title: Salerno

text: Salerno (, , ; , ) is an ancient city and "comune" in Campania (southwestern Italy) and is the capital of the namesake province. It is located on the Gulf of Salerno on the Tyrrhenian Sea. In recent history the city hosted Victor Emmanuel III, the King of Italy, who moved from Rome in 1943 after Italy negotiated a peace with the Allies in World War II, making Salerno the capital of the "Government of the South" ("Regno del Sud") and therefore provisional government seat for six months. Some of the Allied landings during Operation Avalanche (the invasion of Italy) occurred near Salerno. Today Salerno is an important cultural and economic centre in Campania and Italy.


title: Salerno

text: Human settlement at Salerno has a rich and vibrant past, dating back to pre-historic times. The site has been one of the most important and strategic ports on the Mediterranean sea, yielding a rich Greco-Roman heritage. It was an independent Lombard principality, Principality of Salerno, in the early Middle Ages. During this time, the Schola Medica Salernitana, the first medical school in the world, was founded. The Normans in 1077 made Salerno the capital of their rule in all continental southern Italy. In the 16th century, under the Sanseverino family, among the most powerful feudal lords in southern Italy, the city became a great centre of learning, culture and the arts, and the family hired several of the greatest intellectuals of the time. Later, in 1694, the city was struck by several catastrophic earthquakes and plagues. During a period of Spanish rule the city suffered a crisis which would last until the 18th century, but under Napoleon Salerno became part of the Parthenopean Republic. In the 19th century Salerno supported ideas of the Risorgimento and welcomed Garibaldi in 1861.


title: Salerno

text: The city is divided into three distinct zones: the medieval sector, the 19th century sector and the more densely populated post-war area, with its several apartment blocks.


title: Salerno

text: A patron saint of Salerno is Saint Matthew, the Apostle, whose relics are kept here at the crypt of Salerno Cathedral.


title: Salerno

text: The area of what is now Salerno has been continuously settled since pre-historical times, as the discoveries of Neolithic mummy remains documents. Inhabited by Oscan-speaking populations, the region was colonized by the Etruscans, who founded the city of Irnthi in the 6th century BC, across the Irno river, in what is today city quarter of Fratte, as a part of their "Dodecapolis" political model they essentially replicated in Campania. This settlement represented an important base for Etruscan trade with the nearby Greek colonies of Posidonia and Elea. It was occupied by the Samnites around the 5th century BC as a consequence of the Battle of Cumae (474 BC) as part of the Syracusan sphere of influence.


title: Salerno

text: With the Roman advance in Campania, Irna began to lose its importance, being supplanted by the new Roman colony (197 BC) of Salernum, developing around an initial "castrum". The new city, which gradually lost its military function in favour of its role as a trade centre, was connected to Rome by the Via Popilia, which ran towards Lucania and Reggio Calabria.


title: Salerno

text: Archaeological remains, although fragmentary, suggest the idea of a flourishing and lively city. Under the Emperor Diocletian, in the late 3rd century AD, Salernum became the administrative centre of the "Lucania and Bruttii" province.


title: Salerno

text: In the following century, during the Gothic Wars, the Goths were defeated by the Byzantines, and the Salerno briefly returned to the control of Constantinople (from 553 to 568), before the Lombards invaded almost the whole peninsula. Like many coastal cities of southern Italy (Gaeta, Sorrento, Amalfi), Salerno initially remained untouched by the newcomers, falling only in 646. It subsequently became part of the Duchy of Benevento.


title: Salerno

text: In 774 Arechis II of Benevento transferred the seat of the Duchy of Benevento to Salerno, in order to elude Charlemagne's offensive and to secure for himself the control of a strategic area, the centre of coastal and internal communications in Campania.


title: Salerno

text: With Arechis II, Salerno became a centre of studies with its famous Medical School. The Lombard prince ordered the city to be fortified; the Castle on the Bonadies mountain had already been built with walls and towers. In 839 Salerno declared independence from Benevento, becoming the capital of a flourishing principality stretching out to Capua, northern Calabria and Apulia up to Taranto. In 871–872, the Aghlabids besieged Salerno, but the city was relieved by Louis II of Italy.


title: Salerno

text: Around the year 1000 prince Guaimar IV annexed Amalfi, Sorrento, Gaeta and the whole duchy of Apulia and Calabria, starting to conceive a future unification of the whole southern Italy under Salerno's arms. The coins minted in the city circulated all over the Mediterranean, with the "Opulenta Salernum" wording to certify its richness.


title: Salerno

text: However, the stability of the Principate was continually shaken by the Saracen attacks and, most of all, by internal struggles. In 1056, one of the numerous plots led to the fall of Guaimar. His weaker son Gisulf II succeeded him, but the decline of the principality had begun. In 1077 Salerno reached its zenith but soon lost all its territory to the Normans.


title: Salerno

text: On 13 December 1076, the Norman conqueror Robert Guiscard, who had married Guaimar IV's daughter Sikelgaita, besieged Salerno and defeated his brother-in-law Gisulf. In this period the royal palace of Castel Terracena and the cathedral were built, and science was boosted as the Schola Medica Salernitana, considered the most ancient medical institution of the European West, reached its maximum splendour. At this time in the late 11th century, the city was home to 50,000 people.


title: Salerno

text: Salerno was the most important city of the Normans for half a century, but with the Norman conquest of southern Italy, the city of Palermo started to substitute Salerno as the most important city for the Normans. Indeed, Salerno played a little part in the fall of the County of Sicily, after the Emperor Henry VI's invasion on behalf of his wife, Constance, the heiress to the kingdom, in 1191, Salerno surrendered and promised loyalty on the mere news of an incoming army.


title: Salerno

text: This so disgusted the archbishop, Nicolò d'Aiello (from Naples), that he abandoned the city and fled to Naples, which held out in a siege. In 1194, the situation reversed itself: Naples capitulated, along with most other cities of the Mezzogiorno, and only Salerno resisted. It was sacked and pillaged, much reducing its importance and prosperity.


title: Salerno

text: Henry had his reasons, though. He had entrusted Constance to some important Salerno citizens (advised & "ruled" by the archbishop d'Aiello) and after his retreat from invasion in 1191 they had received letters about the events from Nicolò D'Aiello and so betrayed Henry, attacked Constance at Castel Terracena and handed her over to King Tancred of Sicily, making the Empress captive for nearly one year. The combined treachery and stubbornness of D'Aiello and his followers cost Salerno much after the Hohenstaufen conquest: Henry's son, Frederick II, moreover, issued a series of edicts that reduced Salerno's role in favour of Naples (in particular, the foundation of the University of Naples in that city).


title: Salerno

text: From the 14th century onwards, most of the Salerno province became the territory of the Princes of Sanseverino, powerful feudal lords who acted as real owners of the region. They accumulated enormous political and administrative power and attracted artists and men of letters in their own princely palace. In the 15th century, the city was the scene of battles between the Angevin and the Aragonese royal houses with whom the local lords took sides alternatingly.


title: Salerno

text: In the first decades of the 16th century, the last descendant of the Sanseverino princes, Ferdinando Sanseverino, was in conflict with the viceroy of the king of Spain, mainly because of his opposition to the Inquisition, causing the ruin of the whole family and the beginning of a long period of decadence for the city.


title: Salerno

text: A slow renewal of the city occurred in the 18th century with the end of the Spanish dominion and the construction of many refined houses and churches characterising the main streets of the historical centre. In 1799 Salerno was incorporated into the Parthenopean Republic. During the Napoleonic era, first Joseph Bonaparte and then Joachim Murat ascended the Neapolitan throne. The latter decreed the closing of the Schola Medica Salernitana, which had been declining for decades to the level of a theoretical school. In the same period, even the religious orders were suppressed and numerous ecclesiastical properties were confiscated.


title: Salerno

text: The city expanded beyond the ancient walls and sea connections were potentiated as they represented an important road network that crossed the town connecting the eastern plain with the area leading to Vietri and Naples.


title: Salerno

text: Salerno was an active center of Carbonari activities supporting the unification of Italy in the 19th century. The majority of the population of Salerno supported ideas of the Risorgimento, and in 1861 many of them joined Garibaldi in his struggle for unification.


title: Salerno

text: After the unification of Italy, a slow urban development continued, many suburban areas were enlarged and large public and private buildings were created. The city went on developing until World War II. Its population rose from 20,000 people around 1861s unification to 80,000 in the early 20th century.


title: Salerno

text: During the 19th century, foreign industries started settling in Salerno: in 1830 the first textile mill was established by the Swiss entrepreneur Züblin Vonwiller, followed by Schlaepfer-Wenner's textile mills and dye factories; the Wenner family settled permanently in Salerno. In 1877 the city was the site of as many as 21 textile mills employing around ten thousand workers; in comparison with the four thousand employed in Turin's textile industry, Salerno was sometimes referred to as the "Manchester of the two Sicilies".


title: Salerno

text: In September 1943, during World War II, Salerno was the scene of Operation Avalanche, the invasion of Italy launched by the Allies of World War II, and suffered a great deal of damage. Henry Wellesley, 6th Duke of Wellington, who was killed in action during the fighting, is buried in Salerno War Cemetery. From 12 February to 17 July 1944, it hosted the Government of Marshal Pietro Badoglio. In those months Salerno was the provisional government seat of the Kingdom of Italy, and the King Vittorio Emanuele III lived in a mansion in its outskirts.


title: Salerno

text: After the war the population of the city doubled in a few years, going from 80,000 in 1946 to nearly 160,000 in 1976.


title: Salerno

text: The city is situated at the northwestern end of the plain of the Sele River, at the exact beginning of the Amalfi coast. The small river Irno crosses through the central section of Salerno. The highest point is "Monte Stella" with its .


title: Salerno

text: Salerno has a Mediterranean climate, with a hot and relatively dry summer (highs of in July and August) and a rainy fall and winter (highs of in January). Usually there is nearly of rain every year. The strong wind that comes from the mountains toward the Gulf of Salerno makes the city very windy (mainly in winter). However, this gives Salerno the advantage of being one of the sunniest towns in Italy.


