1+ Kd7 17.Qf7+ Be7 18.Re6 winning.

3.Bc4
White's 3.Bc4 may lead to perhaps the most notorious and heavily analysed line of the Latvian, which begins 3...fxe4 4.Nxe5 Qg5 5.d4 Qxg2 6.Qh5+ g6 7.Bf7+ Kd8 8.Bxg6! Qxh1+ 9.Ke2 Qxc1 (9...c6 is a major alternative) 10.Nf7+ Ke8 11.Nxh8+ hxg6 12.Qxg6+ Kd8 13.Nf7+ Ke7 14.Nc3! (diagram).

Instead of 4...Qg5, however, "nowadays players often give preference to 4...d5", the Svedenborg or Polerio Variation. According to Latvian Gambit experts Kon Grivainis and John Elburg, Black wins more often than White in this line. After 4...d5 5.Qh5+ g6 6.Nxg6, Black chooses between 6...Nf6 and 6...hxg6. 6...Nf6 usually leads, after 7.Qe5+ Be7 8.Bb5+! (a small zwischenzug to deprive Black's knight of the c6-square) 8...c6 9.Nxe7 Qxe7 10.Qxe7+ Kxe7 11.Be2 (or 11.Bf1), to an endgame where Black is a pawn down but has positional compensation. Sharper is 6...hxg6, when 7.Qxh8 Kf7 9.Qd4 Be6 gives White a large advantage, but his "position is constantly on the edge of a precipice", and the line has accordingly fallen out of favour. More often, White plays 7.Qxg6+ Kd7 8.Bxd5 Nf6, leading to sharp and unclear play.

Black's best response is 3...fxe4. Some sample continuations are
 * 4.Nxe5 Qg5 5.Nxf7 Qxg2 6.Rf1 d5 7.Nxh8 (a common mistake is 7.Bxd5? Nc6! 8.Nxh8 Bg4 9.f3 Be7 10.Qe2 Bh4+ 11.Kd1 Qxe2+ 12.Kxe2 Nd4+) 7...Nf6
 * 4.Nxe5 Qg5 5.d4 Qxg2 6.Qh5+ g6 7.Bf7+ Kd8 8.Bxg6 Qxh1+ 9.Ke2 Qxc1 10.Nf7+ Ke8 11.Nd6+ Kd8 12.Nf7+ Ke8 13.Nxh8+ hxg6 14.Qxg6+ Kd8 15.Nf7+ Ke7 16.Nc3 Qxc2+ 17.Ke1 d6 18.Nd5+ Kd7 19.Qxg8 e3 20.fxe3 Be7 21.Ng5 Na6
 * 4.Bxg8 Rxg8 5.Nxe5 Qg5 6.Ng4 d5 7.h3 Qg6

Assessment : Black is usually down material, but has excellent compensation. Most of White's pieces are still on the back rank. IM Mio argues Black is better.

Other responses for White
Several other responses for White have been analysed.

3.Nc3
White's 3.Nc3 was originally analysed by the American master Stasch Mlotkowski (1881–1943) in the 1916 British Chess Magazine. Kosten gives as Black's two main responses 3...Nf6 4.Bc4 (4.exf5 is also possible) fxe4 5.Nxe5 d5 6.Nxd5! Nxd5 7.Qh5+ g6 8.Nxg6! hxg6! 9.Qxg6+ Kd7 10.Bxd5 Qe7 11.Qxe4 Rh4 12.Qxe7+ Bxe7, reaching an endgame where White has four pawns for a, and 4...fxe4 5.Nxe5 Qf6, when White can choose from 6.Nc4! (transposing to the main line 3.Nxe5 Qf6 4.Nc4 fxe4 6.Nc3), 6.d4, and 6.f4!? Black can also play 3...d6, when 4.d4 to the Philidor Countergambit (1.e4 e5 2.Nf3 d6 3.d4 f5!?), which was favoured by Paul Morphy in the mid-19th century and is still seen occasionally today.

Today, however, Black's response is considered to be 3...fxe4.
 * 4.Nxe4 d5 5.Nxe5 dxe4 6.Qh5+ g6 7.Nxg6 hxg6 8.Qxh8 Be6 9.Qe5 Kf7 10.Qxe4 Nf6 11.Qxb7 Nbd7
 * 4.Nxe4 d5 5.Ng3 e4 6.Nd4 Nf6 7.d3 c5 8.Ndf5 Nc6

Assessment : One of the best lines for Black. Black has better bishops and a strong centre.

