text:
San Juan Mountains

The San Juan Mountains is a high and rugged mountain range in the Rocky Mountains in southwestern Colorado and northwestern New Mexico. The area is highly mineralized (the Colorado Mineral Belt) and figured in the gold and silver mining industry of early Colorado. Major towns, all old mining camps, include Creede, Lake City, Silverton, Ouray, and Telluride. Large scale mining has ended in the region, although independent prospectors still work claims throughout the range. The last large-scale mines were the Sunnyside Mine near Silverton, which operated until late in the 20th century, and the Idarado Mine on Red Mountain Pass, which closed in the 1970s. Famous old San Juan mines include the Camp Bird and Smuggler Union mines, both located between Telluride and Ouray.

The Summitville mine was the scene of a major environmental disaster in the 1990s when the liner of a cyanide-laced tailing pond began leaking heavily. Summitville is in the Summitville caldera, one of many extinct volcanoes making up the San Juan volcanic field. One, La Garita Caldera, is 35 mi in diameter. Large beds of lava, some extending under the floor of the San Luis Valley, are characteristic of the eastern slope of the San Juans.

Tourism is a major part of the regional economy, with the narrow gauge railway between Durango and Silverton being an attraction mostly in the summer and fall. Jeeping is popular on the old trails which linked the historic mining camps, including the notorious Black Bear Road. Visiting old ghost towns is popular, as is wilderness trekking and mountain climbing. Many of the old mining camps are popular sites of summer homes. Though the San Juans are extremely steep and receive much snow, so far only Telluride has made the transition to a major ski resort. Purgatory Resort, once known as Durango Mountain Resort, is a small ski area 26 miles north of Durango. There is also skiing on Wolf Creek Pass at the Wolf Creek ski area. Recently Silverton Mountain ski area has begun operation near Silverton. The range is also a popular destination for endurance sports like trail running and mountain biking; Silverton is home to the Hardrock 100 Endurance Run one of the most difficult and technical ultra-marathons in the world.

The Rio Grande drains the east side of the range. The other side of the San Juans, the western slope of the continental divide, is drained by tributaries of the San Juan, Dolores and Gunnison rivers, which all flow into the Colorado River.

The San Juan and Uncompahgre National Forests cover a large portion of the San Juan Mountains. The Continental Divide Trail, a long-distance hiking trail follows the crest of the San Juan Mountains. The Weminuche Wilderness, Colorado's largest wilderness area, with an area of 499771 acre is in the San Juans.

The San Juan Mountains are also distinctive for their high altitude plateaus and peaks. As a result, facilities in the towns and cities of the region are among the highest in the nation. Telluride Airport, at an elevation of 9,070 feet, is the highest in the United States with regularly scheduled commercial service.

Prominent peaks

 * Note: This is only a partial list of important peaks in the San Juans, listing peaks by prominence only. There are dozens more summits over 12,000 feet.

History of the area
Mining operators in the San Juan mountain area formed the San Juan District Mining Association (SJDMA) in 1903, as a direct result of a Western Federation of Miners proposal to the Telluride Mining Association for the eight-hour day, which had been approved in a referendum by 72 percent of Colorado voters. The new association consolidated the power of thirty-six mining properties in San Miguel, Ouray, and San Juan counties. The SJDMA refused to consider any reduction in hours or increase in wages, helping to provoke a bitter strike.

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

title: San Juan Mountains


text:
Quest Software

Quest Software, also known as Quest, is a privately held software company headquartered in Aliso Viejo, California, United States. Quest provides cloud management, software as a service, security, workforce mobility, and backup & recovery. The company was founded in 1987 and has 53 offices in 24 countries.

History
Quest Software was founded in 1987 in Newport Beach, California, with a line of products for HP Multi-Programming Executive (MPE). In 1995, Vinny Smith joined the company. The following year, Quest entered the database management market with an Oracle SQL database tuning product. In 1997, Quest opened an office in the United Kingdom.

Doug Garn joined Quest as the Vice President of Sales in 1998. That same year, Quest added offices in Germany and Australia, and Smith became CEO.

In October, Quest acquired TOAD.

On August 13, 1999, Quest Software went public.

In 2002, a Quest office opened in Japan. The next year, Quest opened new offices in Asia, specifically in Singapore, Korea, and China.

In 2004, Gartner named Quest number one in application management. Doug Garn became president of Quest Software in 2005.

Doug Garn became CEO and president, and Vinny Smith became executive chairman of Quest in 2008. In 2009, Alan Fudge became vice president of sales. In 2011, Vinny Smith became CEO and chairman, and Doug Garn became vice chairman.

On September 28, 2012, Dell announced it had completed the acquisition of Quest Software.

In 2016, Quest Software acquired ScriptLogic, and Charonware s.r.o from the Czech Republic. Charonware made CASE Studio2, and after being acquired, Quest folded it into the TOAD Data Modeler product.

On November 1, 2016, Francisco Partners and Elliott Management completed the purchase of Dell Software, and the company re-launched itself as Quest Software.

On June 1, 2017, One Identity was announced as an independent brand, but remained part of the Quest family of businesses.

On September 2, 2020, Quest acquired Binary Tree. On January 5, 2021, Quest acquired erwin, Inc., including erwin Data Modeler.

On November 29, 2021, Clearlake Capital bought Quest from Francisco Partners for $5.4 billion, including debt.

title: Quest Software


text:
User:Dizzley

Dizzley is Peter Hitchmough. I'm a Brit. I work in IT as a technical architect on Oracle-centric projects. I'm keen to see projects like Wikipedia work, though I joined on the day I noticed [Larry Sanger]] had left the project. Ah well.

I'll write more when I have time.

