title: Emergency vehicle lighting

text: On ambulances and policy vehicles, a green beacon indicates the command vehicle when multiple units are responding to an incident - usually this is the first vehicle that arrives on the scene. Newer ambulance models also have a text display that will alternate the words ‘Ambulance’ and ‘"Spoed"’ (‘urgent’). When ever the vehicles are on scene (usually fire brigade vehicles and some police vans), or staying in place for another reason, they need to switch to amber lighting to signal that they are not moving.


title: Emergency vehicle lighting

text: In New Zealand, the colors used on lightbars and beacons are defined by the New Zealand Transport Agency regulations.


title: Emergency vehicle lighting

text: Volunteers in general are afforded no special privileges and cannot use flashing lights or sirens in order to navigate traffic. However, in the case of FENZ volunteer operational support members, who respond to calls in their own private vehicles, may be authorized by their unit or brigade to display a red beacon, for reasons of safety and identification. However, these lights may only be fitted and operational while stationary at an emergency scene, not while mobile in traffic.


title: Emergency vehicle lighting

text: Emergency services in Norway use only blue lighting. If a blue flashing light is seen in either traffic or the sea, other vehicles must yield to let that vehicle pass. Blue flashing lights are used by police, military police, customs, fire departments, rescue services, and ambulances. Government, VIP, and embassy vehicles may also use blue if accompanied by local police. Any vehicle equipped with a blue flashing light must have a permission issued by the DMV. The operator of such vehicle must be a qualified emergency vehicle operator and have a ‘code 160’ endorsement on their driver's license. Blue lights can be used alone or with an additional siren. The siren may not be used alone. The operator of an emergency vehicle may disregard speed limits and traffic lights with caution. Amber lights, however, are not regulated, but are used for any vehicle that need special attention, such as tow-trucks, snow plows, and parking enforcement. Red flashing lights are no longer in use, and were last used in the early 1960s.


title: Emergency vehicle lighting

text: Only designated vehicles (such as police, fire service, ambulances, Internal Affairs, etc.) are permitted to use blue light. The sale of a blue emergency light is permitted; however, the possession of such a light in vehicles (whether turned on or off, visible or not) is strictly illegal. Red lights are used by the first and last vehicle of a convoy of designated vehicles and also are strictly regulated. Amber lights are seeing increasing popularity in recent years, but specific uses are designated according to the Polish "Kodeks Drogowy". There are no specific rules governing the use of other colors such as purple, green, or clear lights.


title: Emergency vehicle lighting

text: The three emergency lights used in Romania are red, blue and amber. At a red flashing light, bringing the vehicle to a full stop is compulsory, while for a blue light yielding, slowing down and moving out of the way is compulsory, and an amber light means other traffic vehicles must proceed with caution due to an oversized or slow vehicle.


title: Emergency vehicle lighting

text: The cars that are allowed to use red lights are the Romanian Police and the Romanian General Inspectorate for Emergency Situations.


title: Emergency vehicle lighting

text: Cars that are allowed to use a blue rotating light are the Romanian Police (including Local Police), Romanian Gendarmerie, Romanian Border Police, emergency medical services (including SMURD), Civil Protection, Ministry of National Defense, Special Units of the Romanian Intelligence Service, Protection and Guard Service, Ministry of Justice - General Directorate of Prisons, Public Ministry when in mission, National Anticorruption Directorate when in mission, and Financial Guard vehicles.


title: Emergency vehicle lighting

text: The amber rotating light mean the vehicle and some accompanying vehicles are oversized, overweight, transporting dangerous goods, work as road/street maintenance, are tow trucks, are tractors, or are agricultural vehicles.


title: Emergency vehicle lighting

text: The law used to allow only the , , and autonomous law-enforcement agencies to use blue lights, so in contrast with convention in Europe, civil defense, ambulances () and fire engines () had to use yellow/amber lights (the only other color authorized, in contrast to convention in which these color lights are used to denote slow vehicles). Some Autonomous Communities allowed other colors, such as blue, red or white (the latter two of which is used by SAMUR in Madrid), however, these are technically illegal to use throughout Spain. In 2018 a new law finally allowed these kind of emergency vehicles to use blue lights, giving them 2 years to make the switch from yellow/amber to blue. Yellow/amber lights are now only used in wide-load trucks and their accompanying vehicles among other special vehicles, such as tractors or tow trucks. A steady burn green light is permitted on taxis available for hire, and was formerly used on buses to indicate a bus was in service and with places free for passengers.


title: Emergency vehicle lighting

text: Municipal police, national police, (gendarmerie), Civil Defence, Ambulance and Fire services are all eligible to claim traffic exemptions such as jumping red lights, illegal parking etc. Municipal police, national police, fire and ambulance services can all claim full exemptions to traffic laws whilst civil defence and are only eligible to claim more limited exemptions to traffic laws.


title: Emergency vehicle lighting

text: Police vehicles, medical vehicles and fire engines along with other government vehicles such as the Swedish Military Police and the Swedish Customs Service use white and dark ‘Euro blue’ emergency lights. Ordinary traffic are required to make way for these vehicles if the lights are on.


title: Emergency vehicle lighting

text: Blue lights and sirens may also be used on vehicles of that belong to private companies or organizations if their role is either life saving or protecting some vital system of society. This includes but is not limited to medical & public transport, gas & electricity companies and security (specifically, security officers in charge of protecting government buildings and ports).


title: Emergency vehicle lighting

text: Amber lights grant no priority in traffic and exist purely to advertise the vehicle's presence, usually as a warning. Most commonly used on heavy machinery, trucks, bulldozers, slow-going, utility vehicles and construction vehicles like are equipped with yellow/amber lights. It is legal to fit these lights to other vehicles, such as privately owned cars.


title: Emergency vehicle lighting

text: The Swedish police use a forward-facing red light to indicate that a driver must pull over and stop. Fire vehicles use a red light to designate the command post.


