title: Siege of Jerusalem (1187)

text: He sent word of his decision to Saladin at Ascalon via a deputation of burgesses, who rejected the sultan's proposals for a negotiated surrender of Jerusalem; however, Saladin arranged for an escort to accompany Maria, their children, and all their household to Tripoli. As the highest-ranking lord remaining in Jerusalem, according to the chronicler Ibn al-Athir, Balian was seen by the Muslims as holding a rank "more or less equal to that of a king."


title: Siege of Jerusalem (1187)

text: Balian found the situation in Jerusalem dire. The city was filled with refugees fleeing Saladin's conquests, with more arriving daily. There were fewer than fourteen knights in the whole city, so he created sixty new knights from the ranks of the squires (knights in training) and burgesses. He prepared for the inevitable siege by storing food and money. The armies of Syria and Egypt assembled under Saladin, and after conquering Acre, Jaffa, and Caesarea, though he unsuccessfully besieged Tyre, the sultan arrived outside Jerusalem on September 20.


title: Siege of Jerusalem (1187)

text: After a brief reconnoitre around the city, Saladin's army came to a rest before the Tower of David and the Damascus Gate. His archers continually pelted the ramparts with arrows. Siege towers/belfries were rolled up to the walls but were pushed back each time. For six days, skirmishes were fought with little result. Saladin's forces suffered heavy casualties after each assault. On September 26, Saladin moved his camp to a different part of the city, on the Mount of Olives where there was no major gate from which the crusaders could counter-attack. The walls were constantly pounded by the siege engines, catapults, mangonels, petraries, Greek fire, crossbows, and arrows. A portion of the wall was mined, and it collapsed on September 29. The crusaders were unable to push Saladin's troops back from the breach, but at the same time, the Muslims could not gain entrance to the city. Soon there were only a few dozen knights and a handful of remaining men-at-arms defending the wall, as no more men could be found even for the promise of an enormous fee.


title: Siege of Jerusalem (1187)

text: The civilians were in great despair. According to a passage possibly written by Ernoul, a squire of Balian, in the "Old French Continuation of William of Tyre", the clergy organized a barefoot procession around the walls, much as the clergy on the First Crusade had done outside the walls in 1099. At Mount Calvary, women cropped their children's hair, after immersing them chin-deep in basins of cold water. These penances were aimed at turning away God's wrath from the city, but "…Our Lord did not deign to hear the prayers or noise that was made in the city. For the stench of adultery, of disgusting extravagance and of sin against nature would not let their prayers rise to God."


title: Siege of Jerusalem (1187)

text: At the end of September, Balian rode out with an envoy to meet with the sultan, offering surrender. Saladin told Balian that he had sworn to take the city by force, and would only accept an unconditional surrender. Saladin told Balian that Saladin's banner had been raised on the city wall, but his army was driven back. Balian threatened that the defenders would destroy the Muslim holy places, slaughter their own families and the 5000 Muslim slaves, and burn all the wealth and treasures of the Crusaders. Saladin, who wanted to take the city with as little bloodshed of his fellow Muslims as possible, insisted that the Crusaders were to unconditionally surrender but could leave by paying a ransom of ten dinars for men, five for women and two for children; those who couldn't pay would be enslaved. Balian told him that there were 20,000 in the city who could never pay that amount. Saladin proposed a total of 100,000 dinars to free all the 20,000 Crusaders who were unable to pay. Balian complained that the Christian authorities could never raise such a sum. He proposed that 7,000 of them would be freed for a sum of 30,000 dinars, and Saladin agreed.


title: Siege of Jerusalem (1187)

text: On Balian's orders, the Crusaders surrendered the city to Saladin's army on October 2. The take-over of the city was relatively peaceful especially in contrast to the Crusader siege of the city in 1099. Balian paid 30,000 dinars for freeing 7,000 of those unable to pay from the treasury of the city. The large golden Christian cross that had been placed over the Dome of the Rock by the Crusaders was pulled down and all Muslim prisoners of war taken by the Crusaders were released by Saladin. According to the Kurdish scholar and historian Baha ad-Din ibn Shaddad, these numbered close to 3,000. Saladin allowed many of the noblewomen of the city to leave without paying any ransom. For example, a Byzantine queen living a monastic life in the city was allowed to leave the city with her retinue and associates, as was Sibylla, the queen of Jerusalem and wife of the captured King Guy. Saladin also granted her safe passage to visit her captive husband in Nablus. The native Christians were allowed to remain in the city while those of Crusader origin were allowed to leave Jerusalem for other lands along with their goods through a safe passage via Akko by paying a ransom of 10 dinars. Saladin's brother Al-Adil was moved by the sight and asked Saladin for 1,000 of them as a reward for his services. Saladin granted his wish and Al-Adil immediately released them all. Heraclius, upon seeing this, asked Saladin for some slaves to liberate. He was granted 700 while Balian was granted 500 and all of them were freed by them. All the aged people who could not pay the ransom were freed by orders of Saladin and allowed to leave the city. Saladin then proceeded to free 1,000 more captives upon request of Muzaffar al-Din Ibn Ali Kuchuk, who claimed they were from his hometown of Urfa. In order to control the departing population, Saladin ordered the gates of the city to be closed. At each gate of the city, a commander was placed to check the movement of the Crusaders and make sure only those who paid the ransom left the city. Saladin then assigned some of his officers the job of ensuring the safe arrival of the Crusaders in Christian lands. 15,000 of those who could not pay the ransom were sold into slavery. According to Imad ad-Din al-Isfahani, 7,000 of them were men and 8,000 were women and children.


title: Siege of Jerusalem (1187)

text: On Saladin's orders, the ransomed inhabitants marched away in three columns accompanied by 50 cavalrymen of Saladin's army. The Knights Templar and Hospitallers led the first two, with Balian and the Patriarch leading the third. Balian joined his wife and family in the County of Tripoli. The refugees first reached Tyre, where only men who could fight were allowed to enter by Conrad of Montferrat. The remaining refugees went to the County of Tripoli, which was under Crusader control. They were denied entrance and robbed of their possessions by raiding parties from within the city. Most of the less affluent refugees went to Armenian and Antiochian territories and were later successful in gaining entrance into Antioch. The remaining refugees fled from Ascalon to Alexandria, where they were housed in makeshift stockades and received hospitable treatment from the city officials and elders. They then boarded Italian ships which arrived from Pisa, Genoa and Venice in March 1188. The captains of the ships at first refused to take the refugees since they were not being paid for them and did not have supplies for them. The governor of Alexandria, who had earlier taken the oars of the ships for payment of taxes, refused to grant sailing permits to the captains until they agreed. The latter then agreed to take the refugees along with them and were made to swear decent treatment and safe arrival of the refugees before they left.


title: Siege of Jerusalem (1187)

text: After the surrender of the city, the Church of the Holy Sepulchre was ordered to be closed for three days by Saladin while he considered what to do with it. Some of his advisers told him to destroy the Church in order to end all Christian interest in Jerusalem. Most of his advisers, however, told him to spare the Church, saying that Christian pilgrimages would continue anyway because of the sanctity of the place and also reminded him of the Caliph Umar, who allowed the Church to remain in Christian hands after conquering the city. Saladin ultimately decided not to destroy the church, saying that he had no intention to discourage Christian pilgrimages to the site; it was reopened after three days on his orders. The Frankish pilgrims were allowed to enter the church upon paying a fee. To solidify Muslim claims to Jerusalem, many holy sites, including the shrine known as Al-Aqsa Mosque, were ritually purified with rose water. Christian furnishings were removed from the mosque and it was fitted with oriental carpets. Its walls were illuminated with candelabras and text from the Quran. The Orthodox Christians and Syriacs were allowed to remain and to worship as they chose. The Copts, who were barred from entering Jerusalem by the Crusader kingdom of Jerusalem as they were considered heretics and atheists, were allowed to enter the city without paying any fees by Saladin as he considered them his subjects. The Coptic places of worship that were earlier taken over by the Crusaders were returned to the Coptic priests. The Copts were also allowed to visit the Church of the Holy Sepulchre and other Christian sites. The Abyssinian Christians were allowed to visit the holy places of Jerusalem without paying any fees.


title: Siege of Jerusalem (1187)

text: The Byzantine emperor, Isaac Angelus, sent a message to Saladin congratulating him on taking the city, requesting him to convert all the churches in the city back to the Orthodox church and all Christian ceremonies to be performed according to the Greek Orthodox liturgy. His request was granted and the rights of other confessions were preserved. The local Christians were allowed to pray freely in their churches and the control of Christian affairs was handed over to the ecumenical patriarch of Constantinople.


title: Siege of Jerusalem (1187)

text: Saladin went on to capture a number of other castles that were still holding out against him, including Belvoir, Kerak, and Montreal, and returned to Tyre to besiege it for a second time.


title: Siege of Jerusalem (1187)

text: Meanwhile, news of the disastrous defeat at Hattin was brought to Europe by Joscius, Archbishop of Tyre, as well as other pilgrims and travellers, while Saladin was conquering the rest of the kingdom throughout the summer of 1187. Plans were immediately made for a new crusade; on October 29, Pope Gregory VIII issued the bull "Audita tremendi", even before hearing of the fall of Jerusalem. In England and France, the Saladin tithe was enacted in order to finance expenses. The Third Crusade did not get underway until 1189, in three separate contingents led by Richard I of England, Philip II of France, and Frederick I, Holy Roman Emperor.


title: Roland Gift

text: Roland Lee Gift (born 28 May 1961) is a British singer, songwriter and actor. He is the former singer/frontman of the pop band Fine Young Cannibals.


title: Roland Gift

text: Gift was born on 28 May 1961 in the Sparkhill district of Birmingham, to an English mother and an Afro-Caribbean father. He lived in Sparkhill until the age of 11, receiving his early formal education at Anderton Park School and Arden Primary School. His family then moved to Kingston upon Hull, where his mother, Pauline, ran several second-hand clothes shops, whilst he was a pupil at Kelvin Hall School.


title: Roland Gift

text: Gift's first recording was as a saxophonist with Akrylykz, a ska band from Hull. The album the second release on York's Red Rhino Records. Although this record was unsuccessful, it did bring him to the attention of Andy Cox and David Steele of the Beat. Akrylykz toured with the Beat, which led to them, in around 1985, asking him to be the lead singer of their new band Fine Young Cannibals after their old band, the Beat, had broken up. He also was a guest artist on the Ska City Rockers' "Time Is Tight" single.


title: Roland Gift

text: Gift has performed as a solo artist, appearing at the Rewind Festival in Henley. On 13 February 2012, Gift appeared on BBC Radio Solent promoting the gigs and announced a potential new album in 2012. This would be a soundtrack to a film Gift was apparently involved with. "The Prisoner" was played on the show and Gift said this would probably be included in the soundtrack.