Diz.

title: User:Dizzley


text:
User:DrewT

List of articles which I have contributed to:

Mathematics:
 * Big O
 * Graph theory
 * Goldbach's weak conjecture
 * Goldbach's strong conjecture
 * The Travelling Salesman Problem
 * Nearest neighbour algorithm

Music & Sound:
 * Pink Floyd
 * Pink Floyd's Dark Side of the Moon
 * Paul Lansky
 * Electronic music
 * Electronic musical instrument
 * Physical modelling synthesis
 * TMBG's Flood
 * They Might Be Giants
 * Speech synthesis
 * Progressive rock

Everything else:
 * Valency (I wrote the first draft of this, and had to copy in a table of *103* elements' valencies. And I made a mistake. :-))
 * Worms computer games
 * Worms computer game - Grenade
 * Worms computer game - Banana Bomb
 * Worms computer game - Cluster Bomb
 * Worms computer game - Dynamite
 * Worms computer game - Teleport
 * Worms computer game - Bungee
 * Dictionary
 * Rime of the Ancient Mariner
 * Samuel Taylor Coleridge
 * Infinite Monkey Theorem
 * Cryptography
 * Global warming potential
 * Anti-ballistic missile
 * Advanced Encryption Standard
 * Six Degrees of Kevin Bacon
 * Bacon number
 * William Rufus Shafter
 * Bacon number of Christopher Lee
 * Magnetoresistance
 * Slashdot
 * Goatse.cx

There are others, but the number of minor edits I've made are so many that I honestly can't remember them all! I don't have any contributions under my 'proper' list of contributions because I haven't figured out how to post a new article whilst staying logged in so far.

title: User:DrewT


text:
1096

Year 1096 (MXCVI) was a leap year starting on Tuesday (link will display the full calendar) of the Julian calendar.

First Crusade

 * Spring – Peter the Hermit begins his preaching of the First Crusade, traveling from Berry (in central France) across Champagne, and down the Meuse Valley to Cologne (modern Germany). He gathers the People's Crusade (some 40,000 supporters), which departs about April 20. Peter's speeches appeal not only to nobles and knights, but also laborers, tradesmen and peasants (among them are former brigands and criminals).
 * May – The People's Crusade, under Peter the Hermit, arrives at Sopron. King Coloman (the Learned) gives them permission to pass through Hungary, and to use the markets. Peter and his followers (some 20,000 men and women) travel from Budapest southwards supported by knights, while lumbering wagons carry stores and a chest of money that he has collected for the journey.
 * May – The Rhineland massacres: Members of the People's Crusade led by Count Emicho destroy most of the Jewish communities along the Rhine in a series of large pogroms in France and Germany. Thousands of Jews are massacred, driven to suicide, or forced to convert to Christianity. Estimates of the number of Jewish men, women and children murdered are 2,000 to 12,000.
 * May 8 – French members of the People's Crusade led by Walter Sans Avoir enter Hungary, without incident they arrive at Semlin, and cross the Sava into Byzantine territory at Belgrade. Meanwhile, Walter demands food but he is refused entry, and the crusaders are forced to pillage the countryside. Eventually Walter is allowed to carry on to Niš, where he is provided with food.
 * May 18–26 – The Worms massacre: Members of the People's Crusade under Emicho besiege Worms in the Rhineland before killing at least 800 Jews, despite the intervention of Bishop Adalbert II. He tries to hide some of them in the bishop's palace, others chose to remain outside its walls. One of the victims is Minna of Worms, an influential Jew among the Christian nobility.
 * May 27 – Members of the People's Crusade under Emicho massacre at least 1,000 Jews in Mainz. Archbishop Ruthard tries to hide some of them in the cellars of Mainz Cathedral but the crusaders learn of this – and murder most of the Jews. Men, women, and children of all ages are slaughtered indiscriminately.
 * May 30 – Members of the People's Crusade led by the priest Folkmar from Saxony persecute Jews in Prague, despite the opposition of the local Catholic hierarchy. Local citizens try to hide them in their own houses. Later the Jews manage to escape to safety in neighboring villages, but are slaughtered by the hundreds.
 * June – Members of the People's Crusade under Emicho set out up the Main towards Hungary. Some followers break off from Emicho's army at Mainz and travel to Metz – where many Jews are persecuted and murdered. They proceed down the Rhine, massacring the Jews at Neuss, Wevelinghofen, and Xanten.
 * June – The People's Crusade under Emicho are refused entry to Hungary on orders of Coloman, who sends troops to defend the bridge at Wieselburg. Emicho decides to build an alternative bridge and crosses the Danube. He besieges the fortress of Wieselburg, but is defeated and routed by the Hungarian army.
 * June – Siege of Semlin: The People's Crusade led by Peter the Hermit arrives at Semlin. Hearing rumors of an attack from the Hungarian count Guz of Semlin on the rearguard, Geoffrey Burel assaults the castle, captures it by surprise, and defeats the Hungarian army. He plunders its supplies, herds and horses.
 * June 26 – The People's Crusade (some 30,000 men) led by Peter the Hermit crosses the Sava (stealing boats from the local fishermen) but are attacked by Pechenegs and Hungarian forces. The citizens of Belgrade flee and the crusaders pillage and burn the city. Peter travels for seven days, and arrives at Niš.
 * July – The People's Crusade led by Peter the Hermit is defeated by the Byzantine army (mostly Hungarian and Bulgar mercenaries) in battle near Niš. The crusader supply train of some 2,000 wagons and Peter's treasury chest is captured by the Byzantines. About a quarter of the People's Crusade is lost.
 * July 12 – The People's Crusade led by Peter the Hermit reaches Sofia, where they meet envoys from Constantinople with orders to keep them supplied along the road. At Philippopolis the Greeks are so deeply moved by the suffering of Peter and his followers that the locals give them money, food and horses.
 * August 1 – The People's Crusade led by Peter the Hermit arrives at Constantinople. He is received by Emperor Alexios I (Komnenos), who gives him financial support. The crusaders commit endless thefts in the suburbs. Peter combines his forces with Walter Sans Avoir and camps outside Constantinople.
 * August 2–6 – The People's Crusade reorganize their forces and gather supplies. Alexios I advises Peter the Hermit to wait for reinforcements but he ignores the advice. The People's army (some 30,000 men) is transported across the Bosporus – by the Byzantine fleet to Civetot (modern Turkey).
 * August – Hugh (the Great), count of Vermandois (a brother of King Philip I), departs to join the First Crusade. He travels with a small army via the Alps to Rome. While sailing the Adriatic Sea from Bari to Dyrrachium his fleet is reduced by shipwreck. Hugh's own ship is stranded on the shore near Epirus.
 * August – Godfrey of Bouillon, duke of Lower Lorraine, accompanied by his younger brother Baldwin, sets off to join the First Crusade (called by Pope Urban II) at the head of an army of some 40,000 men. He pledges his allegiance to Emperor Henry IV who issues an order not to harm Jewish communities.
 * September – French forces (7,000 infantry and 300 knights) led by Geoffrey Burel raid around Nicaea (the capital of the Rum Seljuk Turks), plundering livestock and villages in the suburbs. They commit atrocities against local Christian peasants. Children are tortured and dismembered by the crusaders.
 * September – German forces (5,000 infantry and 200 knights) led by Rainald of Breis raid the region of Nicaea. They advance eastward and assault the Seljuk garrison in the castle of Xerigordos. They manage to capture; and, find it well stocked with provisions. The Greek Christians inside are spared.
 * September 29 – Siege of Xerigordos: Sultan Kilij Arslan I sends a Seljuk expeditionary force to assault and recapture the castle of Xerigordos. They cut off the water supply, and Rainald of Breis is forced to surrender. Many of the crusaders are killed but others convert to Islam and become slaves.
 * October – Robert II (Curthose), duke of Normandy (a brother of King William II), sets off to join the First Crusade. He assembles his army at Pontarlier – and travels through Italy to Rome. To raise money for the Crusade Robert mortgages the Norman duchy to William, for the sum of 10,000 pennies.
 * October – Raymond IV (Saint-Gilles), count of Toulouse, sets off to join the First Crusade. He travels with his army, accompanied by his wife Elvira and Bishop Adhemar of Le Puy, via Provence through the Balkan route (along the coast of Croatia). He arrives at Dyrrachium to march to Thessaloniki.
 * October – Bohemond I, Italo-Norman prince of Taranto (the son of Duke Robert Guiscard), departs to join the First Crusade. He crosses the Adriatic Sea from Brindisi with his army (some 4,000 men), and arrives in Vorë. While traveling, Bohemond gives strict orders not to plunder Byzantine villages.
 * October 21 – Battle of Civetot: The Seljuk Turks led by Kilij Arslan I defeat the People's army (20,000 men) near Nicaea. The crusaders are slaughtered, and the camp at Civetot is captured. Only children are spared and sent into slavery. Around 3,000 manage to escape back to Constantinople.
 * December – The last of the four planned Crusader armies arrives at Constantinople, bringing the total numbers to 60,000 infantry and knights. Curiously there isn't a single king among the Crusaders' leaders. At this time Philip I, William II, and Henry IV are all under excommunication by Urban II.
 * December 25 – Godfrey of Bouillon is appointed the primary leader of the First Crusade, making it a largely French war in practice and causing the inhabitants of the Holy Land to refer to Europeans generally as "Franks". Godfrey and the other leaders agree to take an oath of loyalty to Alexios I.