title: Salerno

text: In 2007, there were 140,580 people residing in Salerno, located in the province of Salerno, Campania, of whom 46.7% were male and 53.3% were female. Minors (children ages 18 and younger) totalled 19.61 per cent of the population compared to pensioners who number 21.86 per cent. This compares with the Italian average of 18.06 per cent (minors) and 19.94 per cent (pensioners). The average age of Salerno residents is 42 compared to the Italian average of 42. In the five years between 2002 and 2007, the population of Salerno grew by 2.02 per cent, while Italy as a whole grew by 3.85 per cent. The current birth rate of Salerno is 7.77 births per 1,000 inhabitants compared to the Italian average of 9.45 births.


title: Salerno

text: As of 31 December 2010, there were 4,355 foreigners in Salerno. The largest immigrant group came from other European countries (mainly Ukraine and Romania). The population is overwhelmingly Roman Catholic.


title: Salerno

text: The economy of Salerno is mainly based on services and tourism, as most of the city's manufacturing base did not survive the economic crisis of the 1970s. The remaining ones are connected to pottery and food production and treatment.


title: Salerno

text: The Port of Salerno is one of the most active of the Tyrrhenian Sea. It handles about 10 million tons of cargo per year, 60% of which is made up by containers.


title: Salerno

text: Salerno station is the main railway station of the city. It is connected to the high-speed railway network via the Milan-Salerno corridor. The main bus stop of Salerno is also at the train station, with both CSTP buses and SITA buses.


title: Salerno

text: A metro light rail line connects the train station with Stadio Arechi, with seven intermediate stops.


title: Salerno

text: A new Maritime Terminal Station, designed by Zaha Hadid Architects, was completed in 2016 and was opened for the 2017 cruise season. Salerno features three marinas: Manfredi Pier, Masuccio Salernitano, and Marina di Arechi (opened in 2015).


title: Salerno

text: Salerno hosted the oldest medical school in the world, the Schola Medica Salernitana, the most important source of medical knowledge in Europe in the early Middle Ages. It was closed in 1811 by Joachim Murat.


title: Salerno

text: In 1944 king Vittorio Emanuele III established Istituto Universitario di Magistero "Giovanni Cuomo". In 1968 the university became state-controlled. Today University of Salerno is located in the neighboring town of Fisciano and has about 34,000 students and ten faculties: Arts and Philosophy, Economics, Education, Engineering, Foreign language and literature, Law, Mathematics, Physics and Natural Sciences, Medicine, Pharmacy and Political Science.


title: Salerno

text: The city's main football team is U.S. Salernitana 1919, that plays in Serie A (the first highest football division in Italy). Their home stadium is Stadio Arechi, opened in 1990 and with a capacity of 37,245.


title: Salerno

text: The most successful team in the city is the women's handball team PDO Handball Team Salerno, with its four national titles, four national cups and two national supercups; other noteworthy teams are Arechi in rugby and Rari Nantes Salerno in water polo.


title: Salerno

text: Salerno is located at the geographical center of a triangle nicknamed "Tourist Triangle of the 3 P's" (namely a triangle with the corners in Pompei, Paestum and Positano). This peculiarity gives Salerno special tourist characteristics that are increased by the many local points of tourist interest like the "Lungomare Trieste" ("Trieste Seafront Promenade"), the "Castello di Arechi" ("Arechis' Castle"), the "Duomo" (cathedral) and the "Museo Didattico della Scuola Medica Salernitana" ("Educational Museum of the Salernitan Medical School").


title: Post hoc ergo propter hoc

text: Post hoc ergo propter hoc (Latin: 'after this, therefore because of this') is an informal fallacy that states: "Since event Y "followed" event X, event Y must have been "caused" by event X." It is often shortened simply to post hoc fallacy. A logical fallacy of the questionable cause variety, it is subtly different from the fallacy "cum hoc ergo propter hoc" ('with this, therefore because of this'), in which two events occur simultaneously or the chronological ordering is insignificant or unknown. Post hoc is a logical fallacy in which one event seems to be the cause of a later event because it occurred earlier.


title: Post hoc ergo propter hoc

text: "Post hoc" is a particularly tempting error because correlation sometimes appears to suggest causality. The fallacy lies in a conclusion based "solely" on the order of events, rather than taking into account other factors potentially responsible for the result that might rule out the connection.


title: Post hoc ergo propter hoc

text: A simple example is "the rooster crows immediately before sunrise; therefore the rooster causes the sun to rise."


title: Post hoc ergo propter hoc

text: When B is undesirable, this pattern is often combined with the formal fallacy of denying the antecedent, assuming the logical inverse holds: Avoiding A will prevent B.


title: Guardians of the Galaxy: Cosmic Rewind

text: "Guardians of the Galaxy": Cosmic Rewind is an enclosed roller coaster at Epcot at Walt Disney World, manufactured by Dutch company Vekoma. Based on the Marvel Cinematic Universe "Guardians of the Galaxy" films, the attraction is the first at Walt Disney World to feature characters from the Marvel Universe. Opened on May 27, 2022, it is Epcot's first roller coaster and Disney's first backwards-launched roller coaster. It replaced the Universe of Energy pavilion, which closed on August 13, 2017.


title: Guardians of the Galaxy: Cosmic Rewind

text: Originally set to open in 2021, the attraction was delayed to summer 2022 as part of Epcot's 40th anniversary celebration, which is part of Walt Disney World's 50th Anniversary celebration. The opening was postponed when Walt Disney World closed due to the COVID-19 pandemic.


title: Guardians of the Galaxy: Cosmic Rewind

text: The attraction was announced as part of an overhaul of Epcot at the 2017 D23 Expo. Ellen's Energy Adventure closed on August 13, 2017 and construction of the roller coaster began later in the same month. The show building that housed Universe of Energy was reused and retrofitted for the new attraction. The roller coaster itself is housed in a new, massive show building situated backstage behind the Universe of Energy building and the PLAY! pavilion, which utilized 960 truckloads of concrete for its foundation. The first track piece of the ride was installed November 2018.


title: Guardians of the Galaxy: Cosmic Rewind

text: At D23 Japan in 2018, it was confirmed that the ride would be one of the world's longest enclosed roller coasters, set to open during the 50th anniversary celebration of Walt Disney World, late 2021.


title: Guardians of the Galaxy: Cosmic Rewind

text: The name of the ride, "Guardians of the Galaxy": Cosmic Rewind, was announced on August 25, 2019, at the D23 Expo 2019. Filming for the ride commenced in October 2021. "Guardians of the Galaxy" film series cast members Chris Pratt, Zoe Saldaña, Dave Bautista, and Glenn Close reprised their roles from the Marvel Cinematic Universe (MCU) as Peter Quill / Star-Lord, Gamora, Drax, and Nova Prime Irani Rael, respectively. The first footage from the ride was released in March 2022. Disney Parks, through social media, also revealed on April 25, 2022, that actor Terry Crews would be part of the pre-show experience, playing Centurion Tal Marik, a new character created specifically for the attraction.


title: Guardians of the Galaxy: Cosmic Rewind

text: Cast Member previews for the attraction began on April 17, 2022, while Walt Disney World Annual Passholders received an early look at the ride beginning on May 8, 2022. The attraction eventually held its grand opening ceremony on May 27, 2022, opening to the public on the same day. Similar to the attractions within Avengers Campus, the attraction is inspired by, but not canonical to, the MCU.


title: Guardians of the Galaxy: Cosmic Rewind

text: On June 23, 2022, Disney announced that Cosmic Rewind would receive a Christmas overlay with a holiday mixtape soundtrack, featuring "a mash-up of seasonal jams". The limited offering began on November 25, 2022, coinciding with the release of "The Guardians of the Galaxy Holiday Special" on Disney+ the same day, running until December 30, 2022.


title: Guardians of the Galaxy: Cosmic Rewind

text: The attraction is presented as the Wonders of Xandar Pavilion, the first Other-world Pavilion at Epcot. Much like the pavilions at the World Showcase, it features exhibits and models of the history and culture of the capital of the Nova Empire, Xandar, presented by the Nova Corps as a cultural exchange from them to the people of Terra (the name by which they refer to Earth). At the entrance of the attraction sits a Starblaster ship of the Xandarian Nova Corps on a perch.


title: Guardians of the Galaxy: Cosmic Rewind

text: The queue begins in the "Galaxarium", a galaxy-equivalent to a planetarium, where a Xandarian super computer named World Mind, explains how they are learning about the culture of Terrans (as the Xandarians refer to the inhabitants of Earth). The queue continues up a ramp into the gallery that features a projection mapping model of Xandar, along with screens showcasing their culture, noting the similarities of the capital of the Nova Empire with Walt Disney's EPCOT concept. Along the gallery, models of Xandarian ships are also displayed, as well as uniforms of the Nova Corps high-ranking officers and interviews with each member of the Guardians of the Galaxy, especially Peter Quill / Star-Lord, who exclaims his excitement to go back and experience the attractions he visited as a child at EPCOT, unaware that the ones he mentions no longer exist.


title: Guardians of the Galaxy: Cosmic Rewind

text: At the end of the gallery, Terrans are ushered to the final stop of the Wonders of Xandar Pavilion, hosted by Nova Prime Irani Rael (portrayed by Glenn Close) of the Nova Corps. She welcomes the guests and begins by explaining how both Xandar and Terra were born of the same moment - the Big Bang. She then details how the Xandarians travelled through the galaxy to reach Terra to showcase their culture: by utilizing a Cosmic Generator, a piece of Xandarian technology that creates "jumpholes" that allowed them to create shortcuts to reach their destination much quicker. As a culmination of the Wonders of Xandar Pavilion, Terrans will be teleported to a Nova ship in space to demonstrate the Cosmic Generator. After Nova Prime's presentation, Centurion Tal Marik (portrayed by Terry Crews) of the Nova Corps, welcomes Terrans and advises the prohibition of communication devices with recording capabilities (i.e. cellphones and smartphones), after which Terrans are ushered into the teleportation chamber.


title: Guardians of the Galaxy: Cosmic Rewind

text: After Terrans have been teleported to the Nova ship, the Cosmic Generator is stolen and the ship loses its power before a demonstration could be presented, prompting Nova Prime to urgently call the Guardians of the Galaxy for help. Peter Quill / Star-Lord (portrayed by Chris Pratt), Gamora (portrayed by Zoe Saldaña), Drax (portrayed by Dave Bautista), Rocket and Groot all appear on screen answering the distress call, only to discover that a Celestial named Eson, seen outside the Nova ship, has stolen the Cosmic Generator. Unhappy with the Terrans, the Celestial uses the Cosmic Generator to send Terra through a jumppoint to the dawn of time, with the intention of erasing its existence, before entering the jumppoint itself.