title: Emergency vehicle lighting

text: Red is the most used color on Thailand emergency vehicles. The Thailand police use light bars mounted on top platform to make them more visible over congested streets. Rotating lights are most commonly used. But some newer vehicles have LED light bars installed. Vehicles with any other light color than red are security or engineers. Wig-wag headlights are not used.


title: Emergency vehicle lighting

text: Usage of emergency vehicle lighting is restricted in the United Kingdom through the Road Vehicle Lighting Regulations 1989. It is illegal for any vehicle to show a flashing coloured light (with the exception of the normal direction indicators or a green anti-lock brake warning indicator), unless it is an emergency or other authorised vehicle. However recently pedal cycles can exhibit a flashing rear red lamp and flashing white front lamp.


title: Emergency vehicle lighting

text: The main colour for emergency service vehicles is overwhelmingly blue, although there is also widespread use of flashing (white) headlights, and many police vehicles have a set of two rear-facing red flashing lights to indicate that the police car is stopped or to indicate caution. The legal definition of an emergency vehicle limits the use of both methods to vehicles used for:


title: Emergency vehicle lighting

text: Blue flashing lights must only be lit at the scene of an emergency, or when the driver considers it desirable to indicate that the journey being undertaken is urgent, and (in terms of the law) convey to other drivers that they should take special care.


title: Emergency vehicle lighting

text: Although not specifically linked to the use of warning beacons, the police, fire brigade and ambulance services (and in certain cases, the blood services and bomb disposal units, but not the other emergency services listed above) may also choose to allow their drivers to claim legal exemptions from certain motoring regulations, such as being able to treat a red traffic light as a give way sign, exceeding the speed limit, passing the wrong side of a keep left/right sign, driving in a bus lane, or parking in restricted areas. They may not, however, ignore ‘no entry’ signs, drive the wrong way down a one-way street or cross a solid white line in the middle of the road (other than the same exceptions granted everyone else, for example to pass a stationary vehicle). In reality some drivers will disobey other laws at their professional judgement but they do so without any automatic protection from the law.


title: Emergency vehicle lighting

text: No qualification other than a driving licence is legally required to use blue lights; whilst provision has been made to require the drivers of emergency vehicles to have suitable training if they will be driving above the speed limit, this has not yet been brought into force. However, most organisations will insist that their drivers are trained in emergency driving techniques for the safety of all on the road. Police forces, specifically, typically have three levels of driving grade, as required by the College of Policing.


title: Emergency vehicle lighting

text: Response and advanced police drivers can be trained in "'initial phase'" pursuit, which involves training in safely pursuing a vehicle under emergency driving conditions. Advanced drivers may further be trained in "'tactical phase"' pursuit, which involves training in Tactical Pursuit And Containment (TPAC).


title: Emergency vehicle lighting

text: Amber lights grant no priority in traffic and exist purely to advertise the vehicle's presence, except when used by Driver & Vehicle Standards Agency or National Highways traffic officers where they can be used to indicate a requirement for another vehicle to stop. The regulations specifies several classes of vehicles that may use amber lights, such as vehicles towing, highway maintenance, pilot vehicles escorting an oversize load, and vehicles unable to travel over 25 mph and fitting these lights to other vehicles (such as privately owned or pedestrian) is legal (these beacons are widely fitted to vehicles as wide-ranging as security).


title: Emergency vehicle lighting

text: Green flashing beacons can be used by doctors (registered with the General Medical Council). Many doctors now either volunteer or are employed as first responders for ambulance services and their vehicles will carry the, usually blue, lights used by the service or both blue and green to indicate their profession.


title: Emergency vehicle lighting

text: Flashing red lights are fitted to the vast majority of police, fire and ambulance vehicles – being used only when the vehicle is stationary to alert other drivers of their presence. 'Rear reds' are also used during large police escorts, with the rearmost vehicle displaying red lights to alert other motorist not to pass. Hazard lights may be wired to function at the same time, to make civilians further conscious of their presence. Rear fog lights may also be used in an alternating left/right pattern. Traffic enforcement vehicle (DVSA) may also use red lighting when stopping a vehicle.


title: Emergency vehicle lighting

text: Steady checkered lights denote command and control vehicles – these are red and white for fire (one of the few situations where a forward-facing red light may be shown), blue and white for police and green and white for ambulance, and are often fitted in the middle of the light bar. Civil enforcement vehicles also use red lights in certain jurisdictions. These red lights represent the vehicles status as above the standard citizen but below law enforcement.


title: Emergency vehicle lighting

text: It should also be noted that UK legislation considers all reflectors and reflective material to also be 'lights', and all items either being or resembling special warning beacons (of any colour), such as on preserved emergency vehicles, must be covered and not just disconnected (as this is a separate offence) while on the public highway. Similarly, no distinction is made between lights mounted on light bars and those mounted anywhere else on the vehicle (e.g. headlights, indicators, brake lights) – all are covered by the same regulations.


title: Emergency vehicle lighting

text: Purple (magenta) flashing beacons are to load pilots escorting a load wider than 5m must display purple beacons to alert other road users there is an oversize load they may need to move out of the way for.


title: Emergency vehicle lighting

text: In the United States, colors are generally regulated at the state and local levels, but there are some commonalities.


title: Emergency vehicle lighting

text: Purple is permitted in some states to denote a funeral vehicle specifically additional Wig-Wag lights (separate from the headlights) are used on funeral vehicle can use purple lights and/or coroner's or Medical examiner's office.


title: Emergency vehicle lighting

text: Police agencies may use red, blue, or both, depending on the state, along with white and amber as optional colors; although amber is usually restricted to face behind the vehicle. Some police cars have an amber directional control bar, also known as an ‘arrow stick’ or a ‘traffic advisor’, located on the back facing part of the lightbar to direct traffic left or right around the vehicle; these usually have 6 or 8 rear-facing lights that flash in sequence.