Europe

 * King Alfonso VI (the Brave) of Castile arranges to marry his daughter Theresa to Henry of Burgundy (House of Burgundy). Theresa's dowry includes the County of Portugal, given to Henry with Porto as the capital.
 * King Peter I of Aragon conquers Huesca from the Moors of the Taifa of Zaragoza. He expands his domains to the south, conquering land from Al Andalus (modern Spain). The capital is moved from Jaca to Huesca.

Asia

 * Phayao, a modern-day province of Thailand, is founded as a city-state kingdom.

Religion

 * February – Robert of Arbrissel founds a monastery at La Roë.
 * The first documented teaching at the University of Oxford in England occurs.
 * Norwich School is founded in England as an episcopal grammar school.
 * In Ireland, the Diocese of Waterford is established.

Births

 * January 15 – Theodora Komnene, Byzantine princess
 * March 12 – Canute Lavard, duke of Schleswig (d. 1131)
 * April 9 – Al-Muqtafi, caliph of the Abbasid Caliphate (d. 1160)
 * December 31 – Al-Amir bi-Ahkam Allah, Fatimid caliph (d. 1130)
 * Ermengol VI (el de Castilla), count of Urgell (d. 1154)
 * Galdino della Sala (or Galdinus), Archbishop of Milan (d. 1176)
 * Henry of Blois, bishop of Winchester (approximate date)
 * Hugh of Saint Victor, German scholar and theologian (d. 1141)
 * Iziaslav II Mstislavich, Grand Prince of Kiev (d. 1154)
 * Minamoto no Tameyoshi, Japanese nobleman (d. 1156)
 * Peter Lombard, French bishop and theologian (d. 1160)
 * Stephen of Blois, king of England (approximate date)
 * Taira no Tadamori, Japanese nobleman (d. 1153)
 * Wang Ximeng, Chinese landscape painter (d. 1119)
 * William VI, count of Auvergne and Velay (d. 1136)

Deaths

 * January 2 – William de St-Calais, Norman bishop and chief councilor
 * January 11 – Adelaide II, German princess and abbess (b. 1045)
 * May – Minna of Worms, German-Jewish moneylender and martyr
 * October 21 – Walter Sans Avoir, French leader of the First Crusade
 * November 11 – Werner I, German nobleman (House of Habsburg)
 * December 23 – Hugh I of Le Puiset, French nobleman
 * Eudokia Makrembolitissa, Byzantine empress and regent
 * Fariburz I, Persian ruler of Shirvan (House of Shirvanshah)
 * Gao Shengtai, Chinese ruler of the Dazhong Kingdom
 * Geoffrey III (the Bearded), French nobleman (b. 1040)
 * Henry III, count of Luxembourg (House of Luxembourg)