title: Roland Gift

text: He also appeared in Jools Holland's 20th annual "Hootenanny" show, which aired overnight on BBC2 on 31 December 2012 / 1 January 2013, the last to be recorded at BBC Television Centre. Gift sang the Fine Young Cannibals hits "Good Thing" and "Suspicious Minds".


title: Roland Gift

text: In 1987, Gift had his first screen role in the film "Sammy and Rosie Get Laid", and also appeared in "Out of Order" the same year. In 1990 he did his first stage work, playing Romeo in the Hull Truck Theatre's production of Shakespeare's "Romeo and Juliet", a production which had a brief run in the United States at the Staller Center for the Arts. He also appeared as a lounge singer (singing songs that were included in the Fine Young Cannibals' album "The Raw and the Cooked") in the 1987 film "Tin Men", directed by Barry Levinson.


title: Roland Gift

text: In December 1992, he began the first of five appearances as the evil Immortal Xavier St. Cloud in the television series "", and appeared in a 1993 episode of the Yorkshire Television series "Heartbeat" (Ser. 2 Ep 6). He also had a small role as the jazz saxophonist Eddie Mullen in the mini-series "Painted Lady" (1997), starring Helen Mirren, and appeared in the movie "The Island of the Mapmaker's Wife" (2001).


title: Roland Gift

text: In 1997, he appeared in a series of commercials to launch BankDirect, an internet and phone based bank.


title: Roland Gift

text: In 2020, he starred as Johnny Holloway, an ex-pop star sent to jail, in the BBC Radio 4 musical drama "Return to Vegas." Gift wrote the play and co-composed the music together with Ben Barson, brother of Madness's Mike Barson).


title: Roland Gift

text: One of Gift's two sons, Louis, was a member of an experimental acrobatic circus company called the 'Barely Methodical Troupe', which staged a public performance at the Edinburgh Fringe Festival in 2016. His wife Louise died in 2019.


title: O2 (UK)

text: O₂ UK (legally incorporated as Telefonica UK Limited, stylized as O₂) is a British telecommunications services provider, headquartered in Slough, England. It operates under the O2 brand. It is owned by Virgin Media O2, a 50:50 joint venture between Telefónica and Liberty Global. O2 is the UK's largest mobile network operator, with 31.3 million subscribers as of September 2021.


title: O2 (UK)

text: The company was formed on 7 January 1985 as Cellnet, a 60:40 joint venture between BT Group and Securicor. Cellnet was one of the first two mobile networks in the UK, alongside Vodafone. In 1999, BT acquired Securicor's share of Cellnet and the company was later rebranded as BT Cellnet. In June 2000, BT Cellnet launched the world's first commercial General Packet Radio Service (GPRS) service. The company, together with BT Group's mobile telecommunications businesses in Germany, Ireland and the Netherlands, was part of the BT Wireless division. This was spun off from the BT Group in 2002 to form a new holding company, mmO2 plc, which introduced the new "O2" brand for the businesses. In 2005, mmO2 plc was renamed O2 plc.


title: O2 (UK)

text: O₂ plc was purchased by the Spanish telecommunications company Telefónica in 2006 for £18 billion. Under the terms of the acquisition, Telefónica agreed to retain the "O₂" brand and the company's UK headquarters. O2 plc was renamed Telefónica O₂ Europe in 2007 and then Telefónica Europe plc in 2008, and became the holding company for Telefónica's operations in the UK.


title: O2 (UK)

text: In May 2020, Telefónica reached an agreement with Liberty Global to merge the company with Virgin Media. On 1 June 2021, O2 and Virgin Media formally merged to create Virgin Media O2 as a joint venture between Telefónica and Liberty Global. and structured as a joint venture between Telefónica and Liberty Global.


title: O2 (UK)

text: Between 1985 and 1989, John Carrington was the CEO of British Telecom's Mobile Division and the Chairman of Cellnet. It was during this period that Carrington launched Cellnet's first cellular service, following innovative development work by BT Spectrum, who built a chain of cells between London Heathrow and BT Tower in January 1985.


title: O2 (UK)

text: Cellnet was established in 1985 as a joint subsidiary of BTCR, British Telecom Cellular Radio, providing the engineering knowledge, and TSCR, Telecom Securicor Cellular Radio Limited, providing the financial investment, resulting in a 60:40 joint venture between British Telecommunications and Securicor.


title: O2 (UK)

text: The equipment used was primarily a Motorola system designed for the American Advanced Mobile Phone System (AMPS) and had to be adapted for the British system, Total Access Communication (TACS). The system was so unready that the initials that Motorola used to designate the network exchanges, EMX, became popularly known as 'European Motorola Experiment' and the exchanges had to be programmed in machine code loaded by tape. In the early days of the system, mobile calls cost £1 per minute.


title: O2 (UK)

text: After months of rumours and speculation, Peter Bonfield publicly announced on 27 July 1999 that BT had agreed to buy Securicor's 40 per cent share of Cellnet for £3.15 billion. Cellnet had five million customers at the time of its acquisition. The company was rebranded as BT Cellnet in 2000, and it became a part of BT Wireless, a group of companies owned by BT.


title: O2 (UK)

text: BT announced on 3 September 2001 that the BT Wireless business would be spun off from the main group as a newly listed holding company, mmO2 plc, operating under the "O2" brand. Shareholders approved the plan at an extraordinary general meeting on 23 October 2001. BT Cellnet relaunched as "O2" on 18 June 2002, along with other former BT subsidiaries: Esat Digifone in Ireland, Viag Interkom in Germany and Telfort Mobiel in the Netherlands.


title: O2 (UK)

text: The rebranding was supported by a European advertising campaign, which began on 16 April 2002, across all four countries, at a cost of £130 million. The main launch campaign ran from 18 June and was developed by Vallance Carruthers Coleman Priest, working alongside brand consultancy Lambie-Nairn, creators of the "O2" brand identity.


title: O2 (UK)

text: On 30 November 2005, O2 agreed to a takeover by Telefónica, a Spanish telecommunications company, for £17.7 billion (£2 per share) in cash. It went through finally in 2006. According to the merger announcement, O2 retained its name and continued to be based in the United Kingdom, keeping both the brand and the management team. The merger became unconditional on 23 January 2006.


title: O2 (UK)

text: Following the acquisition of O2, Telefónica undertook a corporate organisational change that saw the merging of its fixed and mobile businesses in Spain, and the transfer of Telefónica's non-Spanish European telecommunications properties into the O2 brand. Thus, the Český Telecom and Eurotel operations in the Czech Republic as well as the Telefónica Deutschland business in Germany were brought under the control of O2, which retained its UK-registered public company status with its own board of directors and corporate structures and processes. Telefónica chose to keep its existing mobile phone operations in the rest of the world under the brand Movistar. This name is used in Spain and in most of the Latin American countries, operated by a separate management team.


title: O2 (UK)

text: On 15 July 2009, O2 entered the financial services industry with the launch of O2 Money, which was the first step in the process of incorporating financial services into mobile phones. Future plans included manufacturing Near Field Communication (NFC) technology in mobile phones in the United Kingdom.


title: O2 (UK)

text: O2 and Vodafone signed a deal in June 2012 which will see the two companies 'pool' their network technology, creating a single national grid of 18,500 transmitter sites. Both networks will continue to carry their own independent mobile spectrum.


title: O2 (UK)

text: On 24 November 2014, it was reported that BT were in talks to buy back O2, while at the same time BT confirmed that it was also in talks to buy EE. BT subsequently entered into exclusive talks with EE.


title: O2 (UK)

text: On 23 January 2015, Li Ka-shing, owner of Hutchison Whampoa and the Three network (which operates in the UK) entered talks to buy O2 for up to £10.25bn ($15.4bn). However, the move faced scrutiny from competition regulators as it would reduce the number of major operators in the UK, when combined with a potential purchase of EE by BT, from four to three. Hutchison Whampoa had previously acquired the O2 network from Telefónica in the Republic of Ireland, which it has since merged into Three. The combined network would have surpassed EE to create the largest mobile network in the UK.


title: O2 (UK)

text: The deal was subject to regulatory approval. The European Commission decided in December 2015 not to refer Hutchison's takeover of Telefónica's O2 business in the UK to the country's Competition and Markets Authority, which had asked to be allowed to investigate the planned acquisition, arguing that as the British competition regulator, it – and not the Commission – should have the right to rule on the transaction, which it argued 'threatens to affect significantly competition in the UK retail mobile and wholesale mobile markets', claiming that its investigation of the takeover would 'avoid duplication and fragmentation'. On 11 May 2016, the European Commission officially blocked the tie-up of O2 and Three, arguing that the merger would reduce consumer choice and lead to a higher cost of services.


title: O2 (UK)

text: In September 2016, Telefónica appointed a number of investment banks to sell the business to investors, ahead of a stock market flotation.


title: O2 (UK)

text: On 7 May 2020, it was announced that Telefónica had agreed to merge Telefonica UK with Liberty Global subsidiary Virgin Media, subject to approval, into a 50/50 joint venture. Subject to approval, the merger was slated for the middle of 2021. The merger was completed on 1 June 2021 with the newly merged company positioning itself as competition with BT.


title: O2 (UK)

text: In July 2012, O2 had to apologise to almost 8 million customers after a network switching subsystem failure led to a 24-hour blackout of the service across the UK and Ireland. The problem, which prevented a third of its customers' phones registering on the network, also affected customers of MVNO networks Tesco Mobile and Giffgaff. To apologise for this, O2 announced that it would be giving hundreds of thousands of its customers compensation for the issue. Pay monthly customers received a 10 per cent discount on their bill whereas Pay As You Go users received a 10 per cent refund on their first top up in September.


title: O2 (UK)

text: On 6 December 2018, a major disruption to the O2 network, caused by faulty software, left up to 32 million users (including those on MVNOs) without access to data services (on both 3G and 4G) for up to 24 hours. During the outage, some voice and text services suffered from congestion.


title: O2 (UK)

text: BT Cellnet launched the world's first GPRS network on 22 June 2000, although GPRS-enabled devices were uncommon at that time.


title: O2 (UK)

text: O2 publicly announced on 15 December 2009 that it had successfully demonstrated a 4G connection using LTE technology installed in six masts in Slough. The technology, which was supplied by Huawei, achieved a peak downlink rate of 150 Mbps.


title: O2 (UK)

text: In January 2012, the company announced plans to provide free internet to millions of residents and visitors in central London, by launching Europe's largest free Wi-Fi zone, along with free Wi-Fi access for anyone on any network in and around every O2 retail store.