3.exf5
White's 3.exf5 followed by 3...e4 4.Ne5 Nf6 5.Be2 is recommended by John L. Watson and Eric Schiller. 4.Qe2, 4.Nd4, and even 4.Ng1!? are also possible.

Black's response should be 3...e4.

Now, White has three possible moves:
 * Ne5 (best move)
 * Nd4
 * Qe2

Sample Continuation #1 4.Ne5 Nf6 5.Be2 d6 6.Bh5+ Ke7! 7.Nf7 Qe8 8.Nxh8 Nxh5 9.Nc3 Kd8

Sample Continuation #2 4.Nd4 Nf6 5.d3 c5 6.Nb3 exd3 7.Bxd3 d5 8.Bb5+ Nc6

Common mistake 4.Qe2? Qe7 5.Nd4 Nc6 6.Qh5+ Kd8 7.Nxc6+ dxc6 8.Be2 Nf6 9.Qg5 h6 10.Qe3 Bxf5 11.0-0 Nd5 12.Qd4 Qd6 13.d3 Nb4

Assessment : While Black is not lost here, this variation is hard to play for Black. It often involves Ke7, allowing Nf7 and saccing the kingside rook.

3.d4
White's 3.d4 followed by 3...fxe4 4.Nxe5 Nf6 5.Bg5 d6 leads, as usual, to sharp play. White often offers a piece with either 6.Nc3!? or 6.Nd2!?, but Black seems to have adequate resources against both.

Black's best response is considered to be 3...fxe4.

Sample Continuation #1 4.Nxe5 Nf6 5.Be2 d6 6.Nc4 Be6 7.Ne3 d5 8.c4 c6 9.Nc3 Be7 10.0-0 0-0

Common mistake 8.O-O? c5!

Sample Continuation #2 4.Nxe5 Nf6 5.Be2 d6 6.Ng4 Be7 7.Nc3 d5 8.Ne5 O-O 9.Bg5 c6 10.O-O Bf5

Assessment : Black has a better pawn structure, and better bishops. Few openings give you such a good position after just 10 moves.

3.d3
This passive move does not promise White any advantage. After 3...Nc6 4.Nc3 Nf6 5.exf5 d5, Black is okay. Alternatively, 3...d6 4.Nc3 Nf6 5.g3 Be7 6.Bg2 is also considered a prudent defense by Black. Black's best response is 3...Nc6.

Sample continuation #1 4.Nc3 Nc6 5.exf5 d5

Sample continuation #2 4.Nc3 Nc6 5.Bg5 Bb4 6.exf5 d5 7.a3 Bxc3+ 8.bxc3 Bxf5

Assessment : Normal position that is comparable to several other openings. White has a weak pawn structure but the bishop pair. However, this is a tough advantage to prove, since White's light-squared bishop is restricted.

title: Latvian Gambit


text:
The Luzhin Defence

The Luzhin Defence is a 2000 romantic drama film directed by Marleen Gorris, starring John Turturro and Emily Watson. The film centres on a mentally tormented chess grandmaster and the young woman he meets while competing at a world-class tournament in Italy. The screenplay was based on the novel The Defense (or The Luzhin Defence) by Vladimir Nabokov.

Emily Watson received best actress nominations at the British Independent Film Awards and the London Film Critics Circle Awards.

Plot
It is the early 1920s and Aleksandr Ivanovich 'Sascha' Luzhin (Turturro), a gifted but tormented chess player, arrives in a Northern Italian city to compete in an international chess competition. Prior to the tournament he meets Natalia Katkov (Watson) and he falls in love with her almost immediately. She in turn finds his manner to be appealing and they begin to see each other in spite of her mother's disapproval.

Competing alongside Luzhin in the championship is Dottore Salvatore Turati (Fabio Sartor), who is approached by Leo Valentinov (Stuart Wilson), a Russian, who is Luzhin's former chess tutor from pre-revolutionary Russia. Valentinov tells the Italian that Luzhin cannot handle pressure and he intimates he will make sure that his former prodigy will be unsettled off-table, giving Turati a winning chance.

The competition starts badly for Luzhin, who is unsettled by the presence of his former friend and coach. He struggles through the early rounds but he soon begins to win again as his relationship with Katkov becomes closer and intimate. She then informs her parents that she is going to marry him. Meanwhile, Luzhin goes on to reach the final and face Turati.