title: Guardians of the Galaxy: Cosmic Rewind

text: Quill urges Centurion Tal Marik to follow Eson while the Guardians rendezvous with the Nova ship to stop the Celestial but is unable to do so due to the lack of power in the ship and needing to send Terrans to evacuation shuttles. However, Rocket suggests he can control the shuttles to have the Terrans follow Eson via jumpholes and rendezvous with them instead, as they are their only way of tracking the Celestial in order to recover the Cosmic Generator. Terrans are then led to the corridors of the loading platforms to board their evacuation shuttles.


title: Guardians of the Galaxy: Cosmic Rewind

text: As the shuttles depart, Terrans begin making their way out of the Nova ship to enter the jumppoint in their evacuation shuttles. Peter Quill / Star-Lord and Gamora assure them that they're tracking the shuttles to meet them, while Drax and Rocket instead make pessimistic remarks about the situation. The Guardians wish the Terrans luck as they set off, and after crossing the jumppoint the Terrans arrive at Eson's location, where it holds the Cosmic Generator. Shortly after, the Guardians of the Galaxy arrive in their ship as Eson prepares to throw the Cosmic Generator towards Terra, who disregards Quill's music from the Guardians' ship as "noise". The Guardians then blast the Cosmic Generator from the Celestial's hands, opening another jumppoint which proceeds to suck everything in, taking them all the way back in time to the Big Bang and eventually fading into complete darkness. Suddenly, the evacuation shuttles are launched backwards in an explosion, and it is at this point that the vehicles begin their spinning profiles on their axis to achieve a sensation of "space travel" while the story develops around them with a randomized song selection out of six.


title: Guardians of the Galaxy: Cosmic Rewind

text: As the evacuation shuttles travel through multiple jumpholes along the way, the Guardians of the Galaxy engage in combat with Eson around the Terrans as they also cross multiple jumppoints. The Guardians finally lead a fleet of Nova Corp Starblasters to Eson, who manage to contain the Celestial and recover the Cosmic Generator. As the Guardians of the Galaxy travel far from the scene, they lead the Terrans to a final series of jumpholes that takes them to the Milky Way, then around the Moon before locking the coordinates for EPCOT and sending them back to Terra. As they arrive, Peter Quill welcomes the Terrans to the Guardians of the Galaxy, the rest of the team remarking amongst themselves as they disembark.


title: Guardians of the Galaxy: Cosmic Rewind

text: Actors from the "Guardians of the Galaxy" films reprised their roles for the attraction. However, Bradley Cooper and Vin Diesel, who voice Rocket and Groot, respectively in the films, were not involved in the project. Terry Crews plays a new character created specifically for the attraction.


title: Guardians of the Galaxy: Cosmic Rewind

text: Like in the "Guardians of the Galaxy" films, music plays a key role in the attraction. Over a hundred songs were considered by Walt Disney Imagineering for the ride experience, narrowing it down to six randomly-selected featured songs, each fitting the same motion profile of the ride vehicles:


title: Guardians of the Galaxy: Cosmic Rewind

text: Additionally, Tyler Bates, composer of "Guardians of the Galaxy" and "Guardians of the Galaxy: Vol. 2", scored over two hours of original music for the queue. An electric guitar cover of the original Universe of Energy attraction's theme song (written by Joel Hirschhorn and Al Kasha) can also be heard before the attraction's backwards launch.


title: Guardians of the Galaxy: Cosmic Rewind

text: On June 23, 2022, Disney announced that Cosmic Rewind would receive a Christmas overlay with a holiday mixtape soundtrack, featuring "a mash-up of seasonal jams". On October 7, 2022, at New York Comic Con, Disney announced the overlay’s title: "Guardians of the Galaxy": Cosmic Rewind Holiday Remix. The limited offering began on November 25, 2022, coinciding with the release of "The Guardians of the Galaxy Holiday Special" on Disney+ the same day, running until December 30, 2022. The Holiday Remix includes five songs, one of which, "Run Rudolph Run" has lyrics changed to reflect Rocket:


title: Reactive oxygen species

text: In chemistry, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (). Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen.


title: Reactive oxygen species

text: The reduction of molecular oxygen () produces superoxide (), which is the precursor to most other reactive oxygen species:


title: Reactive oxygen species

text: Hydrogen peroxide in turn may be partially reduced, thus forming hydroxide ions and hydroxyl radicals (), or fully reduced to water:


title: Reactive oxygen species

text: In a biological context, ROS are byproducts of the normal metabolism of oxygen. ROS have roles in cell signaling and homeostasis. ROS are intrinsic to cellular functioning, and are present at low and stationary levels in normal cells. In plants, ROS are involved in metabolic processes related to photoprotection and tolerance to various types of stress. However, ROS can cause irreversible damage to DNA as they oxidize and modify some cellular components and prevent them from performing their original functions. This suggests that ROS has a dual role; whether they will act as harmful, protective or signaling factors depends on the balance between ROS production and disposal at the right time and place. In other words, oxygen toxicity can arise both from uncontrolled production and from the inefficient elimination of ROS by the antioxidant system.


title: Reactive oxygen species

text: During times of environmental stress (e.g., UV or heat exposure), ROS levels can increase dramatically. This may result in significant damage to cell structures. Cumulatively, this is known as oxidative stress. The production of ROS is strongly influenced by stress factor responses in plants, these factors that increase ROS production include drought, salinity, chilling, defense of pathogens, nutrient deficiency, metal toxicity and UV-B radiation. ROS are also generated by exogenous sources such as ionizing radiation generating irreversible effects in the development of tissues in both animals and plants.


title: Reactive oxygen species

text: ROS are produced by biochemical reactions that occur during the processes of respiration and photosynthesis in organelles such as mitochondria, peroxisomes and chloroplasts. During the respiration process the mitochondria convert energy for the cell into a usable form, adenosine triphosphate (ATP). The process of ATP production in the mitochondria, called oxidative phosphorylation, involves the transport of protons (hydrogen ions) across the inner mitochondrial membrane by means of the electron transport chain. In the electron transport chain, electrons are passed through a series of proteins via oxidation-reduction reactions, with each acceptor protein along the chain having a greater reduction potential than the previous. The last destination for an electron along this chain is an oxygen molecule. In normal conditions, the oxygen is reduced to produce water; however, in about 0.1–2% of electrons passing through the chain (this number derives from studies in isolated mitochondria, though the exact rate in live organisms is yet to be fully agreed upon), oxygen is instead prematurely and incompletely reduced to give the superoxide radical (), most well documented for Complex I and Complex III.


title: Reactive oxygen species

text: Another source of ROS production in animal cells is the electron transfer reactions catalyzed by the mitochondrial P450 systems in steroidogenic tissues.


title: Reactive oxygen species

text: These P450 systems are dependent on the transfer of electrons from NADPH to P450. During this process, some electrons "leak" and react with O producing superoxide. To cope with this natural source of ROS, the steroidogenic tissues, ovary and testis, have a large concentration of antioxidants such as vitamin C (ascorbate) and β-carotene and anti-oxidant enzymes.


title: Reactive oxygen species

text: In addition, ROS are produced in immune cell signaling via the NOX pathway. Phagocytic cells such as neutrophils, eosinophils, and mononuclear phagocytes produce ROS when stimulated.


title: Reactive oxygen species

text: In chloroplasts, the carboxylation and oxygenation reactions catalyzed by rubisco ensure that the functioning of the electron transport chain (ETC) occurs in an environment rich in O. The leakage of electrons in the ETC will inevitably produce ROS within the chloroplasts.


title: Reactive oxygen species

text: ETC in photosystem I (PSI) was once believed to be the only source of ROS in chloroplasts. According to Huang et al. the flow of electrons from the excited reaction centers is directed to the NADP and these are reduced to NADPH, and then they enter the Calvin cycle and reduce the final electron acceptor, CO. In cases where there is an ETC overload, part of the electron flow is diverted from ferredoxin to O, forming the superoxide free radical (by the Mehler reaction). In addition, electron leakage to O can also occur from the 2Fe-2S and 4Fe-4S clusters in the PSI ETC. However, PSII also provides electron leakage locations (QA, QB) for O-producing O-. Superoxide (O-) is generated from PSII, instead of PSI; QB is shown as the location for the generation of O•-.


title: Reactive oxygen species

text: The formation of ROS can be stimulated by a variety of agents such as pollutants, heavy metals, tobacco, smoke, drugs, xenobiotics, microplastics, or radiation. In plants, in addition to the action of dry abiotic factors, high temperature, interaction with other living beings can influence the production of ROS.


title: Reactive oxygen species

text: Ionizing radiation can generate damaging intermediates through the interaction with water, a process termed radiolysis. Since water comprises 55–60% of the human body, the probability of radiolysis is quite high under the presence of ionizing radiation. In the process, water loses an electron and becomes highly reactive. Then through a three-step chain reaction, water is sequentially converted to hydroxyl radical (OH), hydrogen peroxide (HO), superoxide radical (), and ultimately oxygen (O).


title: Reactive oxygen species

text: The hydroxyl radical is extremely reactive and immediately removes electrons from any molecule in its path, turning that molecule into a free radical and thus propagating a chain reaction. However, hydrogen peroxide is actually more damaging to DNA than the hydroxyl radical, since the lower reactivity of hydrogen peroxide provides enough time for the molecule to travel into the nucleus of the cell, subsequently reacting with macromolecules such as DNA.


title: Reactive oxygen species

text: In plants, the production of ROS occurs during events of abiotic stress that lead to a reduction or interruption of metabolic activity. For example, the increase in temperature, drought are factors that limit the availability of CO due to stomatal closure, increasing the production of ROS, such as O·- and O in chloroplasts. The production of O in chloroplasts can cause reprogramming of the expression of nucleus genes leading to chlorosis and programmed cell death.


title: Reactive oxygen species

text: In cases of biotic stress, the generation of ROS occurs quickly and weakly initially and then becomes more solid and lasting. The first phase of ROS accumulation is associated with plant infection and is probably independent of the synthesis of new ROS-generating enzymes. However, the second phase of ROS accumulation is associated only with infection by non-virulent pathogens and is an induced response dependent on increased mRNA transcription encoding enzymes.