title: Emergency vehicle lighting

text: Some privately operated special police are allowed to display the same colors as regular police, generally, if they receive their special police authority at the state level. This can include railroad, university, hospital, and SPCA and humane society police departments, Animal control and regulatory officers, Fish and Wildlife conservation officers and Federal and State park rangers, and Beach Safety lifeguards that are law enforcement certified.


title: Emergency vehicle lighting

text: Fire and emergency medical services generally use red lights with amber and white as optional colors. Vehicles operated by fire departments, such as fire engines and heavy rescue vehicles, prominently use red, a color with strong cultural associations with the fire service, along with some amber and white. Some more modern fire trucks and airport crash units use a yellow-green color, however.


title: Emergency vehicle lighting

text: Many fire chiefs’ cars have, in addition to the red lights, a single green beacon to indicate command post status. On the other hand, in Chicago and some nearby communities, fire vehicles show a green light on the right, or starboard, side of the vehicle. This initially was in relation to nautical tradition but has since become tied to a sense of courage and the remembrance of fallen firefighters


title: Emergency vehicle lighting

text: Emergency medical vehicles, such as ambulances and paramedic fly-cars, generally use white, amber, and red as well. Some states have a specific rule authorizing light colors for EMS vehicles, while some EMS vehicles ‘inherit’ their light colors from the fire or police department they are operated by or contracted to, and may show blue lights.


title: Emergency vehicle lighting

text: The National Fire Protection Association publishes the NFPA-1901 standards for fire vehicles, which specifies the degree of lighting on various parts of the vehicles, with some flexibility as to color. There is also a GSA procurement specification for ambulances known as KKK-A-1822-F, which many local authorities follow.


title: Emergency vehicle lighting

text: Many U.S. states allow volunteer fire, EMS and search & rescue personnel to place emergency warning lights in their personal vehicles for use when responding to emergencies. The degree of lighting is mandated by law and also by local custom in most areas, and can vary from a single rotating light on the dashboard or roof, to a setup much like modern police cruisers. Some states also allow volunteer use of sirens and air horns to request the right of way.


title: Emergency vehicle lighting

text: Virginia state law allows emergency personnel to equip one private vehicle "with no more than two flashing or steady-burning red or red and white combination warning lights".


title: Emergency vehicle lighting

text: In some states, volunteers are allowed to use the normal red lights, while in other states volunteers must use some other color, usually blue or green. In the latter case, the lights are used as a courtesy to ‘request’ the right of way and generally do not mandate pulling over. Some states, such a Pennsylvania, limit volunteer use of red lights to chiefs and captains of squads.


title: Emergency vehicle lighting

text: Separate colors may be used for fire versus EMS volunteers. In Connecticut, Indiana, Minnesota, and New York, volunteer firefighters use blue while volunteer EMTs use green. In New Jersey, volunteer fire and ambulance personnel use blue lights in their personal vehicles while responding to their stations. In NJ red lights are only allowed for emergency vehicles, fire chiefs, chief officers of first aid or rescue squads, or other law enforcement vehicles. In Iowa, volunteer firefighters can use flashing blue lights on their personal vehicles, while volunteer EMTs can use flashing white (clear) lights.


title: Emergency vehicle lighting

text: New York also certifies some volunteer EMTs to use red lights and sirens provided their vehicles carry certain equipment; this is often used by Hatzolah volunteers in the NYC area. Typically in New York state, volunteer firefighters use blue lights in their personal vehicles and volunteer EMS use green lights. This may generate confusion, as green lights are also used to signify an incident command vehicle. In the state of Texas, “a private vehicle of a volunteer firefighter or a certified emergency medical services employee or volunteer when responding to a fire alarm or medical emergency” is considered an “authorized emergency vehicle” and may use alternately flashing lighting equipment or may be equipped with a siren, exhaust whistle, or bell.


title: Emergency vehicle lighting

text: The conflicting color assignments can create issues for volunteers who drive their vehicles out of state. One color in their state may mean firefighter or EMT when in another state it may mean police. While some authorities may be satisfied with covering the lights with an ‘Out Of Service’ tarpaulin, compliance may be more difficult in other jurisdictions. For example, Arkansas bars civilian possession of blue lights on or in a vehicle unless sealed in the manufacturer's original package.


title: Emergency vehicle lighting

text: Amber lights are often used on vehicle involved in non-emergency work. Most utility companies, towing services, oversize load vehicles, slow vehicles, and certain types of construction equipment mount some type of lightbar or lighting system for a higher degree of visibility.


title: Emergency vehicle lighting

text: In Detroit, Michigan, Angels' Night volunteers will patrol neighborhoods with yellow lights to help deter vandalism during Devil's Night and Halloween. Typically these lights are the single beacon kind, although lightbars have been used for vehicles of this type, especially on wreckers/tow trucks.


title: Emergency vehicle lighting

text: In Memphis, Tennessee, Minneapolis, Minnesota and Saint Paul, Minnesota most city maintenance vehicles (including MLG&W utility trucks) with flashing lights use yellow lights; however, some vehicles with the traffic engineering department use red flashing lights, especially vehicles equipped with cherry pickers used to repair traffic signals.


title: Emergency vehicle lighting

text: In states that do not enforce specific rules about green, yellow or white lights, these colors are often used by entities like private security companies which may be ineligible to use blue or red lights but need emergency lights for traffic and site visibility. Security vehicles generally use their lights on private property, in addition some security vehicles are off-road only such as ATV, Golf cart type vehicles and in most jurisdictions security vehicles are generally not allowed a ‘courtesy’ or ‘emergency’ status on public roads.


title: Emergency vehicle lighting

text: While certain colors are customarily used by different services, often other colors are optionally used, such as amber and white. Sometimes, this is done to satisfy particular regulations; for example, California requires a steady red light facing forward and a flashing amber light to the rear on every emergency vehicle.