title: O2 (UK)

text: On 20 February 2013, Ofcom announced that O2 had been awarded spectrum in the 800 MHz band for 4G LTE coverage, bidding around £550 million for the spectrum. This spectrum came with a coverage obligation from Ofcom, and O2 is obliged to provide a mobile broadband service for indoor reception to at least 98 per cent of the UK population (expected to cover at least 99 per cent when outdoors) and at least 95 per cent of the population of each of the UK nations – England, Northern Ireland, Scotland and Wales – by the end of 2017 at the latest. The 4G LTE service became available to customers in London, Leeds and Bradford on 29 August 2013, and expanded to a further ten cities by the end of the year.


title: O2 (UK)

text: On 27 March 2017, following the release of iOS 10.3, O2 launched VoLTE (4G) and WiFi Calling for iPhone 7 and iPhone 7 Plus users, and stated more devices would be eligible at a later date. The facility was later extended to other makes and models of mobile phone.


title: O2 (UK)

text: Alongside mobile telephone services, the company also provided fixed line services and home broadband.


title: O2 (UK)

text: O2 purchased Be Un Limited, an internet service provider in the UK, for £50 million in June 2006. O2 retained the Be brand, and launched a separate O2-branded broadband service on 15 October 2007, using the Be network.


title: O2 (UK)

text: O2 announced in June 2011 a fibre optic broadband service designed to compete with the BT Infinity product, using FTTC technology.


title: O2 (UK)

text: BSkyB agreed on 1 March 2013 to buy the fixed telephone line and broadband business of Telefonica UK, trading under the O2 and Be brands. The company agreed to pay £180 million initially, followed by a further £20 million after all customers had been transferred to Sky's existing business. The sale was subject to regulatory approval in April 2013, and was subsequently approved by the Office of Fair Trading on 16 May 2013.


title: O2 (UK)

text: O2 began trialling a Near Field Communication (NFC) payment system in 2007. In 2009, O2 was in discussions with large retailers, such as Tesco and W. H. Smith, for the deployment of the necessary electronic point of sale units, and with handset manufacturers, such as Apple and Samsung, to enable NFC technology on all future devices.


title: O2 (UK)

text: On 23 February 2011, O2 announced it would launch a "second phase" for O2 Money, by discontinuing its branded cash cards in favour of a "mobile wallet" application for Android and iOS devices. The application would use NFC technology embedded in a phone to access money.


title: O2 (UK)

text: The BT Cellnet consumer brand was renamed O – the chemical symbol for an oxygen molecule – as were all the group's other businesses (other than Manx Telecom). The rebranding was overseen by the Lambie-Nairn design agency, which developed the idea of the company supplying services that were essential, much the same as oxygen is essential for life. The company logo and associated graphics were designed using air bubbles to present this concept. The bubbles were photographed by London-based photographer Jonathan Knowles.


title: O2 (UK)

text: O2 adopted the slogan "See what you can do" in 2002 after the company's demerger from BT. The slogan was later changed to "It's your O2" in May 2006, on 10 April 2008 to "We’re better, connected", in 2013 to "Be more dog", in 2016 to "More for you", and finally in 2020 to “We’re better, connected”. All of O2's marketing campaigns to date have been created by London advertising agency VCCP.


title: O2 (UK)

text: O2 currently sponsor the England rugby team, and in 2003 launched a mobile video service allowing customers to download or stream video content related to the 2003 Rugby World Cup. The initial deal was signed in 1995, as Cellnet, and then renewed in 2000 as BT Cellnet. In 2005, Telefónica O2 extended their involvement in rugby union, signing a new deal with the England rugby team and the Rugby Football Union, as well as O2 rugbyclass and Premier Rugby Ltd for the English Premiership. Their latest renewal of the sponsorship was in 2016, which will run for five years until September 2021.


title: O2 (UK)

text: Additionally, Telefónica O2 had a long-standing relationship with Arsenal F.C., being their shirt sponsor until the end of the 2005/2006 season. In 2005, a three-year deal was signed that saw Telefónica O2 become the team's exclusive mobile communications partner.


title: O2 (UK)

text: O2 were the main sponsor of the Channel 4 reality TV show "Big Brother" from its second series (as BT Cellnet) in 2001 until its fourth series in 2003. They also sponsored the spin-off shows "Celebrity Big Brother 2" in 2002 and "" in 2003. In total O2 sponsored five series of the show.


title: O2 (UK)

text: O2 is the sponsor of The O2 in London. Since its launch in 2007 the Millennium Dome has been transformed and rebranded by O2 into an entertainment venue.


title: O2 (UK)

text: The O2 Arena was the site of the artistic gymnastics events and medal rounds in basketball for the 2012 Summer Olympics.


title: O2 (UK)

text: In February 2017, in a continuation of its agreement with AEG, the developers of the site, O2 announced that it had renewed its naming rights for a further ten years.


title: O2 (UK)

text: Since 2008, O2 is partnered with Live Nation and the Academy Music Group, allowing O2 to rename the music venues. The partnership allows O2 to offer customers priority access to all events at O2 Academy venues as well as Live Nation promoted events across the United Kingdom. The partnership was renewed in 2017 for a further ten years.


title: O2 (UK)

text: In February 2009, O2 became the first mobile telecommunications provider to be certified with the Carbon Trust Standard in recognition of its commitment to reduce its carbon footprint. O2 attained the standard after saving 47,000 tonnes of carbon over the previous three years through its energy efficiency measures, including a £1.4 million distribution of smart metering technology across the company's cell sites, offices and retail stores, and upgrades to more energy efficient systems across its mobile phone network. In addition to distributing energy efficient LED lighting and boiler system controls, the company was also able to reduce energy use by removing air conditioning units from some of its cell sites and reducing computer monitor standby times.


title: O2 (UK)

text: O2 is a voluntary participant in the climate change campaign, which required participants to cut their carbon emissions by 10 per cent by the end of 2010, and has since broadened its approach to include a range of projects focused on carbon reduction and renewable energy.


title: O2 (UK)

text: In July 2016 Cyber Security company Insinia raised fears that customer data from an O2 cyber breach was being sold on the dark web. O2 denied this was true telling the BBC: "We have not suffered a data breach. Credential stuffing is a challenge for businesses and can result in many company's customer data being sold on the dark net".


title: O2 (UK)

text: In October 2017, an inquiry was launched in the UK concerning overcharging customers for handset sales integrated with the data and call charges. Responding to questions, O2's CEO indicated that the company's billing allows for separation of handset charges and telephony/data charges. He added that "if we can do it, they can do it too" in reference to Vodafone and EE, O2's biggest competitors and the UK's top three mobile-telecoms companies.


title: American crow

text: The American crow (Corvus brachyrhynchos) is a large passerine bird species of the family Corvidae. It is a common bird found throughout much of North America. American crows are the New World counterpart to the carrion crow of Europe and the hooded crow of Eurasia; they all occupy the same ecological niche. Although the American crow and the hooded crow are very similar in size, structure and behavior, their calls and visual appearance are different.


title: American crow

text: From beak to tail, an American crow measures , almost half of which is tail. Mass varies from about , with males tending to be larger than females. Plumage is all black, with iridescent feathers. It looks much like other all-black corvids. They are very intelligent, and adaptable to human environments. The most usual call is "". They can be distinguished from the common raven ("C. corax") because American crows are smaller and the beak is slightly less pronounced; from the fish crow ("C. ossifragus") because American crows do not hunch and fluff their throat feathers when they call; and from the carrion crow ("C. corone") by size, as the carrion crow is larger and of a stockier build.


title: American crow

text: American crows are common, widespread, and susceptible to the West Nile virus, making them useful as a bioindicator to track the virus's spread. Direct transmission of the virus from crows to humans is impossible. They are considered an agricultural pest, and are subject to hunting and management.


title: American crow

text: The American crow was described by German ornithologist Christian Ludwig Brehm in 1822. Its scientific name means literally 'short-billed crow', from Ancient Greek ('short-') and ('billed').


title: American crow

text: A 2012 genetic analysis of the genus "Corvus" by Knud A Jønsson and colleagues using nuclear and mitochondrial DNA calculated that the American crow diverged from a lineage that gave rise to the collared, carrion and hooded crows around 5 million years ago.


title: American crow

text: "American crow" has been designated the official name by the International Ornithologists' Union (IOC).


title: American crow

text: The number of subspecies varies by authority, ranging between three and five. The unclear taxonomy of the northwestern crow, previously its own species, has complicated subspecies determinations. Subspecies differ in bill proportion and form a rough NE–SW clinal in size across North America. Birds are smallest in the far west and on the southern coast.


title: American crow

text: The American crow is a large, distinctive bird with iridescent black feathers all over. Its legs, feet and bill are also black. They measure in length, of which the tail makes up about 40%. The wing chord is , with the wingspan ranging from . The bill length can be from , varying strongly according to location. The tarsus is and the tail is . The body mass can vary from . Males tend to be larger than females.


title: American crow

text: The most usual call is a loud, short, and rapid "". Usually, the birds thrust their heads up and down as they utter this call. American crows can also produce a wide variety of sounds and sometimes mimic noises made by other animals, including other birds such as barred owls.


title: American crow

text: Visual differentiation from the fish crow ("C. ossifragus") is extremely difficult and often inaccurate. Nonetheless, differences apart from size do exist. Fish crows tend to have more slender bills and feet. There may also be a small sharp hook at the end of the fish crow's upper bill. Fish crows also appear as if they have shorter legs when walking. More dramatically, when calling, fish crows tend to hunch and fluff their throat feathers.


title: American crow

text: If seen flying at a distance from where size estimates are unreliable, the distinctly larger common ravens ("C. corax") can be distinguished by their almost lozenge-shaped tail and their larger-looking heads. They also fluff their throat feathers when calling — like fish crows, only more so. Ravens also soar for extended periods, unlike crows, which rarely fly more than a few seconds without flapping their wings.


title: American crow

text: Crows have been noted to be intelligent. They have the same brain-weight-to-body ratio as humans. This has led to some studies that have identified that crows are self-aware and that young crows take time to learn from tolerant parents. While a human has a neocortex, the crow has a different area in their brain that is equally complex.


title: American crow

text: The average lifespan of the American crow in the wild is 7–8 years. Captive birds are known to have lived up to 30 years.


title: American crow

text: The range of the American crow now extends from the Pacific Ocean to the Atlantic Ocean in Canada, on the French islands of Saint-Pierre and Miquelon, south through the United States, and into northern Mexico. The increase in trees throughout the Great Plains during the past century due to fire suppression and tree planting facilitated range expansions of the American crow as well as range expansions of many other species of birds. Virtually all types of country from wilderness, farmland, parks, open woodland to towns and major cities are inhabited; it is absent only from tundra habitat, where it is replaced by the common raven. This crow is a permanent resident in most of the US, but most Canadian birds migrate some distances southward in winter. Outside of the nesting season these birds often gather in large (thousands or even millions) communal roosts at night.