 * The Worms massacre:
 * Kalonymus ben Meshullam, French Jewish martyr
 * Minna of Worms, German Jewish female martyr

 * Ralph de Gael, Norman nobleman (approximate date)
 * Sarakhsi, Persian scholar, jurist and writer (approximate date)
 * Stephen II, German nobleman (House of Sponheim)

title: 1096


text:
Physical modelling synthesis

Physical modelling synthesis refers to sound synthesis methods in which the waveform of the sound to be generated is computed using a mathematical model, a set of equations and algorithms to simulate a physical source of sound, usually a musical instrument.

General methodology
Modelling attempts to replicate laws of physics that govern sound production, and will typically have several parameters, some of which are constants that describe the physical materials and dimensions of the instrument, while others are time-dependent functions describing the player's interaction with the instrument, such as plucking a string, or covering toneholes.

For example, to model the sound of a drum, there would be a mathematical model of how striking the drumhead injects energy into a two-dimensional membrane. Incorporating this, a larger model would simulate the properties of the membrane (mass density, stiffness, etc.), its coupling with the resonance of the cylindrical body of the drum, and the conditions at its boundaries (a rigid termination to the drum's body), describing its movement over time and thus its generation of sound.

Similar stages to be modelled can be found in instruments such as a violin, though the energy excitation in this case is provided by the slip-stick behavior of the bow against the string, the width of the bow, the resonance and damping behavior of the strings, the transfer of string vibrations through the bridge, and finally, the resonance of the soundboard in response to those vibrations.

In addition, the same concept has been applied to simulate voice and speech sounds. In this case, the synthesizer includes mathematical models of the vocal fold oscillation and associated laryngeal airflow, and the consequent acoustic wave propagation along the vocal tract. Further, it may also contain an articulatory model to control the vocal tract shape in terms of the position of the lips, tongue and other organs.

Although physical modelling was not a new concept in acoustics and synthesis, having been implemented using finite difference approximations of the wave equation by Hiller and Ruiz in 1971, it was not until the development of the Karplus-Strong algorithm, the subsequent refinement and generalization of the algorithm into the extremely efficient digital waveguide synthesis by Julius O. Smith III and others, and the increase in DSP power in the late 1980s that commercial implementations became feasible.

Yamaha contracted with Stanford University in 1989 to jointly develop digital waveguide synthesis; subsequently, most patents related to the technology are owned by Stanford or Yamaha.

The first commercially available physical modelling synthesizer made using waveguide synthesis was the Yamaha VL1 in 1994.

While the efficiency of digital waveguide synthesis made physical modelling feasible on common DSP hardware and native processors, the convincing emulation of physical instruments often requires the introduction of non-linear elements, scattering junctions, etc. In these cases, digital waveguides are often combined with FDTD, finite element or wave digital filter methods, increasing the computational demands of the model.

Technologies associated with physical modelling
Examples of physical modelling synthesis:
 * Karplus-Strong string synthesis
 * Digital waveguide synthesis
 * Mass-interaction networks
 * Formant synthesis
 * Articulatory synthesis

title: Physical modelling synthesis


text:
Terrorism in Yemen

In its war on terrorism in Yemen, the US government describes Yemen as "an important partner in the global war on terrorism". There have been attacks on civilian targets and tourists, and there was a cargo-plane bomb plot in 2010. Counter-terrorism operations have been conducted by the Yemeni police, the Yemeni military, and the United States Armed Forces.

Limburg attack
In October 2002, near the port of Mukalla, suicide bombers rammed an explosive-laden boat into the Limburg, a French oil tanker, killing a Bulgarian crew member and spilling 90000 oilbbl of oil into the Gulf of Aden. Saudi born Abdulraheem al-Nashiri, prime suspect of the USS Cole bombing, paid $40,000 to fund the Limburg attack. With that money, the former Al Qaida leader Abu Ali al-Harithi bought the explosives and transported them from his house in Shabwa to Mukalla in Hadramut.

Civil Aviation, Meteorological Authority and helicopter attacks
On 3 November 2002 there was an attack on a helicopter carrying Hunt Oil Co. Employees shortly after taking off from Sana'a. A missile and a machine gun were fired at the helicopter injuring two American citizens. One person was jailed for the helicopter attack as well as for bombing the Civil Aviation and Meteorological Authority building in Sana'a.

Jibla hospital
On December 30, 2002, a suspected Islamic fundamentalist killed three US workers and wounded one in a hospital in Jibla with a semi-automatic rifle. Two men were eventually convicted and executed for the attack - the gunman Abid Abdulrazzaq Al-Kamil, and the 'mastermind' Ali Ahmed Mohamed al-Jarallah, who had also been convicted of the 2002 murder of Yemeni politician Jarallah Omar.

Al-Salem letter threats
Jews in Yemen reportedly fled their homes due to threats from Muslim extremists. Al-Qaeda members sent letters to 45 Jews living in al-Salem (near Sana'a) on January 19, 2007, accusing them of involvement in an "international Zionist conspiracy". The Jewish community sent a complaint to President Ali Abdullah Saleh and temporarily moved to a hotel near Sana'a. The Yemeni government promised to protect their homes and reassured them that they could return.

US Embassy
On September 17, 2008, Al-Qaeda militants attacked the US Embassy in Sana'a. 20 people were killed, including six militants, six policemen and seven civilians. One American was also among those killed.

Attacks on tourists
A suicide bomber killed eight Spanish tourists and their two Yemeni drivers in Ma'rib on July 2, 2007. On January 18, 2008, Al-Qaeda militants opened fire on a convoy of tourists in Hadhramaut, killing two Belgian tourists, two Yemenis, the tourists' driver and their guide. In March 2009, four South Korean tourists and their local Yemeni guide were killed. Two attackers also died.