title: Reactive oxygen species

text: Superoxide dismutases (SOD) are a class of enzymes that catalyzes the dismutation of superoxide into oxygen and hydrogen peroxide. As such, they are an important antioxidant defense in nearly all cells exposed to oxygen. In mammals and most chordates, three forms of superoxide dismutase are present. SOD1 is located primarily in the cytoplasm, SOD2 in the mitochondria and SOD3 is extracellular. The first is a dimer (consists of two units), while the others are tetramers (four subunits). SOD1 and SOD3 contain copper and zinc ions, while SOD2 has a manganese ion in its reactive centre. The genes are located on chromosomes 21, 6, and 4, respectively (21q22.1, 6q25.3 and 4p15.3-p15.1).


title: Reactive oxygen species

text: where M = Cu ("n" = 1); Mn ("n" = 2); Fe ("n" = 2); Ni ("n" = 2). In this reaction the oxidation state of the metal cation oscillates between "n" and "n" + 1.


title: Reactive oxygen species

text: Catalase, which is concentrated in peroxisomes located next to mitochondria, reacts with the hydrogen peroxide to catalyze the formation of water and oxygen. Glutathione peroxidase reduces hydrogen peroxide by transferring the energy of the reactive peroxides to a sulfur-containing tripeptide called glutathione. The sulfur contained in these enzymes acts as the reactive center, carrying reactive electrons from the peroxide to the glutathione. Peroxiredoxins also degrade HO, within the mitochondria, cytosol, and nucleus.


title: Reactive oxygen species

text: Another type of reactive oxygen species is singlet oxygen (O) which is produced for example as byproduct of photosynthesis in plants. In the presence of light and oxygen, photosensitizers such as chlorophyll may convert triplet (O) to singlet oxygen:


title: Reactive oxygen species

text: Singlet oxygen is highly reactive, especially with organic compounds that contain double bonds. The resulting damage caused by singlet oxygen reduces the photosynthetic efficiency of chloroplasts. In plants exposed to excess light, the increased production of singlet oxygen can result in cell death. Various substances such as carotenoids, tocopherols and plastoquinones contained in chloroplasts quench singlet oxygen and protect against its toxic effects. In addition to direct toxicity, singlet oxygen acts a signaling molecule. Oxidized products of β-carotene arising from the presence of singlet oxygen act as second messengers that can either protect against singlet oxygen induced toxicity or initiate programmed cell death. Levels of jasmonate play a key role in the decision between cell acclimation or cell death in response to elevated levels of this reactive oxygen species.


title: Reactive oxygen species

text: Effects of ROS on cell metabolism are well documented in a variety of species. These include not only roles in apoptosis (programmed cell death) but also positive effects such as the induction of host defencegenes and mobilization of ion transporters. This implicates them in control of cellular function. In particular, platelets involved in wound repair and blood homeostasis release ROS to recruit additional platelets to sites of injury. These also provide a link to the adaptive immune system via the recruitment of leukocytes.


title: Reactive oxygen species

text: Reactive oxygen species are implicated in cellular activity to a variety of inflammatory responses including cardiovascular disease. They may also be involved in hearing impairment via cochlear damage induced by elevated sound levels, in ototoxicity of drugs such as cisplatin, and in congenital deafness in both animals and humans. ROS are also implicated in mediation of apoptosis or programmed cell death and ischaemic injury. Specific examples include stroke and heart attack.


title: Reactive oxygen species

text: When a plant recognizes an attacking pathogen, one of the first induced reactions is to rapidly produce superoxide () or hydrogen peroxide () to strengthen the cell wall. This prevents the spread of the pathogen to other parts of the plant, essentially forming a net around the pathogen to restrict movement and reproduction.


title: Reactive oxygen species

text: In the mammalian host, ROS is induced as an antimicrobial defense. To highlight the importance of this defense, individuals with chronic granulomatous disease who have deficiencies in generating ROS, are highly susceptible to infection by a broad range of microbes including "Salmonella enterica", "Staphylococcus aureus", "Serratia marcescens", and "Aspergillus" spp.


title: Reactive oxygen species

text: Studies on the homeostasis of the "Drosophila melanogaster"’s intestines have shown the production of ROS as a key component of the immune response in the gut of the fly. ROS acts both as a bactericide, damaging the bacterial DNA, RNA and proteins, as well as a signalling molecule that induces repair mechanisms of the epithelium. The uracil released by microorganism triggers the production and activity of Duox, the ROS-producing enzyme in the intestine. Duox activity is induced according to the level of uracil in the gut; under basal conditions, it is down-regulated by the protein kinase MkP3. The tight regulation of Duox avoids excessive production of ROS and facilitates differentiation between benign and damage-inducing microorganisms in the gut.


title: Reactive oxygen species

text: The manner in which ROS defends the host from invading microbe is not fully understood. One of the more likely modes of defense is damage to microbial DNA. Studies using Salmonella demonstrated that DNA repair mechanisms were required to resist killing by ROS. A role for ROS in antiviral defense mechanisms has been demonstrated via Rig-like helicase-1 and mitochondrial antiviral signaling protein. Increased levels of ROS potentiate signaling through this mitochondria-associated antiviral receptor to activate interferon regulatory factor (IRF)-3, IRF-7, and nuclear factor kappa B (NF-κB), resulting in an antiviral state. Respiratory epithelial cells induce mitochondrial ROS in response to influenza infection. This induction of ROS led to the induction of type III interferon and the induction of an antiviral state, limiting viral replication. In host defense against mycobacteria, ROS play a role, although direct killing is likely not the key mechanism; rather, ROS likely affect ROS-dependent signalling controls, such as cytokine production, autophagy, and granuloma formation.


title: Reactive oxygen species

text: In aerobic organisms the energy needed to fuel biological functions is produced in the mitochondria via the electron transport chain. Reactive oxygen species (ROS) with the potential to cause cellular damage are produced along with the release of energy. ROS can damage lipids, DNA, RNA, and proteins, which, in theory, contributes to the physiology of aging.


title: Reactive oxygen species

text: ROS are produced as a normal product of cellular metabolism. In particular, one major contributor to oxidative damage is hydrogen peroxide (HO), which is converted from superoxide that leaks from the mitochondria. Catalase and superoxide dismutase ameliorate the damaging effects of hydrogen peroxide and superoxide, respectively, by converting these compounds into oxygen and hydrogen peroxide (which is later converted to water), resulting in the production of benign molecules. However, this conversion is not 100% efficient, and residual peroxides persist in the cell. While ROS are produced as a product of normal cellular functioning, excessive amounts can cause deleterious effects.


title: Reactive oxygen species

text: Memory capabilities decline with age, evident in human degenerative diseases such as Alzheimer's disease, which is accompanied by an accumulation of oxidative damage. Current studies demonstrate that the accumulation of ROS can decrease an organism's fitness because oxidative damage is a contributor to senescence. In particular, the accumulation of oxidative damage may lead to cognitive dysfunction, as demonstrated in a study in which old rats were given mitochondrial metabolites and then given cognitive tests. Results showed that the rats performed better after receiving the metabolites, suggesting that the metabolites reduced oxidative damage and improved mitochondrial function. Accumulating oxidative damage can then affect the efficiency of mitochondria and further increase the rate of ROS production. The accumulation of oxidative damage and its implications for aging depends on the particular tissue type where the damage is occurring. Additional experimental results suggest that oxidative damage is responsible for age-related decline in brain functioning. Older gerbils were found to have higher levels of oxidized protein in comparison to younger gerbils. Treatment of old and young mice with a spin trapping compound caused a decrease in the level of oxidized proteins in older gerbils but did not have an effect on younger gerbils. In addition, older gerbils performed cognitive tasks better during treatment but ceased functional capacity when treatment was discontinued, causing oxidized protein levels to increase. This led researchers to conclude that oxidation of cellular proteins is potentially important for brain function.


title: Reactive oxygen species

text: According to the free radical theory of aging, oxidative damage initiated by reactive oxygen species is a major contributor to the functional decline that is characteristic of aging. While studies in invertebrate models indicate that animals genetically engineered to lack specific antioxidant enzymes (such as SOD), in general, show a shortened lifespan (as one would expect from the theory), the converse manipulation, increasing the levels of antioxidant enzymes, has yielded inconsistent effects on lifespan (though some studies in "Drosophila" do show that lifespan can be increased by the overexpression of MnSOD or glutathione biosynthesizing enzymes). Also contrary to this theory, deletion of mitochondrial SOD2 can extend lifespan in "Caenorhabditis elegans".


title: Reactive oxygen species

text: In mice, the story is somewhat similar. Deleting antioxidant enzymes, in general, yields shorter lifespan, although overexpression studies have not (with some exceptions) consistently extended lifespan. Study of a rat model of premature aging found increased oxidative stress, reduced antioxidant enzyme activity and substantially greater DNA damage in the brain neocortex and hippocampus of the prematurely aged rats than in normally aging control rats. The DNA damage 8-OHdG is a product of ROS interaction with DNA. Numerous studies have shown that 8-OHdG increases with age (see DNA damage theory of aging).


title: Reactive oxygen species

text: Exposure of spermatozoa to oxidative stress is a major causative agent of male infertility. Sperm DNA fragmentation, caused by oxidative stress, appears to be an important factor in the etiology of male infertility. A high level of the oxidative DNA damage 8-OHdG is associated with abnormal spermatozoa and male infertility.


title: Reactive oxygen species

text: ROS are constantly generated and eliminated in the biological system and are required to drive regulatory pathways. Under normal physiological conditions, cells control ROS levels by balancing the generation of ROS with their elimination by scavenging systems. But under oxidative stress conditions, excessive ROS can damage cellular proteins, lipids and DNA, leading to fatal lesions in the cell that contribute to carcinogenesis.


title: Reactive oxygen species

text: Cancer cells exhibit greater ROS stress than normal cells do, partly due to oncogenic stimulation, increased metabolic activity and mitochondrial malfunction. ROS is a double-edged sword. On one hand, at low levels, ROS facilitates cancer cell survival since cell-cycle progression driven by growth factors and receptor tyrosine kinases (RTK) require ROS for activation and chronic inflammation, a major mediator of cancer, is regulated by ROS. On the other hand, a high level of ROS can suppress tumor growth through the sustained activation of cell-cycle inhibitor and induction of cell death as well as senescence by damaging macromolecules. In fact, most of the chemotherapeutic and radiotherapeutic agents kill cancer cells by augmenting ROS stress. The ability of cancer cells to distinguish between ROS as a survival or apoptotic signal is controlled by the dosage, duration, type, and site of ROS production. Modest levels of ROS are required for cancer cells to survive, whereas excessive levels kill them.