title: Anteros

text: In Greek mythology, Anteros (; Ancient Greek: Ἀντέρως "Antérōs") was the god of requited love (literally "love returned" or "counter-love") and also the punisher of those who scorn love and the advances of others, or the avenger of unrequited love. He is one of the Erotes.


title: Anteros

text: Anteros was the son of Ares and Aphrodite in Greek mythology, given as a playmate to his brother Eros, who was lonely – the rationale being that love must be answered if it is to prosper. Alternatively, he was said to have arisen from the mutual love between Poseidon and Nerites. Physically, he is depicted as similar to Eros in every way, but with long hair and plumed butterfly wings. He has been described also as armed with either a golden club or arrows of lead.


title: Anteros

text: Anteros, with Eros, was one of a host of winged love gods called Erotes, the ever-youthful winged gods of love, usually depicted as winged boys in the company of Aphrodite or her attendant goddesses.


title: Anteros

text: An altar to Anteros was put up by the metics in Athens in commemoration of the spurned love of the metic , who was rejected by the Athenian Meles. Upon hearing Timagoras' declaration of love for him, the young man mockingly ordered him to throw himself down from the top of a tall rock. Seeing Timagoras dead, Meles repented and threw himself down from the same rock.


title: Anteros

text: Describing the nature of the emotion, Plato asserts that it is the result of the great love for another person. The lover, inspired by beauty, is filled with divine love and "filling the soul of the loved one with love in return." As a result, the loved one falls in love with the lover, though the love is only spoken of as friendship. They experience pain when the two are apart, and relief when they are together, the mirror image of the lover's feelings, is anteros, or "counter-love".


title: Anteros

text: Anteros is the subject of the Shaftesbury Memorial Fountain in Piccadilly Circus, London, where he symbolises the selfless philanthropic love of the Earl of Shaftesbury for the poor. The memorial is sometimes given the name The Angel of Christian Charity and is popularly mistaken for Eros.


title: Viking Age arms and armour

text: Knowledge about military technology of the Viking Age (late 8th to mid-11th century Europe) is based on relatively sparse archaeological finds, pictorial representation, and to some extent on the accounts in the Norse sagas and laws recorded in the 14th century.


title: Viking Age arms and armour

text: According to custom, all free Norse men were required to own weapons, and permitted to carry them at all times. Indeed, the "Hávamál", purported to be sage advice given by Odin, states "Don't leave your weapons lying about behind your back in a field; you never know when you may need all of sudden your spear."


title: Viking Age arms and armour

text: As war was the most prestigious activity in Viking Age Scandinavia, beautifully finished weapons were an important way for a warrior to display his wealth and status. A wealthy Viking would likely have a complete ensemble of a spear, a wooden shield, and either a battle axe or a sword. Battle axes were considered the "normal weapon" for middle class Vikings. Swords were normally reserved for upper class and nobles. Much poetry was associated with Viking weapons. The richest might have a helmet and mail armour; these are thought to have been limited to the nobility and their professional warriors (retainers). Several layers of thick woollen clothing may have been used by poorer warriors. The average farmer was likely limited to a spear, shield, and perhaps a common axe or large knife (seax). Some would also bring their hunting bows (mostly long bow or flat bow) to use in the opening stages of battle.


title: Viking Age arms and armour

text: Two distinct classes of knives were in use by Vikings. The more common one was a rather plain, single edge knife of normal construction, called a . These are found in most graves, being the only weapon allowed for all, even slaves. Smaller versions served as the everyday utility tool, while longer versions were likely meant for hunting or combat or both. Weapon knives sometimes had ornamental inlays on the blade. The construction was similar to traditional Scandinavian knives. The tang ran through a more or less cylindrical handle, the blade was straight with the edge sweeping upward at the tip to meet the back of the blade in a point. The knife apparently played an important role for all Scandinavians. This is evidenced by the large number of knives found in burial sites of not just the men, but the women and the children too.


title: Viking Age arms and armour

text: The other type was the "seax". The type associated with Vikings is the so-called broken-back style seax. It was usually a bit heavier than the regular knife and would serve as a machete- or falchion-like arm. A wealthier man might own a larger seax, some being effectively swords. With the single edge and heavy blade, this somewhat crude weapon would be relatively simple to use and produce, compared to the regular sword. A rather long tang is fitted to many examples, indicating they may have had a longer handle for two-handed use. The smaller knife-like seaxes were likely within the fabrication ability of a common blacksmith.


title: Viking Age arms and armour

text: The Seax was in widespread use among the Migration period Germanic tribes, and is even eponymous of the Saxons. It appears in Scandinavia from the 4th century, and shows a pattern of distribution from the lower Elbe (the Irminones) to Anglo-Saxon England. While its popularity on the continent declines with the end of the Migration period, it remained in the British Isles where it was taken up by the Vikings. The large, sword-like seaxes are primarily found in connection with Viking settlements in England and Ireland, but do not appear very commonly in Scandinavia.


title: Viking Age arms and armour

text: The Viking Age sword was for single-handed use to be combined with a shield, with a double edged blade length of up to 90 cm. Its shape was still very much based on the Roman spatha with a tight grip, long deep fuller and no pronounced cross-guard. It was not exclusive to the Vikings, but rather was used throughout Europe


title: Viking Age arms and armour

text: Swords were very costly to make, and a sign of high status. They were rarely used and some swords found in graves were probably not sturdy enough for battle or raiding, and instead were likely decorative items. Like Roman "spathae", they were worn in leather-bound wooden scabbards suspended from a strap across the right shoulder. Early blades were pattern welded, a technique in which strips of wrought iron and mild steel were twisted and forged together, with the addition of a hardened edge. Later blades of homogeneous steel, imported probably from the Rhineland, many bearing inlaid makers' marks and inscriptions, such as INGELRII or VLFBERHT. Local craftsmen often added their own elaborately decorated hilts, and many swords were given names, such as Leg-biter and Gold-hilt. The sword grip was usually made of an organic material, such as wood, horn, or antler (which does not often survive for archaeological uncovering), and may well have been wound around with textile.