UAE-run secret prisons
In the name of punishment, Yemenis are tortured at the hands of Houthis and Saudi Arabia-led military. According to a report published by the Associated Press, the United Arab Emirates runs a network of secret prisons across southern Yemen, where several hundreds of Yemenis on suspicion of being al-Qaida or Islamic State militants are held.

According to former detainees, families of prisoners, civil rights lawyers and Yemeni military officials, there are at least 18 lock-ups hidden away in military bases, air and seaports, the basements of private villas and even a nightclub. Prisoners are held without any charges, with the Yemeni government having no control over these UAE-run prisons.

Beir Ahmed prison in the southern city of Aden is one such prison, where detainees are tortured and sexually assaulted by the UAE officers. Prisoners are electrocuted by their genitals and rocks are hung from their testicles. They are also sexually violated with wooden and steel poles. In March 2018, Emirati officers blind-folded and handcuffed all the detainees of Beir Ahmed prison and made them stand under the sun until noon. The detainees were asked to undress and lie down with their legs spread open. The Emirati forces then touched their genitals and probed their rectums in search of mobile phones.

Bin Salman mosque bombing
The Bin Salman mosque was bombed on 2 May 2008 at the Bin Salman Mosque in Sa'dah, and killed 15 and injured 55. Local officials believed the bomb was hidden in a car or a motorcycle.

Some witnesses said the target may have been the mosque's imam, or prayer leader, an army officer who adheres to the Salafi school of Sunni Islam. Witnesses said he was not hurt. Military personnel are among those who usually pray at the Bin Salman mosque, which like others in Yemen caters for both the majority Sunni community and Shia Zaidis.

Wadi Dawan attack
On January 18, 2008, there was an ambush attack on Belgian tourists traveling in a convoy through Hadhramaut in the Wadi Dawan desert valley A convoy of four jeeps carrying 15 tourists to Shibam was ambushed by gunmen in a hidden pickup truck. Two Belgian women, Claudine Van Caillie, of Bruges, 63, and Katrine Glorie, from East Flanders, 54, as well as two Yemenis, a driver and a guide, were killed; another man was also heavily wounded, several others suffered minor wounds. The tourists were repatriated to Belgium on January 19, except the injured man, who remained in Sanaa.

In the wake of the attack, Belgian Minister of Foreign Affairs, Karel De Gucht originally rejected that Al-Qaeda might be responsible, explaining that although the possibility could be avoided, internecine disputes and latent Islamism also to be taken into account. A number of arrests were made on January 21. President of the European Council Slovenia released a statement saying "The EU Presidency strongly condemns all forms of violence and calls on the government of Yemen to bring the perpetrators of these crimes to justice."

Military and police counter-terrorism operations
After the September 11, 2001 attacks in the United States, President Ali Abdullah Saleh attempted to eliminate the Islamist militant presence. By November 2002, Yemeni government troops had detained 104 suspected al-Qaeda members.

In December 2001 a search by government forces for two Yemenis believed to be senior al-Qaeda members hiding near Ma'rib led to a gun battle with tribesmen which ended in the deaths of 34 people, including 18 soldiers. To defuse the situation, ten Ma'rib sheikhs were detained as hostages of the state in the presidential palace for 35 days, until 43 lesser tribesmen took their place.

At the request of the United States, Spanish troops boarded and detained a ship transporting Scud missiles from North Korea to Yemen in December 2002. After two days, when the United States determined that it had no right under international law to continue detaining the shipment, it was allowed to continue on its way to Yemen.

On July 30, 2009, three soldiers were killed in a clash with al-Qaeda militants in Marib province. On December 17 the village of Al Ma`jalah was hit by a cruise missile which killed 41 people, including 14 women and 21 children; 14 were alleged al-Qaeda members. While the Yemeni government initially took responsibility, photographs of American components and a leaked diplomatic cable suggested that it was carried out by the United States. ABC News reported that US cruise missiles were part of the camp bombardment targeting Abu Hureira Qasm al-Rimi. According to a local official and a tribal source, 49 civilians (including 23 women and 17 children) were among those killed in the strike. That day, a clash between security forces and al-Qaeda members in Abhar left four militants dead.

An air raid targeted an al-Qaeda meeting in Wadi Rafadh, Shabwa province on December 24, 2009. Thirty-four al-Qaeda militants were killed in the attack. According to security forces, Saudis and Iranians were among those killed. The number of al-Qaeda members arrested the previous week rose to 29.

US air attacks
The US first said that it used targeted killing in November 2002, with the cooperation and approval of the Yemeni government. In 2004, the Australian Broadcasting Corporation (ABC-TV) international-affairs program Foreign Correspondent investigated the targeted killing and the involvement of the US ambassador as part of a report entitled "The Yemen Option". The report examined evolving tactics and countermeasures in dealing with al-Qaeda-inspired attacks.

An estimated 98 US drone attacks were conducted in Yemen from 2002 to 2015: 41 in 2012, 26 in 2013 and 14 in 2014.

2002 Al-Harethi killing
Early in 2002 the Bush administration approved sending about 100 Special Operations Forces to Yemen.

Six Yemeni suspected al-Qaeda members were blown up in their car in Marib province in November 2002 by a Hellfire missile from an unmanned CIA Predator drone. Among the dead were Qaed Salim Sinan al-Harethi (aka Abu Ali al-Harithi), a suspected senior al-Qaeda lieutenant believed to have helped mastermind the October 2000 USS Cole bombing. Al-Harethi was on a list of targets whose capture or death had been ordered by US President George W. Bush. and Kamal Derwish (aka Ahmed Hijazi), an American.