title: Reactive oxygen species

text: Metabolic adaptation in tumours balances the cells' need for energy with equally important need for macromolecular building blocks and tighter control of redox balance. As a result, production of NADPH is greatly enhanced, which functions as a cofactor to provide reducing power in many enzymatic reactions for macromolecular biosynthesis and at the same time rescuing the cells from excessive ROS produced during rapid proliferation. Cells counterbalance the detrimental effects of ROS by producing antioxidant molecules, such as reduced glutathione (GSH) and thioredoxin (TRX), which rely on the reducing power of NADPH to maintain their activities.


title: Reactive oxygen species

text: Most risk factors associated with cancer interact with cells through the generation of ROS. ROS then activate various transcription factors such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), activator protein-1 (AP-1), hypoxia-inducible factor-1α and signal transducer and activator of transcription 3 (STAT3), leading to expression of proteins that control inflammation; cellular transformation; tumor cell survival; tumor cell proliferation; and invasion, angiogenesis as well as metastasis. And ROS also control the expression of various tumor suppressor genes such as p53, retinoblastoma gene (Rb), and phosphatase and tensin homolog (PTEN).


title: Reactive oxygen species

text: ROS-related oxidation of DNA is one of the main causes of mutations, which can produce several types of DNA damage, including non-bulky (8-oxoguanine and formamidopyrimidine) and bulky (cyclopurine and etheno adducts) base modifications, abasic sites, non-conventional single-strand breaks, protein-DNA adducts, and intra/interstrand DNA crosslinks. It has been estimated that endogenous ROS produced via normal cell metabolism modify approximately 20,000 bases of DNA per day in a single cell. 8-oxoguanine is the most abundant among various oxidized nitrogeneous bases observed. During DNA replication, DNA polymerase mispairs 8-oxoguanine with adenine, leading to a G→T transversion mutation. The resulting genomic instability directly contributes to carcinogenesis. Cellular transformation leads to cancer and interaction of atypical PKC-ζ isoform with p47phox controls ROS production and transformation from apoptotic cancer stem cells through blebbishield emergency program.


title: Reactive oxygen species

text: Uncontrolled proliferation is a hallmark of cancer cells. Both exogenous and endogenous ROS have been shown to enhance proliferation of cancer cells. The role of ROS in promoting tumor proliferation is further supported by the observation that agents with potential to inhibit ROS generation can also inhibit cancer cell proliferation. Although ROS can promote tumor cell proliferation, a great increase in ROS has been associated with reduced cancer cell proliferation by induction of G2/M cell cycle arrest; increased phosphorylation of ataxia telangiectasia mutated (ATM), checkpoint kinase 1 (Chk 1), Chk 2; and reduced cell division cycle 25 homolog c (CDC25).


title: Reactive oxygen species

text: A cancer cell can die in three ways: apoptosis, necrosis, and autophagy. Excessive ROS can induce apoptosis through both the extrinsic and intrinsic pathways. In the extrinsic pathway of apoptosis, ROS are generated by Fas ligand as an upstream event for Fas activation via phosphorylation, which is necessary for subsequent recruitment of Fas-associated protein with death domain and caspase 8 as well as apoptosis induction. In the intrinsic pathway, ROS function to facilitate cytochrome c release by activating pore-stabilizing proteins (Bcl-2 and Bcl-xL) as well as inhibiting pore-destabilizing proteins (Bcl-2-associated X protein, Bcl-2 homologous antagonist/killer). The intrinsic pathway is also known as the caspase cascade and is induced through mitochondrial damage which triggers the release of cytochrome c. DNA damage, oxidative stress, and loss of mitochondrial membrane potential lead to the release of the pro-apoptotic proteins mentioned above stimulating apoptosis. Mitochondrial damage is closely linked to apoptosis and since mitochondria are easily targeted there is potential for cancer therapy.


title: Reactive oxygen species

text: The cytotoxic nature of ROS is a driving force behind apoptosis, but in even higher amounts, ROS can result in both apoptosis and necrosis, a form of uncontrolled cell death, in cancer cells.


title: Reactive oxygen species

text: Numerous studies have shown the pathways and associations between ROS levels and apoptosis, but a newer line of study has connected ROS levels and autophagy. ROS can also induce cell death through autophagy, which is a self-catabolic process involving sequestration of cytoplasmic contents (exhausted or damaged organelles and protein aggregates) for degradation in lysosomes. Therefore, autophagy can also regulate the cell's health in times of oxidative stress. Autophagy can be induced by ROS levels through many pathways in the cell in an attempt to dispose of harmful organelles and prevent damage, such as carcinogens, without inducing apoptosis. Autophagic cell death can be prompted by the over expression of autophagy where the cell digests too much of itself in an attempt to minimize the damage and can no longer survive. When this type of cell death occurs, an increase or loss of control of autophagy regulating genes is commonly co-observed. Thus, once a more in-depth understanding of autophagic cell death is attained and its relation to ROS, this form of programmed cell death may serve as a future cancer therapy.


title: Reactive oxygen species

text: Autophagy and apoptosis are distinct mechanisms for cell death brought on by high levels of ROS. Aautophagy and apoptosis, however, rarely act through strictly independent pathways. There is a clear connection between ROS and autophagy and a correlation seen between excessive amounts of ROS leading to apoptosis. The depolarization of the mitochondrial membrane is also characteristic of the initiation of autophagy. When mitochondria are damaged and begin to release ROS, autophagy is initiated to dispose of the damaging organelle. If a drug targets mitochondria and creates ROS, autophagy may dispose of so many mitochondria and other damaged organelles that the cell is no longer viable. The extensive amount of ROS and mitochondrial damage may also signal for apoptosis. The balance of autophagy within the cell and the crosstalk between autophagy and apoptosis mediated by ROS is crucial for a cell's survival. This crosstalk and connection between autophagy and apoptosis could be a mechanism targeted by cancer therapies or used in combination therapies for highly resistant cancers.


title: Reactive oxygen species

text: After growth factor stimulation of RTKs, ROS can trigger activation of signaling pathways involved in cell migration and invasion such as members of the mitogen activated protein kinase (MAPK) family – extracellular regulated kinase (ERK), c-jun NH-2 terminal kinase (JNK) and p38 MAPK. ROS can also promote migration by augmenting phosphorylation of the focal adhesion kinase (FAK) p130Cas and paxilin.


title: Reactive oxygen species

text: Both in vitro and in vivo, ROS have been shown to induce transcription factors and modulate signaling molecules involved in angiogenesis (MMP, VEGF) and metastasis (upregulation of AP-1, CXCR4, AKT and downregulation of PTEN).


title: Reactive oxygen species

text: Experimental and epidemiologic research over the past several years has indicated close associations among ROS, chronic inflammation, and cancer. ROS induces chronic inflammation by the induction of COX-2, inflammatory cytokines (TNFα, interleukin 1 (IL-1), IL-6), chemokines (IL-8, CXCR4) and pro-inflammatory transcription factors (NF-κB). These chemokines and chemokine receptors, in turn, promote invasion and metastasis of various tumor types.


title: Reactive oxygen species

text: Both ROS-elevating and ROS-eliminating strategies have been developed with the former being predominantly used. Cancer cells with elevated ROS levels depend heavily on the antioxidant defense system. ROS-elevating drugs further increase cellular ROS stress level, either by direct ROS-generation (e.g. motexafin gadolinium, elesclomol) or by agents that abrogate the inherent antioxidant system such as SOD inhibitor (e.g. ATN-224, 2-methoxyestradiol) and GSH inhibitor (e.g. PEITC, buthionine sulfoximine (BSO)). The result is an overall increase in endogenous ROS, which when above a cellular tolerability threshold, may induce cell death. On the other hand, normal cells appear to have, under lower basal stress and reserve, a higher capacity to cope with additional ROS-generating insults than cancer cells do. Therefore, the elevation of ROS in all cells can be used to achieve the selective killing of cancer cells.


title: Reactive oxygen species

text: Radiotherapy also relies on ROS toxicity to eradicate tumor cells. Radiotherapy uses X-rays, γ-rays as well as heavy particle radiation such as protons and neutrons to induce ROS-mediated cell death and mitotic failure.


title: Reactive oxygen species

text: Due to the dual role of ROS, both prooxidant and antioxidant-based anticancer agents have been developed. However, modulation of ROS signaling alone seems not to be an ideal approach due to adaptation of cancer cells to ROS stress, redundant pathways for supporting cancer growth and toxicity from ROS-generating anticancer drugs. Combinations of ROS-generating drugs with pharmaceuticals that can break the redox adaptation could be a better strategy for enhancing cancer cell cytotoxicity.


title: Reactive oxygen species

text: James Watson and others have proposed that lack of intracellular ROS due to a lack of physical exercise may contribute to the malignant progression of cancer, because spikes of ROS are needed to correctly fold proteins in the endoplasmatic reticulum and low ROS levels may thus aspecifically hamper the formation of tumor suppressor proteins. Since physical exercise induces temporary spikes of ROS, this may explain why physical exercise is beneficial for cancer patient prognosis. Moreover, high inducers of ROS such as 2-deoxy-D-glucose and carbohydrate-based inducers of cellular stress induce cancer cell death more potently because they exploit the cancer cell's high avidity for sugars.


title: Reactive oxygen species

text: Two reviews summarize the large body of evidence, reported largely between 1996 and 2011, for the critical and essential role of ROS in memory formation. An additional body of evidence indicates that both the formation and storage of memory depend on epigenetic modifications in neurons, including alterations in neuronal DNA methylation. The two bodies of information on memory formation appear to be connected in 2016 by the work of Zhou et al., who showed that ROS have a central role in epigenetic DNA demethylation.