title: Viking Age arms and armour

text: Owning a sword was a matter of high honour. Persons of status might own ornately decorated swords with silver accents and inlays. Most Viking warriors would own a sword as one raid was usually enough to afford a good blade. Most freemen would own a sword with "goðar", "jarls" and sometimes richer freemen owning much more ornately decorated swords. The poor farmers would use an axe or spear instead but after a couple of raids they would then have enough to buy a sword. One sword mentioned in the "Laxdæla saga" was valued at half a crown, which would correspond to the value of 16 milk-cows. Constructing such weapons was a highly specialized endeavour and many sword-blades were imported from foreign lands, such as the Rhineland. Swords could take up to a month to forge and were of such high value that they were passed on from generation to generation. Often, the older the sword, the more valuable it became.


title: Viking Age arms and armour

text: A distinct class of early single edged swords is known from Eastern Norway at the time. These had the same grips as the double edged swords, and blades of comparable length. The blades varied from long and slim, like the more common two edged swords, to somewhat heavy, giving the weapon a more cleaver-like balance. Confusingly, the same finds are sometimes classified as "sabres" or "seaxes" in English literature.


title: Viking Age arms and armour

text: As mentioned above, a sword was so valued in Norse society that good blades were prized by successive generations of warriors. There is even some evidence from Viking burials for the deliberate and possibly ritual "killing" of swords, which involved the blade being bent so that it was unusable. Because Vikings were often buried with their weapons, the "killing" of swords may have served two functions, namely a ritualistic function in retiring a weapon with a warrior, and a practical one in deterring any grave robbers from disturbing the burial in order to get one of these costly weapons. Indeed, archaeological finds of the bent and brittle pieces of metal sword remains testify to the regular burial of Vikings with weapons, as well as the habitual "killing" of swords.


title: Viking Age arms and armour

text: The most common hand weapon among Vikings was the axe – swords were more expensive to make and only wealthy warriors could afford them. The prevalence of axes in archaeological sites can likely be attributed to its role as not just a weapon, but also a common tool. This is supported by the large number of grave sites of female Scandinavians containing axes. Several types of larger axes specialized for use in battle evolved, with larger heads and longer shafts, including various types of bearded axes. The larger forms were as long as a man and made to be used with both hands, called the Dane Axe. Some axe heads were inlaid with silver designs. In the later Viking era, there were axe heads with crescent shaped edges measuring up to called "breiðöx" (broadaxe). The double-bitted axes depicted in modern "Viking" art would have been very rare as it used more material and was seen as a waste during hard times, if they existed at all. No surviving examples, authentic artwork or clear descriptions from records support the existence of double-bitted axes used by Vikings. Double-bitted axes were not forged by the Norse. Just about every axe they forged was single headed.


title: Viking Age arms and armour

text: Vikings most commonly carried sturdy axes that could be thrown or swung with head-splitting force. The Mammen Axe is a famous example of such battle-axes, ideally suited for throwing and melee combat.


title: Viking Age arms and armour

text: An axe head was mostly wrought iron, with a steel cutting edge. This made the weapon less expensive than a sword, and was a standard item produced by blacksmiths, historically.


title: Viking Age arms and armour

text: Like most other Scandinavian weaponry, axes were often given names. According to Snorri Sturluson's "Prose Edda", axes were often named after she-trolls.


title: Viking Age arms and armour

text: The spear was the most common weapon of the Scandinavian peasant class. Throwing spears were constantly used by the warrior class; despite popular belief, it was also the principal weapon of the Viking warrior, an apt fit to their formations and tactics. They consisted of metal heads with a blade and a hollow shaft, mounted on wooden shafts of two to three metres in length, and were typically made from ash wood. The spear heads could measure between twenty and sixty centimetres with a tendency towards longer heads in the later Viking Age. Spear heads with wings are called "krókspjót" (hooked spear) in the sagas. Some larger-headed spears were called "höggspjót" (chopping spear) and could also be used for cutting. The barbed throwing spears were often less decorated than the ostentatious thrusting spears, as the throwing spears were often lost in battle.


title: Viking Age arms and armour

text: The spear was used both as a throwing weapon and as a thrusting weapon, although there was some specialization in design. Lighter, narrower spearheads were made for throwing; heavier broader ones, for stabbing.


title: Viking Age arms and armour

text: Most evidence indicates that they were used in one hand. Limited evidence from a saga indicates that they may have been used with two hands, but not in battle. The head was held in place with a pin, which saga characters occasionally pull out to prevent a foe from re-using the weapon.


title: Viking Age arms and armour

text: Compared with a sword, the spear can be made with inferior steel and far less metal overall. This made the weapon cheaper and probably within the capability of a common blacksmith to produce. Despite this, the spear held great cultural significance to the Viking warrior, as the primary weapon of Odin, the king of the Norse gods and the god of warfare, was the spear Gungnir. The "Eyrbyggja saga" alludes that a customary start to a battle included throwing a spear right over the enemy army to claim it for Odin. Possibly due to its cultural significance, pattern welded blades are common in spear heads, and the sockets were often decorated with silver inlaid patterns.


title: Viking Age arms and armour

text: A polearm known as the "atgeir" is mentioned in several sagas of Icelanders and other literature. "Atgeir" is usually translated as "halberd", akin to a glaive. Gunnar Hámundarson is described in "Njáls saga" as cutting and impaling foes on his "atgeir".


title: Viking Age arms and armour

text: Several weapons (including the "kesja" and the "höggspjót") appearing in the sagas are Viking halberds. No weapon matching their descriptions have been found in graves. These weapons may have been rare, or may not have been part of the funerary customs of the Vikings. A more likely explanation however is that these polearms are descriptions of early medieval weapons that have been added into the sagas; likely because they were written down during the same period.