2010 al-Shabwani killing
In May 2010 an errant US drone attack targeting al Qaeda terrorists in Wadi Abida killed five people, including Ma'rib province deputy governor Jaber al-Shabwani (who was mediating between the government and the militants). The killing angered Shabwani's tribesmen and in subsequent weeks they fought government security forces, twice attacking a major oil pipeline in the province.

2011 airstrikes
On May 5, 2011, a missile fired from a US drone killed Abdullah and Mosaad Mubarak, brothers who may have been al-Qaeda militants. The missile struck their car, and both died instantly. The strike intended to kill al-Qaeda propagandist Anwar al-Awlaki, but he was not hit in the strike.

On June 3, 2011, American manned jets (or drones) killed Ali Abdullah Naji al-Harithi, a mid-level al-Qaeda operative, and several other militant suspects, including Ammar Abadah Nasser al-Wa'eli, in a strike in southern Yemen. Four civilians were also reportedly killed in the strike, reportedly coordinated by American special forces and CIA operatives based in Sanaa. According to the Associated Press, in 2011 the US government began building an air base near Yemen from which the CIA and the US military planned to fly drones over Yemen. This base is located at Umm Al Melh, just north of Yemen inside Saudi Arabia. The Washington Post reported that the US previously used a base in Djibouti to fly drones over Yemen, while The Wall Street Journal reported that a US drone base in the Seychelles could be used to fly drones over Yemen.

According to local residents and unnamed American and Yemeni government officials, on July 14, 2011, US manned aircraft (or drones) attacked and destroyed a police station in Mudiya, Abyan Governorate which had been occupied by al-Qaeda militants. Yemeni media and government accounts conflicted on the number of fatalities, estimated at between 6 and 50. The same day and nearby, drone missiles reportedly hit a car belonging to Yemeni al-Qaeda leader Fahd al-Quso, but al-Quso survived the attack.

On August 1, 2011, US drones and reported Yemeni aircraft attacked three targets with bombs and missiles in southern Yemen, killing 15 suspected al-Qaeda militants and wounding 17 others. Targeted locations included al-Wahdah, al-Amodiah, and al-Khamilah in Abyan Governorate. One of those killed was reportedly militant leader Naser al-Shadadi. According to the Yemen Post online newspaper, "At least 35 US drone attacks were reported in Yemen over the last two months". On August 24, unidentified aircraft attacked suspected al-Qaeda militants near Zinjibar. The strikes reportedly killed 30 militants and wounded 40 others.

According to Yemeni officials, as reported in the Long War Journal, US airstrikes in southeast Abyan province from August 30 to September 1 killed 30 AQAP militants reportedly engaged in combat with Yemeni military forces. Two airstrikes by US-operated aircraft on September 21 reportedly killed four AQAP fighters in Abyan and seven AQAP fighters in Shaqra. On September 30 US drone-launched missiles killed four people, including al-Qaeda propagandist Anwar al-Awlaki, in Al Jawf Governorate. The strike also killed Samir Kahn, the American-born editor of Inspire magazine. It was the first known time that the US deliberately targeted US citizens in a drone attack.

A reported drone strike in Zinjibar on October 5 killed five AQAP militants. Yemeni government officials said that an October 14 US airstrike killed seven AQAP militants, including Egyptian-born AQAP media chief Ibrahim al-Bana. Eight militants were reportedly killed in an airstrike near Jaar on December 17; a December 22 drone strike near Zinjibar reportedly killed Abdulrahman al-Wuhayshi, a relative of Yemeni al-Qaeda leader Nasir al-Wuhayshi.

2012 airstrikes
A reported US airstrike on January 31, 2012, near the city of Lawder in Abyan province killed 11 AQAP militants. The dead reportedly included Abdul Monem al-Fahtani, a participant in the USS Cole bombing. Drones engaged in three attacks in three days on March 9–11, 2012. The first strike targeted an AQAP hideout near Al Baydah, Baydah province, reportedly killing local AQAP leader Abdulwahhab al-Homaiqani and 16 of followers. The second strike, on Jaar in Abyan province, reportedly killed 20 AQAP fighters. The third strike, also on Jaar, reportedly killed three AQAP militants and targeted a storage location for weapons seized by AQAP after it overran a Yemeni military base in Al Koud the previous week. A fourth drone strike, on March 14 in Al Bydah, reportedly killed four AQAP militants in a vehicle.

On April 11, 14 militants were killed in a drone strike in the town of Lauder (northeast of Zinjibar in Abyan province). An April 22 drone strike in the Al Samadah area, near the border of Marib and Al Jawf provinces, killed AQAP senior leader Mohammed Saeed al Umda (also known as Ghareeb al Taizi). A suspected US drone strike killed Fahd Mohammed Ahmed al-Quso and another al-Qaida militant in southern Shabwa province on May 6.

2013 Rada' wedding convoy strike
On December 12, 2013, 17 people in a wedding convoy were killed in the Rada' District of the Governorate of Al-Bayda'. The US drone mistakenly targeted the wedding convoy after intelligence reports identified the vehicles as carrying suspected AQAP members. Although five of the killed were suspects, the remainder were civilians.

2014 airstrikes
On March 3, 2014, an airstrike believed carried out by an American drone killed three suspected AQAP members. Mujahid Gaber Saleh al Shabwani, one of Yemen's 25 most-wanted AQAP operatives, was thought to have been one of those killed. According to a statement released by the Yemeni Interior Ministry, on April 20–21 three US drone strikes killed at least two dozen suspected AQAP members and destroyed one of the group's training camps in southern Yemen. Five civilians were wounded and three killed in the attack. A June 13 suspected US drone strike targeted a car in the Mafraq al-Saeed region of Shabwah province, killing the five alleged AQAP operatives inside.

title: Terrorism in Yemen


text:
Dalton (unit)

The dalton or unified atomic mass unit (symbols: Da or u) is a non-SI unit of mass defined as $1$ of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at rest. The atomic mass constant, denoted mu, is defined identically, giving mu = $1,822.888$ m($1⁄12$C) = 1 Da.