title: Reactive oxygen species

text: In mammalian nuclear DNA, a methyl group can be added, by a DNA methyltransferase, to the 5th carbon of cytosine to form 5mC (see red methyl group added to form 5mC near the top of the first figure). The DNA methyltransferases most often form 5mC within the dinucleotide sequence "cytosine-phosphate-guanine" to form 5mCpG. This addition is a major type of epigenetic alteration and it can silence gene expression. Methylated cytosine can also be demethylated, an epigenetic alteration that can increase the expression of a gene. A major enzyme involved in demethylating 5mCpG is TET1. However, TET1 is only able to act on 5mCpG if an ROS has first acted on the guanine to form 8-hydroxy-2'-deoxyguanosine (8-OHdG), resulting in a 5mCp-8-OHdG dinucleotide (see first figure). However, TET1 is only able to act on the 5mC part of the dinucleotide when the base excision repair enzyme OGG1 binds to the 8-OHdG lesion without immediate excision. Adherence of OGG1 to the 5mCp-8-OHdG site recruits TET1 and TET1 then oxidizes the 5mC adjacent to 8-OHdG, as shown in the first figure, initiating a demethylation pathway shown in the second figure.


title: Reactive oxygen species

text: In 2016 Halder et al. using mice, and in 2017 Duke et al. using rats, subjected the rodents to contextual fear conditioning, causing an especially strong long-term memory to form. At 24 hours after the conditioning, in the hippocampus of rats, the expression of 1,048 genes was down-regulated (usually associated with hypermethylated gene promoters) and the expression of 564 genes was up-regulated (often associated with hypomethylated gene promoters). At 24 hours after training, 9.2% of the genes in the rat genome of hippocampus neurons were differentially methylated. However while the hippocampus is essential for learning new information it does not store information itself. In the mouse experiments of Halder, 1,206 differentially methylated genes were seen in the hippocampus one hour after contextual fear conditioning but these were reversed and not seen after four weeks. In contrast with the absence of long-term methylation changes in the hippocampus, substantial differential methylation could be detected in cortical neurons during memory maintenance. There were 1,223 differentially methylated genes in the anterior cingulate cortex of mice four weeks after contextual fear conditioning.


title: Reactive oxygen species

text: The thousands of CpG sites being demethylated during memory formation depend on ROS in an initial step. The altered protein expression in neurons, controlled in part by ROS-dependent demethylation of CpG sites in gene promoters within neuron DNA, are central to memory formation.


title: Remittance

text: A remittance is a non-commercial transfer of money by a foreign worker, a member of a diaspora community, or a citizen with familial ties abroad, for household income in their home country or homeland. Money sent home by migrants competes with international aid as one of the largest financial inflows to developing countries. Workers' remittances are a significant part of international capital flows, especially with regard to labor-exporting countries.


title: Remittance

text: According to the World Bank, in 2018 overall global remittance grew 10% to US$689 billion, including US$528 billion to developing countries. Overall global remittance is expected to grow 3.7% to US$715 billion in 2019, including US$549 billion to developing nations.


title: Remittance

text: Due to its large diaspora and overseas expats population, India consecutively remains the top receiver of remittance, e.g. with US$80 billion in 2018, US$65.3 billion (2.7% of India's GDP) in 2017, US$62.7 billion in 2016 and US$70 billion in 2014. Other top recipients in 2020 were US$67 billion to China, US$34 billion each to Philippines and Mexico and US$26 billion to Egypt.


title: Remittance

text: Remittances are playing an increasingly large role in the economies of many countries. They contribute to economic growth and to the livelihoods of those countries. According to World Bank estimates, remittances will total US$573 billion in 2019, of which US$422 billion went to developing countries that involved 250 million migrant workers. For some individual recipient countries, remittances can be as high as a third of their GDP.


title: Remittance

text: International remittances have a major impact on the developing economies of the world with the majority of remittances, $441 billion in 2015, going to developing nations. This amount is nearly triple the $131 billion of global Official Development Assistance. For many developing nations, remittances received make up a significant portion of their economies, even receiving over 10% of their GDP in remittances each year.


title: Remittance

text: Note: The countries mentioned below are the largest 15 recipient countries of remittances "only" for the year 2013. World Bank data is used for all countries and years.


title: Remittance

text: As a share of GDP, the top recipients of remittances in 2013 were Tajikistan (42.1%), Kyrgyzstan (31.5%), Nepal (28.8%), Moldova (24.9%), Lesotho (24.4%), Samoa (23.8%), Haiti (21.1%), Armenia (21.0%), The Gambia (19.8%), Liberia (18.5%), Lebanon (17.0%), Honduras (16.9%), Timor-Leste (16.6%), El Salvador (16.4%), Kosovo (16.1%), Jamaica (15.0%) and Bosnia and Herzegovina (8.82%, which is 1.540 billion $ for 2017 on 31 December 2017 conversion rate between € and US$).


title: Remittance

text: The remittance industry has mostly been dominated by companies headquartered in European financial centers and the American West, with Western Union having the largest market share as of 2019. Other companies such as MoneyGram have also been a key player for decades. Most companies in the industry are pure play money transfer providers, although they may be owned by parent companies with more diverse interests.


title: Remittance

text: Each of these companies focus on different consumer bases. Wise has been the fastest-growing money transfer startup in terms of total annual volume transferred, and focuses on transferring funds between bank accounts, often between developed countries. Ria Money Transfer has had an established presence among Spanish speakers in North America and Spain. WorldRemit has a higher share of African migrants located worldwide, while Azimo focuses specifically on the European market with an emphasis on migrant communities. Companies such as WorldRemit, Remitly, and Azimo have smaller average transfer amounts due to the higher share of working-class migrants using their services.


title: Remittance

text: Although the remittance market share has diversified since the advent of money transfer "fintech" (financial technology startups) during the 2010s, Western Union continues to dominate the majority of the remittance market share. Since the advent of fintech, many digital remittances have emerged on the scene, leading to the rise of comparison platforms or aggregators such as FXcompared and Monito in Europe and Send4x in Southeast Asia. Blockchain-based remittances companies are also starting to be used and offer such advantages as fast transfer time and relatively low transaction costs.


title: Remittance

text: There is also a relevant initiative, launched by the Bill and Melinda Gates Foundation in 2017, called Mojaloop. It is designed (in cooperation with Ripple, Dwolla, ModusBox, Crosslake Technologies and Software Group) to deliver financial support to people living in areas underserved by banks.


title: Remittance

text: The US has been the leading source of remittances globally every year since 1983. Russia, Saudi Arabia, and Switzerland have been the next largest senders of remittances since 2007. Between 9 million and 11 million workers send remittances from Russia each year.


title: Remittance

text: A majority of the remittances have been directed to Asian countries like India (approx. US$87.0 billion in 2021), China (approx. US$ 60.0 billion in 2021), the Philippines (approx. US$33.5 billion in 2020), Pakistan (US$26.0 billion in 2020), Bangladesh (US$21.5 billion in 2020) and more. Asian countries such as Tajikistan and Nepal are among the countries that rely the most on remittances, accounting for 35% and 25% of their GDP respectively.


title: Remittance

text: Most of the remittances happen by the conventional channel of agents, like Western Union, Ria Money Transfer, Sigue Money Transfer, MoneyGram, UAE Exchange, and similar. However, with the increasing relevance and reach of the Internet, online and mobile phone money transfers have grown significantly.


title: Remittance

text: Remittances are a major component of the Armenian economy. making up about 13% of Armenia’s GDP in 2011. In 2013 around 40% of families of Armenia have received remittances. As a result, Armenia falls in the top 20 countries worldwide for receiving remittances. Total remittances to Armenia have reached their peak in 2013 being equal to $2.192 billion but plummeted after the 2014 Russian ruble devaluation and reached $1.528 billion in 2019.


title: Remittance

text: Armenia falls in the top 20 countries worldwide for receiving remittances. Armenia, being a country with one of the largest diasporas in the world, provides a case study of a developing economy that is dependent on remittances and the financial support they provide. Total remittances to Armenia reached $1.87 billion in 2013, a 10.8%. A study conducted in 2004 examined the impact of remittances from a micro perspective, and determined that households with average income were the most likely to have a family member abroad because poorer households lacked the financial ability to send family members out of the country and the most wealthy households did not have a reason to.


title: Remittance

text: In 2017, the majority of remittance flows to Armenia originated from Russia, about 60.5% of overall remittances. The figure amounted to nearly $945 million due to more than 2 million Armenian population living in Russia. The next biggest inflows were recorded from the US, over $160 million, 10.25% of the overall figure (around 500,000-1,000,000 Armenian population). According to the IMF, starting from 2010 remittances in USD, AMD (Armenian dram), and Rubles, grew until they hit their peak in 2014 and started declining after that in a volatile fashion as a result of the Russian ruble devaluation. Remittances in AMD and USD declined to almost their 2010 levels.


title: Remittance

text: An estimated 10 million Bangladeshis, working abroad have sent $15 billion to home in 2018 and $18.32 billion in 2019. It is country's second-largest source of foreign earnings after its gigantic textile industry. Bangladesh is one of the top 10 countries in the world for migration and remittance according to World Bank. Most of the remittances come from gulf countries.


title: Remittance

text: India is the world's top receiver of remittances, claiming more than 12% of the world's remittances in 2015. Indians living overseas are the world's largest diaspora. As per the Ministry of Overseas Indian Affairs (MOIA), remittance is received from the approximately 35 million members of the Indian diaspora. Remittances to India stood at billion in 2017 and remittances from India to other countries totalled billion, for a net inflow of billion in 2017.


title: Remittance

text: The flow of remittances to Jordan experienced rapid growth during the 1970s and 1980s when Jordan started exporting skilled labor to the Persian Gulf. These remittances represent an important source of funding for many developing countries, including Jordan. According to the World Bank data on remittances, with about US$3 billion in 2010 Jordan ranked at 10th place among all developing countries. Jordan ranked among the top 20 recipients of remittances for the preceding decade. In addition, the Arab Monetary Fund (AMF) statistics in 2010 indicate that Jordan was the third biggest recipient of remittances among Arab countries after Egypt and Lebanon. The host countries that have absorbed most of the Jordanian expatriates are Saudi Arabia and the United Arab Emirates, where the available data indicate that about 90% of Jordanian migrants are working in the Persian Gulf.


title: Remittance

text: According to a World Bank Study, the Philippines is the second largest recipient for remittances in Asia. It was estimated in 1994 that migrants sent over US$2.6 billion back to the Philippines through formal banking systems. With the addition of money sent through private finance companies and return migrants, the 1994 total was closer to US$6 billion annually.