title: American crow

text: Studying the behavior of American crows is laborious due to the difficulty in catching them to band them, let alone catching them again. Thus much of their behavior, including daily routine, migration, molting, survivorship, age of first breeding, nestling development, nature of nesting helpers, and more remains poorly studied.


title: American crow

text: The American crow is omnivorous. It will feed on invertebrates of all types, carrion, scraps of human food, fruits, nuts such as walnuts and almonds, seeds, eggs and nestlings, stranded fish on the shore and various grains. American crows are active hunters and will prey on mice, young rabbits, frogs, and other small animals. In the winter and autumn, the diet of American crows is more dependent on nuts and acorns. Occasionally, they will visit bird feeders. The American crow is one of only a few species of bird that has been observed modifying and using tools to obtain food.


title: American crow

text: Like most crows, they will scavenge at landfills, scattering garbage in the process. Where available, corn, wheat and other crops are a favorite food. These habits have historically caused the American crow to be considered a nuisance. However, it is suspected that the harm to crops is offset by the service the American crow provides by eating insect pests.


title: American crow

text: American crows are socially monogamous cooperative breeding birds. Mated pairs form large families of up to 15 individuals from several breeding seasons that remain together for many years. Offspring from a previous nesting season will usually remain with the family to assist in rearing new nestlings. American crows do not reach breeding age for at least two years. Most do not leave the nest to breed for four to five years.


title: American crow

text: The nesting season starts early, with some birds incubating eggs by early April. American crows build bulky stick nests, nearly always in trees but sometimes also in large bushes and, very rarely, on the ground. They will nest in a wide variety of trees, including large conifers, although oaks are most often used. Three to six eggs are laid and incubated for 18 days. The young are usually fledged by about 36 days after hatching. Predation primarily occurs at the nest site and eggs and nestlings are frequently eaten by snakes, raccoons, ravens and domestic cats. Adults are less frequently predated, but face potential attack from great horned owls, red-tailed hawks, peregrine falcons and eagles. They may be attacked by predators such as coyotes or bobcats at carrion when incautious, although this is even rarer.


title: American crow

text: American crows succumb easily to West Nile virus infection. This was originally a mosquito-borne African virus causing encephalitis in humans and livestock since about 1000 AD, and was accidentally introduced to North America in 1999, apparently by an infected air traveller who got bitten by a mosquito after arrival. It is estimated that the American crow population has dropped by up to 45% since 1999. Despite this decline, the crow is considered a species of least concern.


title: American crow

text: The disease runs most rampant in the subtropical conditions which encourage reproduction of its mosquito vectors among which "Culex tarsalis" is most significant. Mortality rates appear to be higher than those in other birds, causing local population losses of up to 72% in a single season. Because of this, American crows are a sentinel species indicating the presence of West Nile virus in an area. Crows cannot transmit the virus to humans directly.


title: American crow

text: American crows, like other corvids, are highly cunning and inquisitive. They are able to steal food from other species, often in creative ways. One example shows a group of crows stealing a fish from a Northern river otter: one bird pecked the otter's tail to distract it while other birds swooped in and stole the fish. They are able to use and modify tools.


title: American crow

text: Crows are a motif in human culture, often associated with death, thieves, graveyards, bad luck, and other negative connotations.


title: American crow

text: The intelligence and adaptability of the American crow has insulated it from threats, and it is instead considered an agricultural pest. In 2012, BirdLife International estimated the American crow population to be around 31 million. The large population and vast range result in the least concern status for the American crow, meaning that the species is not threatened with extinction.


title: American crow

text: Crows have been killed in large numbers by humans, both for recreation and as part of organized campaigns of extermination. In Canada, American crows have no protections, aside from Quebec which bans their hunting during the nesting season. Laws on their hunting vary throughout the United States. New Jersey allows for a limited hunting season, unless if they are agricultural pests in which case they may be killed. Oklahoma allows hunting even during the nesting season. In the first half of the 20th century, state sponsored campaigns dynamited roosting areas, taking large numbers of crows. A campaign in Oklahoma from 1934 to 1945 dynamited 3.8 million birds. The effect on populations was negligible and damage to agricultural crops did not decrease, and thus the campaign was halted as ineffective. In a study taking data from 1917 to 1999, intentional killings were the overwhelming cause of death for crows, accounting for 68% of all recovered bird bands.


title: American crow

text: Non-deadly methods of managing crows are varied but usually limited in their effectiveness. High value crops may be netted, but this is cost prohibitive for most other crops. Frightening may be used to disperse crows, including loud noises from guns, fake hawks flown from balloons, fake owls that move with the wind, strips of reflective tape on fences, or recordings of crow distress calls. Poisoned baits are of limited effectiveness, as only the most toxic baits work, and those are generally unacceptable for use. Crows quickly learn to avoid the less-toxic baits, as the baits make crows sick. The actual effect of crows on agriculture has been poorly studied. There is some suggestion that they may be a benefit to farmers, by eating insect pests and chasing off livestock predators like hawks.


title: Oxymetazoline

text: Oxymetazoline, sold under the brand name Afrin among others, is a topical decongestant and vasoconstrictor medication. It is available over-the-counter as a nasal spray to treat nasal congestion and nosebleeds, as eyedrops to treat eye redness due to minor irritation, and (in the United States) as a prescription topical cream to treat persistent facial redness due to rosacea in adults. Its effects begin within minutes and last for up to 6 hours. Intranasal use for longer than three days may cause congestion to recur or worsen, resulting in physical dependence.


title: Oxymetazoline

text: Oxymetazoline is a derivative of imidazole. It was developed from xylometazoline at E. Merck Darmstadt by Wolfgang Fruhstorfer and Helmut Müller-Calgan in 1961. A direct sympathomimetic, oxymetazoline binds to and activates α adrenergic receptors and α adrenergic receptors, most notably. One study classified it in the following order: α(2A) > α(1A) ≥ α(2B) > α(1D) ≥ α(2C) » α(1B), but this is not universally agreed upon. There is little consistency across the (relatively large) number of in-vitro studies with respect to binding affinity/selectivity.


title: Oxymetazoline

text: Oxymetazoline is available over-the-counter as a topical decongestant in the form of oxymetazoline hydrochloride in nasal sprays such as Otrivin, Afrin, Operil, Dristan, Dimetapp, Oxyspray, Facimin, Nasivin, Nostrilla, Utabon, Sudafed OM, Vicks Sinex, Zicam, SinuFrin, Drixoral


title: Oxymetazoline

text: In the United States, oxymetazoline 1% cream is approved by the Food and Drug Administration for topical treatment of persistent facial erythema (redness) associated with rosacea in adults.


title: Oxymetazoline

text: Due to its vasoconstricting properties, oxymetazoline is also used to treat nose bleeds and eye redness due to minor irritation (marketed as Visine L.R. in the form of eye drops).


title: Oxymetazoline

text: In July 2020, oxymetazoline received approval by the FDA for the treatment of acquired drooping eyelid.


title: Oxymetazoline

text: Rebound congestion, or rhinitis medicamentosa, may occur. A 2006 review of the pathology of rhinitis medicamentosa concluded that use of oxymetazoline for more than three days may result in rhinitis medicamentosa and recommended limiting use to three days.


title: Oxymetazoline

text: In a submission to the Therapeutic Goods Administration, a Novartis representative concluded, "The justification was not based on evidence." Citing an existing extensive body of evidence and noting a range of recommended periods from five to ten days, Novartis recommended the established five day period for its use for self-medication without medical consultation as it coincides with the typical duration of the common cold.


title: Oxymetazoline

text: The Food and Drug Administration places oxymetazoline in category C, indicating risk to the fetus cannot be ruled out. While it has been shown that a single dose does not significantly alter either maternal or fetal circulation, this subject has not been studied extensively enough to draw reliable conclusions.


title: Oxymetazoline

text: If accidentally ingested, standard methods to remove unabsorbed drugs should be considered. There is no specific antidote for oxymetazoline, although its pharmacological effects may be reversed by an adrenergic antagonists such as phentolamine. In the event of a possibly life-threatening overdose (such as a hypertensive crisis), benzodiazepines should be considered to decrease the likelihood of seizures and convulsions, as well as reduce anxiety and to lower blood pressure. In children, oxymetazoline may produce profound central nervous system depression due to stimulation of central α receptors and imidazoline receptors, much like clonidine.


title: Oxymetazoline

text: Oxymetazoline is a sympathomimetic that selectively agonizes α and, partially, α adrenergic receptors. Since vascular beds widely express α receptors, the action of oxymetazoline results in vasoconstriction. In addition, the local application of the drug also results in vasoconstriction due to its action on endothelial postsynaptic α receptors; systemic application of α agonists, in contrast, causes vasodilation because of centrally-mediated inhibition of sympathetic tone via presynaptic α receptors. Vasoconstriction of vessels results in relief of nasal congestion in two ways: first, it increases the diameter of the airway lumen; second, it reduces fluid exudation from postcapillary venules. It can reduce nasal airway resistance (NAR) up to 35.7% and reduce nasal mucosal blood flow up to 50%.


title: Oxymetazoline

text: Since imidazolines are sympathomimetic agents, their primary effects appear on α adrenergic receptors, with little if any effect on β adrenergic receptors. Like other imidazolines, Oxymetazoline is readily absorbed orally. Effects on α receptors from systemically absorbed oxymetazoline hydrochloride may persist for up to 7 hours after a single dose. The elimination half-life in humans is 5–8 hours. It is excreted unchanged both by the kidneys (30%) and in feces (10%).


title: Oxymetazoline

text: The oxymetazoline brand Afrin was first sold as a prescription medication in 1966. After finding substantial early success as a prescription medication, it became available as an over-the-counter drug in 1975. Schering-Plough did not engage in heavy advertising until 1986.


title: Oxymetazoline

text: From the mid-1980s to mid-1990s, the brand Sinex was featured in many television advertisements. Some of these commercials showed men, women, and children using other brands of nasal sprays, and then standing upside down on a sidewalk, or against a wall, etc. or hanging upside down from various playground equipment to prevent their nasal spray from dripping out. This was juxtaposed with Sinex users not having to hang upside side down or stand on their heads as it didn't drip out.


title: Oxymetazoline

text: Brand names include Afrin, Dristan, Drixine, Drixoral, Nasivin, Nasivion, Nezeril, Nostrilla, Logicin, Vicks Sinex, Visine L.R., Sudafed OM, Zicam, Otrivin Oxy, SinuFrin, Upneeq, and Mucinex Sinus-Max.