This unit is commonly used in physics and chemistry to express the mass of atomic-scale objects, such as atoms, molecules, and elementary particles, both for discrete instances and multiple types of ensemble averages. For example, an atom of helium-4 has a mass of $1⁄12$. This is an intrinsic property of the isotope and all helium-4 atoms have the same mass. Acetylsalicylic acid (aspirin),, has an average mass of about $12$. However, there are no acetylsalicylic acid molecules with this mass. The two most common masses of individual acetylsalicylic acid molecules are $4.003 Da$, having the most common isotopes, and $180.157 Da$, in which one carbon is carbon-13.

The molecular masses of proteins, nucleic acids, and other large polymers are often expressed with the units kilo dalton (kDa) and mega dalton (MDa). Titin, one of the largest known proteins, has a molecular mass of between 3 and 3.7 megadaltons. The DNA of chromosome 1 in the human genome has about 249 million base pairs, each with an average mass of about $180.042 Da$, or $181.046 Da$ total.

The mole is a unit of amount of substance used in chemistry and physics, which defines the mass of one mole of a substance in grams as numerically equal to the average mass of one of its particles in daltons. That is, the molar mass of a chemical compound is meant to be numerically equal to its average molecular mass. For example, the average mass of one molecule of water is about 18.0153 daltons, and one mole of water is about 18.0153 grams. A protein whose molecule has an average mass of $650 Da$ would have a molar mass of $156 GDa$. However, while this equality can be assumed for practical purposes, it is only approximate, because of the 2019 redefinition of the mole.

In general, the mass in daltons of an atom is numerically close but not exactly equal to the number of nucleons in its nucleus. It follows that the molar mass of a compound (grams per mole) is numerically close to the average number of nucleons contained in each molecule. By definition, the mass of an atom of carbon-12 is 12 daltons, which corresponds with the number of nucleons that it has (6 protons and 6 neutrons). However, the mass of an atomic-scale object is affected by the binding energy of the nucleons in its atomic nuclei, as well as the mass and binding energy of its electrons. Therefore, this equality holds only for the carbon-12 atom in the stated conditions, and will vary for other substances. For example, the mass of an unbound atom of the common hydrogen isotope (hydrogen-1, protium) is $64 kDa$, the mass of a proton is the mass of a free neutron is  and the mass of a hydrogen-2 (deuterium) atom is $64 kg/mol$. In general, the difference (absolute mass excess) is less than 0.1%; exceptions include hydrogen-1 (about 0.8%), helium-3 (0.5%), lithium-6 (0.25%) and beryllium (0.14%).

The dalton differs from the unit of mass in the atomic units systems, which is the electron rest mass (m$1.008 Da$).

Energy equivalents
The atomic mass constant can also be expressed as its energy-equivalent, m$2.014 Da$c$e$. The CODATA recommended values are:

The mass-equivalent is commonly used in place of a unit of mass in particle physics, and these values are also important for the practical determination of relative atomic masses.

Origin of the concept
The interpretation of the law of definite proportions in terms of the atomic theory of matter implied that the masses of atoms of various elements had definite ratios that depended on the elements. While the actual masses were unknown, the relative masses could be deduced from that law. In 1803 John Dalton proposed to use the (still unknown) atomic mass of the lightest atom, hydrogen, as the natural unit of atomic mass. This was the basis of the atomic weight scale.

For technical reasons, in 1898, chemist Wilhelm Ostwald and others proposed to redefine the unit of atomic mass as $u$ the mass of an oxygen atom. That proposal was formally adopted by the International Committee on Atomic Weights (ICAW) in 1903. That was approximately the mass of one hydrogen atom, but oxygen was more amenable to experimental determination. This suggestion was made before the discovery of isotopes in 1912. Physicist Jean Perrin had adopted the same definition in 1909 during his experiments to determine the atomic masses and the Avogadro constant. This definition remained unchanged until 1961. Perrin also defined the "mole" as an amount of a compound that contained as many molecules as 32 grams of oxygen. He called that number the Avogadro number in honor of physicist Amedeo Avogadro.

Isotopic variation
The discovery of isotopes of oxygen in 1929 required a more precise definition of the unit. Two distinct definitions came into use. Chemists choose to define the AMU as $2$ of the average mass of an oxygen atom as found in nature; that is, the average of the masses of the known isotopes, weighted by their natural abundance. Physicists, on the other hand, defined it as $1⁄16$ of the mass of an atom of the isotope oxygen-16 (16O).

Definition by IUPAC
The existence of two distinct units with the same name was confusing, and the difference (about $1⁄16$ in relative terms) was large enough to affect high-precision measurements. Moreover, it was discovered that the isotopes of oxygen had different natural abundances in water and in air. For these and other reasons, in 1961 the International Union of Pure and Applied Chemistry (IUPAC), which had absorbed the ICAW, adopted a new definition of the atomic mass unit for use in both physics and chemistry; namely, $1⁄16$ of the mass of a carbon-12 atom. This new value was intermediate between the two earlier definitions, but closer to the one used by chemists (who would be affected the most by the change).

The new unit was named the "unified atomic mass unit" and given a new symbol "u", to replace the old "amu" that had been used for the oxygen-based units. However, the old symbol "amu" has sometimes been used, after 1961, to refer to the new unit, particularly in lay and preparatory contexts.

With this new definition, the standard atomic weight of carbon is about $1$, and that of oxygen is about $1⁄12$. These values, generally used in chemistry, are based on averages of many samples from Earth's crust, its atmosphere, and organic materials.

Adoption by BIPM
The IUPAC 1961 definition of the unified atomic mass unit, with that name and symbol "u", was adopted by the International Bureau for Weights and Measures (BIPM) in 1971 as a non-SI unit accepted for use with the SI.