title: Viking Age arms and armour

text: The Viking age sling was easy to manufacture, consisting of a rope and sometimes a leather cup to assist with loading, giving many of the lower class access to a formidable weapon. Slingers make effective light infantry due to their lack of heavy equipment and open formation, and the concussive effect of slingstones even through metal armour.


title: Viking Age arms and armour

text: The bow and arrow was used for both hunting and warfare. They were made from yew, ash or elm. The draw force of a 10th-century bow may have reached some 90 pounds force (400 N) or more, resulting in an effective range of at least depending on the weight of the arrow. A yew bow found at Viking Hedeby, which probably was a full-fledged war bow, had a draw force of well over 100 pounds. Replica bows using the original dimensions have been measured to between draw weight. A unit of length used in the Viking Age called a bow shot corresponded to what was later measured as . Illustrations from the time show bows being pulled back to the chest, rather than to the corner of the mouth or under the chin, as is common today.


title: Viking Age arms and armour

text: Arrowheads were typically made from iron and produced in various shapes and dimensions, according to place of origin. Most arrowheads were fixed onto the arrow shaft by a shouldered tang that was fitted into the end of a shaft of wood. Some heads were also made of wood, bone or antler. Evidence for eagle feather flights has been found with the feathers being bound and glued on. The end of the shaft was flared with shallow self nocks, although some arrows possessed bronze cast nocks. The historical record also indicates that Vikings may have used barbed arrows, but the archaeological evidence for such technology is limited.


title: Viking Age arms and armour

text: The earliest find of these relics were found in Denmark, seemingly belonging to the leading-warrior class based on the graves in which they were found.


title: Viking Age arms and armour

text: The shield was the most common means of defence. The sagas specifically mention linden wood for shield construction, although finds from graves show mostly other timbers, such as fir, alder and poplar with steel or iron shield boss. These timbers are not very dense and are light in the hand. They are also not inclined to split, unlike oak. Also, the fibres of the timber bind around blades preventing the blade from cutting any deeper unless a lot more pressure is applied. In conjunction with stronger wood, Vikings often reinforced their shields with leather or, occasionally, iron around the rim. Round shields seem to have varied in size from around in diameter but is by far the most common.


title: Viking Age arms and armour

text: The smaller shield sizes came from the pagan period for the Saxons and the larger sizes from the 10th and 11th centuries. Most shields are shown in illuminations as being painted a single colour although some have a design painted onto them; the most common designs are simple crosses or derivations of sun wheels or segments. The few round shields that survived have much more complicated designs painted on them and sometimes very ornate silver and gold work applied around the boss and the strap anchors.


title: Viking Age arms and armour

text: The Gokstad ship has places for shields to be hung on its railing and the Gokstad shields have holes along the rim for fastening some sort of non-metallic rim protection. These were called shield lists and they protected ship crews from waves and the wind. Some Viking shields may have been decorated by simple patterns although some skaldic poems praising shields might indicate more elaborate decoration and archaeological evidence has supported this. In fact, there is a complete subgenre of Skaldic poetry dedicated to shields, known as "shield poems", that describe scenes painted on shields. For example, the late-9th-century skaldic poem, "Ragnarsdrápa", describes some shields painted with mythological scenes. Viking shields were also heavily used in formations. The shield wall or "skjaldborg" was a main formation in which accomplished Viking warriors would create a line of interlocked shields and thrust spears at adversaries. Other notable tactics included the "svinfylking" "boarsnout", in which warriors would create a wedge configuration and attempt to burst through the front line of nearby foes.


title: Viking Age arms and armour

text: It has been proposed that the medieval era "kite shield" favoured by the Normans was introduced to Europe by the Vikings. However, no documentation or remains of kite shields from the Viking period have been located by archaeologists.


title: Viking Age arms and armour

text: Of the four helmet fragments found in Scandinavia, only the remains from Gjermundbu were of use in significant reconstruction.


title: Viking Age arms and armour

text: The Gjermundbu helmet dates to the 10th century. It was excavated on a farm called Gjermundbu in Ringerike in central Norway. Gjermundbu is located in Haugsbygd, a village in northeast of Hønefoss, in Buskerud, Norway. This helmet was made of iron from four plates after the spangenhelm pattern. This helmet has a rounded cap, and there is evidence that it also may have had a mail aventail. It has a "spectacle" guard around the eyes and nose which formed a sort of mask, which suggests a close affinity with the earlier Vendel Period helmets.


title: Viking Age arms and armour

text: The Yarm helmet was discovered in the 1950s by workmen digging pipe trenches in Chapel Yard, Yarm, near the River Tees. Research led by Chris Caple of Durham University, and published in 2020, established that the helmet dates to the 10th century. This helmet is made of iron bands and plates, riveted together, with a simple knop at the top. Below the brow band it has a "spectacle" guard around the eyes and nose forming a sort of mask, which suggests an affinity with earlier Vendel Period helmets. The lower edge of the brow band is pierced with circular holes, where a mail curtain (or aventail) may have been attached.


title: Viking Age arms and armour

text: From runestones and other illustrations, it is known that the Vikings also wore simpler helmets, often caps with a simple noseguard. Research indicates that Vikings may have only rarely used metal helmets. Helmets with metal horns, presumably for ceremonial use, are known from the Nordic Bronze Age, 2,000 years prior to the Viking Age.


title: Viking Age arms and armour

text: Despite popular culture, there is no evidence that Vikings used horned helmets in battle as such horns would be impractical in a melee, but it is possible that horned head dresses were used in ritual contexts. The horned and winged helmets associated with the Vikings in popular mythology were the invention of 19th-century Romanticism. The horned helmet may have been introduced in Richard Wagner's "Ring" operas (set in Germany): The male chorus wore horned helmets, while the other characters had winged helmets.