title: Juice Wrld discography

text: American rapper and singer Juice Wrld released four studio albums, nine extended plays, two mixtapes, 35 singles (including four as featured artist), and one promotional single, including posthumous releases. He released his first mixtape and EP, under the pseudonym JuiceTheKidd in early 2015 and 2016. Throughout 2017, he released several EPs independently.


title: Juice Wrld discography

text: Following his signing to Grade A, a subsidiary of Interscope, Juice Wrld released his debut album "Goodbye & Good Riddance" in May 2018. The album debuted at 15 and peaked at 4 on the "Billboard" 200. On December 5, 2018, the album was certified platinum by the Recording Industry Association of America (RIAA). It spawned five singles, including his debut single "All Girls Are the Same", certified sextuple platinum and his breakthrough hit "Lucid Dreams", which peaked at No. 2 on the "Billboard" Hot 100 and is certified diamond by the RIAA. In June 2018, Juice Wrld released a tribute EP, "Too Soon..", in honor of rappers Lil Peep and XXXTentacion. The EP produced the singles "Rich and Blind" and "Legends", which were respectively certified gold and platinum by the RIAA. Juice Wrld released a collaborative mixtape alongside Future, titled "Wrld on Drugs" in October 2018. It debuted at No. 2 on the "Billboard" 200, selling 98,000 album-equivalent units, which included 8,000 pure album sales. Furthermore, it peaked in the top twenty in Denmark, Sweden, Netherlands, Norway and peaked at No. 5 in Canada. The mixtape was supported through the single "Fine China", which peaked at No. 26 on the "Billboard" Hot 100 and is certified 2× platinum by the RIAA.


title: Juice Wrld discography

text: Juice Wrld's second studio album "Death Race for Love," was released in March 2019. Led by the singles "Robbery" and "Hear Me Calling", it debuted at number one on the "Billboard" 200 with 165,000 album-equivalent units. "Bandit" with YoungBoy Never Broke Again was Juice Wrld's final release before his death.


title: Juice Wrld discography

text: On April 23, 2020, Higgins' estate announced on his Instagram account that his first posthumous single, "Righteous", would be released later that night. "Righteous" was released at midnight on April 24, 2020, and an accompanying music video with footage of Higgins was uploaded to his YouTube channel. Higgins recorded the song at his home studio in Los Angeles. On May 29, the song "Tell Me U Luv Me" featuring Trippie Redd was released alongside a music video directed by Cole Bennett. These songs are included on his first posthumous album, titled "Legends Never Die".


title: Juice Wrld discography

text: On July 6, Higgins' estate publicly announced the late rapper's first posthumous album "Legends Never Die". On the same day, Higgins' estate also released "Life's a Mess" featuring Halsey and "Come & Go" a few days later on July 9 featuring Marshmello. The album was released on July 10, 2020, with 21 songs and 5 singles that Higgins' estate claims "best represents the music Juice was in the process of creating". The album debuted at number one on the "Billboard" 200 with 497,000 album-equivalent units. Five of the songs reached the top 10 of the "Billboard" Hot 100 on the week ending July 25, 2020: "Come & Go", "Wishing Well", "Conversations", "Life's a Mess", and "Hate the Other Side", which reached number two, five, seven, nine, and ten, respectively. Higgins is the third artist to ever accomplish this feat, the other two being The Beatles and Drake. "Life's a Mess" notably jumped from number 74 to number nine that week.


title: Hang Seng Index

text: The Hang Seng Index (HSI) is a freefloat-adjusted market-capitalization-weighted stock-market index in Hong Kong. It is used to record and monitor daily changes of the largest companies of the Hong Kong stock market and is the main indicator of the overall market performance in Hong Kong. These 66 constituent companies represent about 58% of the capitalisation of the Hong Kong Stock Exchange.


title: Hang Seng Index

text: HSI was started on November 24, 1969, and is currently compiled and maintained by Hang Seng Indexes Company Limited, which is a wholly owned subsidiary of Hang Seng Bank, one of the largest banks registered and listed in Hong Kong in terms of market capitalisation. It is responsible for compiling, publishing and managing the Hang Seng Index and a range of other stock indexes, such as "Hang Seng China Enterprises Index", "Hang Seng China AH Index Series", "Hang Seng China H-Financials Index", "Hang Seng Composite Index Series", "Hang Seng China A Industry Top Index", "Hang Seng Corporate Sustainability Index Series" and "Hang Seng Total Return Index Series". Hang Seng in turn, despite being a public company, is controlled by another listed international financial institution HSBC Holdings plc. Both HSBC Holdings and Hang Seng are constituents of the index.


title: Hang Seng Index

text: Ho Sin Hang, chairman of the Hang Seng Bank, conceived the idea of creating the Hang Seng Index as a "Dow Jones Index for Hong Kong". Along with Hang Seng Director Lee Quo-wei, he commissioned Hang Seng's head of Research Stanley Kwan to create the index, which debuted on November 24, 1969.


title: Hang Seng Index

text: When the Hang Seng Index was first published, its base of 100 points was set equivalent to the stocks' total value as of the market close on July 31, 1964. Its all-time low is 58.61 points, reached retroactively on August 31, 1967, after the base value was established but before the publication of the index. The Hang Seng passed the 10,000 point milestone for the first time in its history on December 10, 1993 and, 13 years later, passed the 20,000 point milestone on December 28, 2006. In less than 10 months, it passed the 30,000 point milestone on October 18, 2007. Its all-time high, set on January 26, 2018, was 33,223.58 points at closing. From October 30, 2007 through March 9, 2008, the index lost 9,426 points or approximately 30%. On September 5, it fell past the 20,000 mark the first time in almost a year to a low of 19,708.39, later closing at 19,933.28. On October 8, 2008, the index closed at 15,431.73, over 50% less than the all-time high and the lowest closing value in over two years. On October 27, 2008, the index further fell to 10,676.29 points, having fallen nearly two-thirds from its all-time peak, but passed the 20,000 point milestone again to 20,063.93 on 24 July 2009. The index reached 25,000.00 on August 19, 2014, reaching as high as 25,201.21 that day, later closing at 24,909.26 points. It continued rising to hit 26,000 on April 8, 2015 with a close of 26,236.86 The following day, it rose to as much as 27,922.67 before closing at 26,944.39. Yet again, another milestone was reached on April 13, 2015 rising to over 28,000 points, or closing to 28,016.34, the highest since December 2007. On July 8, 2015, the index fell as much as 2139 points. On 21 August the index entered a bear market.


title: Hang Seng Index

text: The index at that point hovered around 18000-19000 points, until it ended in February 2016. In 24 June 2016, the market fell 1,000 points in response to UK EU referendum results that "Leave" won the vote against "Remain". Then, the markets continuously fell on 27 and 28 June 2016 before recovered slightly on 29 June 2016.


title: Hang Seng Index

text: The Hang Seng Index is traded as a future on the Hong Kong Futures Exchange (HKFE). The full contract specifications are below:


title: Hang Seng Index

text: The following table shows the annual development of the Hang Seng Index, which was calculated back to 1965.


title: Hang Seng Index

text: On January 2, 1985, four sub-indices were established in order to make the index clearer and to classify constituent stocks into four distinct sectors. There are 73 HSI constituent stocks in total. As of October 8, 2022 they are:


title: Hang Seng Index

text: The Hang Seng Composite Index Series (恒生綜合指數) was launched on October 3, 2001, targeting on providing a broad standard of the performance of the Hong Kong stock market. It was last revamped on March 8, 2010, and comprises 307 constituents (will become 306 from August 9, 2010). The market capitalisation of these companies accounts for about 95% of the total capitalisation of the stocks in Hong Kong.


title: Hang Seng Index

text: To ensure the impartiality of its operation, Hang Seng Indexes Company Limited established an Independent Advisory Committee to give advice on issues pertaining to the indexes, including constituent changes and the development of new indexes.


title: Hang Seng Index

text: Hang Seng Industry Classification System (formerly called Hang Seng Stock Classification System) is a comprehensive system designed for the Hong Kong stock market by Hang Seng Indexes Company Limited. It reflects the stock performance in different sectors. It caters for the unique characteristics of the Hong Kong stock market and maintains the international compatibility with a mapping to international industry classification


title: Hang Seng Index

text: i) The sales revenue arising from each business area of a company is the primary parameter of stock classification. Profit or assets will also be taken into consideration where these better reflects the company's business.


title: Hang Seng Index

text: ii) A company will be classified into different sectors according to its majority source of sales revenue(or profit or assets if relevant).


title: Hang Seng Index

text: iii) Re-classification of a stock's Industry Sector will occur once the company's business has undergone a major change, such as, substantial merger or acquisition.


title: Hang Seng Index

text: The classification of each stock is based on the information available to the public, for example the annual reports and company announcements.


title: Hang Seng Index

text: HSI constituent stocks are selected with the use of extensive analysis, together with external consultation. To be qualified for selection, a company:


title: Hang Seng Index

text: "For a newly listed large-cap stock, the minimum listing time required for inclusion in the stock universe for the HSI review is as follows:"


title: Hang Seng Index

text: The representativeness of the HSI can be studied by the turnover of the whole stock market and by how much its market capitalisation covers. The aggregate market value of the HSI constituent stocks is maintained at approximately 60% of the total market value. This coverage ratio compares favorably with major overseas stock indices.


title: Eddie Fisher

text: Edwin Jack Fisher (August 10, 1928 – September 22, 2010) was an American singer and actor. He was one of the most popular artists during the 1950s, selling millions of records and hosting his own TV show, "The Eddie Fisher Show". Actress Elizabeth Taylor was best friends with Fisher's first wife, actress Debbie Reynolds. After Taylor's third husband, Mike Todd, was killed in a plane crash, Fisher divorced Reynolds and he and Taylor married that same year. The scandalous affair that Fisher and Taylor had been having while each were already married was widely reported and brought unfavorable publicity to both Fisher and Taylor. Approximately five years later, he and Taylor divorced and he later married Connie Stevens. Fisher is the father of Carrie Fisher and Todd Fisher, whose mother is Reynolds, and the father of Joely Fisher and Tricia Leigh Fisher, whose mother is Stevens.


title: Eddie Fisher

text: Fisher was born in Philadelphia on August 10, 1928, the fourth of seven children born to Gitte Kathrine "Kate" Tisch (née Minicker, later Stup; b. 1901; d. 1991) and Joseph Fisher (né Tisch; 1900–1972), both Jewish immigrants from the Russian Empire. His father's surname was originally Tisch, but was changed to Fisher by the time of the 1940 census. To his family, Fisher was always called "Sonny Boy", a nickname derived from the song of the same name in Al Jolson's film "The Singing Fool" (1928). His siblings were Sidney, Nettie, Miriam, Janet, Alvin, and Eileen. Kate and Joseph divorced when Fisher was an adult, after 33 years of marriage, and Kate married Max Stup.