But in the finals the Russian Émigré loses out to the time clock, forcing the game to adjourn. However, outside the venue, he is whisked away by an accomplice of Valentinov who abandons him in the countryside. His former teacher knows that this will completely unhinge him because of the memory of his parents' abandonment many years ago. Luzhin wanders aimlessly until he collapses and is found by a group of Blackshirts.

Luzhin is taken to the hospital suffering from complete mental exhaustion. The doctor informs Katkov that he will die if he keeps playing chess as he is addicted to the game and it is consuming his very being. Nevertheless, even while recuperating Valentinov comes around with a chess board encouraging Luzhin to finish the match with the Italian, Turati. Natalia defends her beloved but urges him to break off with the game. Luzhin seems to agree.

Eventually Luzhin leaves the hospital. He and Natalia then agree to marry at the earliest opportunity. However, on the morning of the wedding, Luzhin is put into a car with Valentinov, who tells him that there is the small matter of finishing the competition. In terror, Luzhin leaps from the car. Dazed, cut and mentally confused, he stumbles back to the hotel where he tries to dig up the rest of the glass chess pieces he buried on the grounds years ago, (1:36:39 "I've got the King but I need the whole army...") but he does not find them.

Luzhin, who is in his muddied wedding suit, sits in his room as Natalia and the hotel staff try to open the door. But before they can get in, the troubled chess grandmaster throws himself out of his bedroom window and dies. The tragic death is witnessed by Valentinov who has just arrived by car.

The film then concludes in the competition hall where Natalia completes the competition using her fiancé's notes. She discovers the papers in his pocket and an experienced chess player explains to her the matter of the notes. In an arranged meeting without public she plays against  Turati who does exactly what Luzhin expected and loses. Katkov and Turati then leave acknowledging the Pyrrhic victory and the genius of Luzhin.

Cast

 * John Turturro as Luzhin
 * Emily Watson as Natalia
 * Geraldine James as Vera
 * Stuart Wilson as Valentinov
 * Christopher Thompson as Stassard
 * Fabio Sartor as Turati
 * Peter Blythe as Ilya
 * Orla Brady as Anna
 * Mark Tandy as Luzhin's Father
 * Kelly Hunter as Luzhin's Mother

Production
Nabokov based The Defense on the life of German chess master Curt von Bardeleben, who seemingly committed suicide by leaping from a window in 1924.

The film was shot entirely in Europe. Budapest, Hungary was used for outdoor scenes as they were set in St Petersburg, these included the Széchenyi Chain Bridge, Hungarian National Museum and Heroes' Square. The chess tournament (although in Italy) was shot inside the main hall of the Museum of Ethnography, Budapest. In Italy, the hotel scenes were filmed at Villa Erba, Cernobbio, on the Lake Como. The scene at the railway station is in Brenna-Alzate, near Como.

In the novel, Valentinov's first name is never mentioned; on the contrary, Luzhin's first name is revealed only in the closing sentences. Another dissimilarity is that the novel ends up by Luzhin's suicide, thereby his game would be never finished.

The finale
The chess position they play for the final between Turati and Luzhin is already a winning position for Black (Luzhin), even though Black is down on material. By playing 1. Kg4 (as opposed to 1. Kf2) White walks into a forced checkmate with a rook sacrifice:
 * 1. Kg4 f5+
 * 2. Kg5 Kg7 If 2. Kh4 Be7#
 * 3. Nd5 Rh3!
 * 4. gxh3 h6+
 * 5. Kh4 Bf2#

If White plays 1. Kf2 instead of 1. Kg4 this leads to a heavy material loss for White and an easy game for Black: and Black is up by a rook.
 * 1. Kf2 Rxc3+
 * 2. Ke1 Rxc1+

In the film Luzhin's final moves were made by his fiancé. The tournament had been paused after Luzhin had a nervous breakdown which had been caused by extreme strain. On the same day he was going to get married he committed suicide by jumping from the hotel balcony. His fiancé later found a piece of paper inside his jacket where he had written down his intended final moves against Turati.

Cinematic error
In Luzhin's previous game, on his way to the final, the film shows an inaccurate checkmating move. The scene shows White (Luzhin) play an apparently brilliant combination culminating in a queen sacrifice followed by Rd1-d8#.

However, White's rook on the d1 square is pinned against its king in the corner at h1 by Black's rook on c1, making the checkmate unplayable.

Nevertheless, Luzhin (White) is shown playing the illegal winning move to wild applause from the audience.