title: Viking Age arms and armour

text: Once again, a single fragmented but possibly complete mail shirt has been excavated in Scandinavia, from the same site as the helmet—Gjermundbu in Haugsbygd. Scandinavian Viking Age burial customs seems to not favour burial with helmet or mail armour, in contrast to earlier extensive armour burials in Sweden Valsgärde or possibly only a small amount of Vikings could afford it. Probably worn over thick clothing, a mail shirt protected the wearer from being cut, but offered little protection from blunt trauma and stabbing attacks from a sharp point such as that of a spear. The difficulty of obtaining mail armour resided in the fact that it required thousands of interlinked iron rings, each one of which had to be individually riveted together by hand. As a result, mail was very expensive in early medieval Europe, and would likely have been worn by men of status and wealth.


title: Viking Age arms and armour

text: The mail worn by Vikings was almost certainly the "four-on-one" type, where four solid (punched or riveted) rings are connected by a single riveted ring. Mail of this type is known as a "byrnie" from Old Norse "brynja". Given scarcity of archeological evidence for Viking armor and the fact that Vikings on a raid tried to avoid pitched battles, it's possible that mail was primarily worn only by the professional warriors going into battle, such as the Great Heathen Army of the mid-9th century in England or at Harald Hardrada's invasion of Northumbria at the Battle of Fulford in 1066, and wealthy nobles.


title: Viking Age arms and armour

text: More than 30 "lamellae" (individual plates for lamellar armour) were found in Birka, Sweden, in 1877, 1934 and 1998–2000. They were dated to the same approximate period as the Gjermundbu mailshirt (900‒950) and may be evidence that some Vikings wore this armour, which is a series of small iron plates laced together or sewed to a stout fabric or leather cats shirt. There is considerable debate however as to whether the lamellae in question were in the possession of a Scandinavian resident or a foreign mercenary.


title: Viking Age arms and armour

text: Quilted cloth (a gambeson) is conjectured as possible options for lower-status Viking warriors, though no reference to such are known from the sagas. Such materials survive poorly in graves, and no archaeological finds have been made. Some runestones depict what appears to be armour which is likely not chain mail. The armour in question may have been the lamellar armour mentioned above, or may not have been armour at all. Several layers of stout linen or hemp canvas would provide a good level of protection, at reasonable expense, as would winter clothing made from thick woollen cloth. Practical experience with maille also suggests an undergarment of some sort would have been worn between the maille and the regular tunic, to protect the latter from dirt and excessive wear, but the descriptions of the effect of axes in the Sagas indicate such garments were lightly padded if at all.


title: Viking Age arms and armour

text: Leather was far pricier during the period than today and thus less affordable for the casual warrior. In the "Legendary Saga of St. Olaf", the kingsbane Thorir Hund is said to have worn a tunic made from reindeer fur, enchanted by "Finns" (Sámi), defending him from sword blows. The tunic is described as "magically" enhanced which may indicate that it may not represent a typical example of such a garment. Leather clothing does, however, occasionally turn up in archaeological finds, and would have offered some degree of protection in combat.


title: Viking Age arms and armour

text: All in all, the case for non-metal forms of armour remains inconclusive. It is likely that the average Viking fought whilst wearing ordinary clothing, with the shield as the only form of protection.


title: Viking Age arms and armour

text: Foreign-made, specifically Frankish, weapons and armour played a special role in Norse society. Norsemen attained them either through trade (an extension of gift-giving in Norse society) or as plunder. Therefore, their possession and display by any individual would signify their station in the social hierarchy and any political allegiances they had. One example of an exchange of weapons between the Franks and the Vikings occurred in 795 when Charlemagne exchanged weapons with the Anglo-Saxon king Offa of Mercia.


title: Viking Age arms and armour

text: Scandinavian affinity towards foreign arms and armour during the Viking Age had an eminently practical aspect. Norse weapon designs were obsolete and sources of iron within Scandinavia were of poor quality. Frankish swords like the VLFBERHT had a higher carbon content (making them more durable) and their design was much more manoeuvrable compared to Scandinavian-produced swords. Although smaller weapons like daggers, knives, and arrowheads could be manufactured in Scandinavia, the best swords and spearheads were undoubtedly imported.


title: Viking Age arms and armour

text: Many of the most important Viking weapons were highly ornate—decorated lavishly with gold and silver. Weapons adorned as such served large religious and social functions. These precious metals were not produced in Scandinavia and they too would have been imported. Once in Scandinavia, the precious metals would have been inlaid in the pommels and blades of weapons creating geometric patterns, depictions of animals, and (later) Christian symbols.


title: Viking Age arms and armour

text: Vikings also used foreign armour. According to "Heimskringla", one hundred Vikings appeared "in coats of ring-mail, and in foreign helmets" at the Battle of Nesjar in 1016.


title: Viking Age arms and armour

text: During the mid-9th century, there was an influx of these high-quality weapons into Scandinavia, and Frankish arms became the standard for all Vikings. As Ahmad ibn Fadlan observed in his account of his journey to Russia, every Viking carried a "sword of the Frankish type". The Franks attempted to limit the Vikings' use of weapons and armour produced in Francia—fearing that they would eventually face equally armed opponents. Chapter 10 of the "Capitulare Bononiense" of 811 made it illegal for any clerical functionary to supply swords or armour to non-Frankish individuals. Laws like this were enacted throughout Francia. Ultimately, in 864, King Charles the Bald of West Francia made the practice punishable by death.


title: Viking Age arms and armour

text: Some scholars have proposed that such laws proved so effective at stemming the flow of Frankish weapons that they initiated the practice of raiding for which Vikings became notorious.


title: Aaron Ramsey (footballer, born 2003)

text: Aaron James Ramsey (born 21 January 2003) is an English professional footballer who plays as a midfielder for EFL Championship club Norwich City, on loan from club Aston Villa. Ramsey is a product of the Aston Villa Academy and has represented England at youth level, he is currently a member of the under-20 squad. His elder brother Jacob also plays for Aston Villa.