title: Eddie Fisher

text: Fisher attended Thomas Junior High School, South Philadelphia High School, and Simon Gratz High School. It was known at an early age that he had talent as a vocalist, and he started singing in numerous amateur contests, which he usually won. He made his radio debut on WFIL, a local Philadelphia radio station. He also performed on "Arthur Godfrey's Talent Scouts", a popular radio show that later moved to television. Because he became a local star, Fisher dropped out of high school in the middle of his senior year to pursue his career.


title: Eddie Fisher

text: By 1946, Fisher was crooning with the bands of Buddy Morrow and Charlie Ventura. He was heard in 1949 by Eddie Cantor at Grossinger's Catskill Resort Hotel in the Borscht Belt. Cantor's so-called discovery of Fisher was later described as a totally contrived, "manipulated' arrangement by Milton Blackstone, Grossinger's publicity director. After performing on Cantor's radio show he was an instant hit and gained nationwide exposure. He then signed a recording contract with RCA Victor.


title: Eddie Fisher

text: Fisher was drafted into the U.S. Army in 1951, sent to Fort Hood, Texas, for basic training, and served a year in Korea. From 1952 to 1953, he was the official vocal soloist for The United States Army Band (Pershing's Own) and a tenor section member in the United States Army Band Chorus (an element of Pershing's Own) assigned at Fort Myer in the Washington, D.C. Military District. During his active duty period, he also made occasional guest television appearances, in uniform, introduced as "PFC Eddie Fisher". After his discharge, he began to sing in top nightclubs and had a variety television series, "Coke Time with Eddie Fisher" on NBC (1953–1957). Fisher also appeared on "The Perry Como Show", "Club Oasis", "The Martha Raye Show", "The Gisele MacKenzie Show", "The Chesterfield Supper Club" and "The George Gobel Show", and starred in another series, "The Eddie Fisher Show" (NBC) (1957–1959, alternating with Gobel's series).


title: Eddie Fisher

text: Fisher's good looks and strong and melodious tenor voice made him a teen idol and one of the most popular singers of the early 1950s. He had 17 songs in the Top 10 on the music charts between 1950 and 1956 and 35 in the Top 40. In 1957 he signed a then record $1 million deal with the newly opened Tropicana Las Vegas to appear there a minimum of 4 weeks a year for 5 years.


title: Eddie Fisher

text: In 1956, Fisher costarred with then-wife Debbie Reynolds in the musical comedy "Bundle of Joy". He played a dramatic role in the 1960 drama "Butterfield 8" with second wife Elizabeth Taylor. His best friend was showman and producer Mike Todd, who died in a plane crash in 1958. Fisher's affair, divorce from Reynolds, and subsequent marriage to Taylor, Todd's widow, caused a show business scandal. Due to the unfavorable publicity surrounding the affair and divorce, NBC canceled Fisher's television series in March 1959.


title: Eddie Fisher

text: Beginning in fall 1959, he established two scholarships at Brandeis University, one for classical and one for popular music, in the name of Eddie Cantor.


title: Eddie Fisher

text: In 1960, RCA Victor dropped him and he briefly recorded on his own label, Ramrod Records. He later recorded for Dot Records. During this time, he had the first commercial recording of "Sunrise, Sunset" from "Fiddler on the Roof". This technically counts as the biggest standard Fisher can claim credit for introducing, although it is rarely associated with him. He also recorded the albums "Eddie Fisher Today" and "Young and Foolish" (both 1965). The Dot contract was not successful in record sales terms, and he returned to RCA Victor and had a minor single hit in 1966 with the song "Games That Lovers Play" with Nelson Riddle, which became the title of his best selling album. When Fisher was at the height of his popularity, in the mid-1950s, singles, rather than albums, were the primary medium for issuing recordings. His last album for RCA Victor was an Al Jolson tribute, "You Ain't Heard Nothin' Yet", released in 1968. In 1983 he attempted a comeback tour but this was not a success. Eddie Fisher's last released album was recorded around 1984 on the Bainbridge record label. Fisher tried to stop the album from being released, but it turned up as "After All". The album was produced by William J. O'Malley and arranged by Angelo DiPippo. DiPippo, a world-renowned arranger, worked with Eddie countless hours to better his vocals but it became useless. His final recordings (never released) were made in 1995 with the London Philharmonic Orchestra. According to arranger-conductor Vincent Falcone in his 2005 autobiography, "Frankly: Just Between Us", these tracks were "the best singing of his life". Fisher performed in top concert halls all over the United States and headlined in major Las Vegas showrooms. He headlined at the Palace Theater in New York City as well as London's Palladium. In the culmination of his return to the concert stage in 1962, Fisher headlined a five-week Broadway show at Winter Garden, calling it a dream of his since youth to perform in the venue Al Jolson had made famous.


title: Eddie Fisher

text: Fisher created interest as a pop culture icon. Betty Johnson's "I Want Eddie Fisher For Christmas", containing references to a number of hit songs, reached No. 28 in the Music Vendor national survey during an 11-week chart run in late 1954.


title: Eddie Fisher

text: Fisher has two stars on the Hollywood Walk of Fame, one for recording, at 6241 Hollywood Boulevard, and one for television, at 1724 Vine Street.


title: Eddie Fisher

text: In 1981, Fisher wrote an autobiography, "Eddie: My Life, My Loves" (). He wrote another autobiography in 1999 titled "Been There, Done That" (). The latter book devotes little space to Fisher's singing career, but recycled the material of his first book and added many new sexual details that were too strong to publish before. Upon the book's publication, his daughter Carrie declared: "I'm thinking of having my DNA fumigated."


title: Eddie Fisher

text: While performing at The Tropicana Hotel in 1957, Fisher had numerous affairs with women which contributed to his turbulent marriage to Debbie Reynolds. One of his notable affairs was with model Pat Sheehan. They eventually parted ways after Fisher refused to divorce Reynolds. He would divorce Reynolds two years later and marry Elizabeth Taylor.


title: Eddie Fisher

text: When she was interviewed, Debbie Reynolds said that she could understand being dumped "for the world's most beautiful woman", referring to Taylor, who was previously a close friend. Taylor and Reynolds later resumed their friendship and mocked Fisher in a TV movie written by Carrie Fisher, "These Old Broads", in which their characters ridiculed the ex-husband they shared, named "Freddie Hunter".


title: Eddie Fisher

text: In his memoirs, Fisher admitted to addictions to drugs and gambling, which aggravated his career problems.


title: Eddie Fisher

text: Fisher suffered from knee, back, hearing, and eyesight problems in his later years, the last of which were worsened by complications stemming from cataract removal surgery, and he rarely appeared in public. According to friends, he remained mentally vigorous and kept himself busy watching television, following news and politics, and singing his old songs while friend George Michalski played the piano. Michalski had worked on several occasions over the years to help Fisher get his name back on the music charts. He said "The '60s passed Eddie by; he missed that entire era of music. I'd play a Beatles song like "Something" for him and he'd think I wrote it."


title: Eddie Fisher

text: Fisher fell and broke his hip on September 9, 2010, and died 13 days later on September 22, 2010, at his home in Berkeley, California, from complications from hip surgery, at the age of 82. His ashes were interred at Cypress Lawn Memorial Park next to his wife Betty Lin who died in 2001.


title: Hamming code

text: In computer science and telecommunication, Hamming codes are a family of linear error-correcting codes. Hamming codes can detect one-bit and two-bit errors, or correct one-bit errors without detection of uncorrected errors. By contrast, the simple parity code cannot correct errors, and can detect only an odd number of bits in error. Hamming codes are perfect codes, that is, they achieve the highest possible rate for codes with their block length and minimum distance of three.


title: Hamming code

text: Richard W. Hamming invented Hamming codes in 1950 as a way of automatically correcting errors introduced by punched card readers. In his original paper, Hamming elaborated his general idea, but specifically focused on the Hamming(7,4) code which adds three parity bits to four bits of data.


title: Hamming code

text: In mathematical terms, Hamming codes are a class of binary linear code. For each integer there is a code-word with block length and message length . Hence the rate of Hamming codes is , which is the highest possible for codes with minimum distance of three (i.e., the minimal number of bit changes needed to go from any code word to any other code word is three) and block length . The parity-check matrix of a Hamming code is constructed by listing all columns of length that are non-zero, which means that the dual code of the Hamming code is the shortened Hadamard code. The parity-check matrix has the property that any two columns are pairwise linearly independent.


title: Hamming code

text: Due to the limited redundancy that Hamming codes add to the data, they can only detect and correct errors when the error rate is low. This is the case in computer memory (usually RAM), where bit errors are extremely rare and Hamming codes are widely used, and a RAM with this correction system is a ECC RAM (ECC memory). In this context, an extended Hamming code having one extra parity bit is often used. Extended Hamming codes achieve a Hamming distance of four, which allows the decoder to distinguish between when at most one one-bit error occurs and when any two-bit errors occur. In this sense, extended Hamming codes are single-error correcting and double-error detecting, abbreviated as SECDED.


title: Hamming code

text: Richard Hamming, the inventor of Hamming codes, worked at Bell Labs in the late 1940s on the Bell Model V computer, an electromechanical relay-based machine with cycle times in seconds. Input was fed in on punched paper tape, seven-eighths of an inch wide, which had up to six holes per row. During weekdays, when errors in the relays were detected, the machine would stop and flash lights so that the operators could correct the problem. During after-hours periods and on weekends, when there were no operators, the machine simply moved on to the next job.


title: Hamming code

text: Hamming worked on weekends, and grew increasingly frustrated with having to restart his programs from scratch due to detected errors. In a taped interview, Hamming said, "And so I said, 'Damn it, if the machine can detect an error, why can't it locate the position of the error and correct it?'". Over the next few years, he worked on the problem of error-correction, developing an increasingly powerful array of algorithms. In 1950, he published what is now known as Hamming code, which remains in use today in applications such as ECC memory.


title: Hamming code

text: A number of simple error-detecting codes were used before Hamming codes, but none were as effective as Hamming codes in the same overhead of space.


title: Hamming code

text: Parity adds a single bit that indicates whether the number of ones (bit-positions with values of one) in the preceding data was even or odd. If an odd number of bits is changed in transmission, the message will change parity and the error can be detected at this point; however, the bit that changed may have been the parity bit itself. The most common convention is that a parity value of one indicates that there is an odd number of ones in the data, and a parity value of zero indicates that there is an even number of ones. If the number of bits changed is even, the check bit will be valid and the error will not be detected.