title: Remittance

text: The total is estimated to have grown by 7.8 percent annually to reach US$21.3 billion in 2010. Remittances are a reliable source of revenue for the Philippines, accounting for 8.9 per cent of the country's GDP.


title: Remittance

text: The Estrada administration in 2000 declared it "The Year of Overseas Filipino Worker in the Recognition of the Determination and Supreme Self-Sacrifice of Overseas Filipino Workers." This declaration connects monetary remittances of overseas workers as the top foreign-exchange earnings in the Philippines.


title: Remittance

text: In Latin America and the Caribbean, remittances play an important role in the economy of the region, totaling over US$66.5 billion in 2007, with about 75% originating in the United States. This total represents more than the sum of Foreign direct investment and official development aid combined. In seven Latin American and Caribbean countries, remittances even account for more than 10% of GDP and exceed the dollar flows of the largest export product in almost every country in the region.


title: Remittance

text: Percentages ranged from 2% in Mexico, to 18% in El Salvador, 21% in Honduras, and up to 30% in Haiti. The Inter American Development Bank's Multilateral Investment Fund (IDB-MIF) has been the leading agency on regional remittance research.


title: Remittance

text: Mexico received remittance inflows of almost US$24 billion in 2007, 95% of which originated in the US.


title: Remittance

text: A 2004 study found that over 60% of the 16.5 million Latin American-born adults who resided in the United States at the time of the survey regularly sent money home. The remittances sent by these 10 million immigrants were transmitted via more than 100 million individual transactions per year and amounted to an estimated $30 billion during 2004. Each transaction averaged about $150–$250, and, because these migrants tended to send smaller amounts more frequently than others, their remittances had a higher percentage of costs due to transfer fees.


title: Remittance

text: Migrants sent approximately 10% of their household incomes; these remittances made up a corresponding 50–80% of the household incomes for the recipients. Significant amounts of remittances were sent from 37 U.S. states, but six states were identified as the "traditional sending" states: New York (which led the group with 81% of its immigrants making regular remittances), California, Texas, Florida, Illinois, and New Jersey. The high growth rate of remittances to Mexico (not the total amount) is unlikely to continue. In fact, according to the Mexican central bank, remittances grew just 0.6 during the first six months of 2007, as compared to 23% during the same period in 2006. Experts attribute the slowdown to a contraction in the U.S. construction industry, tighter border controls, and a crackdown in the U.S. on illegal immigration.


title: Remittance

text: Remittance culture in the United States has contributed to the formation of "micro-geographies", tightly knit networks that integrate U.S. communities with communities throughout Latin America, such as migrants from Oaxaca, Mexico, who have settled in Venice Beach, California. Oaxacans not only send money back to their communities, but they also travel back and forth extensively.


title: Remittance

text: As of recently, remittances from the United States to Latin America have been on the decline. While there were US$69.2 billion worth of remittances sent in 2008, that figure has fallen to $58.9 billion for 2011. This trend is a result of many factors including the global recession, more economic opportunity in Latin American countries, and rising fees charged by coyotes to smuggle immigrants across the border.


title: Remittance

text: The pattern of migration has changed from a circular flow, in which immigrants work in the United States for a few years before returning to their families in their home countries, to a one-way stream whereby migrants find themselves stuck in the United States. As a result, the new wave of migrants is both less likely to leave and more likely to stay in the United States for longer periods of time. Overall, this trend has contributed to falling levels of remittances sent to Latin American countries from the United States.


title: Remittance

text: Remittances to Africa play an important role in national economies. However, little data exists as many rely on informal channels to send money home. Immigrants from Africa today number approximately 20 to 30 million adults, who send around US$40 billion annually to their families and local communities back home. For the region as a whole, this represents 50 percent more than net official development assistance (ODA) from all sources, and, for most countries, the amount also exceeds foreign direct investment (FDI). In several fragile states, remittances are estimated to exceed 50 percent of GDP.


title: Remittance

text: Most African countries restrict the payment of remittances to banks, which in turn, typically enter into exclusive arrangements with large money transfer companies, like Western Union or Money Gram, to operate on their behalf. This results in limited competition and limited access for consumers, which allows these Money Transfer Operators (MTOs) to charge the highest fees for remittances in the world. However, there are a number of new players aiming to disrupt this established MTO model, such as Xoom and Willstream, which leverage increasing mobile phone penetration in the region and provide different rate structures to Diaspora customers. Additionally, global initiative like the United Nations Sustainable Development Goal 10 has a target of reducing the transaction costs of migrant remittances to less than 3 percent by 2030.


title: Remittance

text: According to a World Bank study, Nigeria is by far the top remittance recipient in Africa, accounting for $10 billion in 2010, a slight increase over the previous year ($9.6 billion). Other top recipients include Sudan ($3.2 billion), Kenya ($1.8 billion), Senegal ($1.2 billion), South Africa ($1.0 billion), Uganda ($0.8 billion), Lesotho ($0.5 billion), Ethiopia ($387 million), Mali ($385 million), and Togo ($302 million). As a share of Gross Domestic Product, the top recipients in 2009 were: Lesotho (25%), Togo (10%), Cape Verde (9%), Guinea-Bissau (9%), Senegal (9%), Gambia (8%), Liberia (6%), Sudan (6%), Nigeria (6%), and Kenya (5%).


title: Remittance

text: A major source of foreign-exchange earnings for Nigeria are remittances sent home by Nigerians living abroad. In 2014, 17.5 million Nigerians lived in foreign countries, with the UK and the US having more than 2 million Nigerians each.


title: Remittance

text: According to the International Organization for Migration, Nigeria witnessed a dramatic increase in remittances sent home from overseas Nigerians, going from US$2.3 billion in 2004 to 17.9 billion in 2007, representing 6.7% of GDP. In 2016, remittances reached a new record of $35 billion. The United States accounts for the largest portion of official remittances, followed by the United Kingdom, Italy, Canada, Spain and France. On the African continent, Egypt, Equatorial Guinea, Chad, Libya, and South Africa are important source countries of remittance flows to Nigeria, while China is the biggest remittance-sending country in Asia.


title: Remittance

text: An August 2016 Nigerian Central Bank (NCB) decision to suspend the operations of all MTOs in the country, except those of Western Union, MoneyGram and Rio, was met with a strong backlash. It was argued that the decision was not appropriately justified, while also standing in contrast to the NCB's previous move to ban all exclusivity agreements with Western Union. The decision was considered to disproportionally strengthen the dominant position of Western Union, MoneyGram and Rio. Under pressure, however, the Central Bank reversed the decision and granted new licenses to a number of competing MTOs.


title: Remittance

text: Somali expatriates often send remittances to their relatives in Greater Somalia through Dahabshiil and other Somali-owned money transfer companies. In order to ensure that these funds go to their intended recipients rather than Al-Shabaab and other militant groups, the governments of the United States, Australia, and a number of other Western countries tightened their banking requirements or stopped processing altogether the remittances. To address the concerns, the United States Congress passed the Money Remittances Improvement Act of 2014.


title: Remittance

text: In April 2015, the Federal Cabinet of Somalia also officially launched the Special Task Force on Remittances (STFR). The multi-agency initiative is mandated with facilitating the Federal Government of Somalia's new national policy pertaining to the money transfer industry. Its main priority is centered on establishing a comprehensive strategy and a consultative implementation plan for the formalization of the local financial sector. Additionally, the STFR is tasked with helping to foster a business environment and financial infrastructure conducive to growth. It is also empowered to coordinate and speed up the endorsement of financial governance instruments and transparency associated legislation, such as the laws on Anti-Money Laundering (AML) and Counter Financing of Terrorism (CFT). In accordance with the Financial Action Task Force (FATF)'s recommendations, the STFR is in turn slated to oversee the Somali federal government's campaign to ratify various international treaties. The Task Forces' membership is scheduled to be announced shortly, and will be drawn from government institutions, the remittance industry, banks, and other key private sector stakeholders.


title: Remittance

text: Remittances are not a new phenomenon in the world, being a normal concomitant of migration which has always been a part of human history. Several European countries, for example Spain, Italy and Ireland were heavily dependent on remittances received from their emigrants during the 19th and 20th centuries. In the case of Spain, remittances amounted to 21% of all of its current account income in 1946.


title: Remittance

text: All of those countries created policies on remittances developed after significant research efforts in the field. For instance, Italy was the first country in the world to enact a law to protect remittances in 1901 while Spain was the first country to sign an international treaty (with Argentina in 1960) to lower the cost of the remittances received.


title: Remittance

text: Since 2000, remittances have increased sharply worldwide, having almost tripled to $529 billion in 2012. In 2012, migrants from India and China alone sent more than $130 billion to their home countries.


title: Remittance

text: In 2004 the G8 met at the Sea Island Summit and decided to take action to lower the costs for migrant workers who send money back to their friends and families in their country of origin. In light of this, various G8 government developmental organizations, such as the UK government's Department for International Development (DFID) and USAID began to look into ways in which the cost of remitting money could be lowered.


title: Remittance

text: In September 2008, the World Bank established the first international database of remittance prices. The Remittance Prices Worldwide Database provides data on sending and receiving remittances for over 200 "country corridors" worldwide. The "corridors" examined include remittance flows from 32 major sending countries to 89 receiving countries, which account for more than 60% of total remittances to developing countries. The resulting publication of the Remittance Prices Worldwide Database serves four major purposes: benchmarking improvements, allowing comparisons across countries, supporting consumers’ choices, and putting pressure on service providers to improve their services.


title: Remittance

text: At the July 2009 summit in L'Aquila, Italy, G8 heads of government and states endorsed the objective of reducing the cost of remittance services by five percentage points in five years. To drive down costs, the World Bank has begun certifying regional and national databases that use a consistent methodology to compare the cost of sending remittances.


title: Remittance

text: At the G20 2011 Summit in Cannes, Bill Gates stated that, "If the transaction costs on remittances worldwide were cut from where they are today at around 10% to an average of 5%…it would unlock $15bn a year in poor countries." A number of low-cost online services have emerged with the objective of lowering the cost of money transfers to developing and emerging economies. There are also a number of comparison sites when it comes to remittance which breaks down the costs of sending money overseas. The World Bank stated that remittance to low- and middle-income countries reached $529 billion in 2018, which was a record high.