The sequence is as follows, Luzhin has just played his rook to e8 (check) although it is not clear if this was a capture or not. Play then continues: White's last move is illegal (see rules of chess). Moving the rook would put White in check, which is prohibited.
 * 1. ... Bf8
 * 2. Rxf8+ Kxf8
 * 3. Nf5+ Kg8
 * 4. Qf8+ Kxf8
 * 5. Rd8#

In the film, the Black rook was erroneously placed on c1 instead of c2, where it was in the actual game this winning combination was played, making it legal, a famous win of Milan Vidmar over future world champion Max Euwe.

Release
The film opened in 59 cinemas in the United Kingdom on 8 September 2000 and grossed £59,779 in its opening weekend, placing at 15th at the UK box office.

title: The Luzhin Defence


text: Talk:Transliteration

title: Talk:Transliteration


text:
User talk:Antonin Slejska

Welcome to Wikipedia! I used to work at an agricultural research institute in Beer-Sheva, Israel, mostly as an editor - so I hope you don't mind me improving your written English! -- Marj Tiefert, Monday, May 6, 2002

Nomination of Czech Biomass Association for deletion
A discussion is taking place as to whether the article Czech Biomass Association is suitable for inclusion in Wikipedia according to Wikipedia's policies and guidelines or whether it should be deleted.

The article will be discussed at Articles for deletion/Czech Biomass Association until a consensus is reached, and anyone, including you, is welcome to contribute to the discussion. The nomination will explain the policies and guidelines which are of concern. The discussion focuses on high-quality evidence and our policies and guidelines.

Users may edit the article during the discussion, including to improve the article to address concerns raised in the discussion. However, do not remove the article-for-deletion notice from the top of the article. Imcdc (talk) 13:46, 8 October 2021 (UTC)

title: User talk:Antonin Slejska


text:
Cnidocyte

A cnidocyte (also known as a cnidoblast) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida (: cnidae)) that can deliver a sting to other organisms. The presence of this cell defines the phylum Cnidaria (corals, sea anemones, hydrae, jellyfish, etc.). Cnidae are used to capture prey and as a defense against predators. A cnidocyte fires a structure that contains a toxin within the cnidocyst; this is responsible for the stings delivered by a cnidarian. Cnidocytes are single-use cells that need to be continuously replaced.

Structure and function
Each cnidocyte contains an organelle called a cnida, cnidocyst, nematocyst, ptychocyst or spirocyst. This organelle consists of a bulb-shaped capsule containing a coiled hollow tubule structure attached to it. An immature cnidocyte is referred to as a cnidoblast or nematoblast. The externally oriented side of the cell has a hair-like trigger called a cnidocil, which is a mechano- and chemo-receptor. When the trigger is activated, the tubule shaft of the cnidocyst is ejected and, in the case of the penetrant nematocyst, the forcefully ejected tubule penetrates the target organism. This discharge takes a few microseconds, and is able to reach accelerations of about 40,000 g. Research from 2006 suggests the process occurs in as little as 700 nanoseconds, thus reaching an acceleration of up to 5,410,000 g. After penetration, the toxic content of the nematocyst is injected into the target organism, allowing the sessile cnidarian to capture the immobilized prey. Recently, in two sea anemone species (Nematostella vectensis and Anthopleura elegantissima), the type I neurotoxin protein Nv1 was shown to be localized in ectodermal gland cells in the tentacles, next to but not in nematocytes. Upon encounter with a crustacean prey, nematocytes discharge and pierce the prey, and Nv1 is massively secreted into the extracellular medium by the nearby gland cells, thus suggesting another mode of entry for toxins.

Cnidocyte capsule composition
The cnidocyte capsule is made of novel Cnidaria-specific genes which combine known protein domains. Minicollagen genes are one of the major structural components of the capsule. They are very short genes containing the characteristic collagen-triple helix sequence, as well as polyproline domains and cystein-rich domains. Trimers of minicollagen proteins assemble through their terminal cystein-rich domain, forming highly organized and rigid supra-structures. Minicollagen 1 Ncol-1 polymers assemble on the inner shell while the outer capsule is composed of polymerized NOWA (Nematocyst Outer Wall Antigen) proteins. Nematogalectin, minicollagen Ncol-15 and chondroitin are novel proteins used to build the tubule shaft. In piercing cnidocytes, the novel protein is used to make the spines present at the base of the shaft.