title: Hamming code

text: Moreover, parity does not indicate which bit contained the error, even when it can detect it. The data must be discarded entirely and re-transmitted from scratch. On a noisy transmission medium, a successful transmission could take a long time or may never occur. However, while the quality of parity checking is poor, since it uses only a single bit, this method results in the least overhead.


title: Hamming code

text: A two-out-of-five code is an encoding scheme which uses five bits consisting of exactly three 0s and two 1s. This provides ten possible combinations, enough to represent the digits 0–9. This scheme can detect all single bit-errors, all odd numbered bit-errors and some even numbered bit-errors (for example the flipping of both 1-bits). However it still cannot correct any of these errors.


title: Hamming code

text: Another code in use at the time repeated every data bit multiple times in order to ensure that it was sent correctly. For instance, if the data bit to be sent is a 1, an "repetition code" will send 111. If the three bits received are not identical, an error occurred during transmission. If the channel is clean enough, most of the time only one bit will change in each triple. Therefore, 001, 010, and 100 each correspond to a 0 bit, while 110, 101, and 011 correspond to a 1 bit, with the greater quantity of digits that are the same ('0' or a '1') indicating what the data bit should be. A code with this ability to reconstruct the original message in the presence of errors is known as an "error-correcting" code. This triple repetition code is a Hamming code with since there are two parity bits, and data bit.


title: Hamming code

text: Such codes cannot correctly repair all errors, however. In our example, if the channel flips two bits and the receiver gets 001, the system will detect the error, but conclude that the original bit is 0, which is incorrect. If we increase the size of the bit string to four, we can detect all two-bit errors but cannot correct them (the quantity of parity bits is even); at five bits, we can both detect and correct all two-bit errors, but not all three-bit errors.


title: Hamming code

text: Moreover, increasing the size of the parity bit string is inefficient, reducing throughput by three times in our original case, and the efficiency drops drastically as we increase the number of times each bit is duplicated in order to detect and correct more errors.


title: Hamming code

text: If more error-correcting bits are included with a message, and if those bits can be arranged such that different incorrect bits produce different error results, then bad bits could be identified. In a seven-bit message, there are seven possible single bit errors, so three error control bits could potentially specify not only that an error occurred but also which bit caused the error.


title: Hamming code

text: Hamming studied the existing coding schemes, including two-of-five, and generalized their concepts. To start with, he developed a nomenclature to describe the system, including the number of data bits and error-correction bits in a block. For instance, parity includes a single bit for any data word, so assuming ASCII words with seven bits, Hamming described this as an "(8,7)" code, with eight bits in total, of which seven are data. The repetition example would be "(3,1)", following the same logic. The code rate is the second number divided by the first, for our repetition example, 1/3.


title: Hamming code

text: Hamming also noticed the problems with flipping two or more bits, and described this as the "distance" (it is now called the "Hamming distance", after him). Parity has a distance of 2, so one bit flip can be detected but not corrected, and any two bit flips will be invisible. The (3,1) repetition has a distance of 3, as three bits need to be flipped in the same triple to obtain another code word with no visible errors. It can correct one-bit errors or it can detect - but not correct - two-bit errors. A (4,1) repetition (each bit is repeated four times) has a distance of 4, so flipping three bits can be detected, but not corrected. When three bits flip in the same group there can be situations where attempting to correct will produce the wrong code word. In general, a code with distance "k" can detect but not correct errors.


title: Hamming code

text: Hamming was interested in two problems at once: increasing the distance as much as possible, while at the same time increasing the code rate as much as possible. During the 1940s he developed several encoding schemes that were dramatic improvements on existing codes. The key to all of his systems was to have the parity bits overlap, such that they managed to check each other as well as the data.


title: Hamming code

text: The following general algorithm generates a single-error correcting (SEC) code for any number of bits. The main idea is to choose the error-correcting bits such that the index-XOR (the XOR of all the bit positions containing a 1) is 0. We use positions 1, 10, 100, etc. (in binary) as the error-correcting bits, which guarantees it is possible to set the error-correcting bits so that the index-XOR of the whole message is 0. If the receiver receives a string with index-XOR 0, they can conclude there were no corruptions, and otherwise, the index-XOR indicates the index of the corrupted bit.


title: Hamming code

text: If a byte of data to be encoded is 10011010, then the data word (using _ to represent the parity bits) would be __1_001_1010, and the code word is 011100101010.


title: Hamming code

text: The choice of the parity, even or odd, is irrelevant but the same choice must be used for both encoding and decoding.


title: Hamming code

text: Shown are only 20 encoded bits (5 parity, 15 data) but the pattern continues indefinitely. The key thing about Hamming Codes that can be seen from visual inspection is that any given bit is included in a unique set of parity bits. To check for errors, check all of the parity bits. The pattern of errors, called the error syndrome, identifies the bit in error. If all parity bits are correct, there is no error. Otherwise, the sum of the positions of the erroneous parity bits identifies the erroneous bit. For example, if the parity bits in positions 1, 2 and 8 indicate an error, then bit 1+2+8=11 is in error. If only one parity bit indicates an error, the parity bit itself is in error.


title: Hamming code

text: With parity bits, bits from 1 up to formula_1 can be covered. After discounting the parity bits, formula_2 bits remain for use as data. As varies, we get all the possible Hamming codes:


title: Hamming code

text: Hamming codes have a minimum distance of 3, which means that the decoder can detect and correct a single error, but it cannot distinguish a double bit error of some codeword from a single bit error of a different codeword. Thus, some double-bit errors will be incorrectly decoded as if they were single bit errors and therefore go undetected, unless no correction is attempted.


title: Hamming code

text: To remedy this shortcoming, Hamming codes can be extended by an extra parity bit. This way, it is possible to increase the minimum distance of the Hamming code to 4, which allows the decoder to distinguish between single bit errors and two-bit errors. Thus the decoder can detect and correct a single error and at the same time detect (but not correct) a double error.


title: Hamming code

text: If the decoder does not attempt to correct errors, it can reliably detect triple bit errors. If the decoder does correct errors, some triple errors will be mistaken for single errors and "corrected" to the wrong value. Error correction is therefore a trade-off between certainty (the ability to reliably detect triple bit errors) and resiliency (the ability to keep functioning in the face of single bit errors).


title: Hamming code

text: This extended Hamming code was popular in computer memory systems, starting with IBM 7030 Stretch in 1961, where it is known as "SECDED" (or SEC-DED, abbreviated from "single error correction, double error detection"). Server computers in 21st century, while typically keeping the SECDED level of protection, no longer use the Hamming's method, relying instead on the designs with longer codewords (128 to 256 bits of data) and modified balanced parity-check trees. The (72,64) Hamming code is still popular in some hardware designs, including Xilinx FPGA families.


title: Hamming code

text: In 1950, Hamming introduced the [7,4] Hamming code. It encodes four data bits into seven bits by adding three parity bits. It can detect and correct single-bit errors. With the addition of an overall parity bit, it can also detect (but not correct) double-bit errors.


title: Hamming code

text: This is the construction of G and H in standard (or systematic) form. Regardless of form, G and H for linear block codes must satisfy


title: Hamming code

text: Since [7, 4, 3] = ["n", "k", "d"] = [2 − 1, 2 − 1 − "m", 3]. The parity-check matrix H of a Hamming code is constructed by listing all columns of length "m" that are pair-wise independent.


title: Hamming code

text: Thus H is a matrix whose left side is all of the nonzero "n"-tuples where order of the "n"-tuples in the columns of matrix does not matter. The right hand side is just the ("n" − "k")-identity matrix.


title: Hamming code

text: So G can be obtained from H by taking the transpose of the left hand side of H with the identity "k"-identity matrix on the left hand side of G.


title: Hamming code

text: Finally, these matrices can be mutated into equivalent non-systematic codes by the following operations:


title: Hamming code

text: Let formula_10 be a row vector of binary data bits, formula_11. The codeword formula_12 for any of the 16 possible data vectors formula_13 is given by the standard matrix product formula_14 where the summing operation is done modulo-2.


title: Hamming code

text: For example, let formula_15. Using the generator matrix formula_16 from above, we have (after applying modulo 2, to the sum),


title: Hamming code

text: The [7,4] Hamming code can easily be extended to an [8,4] code by adding an extra parity bit on top of the (7,4) encoded word (see Hamming(7,4)).


title: Hamming code

text: Note that H is not in standard form. To obtain G, elementary row operations can be used to obtain an equivalent matrix to H in systematic form:


title: Hamming code

text: For example, the first row in this matrix is the sum of the second and third rows of H in non-systematic form. Using the systematic construction for Hamming codes from above, the matrix A is apparent and the systematic form of G is written as


title: Hamming code

text: The non-systematic form of G can be row reduced (using elementary row operations) to match this matrix.


title: Hamming code

text: The addition of the fourth row effectively computes the sum of all the codeword bits (data and parity) as the fourth parity bit.


title: Hamming code

text: For example, 1011 is encoded (using the non-systematic form of G at the start of this section) into 01100110 where blue digits are data; red digits are parity bits from the [7,4] Hamming code; and the green digit is the parity bit added by the [8,4] code.


title: Hamming code

text: Finally, it can be shown that the minimum distance has increased from 3, in the [7,4] code, to 4 in the [8,4] code. Therefore, the code can be defined as [8,4] Hamming code.


title: Hamming code

text: To decode the [8,4] Hamming code, first check the parity bit. If the parity bit indicates an error, single error correction (the [7,4] Hamming code) will indicate the error location, with "no error" indicating the parity bit. If the parity bit is correct, then single error correction will indicate the (bitwise) exclusive-or of two error locations. If the locations are equal ("no error") then a double bit error either has not occurred, or has cancelled itself out. Otherwise, a double bit error has occurred.


title: Hydroxide

text: Hydroxide is a diatomic anion with chemical formula OH. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, a ligand, a nucleophile, and a catalyst. The hydroxide ion forms salts, some of which dissociate in aqueous solution, liberating solvated hydroxide ions. Sodium hydroxide is a multi-million-ton per annum commodity chemical.


title: Hydroxide

text: The corresponding electrically neutral compound HO is the hydroxyl radical. The corresponding covalently bound group –OH of atoms is the hydroxy group.


title: Hydroxide

text: Both the hydroxide ion and hydroxy group are nucleophiles and can act as catalysts in organic chemistry.


title: Hydroxide

text: Many inorganic substances which bear the word "hydroxide" in their names are not ionic compounds of the hydroxide ion, but covalent compounds which contain hydroxy groups.