Unit name
In 1993, the IUPAC proposed the shorter name "dalton" (with symbol "Da") for the unified atomic mass unit. As with other unit names such as watt and newton, "dalton" is not capitalized in English, but its symbol, "Da", is capitalized. The name was endorsed by the International Union of Pure and Applied Physics (IUPAP) in 2005.

In 2003 the name was recommended to the BIPM by the Consultative Committee for Units, part of the CIPM, as it "is shorter and works better with [SI] prefixes". In 2006, the BIPM included the dalton in its 8th edition of the SI brochure of formal definitions as a non-SI unit accepted for use with the SI. The name was also listed as an alternative to "unified atomic mass unit" by the International Organization for Standardization in 2009. It is now recommended by several scientific publishers, and some of them consider "atomic mass unit" and "amu" deprecated. In 2019, the BIPM retained the dalton in its 9th edition of the SI brochure, while dropping the unified atomic mass unit from its table of non-SI units accepted for use with the SI, but secondarily notes that the dalton (Da) and the unified atomic mass unit (u) are alternative names (and symbols) for the same unit.

2019 redefinition of the SI base units
The definition of the dalton was not affected by the 2019 redefinition of SI base units,  that is, 1 Da in the SI is still $12.011 Da$ of the mass of a carbon-12 atom, a quantity that must be determined experimentally in terms of SI units. However, the definition of a mole was changed to be the amount of substance consisting of exactly entities and the definition of the kilogram was changed as well. As a consequence, the molar mass constant remains close to but no longer exactly 1 g/mol, meaning that the mass in grams of one mole of any substance remains nearly but no longer exactly numerically equal to its average molecular mass in daltons, although the relative standard uncertainty of $15.999 Da$ at the time of the redefinition is insignificant for all practical purposes.

Measurement
Though relative atomic masses are defined for neutral atoms, they are measured (by mass spectrometry) for ions: hence, the measured values must be corrected for the mass of the electrons that were removed to form the ions, and also for the mass equivalent of the electron binding energy, E$1⁄12$/m$4.5$c$b$. The total binding energy of the six electrons in a carbon-12 atom is $u$ = $2$: Eb/muc2 = $1,030.109 eV$, or about one part in 10 million of the mass of the atom.

Before the 2019 redefinition of SI units, experiments were aimed to determine the value of the Avogadro constant for finding the value of the unified atomic mass unit.

Josef Loschmidt
A reasonably accurate value of the atomic mass unit was first obtained indirectly by Josef Loschmidt in 1865, by estimating the number of particles in a given volume of gas.

Jean Perrin
Perrin estimated the Avogadro number by a variety of methods, at the turn of the 20th century. He was awarded the 1926 Nobel Prize in Physics, largely for this work.

Coulometry
The electric charge per mole of elementary charges is a constant called the Faraday constant, F, whose value had been essentially known since 1834 when Michael Faraday published his works on electrolysis. In 1910, Robert Millikan obtained the first measurement of the charge on an electron, −e. The quotient F/e provided an estimate of the Avogadro constant.

The classic experiment is that of Bower and Davis at NIST, and relies on dissolving silver metal away from the anode of an electrolysis cell, while passing a constant electric current I for a known time t. If m is the mass of silver lost from the anode and A$1.65 J$ the atomic weight of silver, then the Faraday constant is given by:

The NIST scientists devised a method to compensate for silver lost from the anode by mechanical causes, and conducted an isotope analysis of the silver used to determine its atomic weight. Their value for the conventional Faraday constant was F$1.106$ = $r$, which corresponds to a value for the Avogadro constant of $90$: both values have a relative standard uncertainty of $96,485.39 C$.

Electron mass measurement
In practice, the atomic mass constant is determined from the electron rest mass m$6.022 mol-1$ and the electron relative atomic mass A$1.3$(e) (that is, the mass of electron divided by the atomic mass constant). The relative atomic mass of the electron can be measured in cyclotron experiments, while the rest mass of the electron can be derived from other physical constants.

where c is the speed of light, h is the Planck constant, α is the fine-structure constant, and R$e$ is the Rydberg constant.

As may be observed from the old values (2014 CODATA) in the table below, the main limiting factor in the precision of the Avogadro constant was the uncertainty in the value of the Planck constant, as all the other constants that contribute to the calculation were known more precisely. The power of having defined values of universal constants as is presently the case can be understood from the table below (2018 CODATA).

X-ray crystal density methods
Silicon single crystals may be produced today in commercial facilities with extremely high purity and with few lattice defects. This method defined the Avogadro constant as the ratio of the molar volume, V$r$, to the atomic volume V$∞$: $$N_{\rm A} =  \frac{V_{\rm m}}{V_{\rm atom}},$$ where V$A$ = $p$ and n is the number of atoms per unit cell of volume Vcell.

The unit cell of silicon has a cubic packing arrangement of 8 atoms, and the unit cell volume may be measured by determining a single unit cell parameter, the length a of one of the sides of the cube. The CODATA value of a for silicon is

In practice, measurements are carried out on a distance known as d$e$(Si), which is the distance between the planes denoted by the Miller indices {220}, and is equal to a/$1,836.153$.

The isotope proportional composition of the sample used must be measured and taken into account. Silicon occurs in three stable isotopes ($9.5$Si, $−0.0003$Si, $u$Si), and the natural variation in their proportions is greater than other uncertainties in the measurements. The atomic weight A$∞$ for the sample crystal can be calculated, as the standard atomic weights of the three nuclides are known with great accuracy. This, together with the measured density ρ of the sample, allows the molar volume V$10,973,731.569 m-1$ to be determined: $$V_{\rm m} = \frac{A_{\rm r}M_{\rm u}}{\rho},$$ where M$5.9$ is the molar mass constant. The CODATA value for the molar volume of silicon is, with a relative standard uncertainty of

title: Dalton (unit)