Discharge mechanism

The cnidocyst capsule stores a large concentration of calcium ions, which are released from the capsule into the cytoplasm of the cnidocyte when the trigger is activated. This causes a large concentration gradient of calcium across the cnidocyte plasma membrane. The resulting osmotic pressure causes a rapid influx of water into the cell. This increase in water volume in the cytoplasm forces the coiled cnidae tubule to eject rapidly. Prior to discharge the coiled cnidae tubule exists inside the cell in an "inside out" condition. The back pressure resulting from the influx of water into the cnidocyte together with the opening of the capsule tip structure or operculum, triggers the forceful eversion of the cnidae tubule causing it to right itself as it comes rushing out of the cell with enough force to impale a prey organism.

That force is to be calculated as the mass of the mechanism's stylet multiplied by its acceleration. The pressure that is generated by this impact into its prey is to be calculated by the stylet's force divided by its area. Researchers have calculated an ejected mass of 1 nanogram, an acceleration of 5,410,000 g and a stylet tip radius of 15 ± 8 nm. Therefore, a pressure of more than 7 GPa was estimated at the stylet tip which they write is in the range of technical bullets.

Fluid dynamics in nematocyst discharge
Few papers have modeled the discharge aside from direct observation. Observational studies typically used a tentacle solution assay with a chemical stimulant to create discharge and cameras to record them. One in 1984 and another in 2006 as imaging technology improved. One study involved computational fluid dynamics where variables such as barb plate size, prey cylindrical diameter and fluid medium Reynolds number were manipulated.

Observational studies indicate that velocities of the barb/stylet decrease throughout the discharge. As such, the incredible maximum acceleration is achieved at the beginning. Dynamic traits such as maximum discharge velocities and trajectory patterns may not correspond to static traits such as tubule lengths and capsule volumes. Therefore, caution is appropriate when using medusan nematocyst assemblages as indicators of prey selection and trophic role. This is possibly the case for other jelly species and hence one cannot generally infer nematocyst static traits to prey size.

Prey detection
Cnidae are "single use" cells, and thus represent a large expenditure of energy to produce. In Hydrozoans, in order to regulate discharge, cnidocytes are connected as "batteries", containing several types of cnidocytes connected to supporting cells and neurons. The supporting cells contain chemosensors, which, together with the mechanoreceptor on the cnidocyte (cnidocil), allow only the right combination of stimuli to cause discharge, such as prey swimming, and chemicals found in prey cuticle or cutaneous tissue. This prevents the cnidarian from stinging itself although sloughed off cnidae can be induced to fire independently.

Types of cnidae
Over 30 types of cnidae are found in different cnidarians. They can be divided into the following groups:
 * 1) Nematocyst (Penetrant or Piercing ): The penetrant or stenotele is the largest and most complex nematocyst. When discharged, it pierces the skin or chitinous exoskeleton of the prey and injects the venomous fluid, hypnotoxin, that either paralyzes the victim or kills it.
 * 2) Ptychocysts (Glutinant or Adhesive ): a sticky surface used to stick to prey, referred to as ptychocysts and found on burrowing (tube) anemones, which help create the tube in which the animal lives
 * 3) Spirocyte (Volvent or Ensnaring ): The volvent or desmoneme is a small and pear-shaped cnidocyte. It contains a short, thick, spineless, smooth and elastic thread tube forming a single loop and closed at the far end. When discharged, it tightly coils around the prey. They are the smallest cnidocytes. A lasso-like string is fired at prey and wraps around a cellular projection on the prey, which are referred to as spirocysts.

Cnidocyte subtypes can be differentially localized in the animal. In the sea anemone Nematostella vectensis, the majority of its non-penetrant sticky cnidocytes, the spirocytes, are found in the tentacles, and are thought to help with prey capture by sticking to the prey. By contrast, the two penetrant types of cnidocytes present in this species display a much broader localization, on the outer epithelial layer of the tentacles and body column, as well as on the pharynx epithelium and within mesenteries.

The diversity of cnidocytes types correlates with the expansion and diversification of structural cnidocyst genes like minicollagen genes. Minicollagen genes form compact gene clusters in Cnidarian genomes, suggesting a diversification through gene duplication and subfunctionalization. Anthozoans display less capsule diversity and a reduced number of minicollagen genes, and medusozoans have more capsule diversity (about 25 types) and a vastly expanded minicollagen genes repertoire. In the sea anemone Nematostella vectensis, some minicollagens display a differential expression pattern in different cnidocytes subtypes.

Cnidocyte development
Cnidocytes are single-use cells that need to be continuously replaced throughout the life of the animal with different mode of renewal across species.