title: Remittance

text: During disasters or emergencies, remittances can be a vital source of income for people whose other forms of livelihood may have been destroyed by conflict or natural disaster. According to the Overseas Development Institute, this is being increasingly recognized as important by aid actors who are considering better ways of supporting people in emergency responses. An illustrative example can be Armenia, that had experienced a devastating earthquake in Spitak on December 7, 1988, when the Karabakh conflict had already started. About 45,000 people have died, while 500,000 became homeless. Armenia got help from different countries, for example, the U.S. government immediately sent $10 million, which helped to more or less recover the economy. Refugees and other displaced populations also often remit to family members left behind in conflict areas.


title: Remittance

text: The recent internationally coordinated effort to stifle possible sources of money laundering and/or terrorist financing has increased the cost of sending remittances, directly increasing costs to the companies facilitating the sending, and indirectly increasing the costs to the person remitting. As in some corridors a sizable amount of remittances is sent through informal channels (family connections, traveling friends, local money lenders, etc.). According to the World Bank, some countries do not report remittances data.


title: Remittance

text: Moreover, when data is available, the methodologies used by countries for remittance data compilation are not publicly available. A 2010 world survey of central banks found significant differences in the quality of remittance data collection across countries: some central banks only used remittances data reported from commercial banks, neglecting to account for remittance flows via money transfer operators and post offices.


title: Remittance

text: Remittances can be difficult to track and potentially sensitive to money laundering (AML) and terror financing (CTF) concerns. Since 9/11 many governments and the Financial Action Task Force (FATF) have taken steps to address informal value transfer systems. This is done through nations' Financial Intelligence Units (FIUs). The principle legislative initiatives in this area are the USA PATRIOT Act, Title III in the United States and, in the EU, through a series of EU Money Laundering Directives. Though no serious terror risk should be associated with migrants sending money to their families, misuse of the financial system remains a serious government concern.


title: Remittance

text: World Bank economists contend that remittance receivers' higher propensity to own a bank account means that remittances can promote access to financial services for the sender and recipient, claimed to be an essential aspect of leveraging remittances to promote economic development. For example, in Armenia, which has one of the highest remittance to GDP ratios, studies suggest that those households which receive remittances have a higher propensity to save, however, as opposed to some theoretic frameworks, these savings are not used to leverage borrowing more from the financial system as a way to grow their businesses. Other studies suggest that another channel through which remittances can foster economic growth is a household investment. For instance, the study conducted in South Caucasus reveals that in Armenia having a migrant household member is associated with a higher probability of establishing a family business by that household. Thus, the remittances sent by migrants can potentially encourage domestic investment, ensuring economic growth. However, new findings for Armenia suggest that remittances help potential migrants to ease the migration process, serving as a resource rather than as a contractual tool between migrants and non-migrants. It is concluded that remittances drastically shift emigration intentions upward. The need for remittances, and the ability and the strength of the migrant social capital (or the network) are factors which jointly determine emigration intentions. Meanwhile, critical migration scholars have expressed concern about the ability of remittances to address the structural causes of economic underdevelopment and see an increasing policy emphasis on finance as symptomatic of a paradigmatic shift towards a 'self-help development' that burdens the poor.


title: Remittance

text: Remittances are generally thought to be counter-cyclical. The stability of remittance flows amidst financial crises and economic downturns make them a reliable source of foreign exchange earnings for developing countries. As migrant remittances are sent cumulatively over the years and not only by new migrants, remittances are able to be persistent over time. This is particularly true of remittances sent by circular migrants, migrant workers who move back and forth between their home and host countries in a temporary and repetitive manner. At the state level, countries with diversified migration destinations are likely to have more sustainable remittance flows.


title: Remittance

text: From a macroeconomic perspective, there is no conclusive relationship between remittances and GDP growth. While remittances can boost aggregate demand and thereby spur economic activity, other research indicates that remittances may also have adverse macroeconomic impacts by increasing income inequality and reducing labour supply among recipient countries.


title: Remittance

text: The World Bank and the Bank for International Settlements have developed international standards for remittance services.


title: World Geodetic System

text: The World Geodetic System (WGS) is a standard for use in cartography, geodesy, and satellite navigation including GPS. This standard includes the definition of the coordinate system's fundamental and derived constants, the normal gravity Earth Gravitational Model (EGM), a description of the associated World Magnetic Model (WMM), and a current list of local datum transformations.


title: World Geodetic System

text: It is established and maintained by the United States National Geospatial-Intelligence Agency since 1984, and last revised in January 2021 (G2139 frame realization). WGS 84 ensemble is static, while frame realisations have an epoch. Earlier schemes included WGS 72, WGS 66, and WGS 60. WGS 84 is the reference coordinate system used by the Global Positioning System.


title: World Geodetic System

text: Not all frame realisations (such as G1762’, 29 January 2017, GPS week 1934) are in EPSG under WGS 84, but under IGS14. G1762’ was the first time IGS14 was used.


title: World Geodetic System

text: The coordinate origin of WGS 84 is meant to be located at the Earth's center of mass; the uncertainty is believed to be less than .


title: World Geodetic System

text: The WGS 84 meridian of zero longitude is the IERS Reference Meridian, 5.3 arc seconds or east of the Greenwich meridian at the latitude of the Royal Observatory. (This is related to the fact that the local gravity field at Greenwich doesn't point exactly through the Earth's center of mass, but rather "misses west" of the center of mass by about that 102 meters.)


title: World Geodetic System

text: The WGS 84 datum surface is an oblate spheroid with equatorial radius = at the equator and flattening = 1/. The refined value of the WGS 84 gravitational constant (mass of Earth's atmosphere included) is = . The angular velocity of the Earth is defined to be = .


title: World Geodetic System

text: This leads to several computed parameters such as the polar semi-minor axis which equals = , and the first eccentricity squared, = .


title: World Geodetic System

text: WGS 84 uses the Earth Gravitational Model 2008. This geoid defines the nominal sea level surface by means of a spherical harmonics series of degree 2160. It is an improvement over the 1996 EGM96 model, which was in turn an improvement over the original WGS 84 geoid, referred to as EGM84. The deviations of the EGM96 geoid from the WGS 84 reference ellipsoid range from about to about .


title: World Geodetic System

text: WGS 84 currently also uses the World Magnetic Model 2020. The next regular update (WMM2025) will occur in December 2024.


title: World Geodetic System

text: Efforts to supplement the various national surveying systems began in the 19th century with F.R. Helmert's famous book ("Mathematical and Physical Theories of Physical Geodesy"). Austria and Germany founded the "Zentralbüro für die Internationale Erdmessung" (Central Bureau of International Geodesy), and a series of global ellipsoids of the Earth were derived (e.g., Helmert 1906, Hayford 1910/ 1924).


title: World Geodetic System

text: In the late 1950s, the United States Department of Defense, together with scientists of other institutions and countries, began to develop the needed world system to which geodetic data could be referred and compatibility established between the coordinates of widely separated sites of interest. Efforts of the U.S. Army, Navy and Air Force were combined leading to the DoD World Geodetic System 1960 (WGS 60). The term "datum" as used here refers to a smooth surface somewhat arbitrarily defined as zero elevation, consistent with a set of surveyor's measures of distances between various stations, and differences in elevation, all reduced to a grid of latitudes, longitudes, and elevations. Heritage surveying methods found elevation differences from a local horizontal determined by the spirit level, plumb line, or an equivalent device that depends on the local gravity field (see physical geodesy). As a result, the elevations in the data are referenced to the geoid, a surface that is not readily found using satellite geodesy. The latter observational method is more suitable for global mapping. Therefore, a motivation, and a substantial problem in the WGS and similar work is to patch together data that were not only made separately, for different regions, but to re-reference the elevations to an ellipsoid model rather than to the geoid.


title: World Geodetic System

text: In accomplishing WGS 60, a combination of available surface gravity data, astro-geodetic data and results from HIRAN and Canadian SHORAN surveys were used to define a best-fitting ellipsoid and an earth-centered orientation for each of initially selected datum. (Every datum is relatively oriented with respect to different portions of the geoid by the astro-geodetic methods already described.) The sole contribution of satellite data to the development of WGS 60 was a value for the ellipsoid flattening which was obtained from the nodal motion of a satellite.


title: World Geodetic System

text: Prior to WGS 60, the U.S. Army and U.S. Air Force had each developed a world system by using different approaches to the gravimetric datum orientation method. To determine their gravimetric orientation parameters, the Air Force used the mean of the differences between the gravimetric and astro-geodetic deflections and geoid heights (undulations) at specifically selected stations in the areas of the major datums. The Army performed an adjustment to minimize the difference between astro-geodetic and gravimetric geoids. By matching the relative astro-geodetic geoids of the selected datums with an earth-centered gravimetric geoid, the selected datums were reduced to an earth-centered orientation. Since the Army and Air Force systems agreed remarkably well for the NAD, ED and TD areas, they were consolidated and became WGS 60.


title: World Geodetic System

text: Improvements to the global system included the Astrogeoid of Irene Fischer and the astronautic Mercury datum. In January 1966, a World Geodetic System Committee composed of representatives from the United States Army, Navy and Air Force was charged with developing an improved WGS, needed to satisfy mapping, charting and geodetic requirements. Additional surface gravity observations, results from the extension of triangulation and trilateration networks, and large amounts of Doppler and optical satellite data had become available since the development of WGS 60. Using the additional data and improved techniques, WGS 66 was produced which served DoD needs for about five years after its implementation in 1967. The defining parameters of the WGS 66 Ellipsoid were the flattening (1/298.25 determined from satellite data) and the semimajor axis ( determined from a combination of Doppler satellite and astro-geodetic data). A worldwide 5° × 5° mean free air gravity anomaly field provided the basic data for producing the WGS 66 gravimetric geoid. Also, a geoid referenced to the WGS 66 Ellipsoid was derived from available astrogeodetic data to provide a detailed representation of limited land areas.


title: World Geodetic System

text: After an extensive effort over a period of approximately three years, the Department of Defense World Geodetic System 1972 was completed. Selected satellite, surface gravity and astrogeodetic data available through 1972 from both DoD and non-DoD sources were used in a Unified WGS Solution (a large scale least squares adjustment). The results of the adjustment consisted of corrections to initial station coordinates and coefficients of the gravitational field.