title: Hydroxide

text: The hydroxide ion is a natural part of water because of the self-ionization reaction in which its complement, hydronium, is passed hydrogen:


title: Hydroxide

text: has a value close to 10 at 25 °C, so the concentration of hydroxide ions in pure water is close to 10 mol∙dm, in order to satisfy the equal charge constraint. The pH of a solution is equal to the decimal cologarithm of the hydrogen cation concentration; the pH of pure water is close to 7 at ambient temperatures. The concentration of hydroxide ions can be expressed in terms of pOH, which is close to (14 − pH), so the pOH of pure water is also close to 7. Addition of a base to water will reduce the hydrogen cation concentration and therefore increase the hydroxide ion concentration (increase pH, decrease pOH) even if the base does not itself contain hydroxide. For example, ammonia solutions have a pH greater than 7 due to the reaction NH + H , which decreases the hydrogen cation concentration, which increases the hydroxide ion concentration. pOH can be kept at a nearly constant value with various buffer solutions.


title: Hydroxide

text: In aqueous solution the hydroxide ion is a base in the Brønsted–Lowry sense as it can accept a proton from a Brønsted–Lowry acid to form a water molecule. It can also act as a Lewis base by donating a pair of electrons to a Lewis acid. In aqueous solution both hydrogen and hydroxide ions are strongly solvated, with hydrogen bonds between oxygen and hydrogen atoms. Indeed, the bihydroxide ion has been characterized in the solid state. This compound is centrosymmetric and has a very short hydrogen bond (114.5 pm) that is similar to the length in the bifluoride ion (114 pm). In aqueous solution the hydroxide ion forms strong hydrogen bonds with water molecules. A consequence of this is that concentrated solutions of sodium hydroxide have high viscosity due to the formation of an extended network of hydrogen bonds as in hydrogen fluoride solutions.


title: Hydroxide

text: In solution, exposed to air, the hydroxide ion reacts rapidly with atmospheric carbon dioxide, acting as an acid, to form, initially, the bicarbonate ion.


title: Hydroxide

text: The equilibrium constant for this reaction can be specified either as a reaction with dissolved carbon dioxide or as a reaction with carbon dioxide gas (see Carbonic acid for values and details). At neutral or acid pH, the reaction is slow, but is catalyzed by the enzyme carbonic anhydrase, which effectively creates hydroxide ions at the active site.


title: Hydroxide

text: Solutions containing the hydroxide ion attack glass. In this case, the silicates in glass are acting as acids. Basic hydroxides, whether solids or in solution, are stored in airtight plastic containers.


title: Hydroxide

text: The hydroxide ion can function as a typical electron-pair donor ligand, forming such complexes as tetrahydroxoaluminate/tetrahydroxidoaluminate [Al(OH)]. It is also often found in mixed-ligand complexes of the type [ML(OH)], where L is a ligand. The hydroxide ion often serves as a bridging ligand, donating one pair of electrons to each of the atoms being bridged. As illustrated by [Pb(OH)], metal hydroxides are often written in a simplified format. It can even act as a 3-electron-pair donor, as in the tetramer [PtMe(OH)].


title: Hydroxide

text: When bound to a strongly electron-withdrawing metal centre, hydroxide ligands tend to ionise into oxide ligands. For example, the bichromate ion [HCrO] dissociates according to


title: Hydroxide

text: The infrared spectra of compounds containing the OH functional group have strong absorption bands in the region centered around 3500 cm. The high frequency of molecular vibration is a consequence of the small mass of the hydrogen atom as compared to the mass of the oxygen atom, and this makes detection of hydroxyl groups by infrared spectroscopy relatively easy. A band due to an OH group tends to be sharp. However, the band width increases when the OH group is involved in hydrogen bonding. A water molecule has an HOH bending mode at about 1600 cm, so the absence of this band can be used to distinguish an OH group from a water molecule.


title: Hydroxide

text: When the OH group is bound to a metal ion in a coordination complex, an M−OH bending mode can be observed. For example, in [Sn(OH)] it occurs at 1065 cm. The bending mode for a bridging hydroxide tends to be at a lower frequency as in [(bipyridine)Cu(OH)Cu(bipyridine)] (955 cm). M−OH stretching vibrations occur below about 600 cm. For example, the tetrahedral ion [Zn(OH)] has bands at 470 cm (Raman-active, polarized) and 420 cm (infrared). The same ion has a (HO)–Zn–(OH) bending vibration at 300 cm.


title: Hydroxide

text: Sodium hydroxide solutions, also known as lye and caustic soda, are used in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents, and as a drain cleaner. Worldwide production in 2004 was approximately 60 million tonnes. The principal method of manufacture is the chloralkali process.


title: Hydroxide

text: Solutions containing the hydroxide ion are generated when a salt of a weak acid is dissolved in water. Sodium carbonate is used as an alkali, for example, by virtue of the hydrolysis reaction


title: Hydroxide

text: Although the base strength of sodium carbonate solutions is lower than a concentrated sodium hydroxide solution, it has the advantage of being a solid. It is also manufactured on a vast scale (42 million tonnes in 2005) by the Solvay process. An example of the use of sodium carbonate as an alkali is when washing soda (another name for sodium carbonate) acts on insoluble esters, such as triglycerides, commonly known as fats, to hydrolyze them and make them soluble.


title: Hydroxide

text: Bauxite, a basic hydroxide of aluminium, is the principal ore from which the metal is manufactured. Similarly, goethite (α-FeO(OH)) and lepidocrocite (γ-FeO(OH)), basic hydroxides of iron, are among the principal ores used for the manufacture of metallic iron.


title: Hydroxide

text: Aside from NaOH and KOH, which enjoy very large scale applications, the hydroxides of the other alkali metals also are useful. Lithium hydroxide is a strong base, with a p"K" of −0.36. Lithium hydroxide is used in breathing gas purification systems for spacecraft, submarines, and rebreathers to remove carbon dioxide from exhaled gas.


title: Hydroxide

text: The hydroxide of lithium is preferred to that of sodium because of its lower mass. Sodium hydroxide, potassium hydroxide, and the hydroxides of the other alkali metals are also strong bases.


title: Hydroxide

text: Beryllium hydroxide Be(OH) is amphoteric. The hydroxide itself is insoluble in water, with a solubility product log "K"* of −11.7. Addition of acid gives soluble hydrolysis products, including the trimeric ion [Be(OH)(HO)], which has OH groups bridging between pairs of beryllium ions making a 6-membered ring. At very low pH the aqua ion [Be(HO)] is formed. Addition of hydroxide to Be(OH) gives the soluble tetrahydroxoberyllate/tetrahydroxidoberyllate anion, [Be(OH)].


title: Hydroxide

text: The solubility in water of the other hydroxides in this group increases with increasing atomic number. Magnesium hydroxide Mg(OH) is a strong base (up to the limit of its solubility, which is very low in pure water), as are the hydroxides of the heavier alkaline earths: calcium hydroxide, strontium hydroxide, and barium hydroxide. A solution or suspension of calcium hydroxide is known as limewater and can be used to test for the weak acid carbon dioxide. The reaction Ca(OH) + CO Ca + + OH illustrates the basicity of calcium hydroxide. Soda lime, which is a mixture of the strong bases NaOH and KOH with Ca(OH), is used as a CO absorbent.


title: Hydroxide

text: The simplest hydroxide of boron B(OH), known as boric acid, is an acid. Unlike the hydroxides of the alkali and alkaline earth hydroxides, it does not dissociate in aqueous solution. Instead, it reacts with water molecules acting as a Lewis acid, releasing protons.


title: Hydroxide

text: In the Bayer process for the production of pure aluminium oxide from bauxite minerals this equilibrium is manipulated by careful control of temperature and alkali concentration. In the first phase, aluminium dissolves in hot alkaline solution as , but other hydroxides usually present in the mineral, such as iron hydroxides, do not dissolve because they are not amphoteric. After removal of the insolubles, the so-called red mud, pure aluminium hydroxide is made to precipitate by reducing the temperature and adding water to the extract, which, by diluting the alkali, lowers the pH of the solution. Basic aluminium hydroxide AlO(OH), which may be present in bauxite, is also amphoteric.


title: Hydroxide

text: In mildly acidic solutions, the hydroxo/hydroxido complexes formed by aluminium are somewhat different from those of boron, reflecting the greater size of Al(III) vs. B(III). The concentration of the species [Al(OH)] is very dependent on the total aluminium concentration. Various other hydroxo complexes are found in crystalline compounds. Perhaps the most important is the basic hydroxide AlO(OH), a polymeric material known by the names of the mineral forms boehmite or diaspore, depending on crystal structure. Gallium hydroxide, indium hydroxide, and thallium(III) hydroxide are also amphoteric. Thallium(I) hydroxide is a strong base.


title: Hydroxide

text: Carbon forms no simple hydroxides. The hypothetical compound C(OH) (orthocarbonic acid or methanetetrol) is unstable in aqueous solution:


title: Hydroxide

text: Carbon dioxide is also known as carbonic anhydride, meaning that it forms by dehydration of carbonic acid HCO (OC(OH)).


title: Hydroxide

text: Silicic acid is the name given to a variety of compounds with a generic formula [SiO(OH)]. "Orthosilicic acid" has been identified in very dilute aqueous solution. It is a weak acid with p"K" = 9.84, p"K" = 13.2 at 25 °C. It is usually written as HSiO, but the formula Si(OH) is generally accepted. Other silicic acids such as "metasilicic acid" (HSiO), "disilicic acid" (HSiO), and "pyrosilicic acid" (HSiO) have been characterized. These acids also have hydroxide groups attached to the silicon; the formulas suggest that these acids are protonated forms of polyoxyanions.


title: Hydroxide

text: Few hydroxo complexes of germanium have been characterized. Tin(II) hydroxide Sn(OH) was prepared in anhydrous media. When tin(II) oxide is treated with alkali the pyramidal hydroxo complex is formed. When solutions containing this ion are acidified, the ion [Sn(OH)] is formed together with some basic hydroxo complexes. The structure of [Sn(OH)] has a triangle of tin atoms connected by bridging hydroxide groups. Tin(IV) hydroxide is unknown but can be regarded as the hypothetical acid from which stannates, with a formula [Sn(OH)], are derived by reaction with the (Lewis) basic hydroxide ion.


title: Hydroxide

text: Hydrolysis of Pb in aqueous solution is accompanied by the formation of various hydroxo-containing complexes, some of which are insoluble. The basic hydroxo complex [PbO(OH)] is a cluster of six lead centres with metal–metal bonds surrounding a central oxide ion. The six hydroxide groups lie on the faces of the two external Pb tetrahedra. In strongly alkaline solutions soluble plumbate ions are formed, including [Pb(OH)].