Modes of renewal
In Hydra polyps, cnidocytes differentiate from a specific population of stem cells, the interstitial cells (I-cells) located within the body column. Developing nematocytes first undergo multiple rounds of mitosis without cytokinesis, giving rise to nematoblast nests with 8, 16, 32 or 64 cells. After this expansion phase, nematoblasts develop their capsules. Nests separate into single nematocytes when the formation of the capsule is complete. Most of them migrate to the tentacles where they are incorporated into battery cells, which hold several nematocytes, and neurons. Battery cells coordinate firing of nematocytes.

In the hydrozoan jellyfish Clytia hemisphaerica, nematogenesis takes place at the base of the tentacles, as well as in the manubrium. At the base of the tentacles, nematoblasts proliferate then differentiate along a proximal-distal gradient, giving rise to mature nematocytes in the tentacles through a conveyor belt system.

In the Anthozoan sea anemone Nematostella vectensis, nematocytes are thought to develop throughout the animal from epithelial progenitors. Furthermore, a single regulatory gene that codes for the transcription factor ZNF845 also called CnZNF1 promotes the development of a cnidocyte and inhibits the development of a RFamide producing neuron cell. This gene evolved in the stem cnidarian through domain shuffling.

Cnidocyst maturation
The nematocyst forms through a multi-step assembly process from a giant post-Golgi vacuole. Vesicles from the Golgi apparatus first fuse onto a primary vesicle: the capsule primordium. Subsequent vesicle fusion enables the formation of a tubule outside of the capsule, which then invaginates into the capsule. Then, an early maturation phase enables the formation of long arrays of barbed spines onto the invaginated tubule through the condensation of spinalin proteins. Finally, a late maturation stage gives rise to undischarged capsules under high osmotic pressure through the synthesis of poly-γ-glutamate into the matrix of the capsule. This trapped osmotic pressure enables rapid thread discharge upon triggering through a massive osmotic shock.

Nematocyst toxicity
Nematocysts are very efficient weapons. A single nematocyst has been shown to suffice in paralyzing a small arthropod (Drosophila larva). The most deadly cnidocytes (to humans, at least) are found on the body of a box jellyfish. One member of this family, the sea wasp, Chironex fleckeri, is "claimed to be the most venomous marine animal known," according to the Australian Institute of Marine Science. It can cause excruciating pain to humans, sometimes followed by death. Other cnidarians, such as the jellyfish Cyanea capillata (the "Lion's Mane" made famous by Sherlock Holmes) or the siphonophore Physalia physalis (Portuguese man o' war, "Bluebottle") can cause extremely painful and sometimes fatal stings. On the other hand, aggregating sea anemones may have the lowest sting intensity, perhaps due to the inability of the nematocysts to penetrate the skin, creating a feeling similar to touching sticky candies. Besides feeding and defense, sea anemone and coral colonies use cnidocytes to sting one another in order to defend or win space. Despite their effectiveness in prey-predator interactions, there is an evolutionary tradeoff as cnidarian venom systems are known to reduce the cnidarian's reproductive fitness and overall growth.

Venom from animals such as cnidarians, scorpions and spiders may be species-specific. A substance that is weakly toxic for humans or other mammals may be strongly toxic to the natural prey or predators of the venomous animal. Such specificity has been used to create new medicines and bioinsecticides, and biopesticides.

Animals in the phylum Ctenophora ("sea-gooseberries" or "comb jellies") are transparent and jelly-like but have no nematocysts, and are harmless to humans.

Certain types of sea slugs, such as the nudibranch aeolids, are known to undergo kleptocnidy (in addition to kleptoplasty), whereby the organisms store nematocysts of digested prey at the tips of their cerata.

title: Cnidocyte


text:
Talk:Diacylglycerol

Shouldn't diacylglycerole be diacylglycerol? There seem to be a few other extra e's tagged onto the end of words, but I'll wait till I'm more awake... -- Marj Tiefert, Saturday, May 4, 2002

The history appears to have gotten hard-to-find with the redirect. Please, whoever wrote this, verify the spelling of "inosite" -- I doubt that it's correct, but don't know exactly what you had in mind. ;-) -- Marj Tiefert, Monday, May 6, 2002
 * Thanks, Malcolm, for the change. I figured it was probably inositol, but it was way past my bedtime. -- Marj Tiefert, Tuesday, May 7, 2002

title: Talk:Diacylglycerol