title: Aaron Ramsey (footballer, born 2003)

text: Ramsey joined Aston Villa alongside his brother Jacob at under-9 level. He moved through the youth ranks, and was given his first professional contract on 16 March 2021. During his time playing for the Aston Villa U23 side, Ramsey was named by "The Guardian" as one of England's top young talents. On 24 May 2021, Ramsey was part of the Aston Villa U18s team that won the FA Youth Cup, beating Liverpool 2–1 in .


title: Aaron Ramsey (footballer, born 2003)

text: Ramsey was promoted to the first-team towards the end of the 2020–21 season, and played his first game with the senior team on 21 July 2021 - scoring in a pre-season friendly against Walsall. Ramsey made his first-team debut on 24 August 2021, in a 6–0 EFL Cup victory over Barrow.


title: Aaron Ramsey (footballer, born 2003)

text: On 11 January 2022, Ramsey joined League One club Cheltenham Town on loan until the end of the season. He made his EFL debut as a second-half substitute in a 1–0 defeat to Rotherham United on 22 January 2022. On 23 April 2022, Ramsey scored his first goal in senior football in a 1–2 home defeat for Cheltenham against Bolton Wanderers.


title: Aaron Ramsey (footballer, born 2003)

text: On 5 August 2022, Ramsey joined Championship club Norwich City on a season-long loan deal, linking up once again with former Villa manager Dean Smith. He made his debut on 9 August 2022, as a substitute in a 2–2 EFL Cup draw against Birmingham City. Norwich won the match on penalties, but Ramsey did not take part in the penalty shoot-out. He scored his first goals for the club on 29 October 2022 when he scored twice in a 3-1 win against Stoke City.


title: Aaron Ramsey (footballer, born 2003)

text: Ramsey has been capped at England under-16, under-17 and under-18 level. He captained the Under-17 national team to a 2–1 victory over Germany on 14 November 2017. On 6 September 2021, after an injury to Harvey Elliott, Ramsey was called up to the England under-21 squad for the first time, ahead of their 2023 UEFA European Under-21 Championship qualification match against Kosovo. Ramsey was an unused substitute for the game.


title: Aaron Ramsey (footballer, born 2003)

text: On 6 October 2021, Ramsey made a goalscoring debut for the England U19s during a 3–1 defeat to France in Marbella.


title: Aaron Ramsey (footballer, born 2003)

text: On 17 June 2022, Ramsey was named in the England squad for the 2022 UEFA European Under-19 Championship finals. Ramsey featured in heavily in the tournament, including on 1 July 2022, scoring the final goal in England's 3–1 extra time victory over Israel in the final.


title: Aaron Ramsey (footballer, born 2003)

text: On 21 September 2022, Ramsey made his England U20 debut during a 3–0 victory over Chile at the Pinatar Arena. He scored his first goal for the U20 team, on 27 September in a 3–0 victory over Australia.


title: Aaron Ramsey (footballer, born 2003)

text: Ramsey lives in Great Barr. His older brother Jacob Ramsey also plays for Aston Villa, whilst his younger brother Cole is in the academy set-up there. His father Mark was a boxer who twice fought Ricky Hatton, once in 1998 and once in 1999.


title: Fish fin

text: Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as seen in sharks. Apart from the tail or caudal fin, fish fins have no direct connection with the spine and are supported only by muscles. Their principal function is to help the fish swim.


title: Fish fin

text: Fins located in different places on the fish serve different purposes such as moving forward, turning, keeping an upright position or stopping. Most fish use fins when swimming, flying fish use pectoral fins for gliding, and frogfish use them for crawling. Fins can also be used for other purposes; male sharks and mosquitofish use a modified fin to deliver sperm, thresher sharks use their caudal fin to stun prey, reef stonefish have spines in their dorsal fins that inject venom, anglerfish use the first spine of their dorsal fin like a fishing rod to lure prey, and triggerfish avoid predators by squeezing into coral crevices and using spines in their fins to lock themselves in place.


title: Fish fin

text: Fins can either be paired or unpaired. The pectoral and pelvic fins are paired, whereas the dorsal, anal and caudal fins are unpaired and situated along the midline of the body. For every type of fin, there are a number of fish species in which this particular fin has been lost during evolution (e.g. pelvic fins in "Bobasatrania", caudal fin in ocean sunfish). In some clades, additional unpaired fins were acquired during evolution (e.g. additional dorsal fins, adipose fin). In some Acanthodii ("spiny sharks"), one or more pairs of "intermediate" or "prepelvic" spines are present between the pectoral and pelvic fins, but these are not associated with fins.


title: Fish fin

text: Bony fishes form a taxonomic group called Osteichthyes (or Euteleostomi, which includes also land vertebrates). They have skeletons made of bone mostly, and can be contrasted with cartilaginous fishes (see below), which have skeletons made mainly of cartilage (except for their teeth, fin spines, and denticles).


title: Fish fin

text: Bony fishes are divided into ray-finned and lobe-finned fish. Most living fish are ray-finned, an extremely diverse and abundant group consisting of over 30,000 species. It is the largest class of vertebrates in existence today, making up more than 50% of species. In the distant past, lobe-finned fish were abundant. Nowadays they are show depauperate diversity, with only eight living species.


title: Fish fin

text: Bony fish have fin spines and rays called lepidotrichia. They typically have swim bladders, which allows the fish to create a neutral balance between sinking and floating without having to use its fins. However, swim bladders are absent in many fish, most notably in Lungfishes, which are the only fish to have retained the primitive lung present in the common ancestor of bony fish from which swim bladders evolved. Bony fishes also have an operculum, which helps them breathe without having to use fins to swim.


title: Fish fin

text: Lobe-finned fishes form a class of bony fishes called Sarcopterygii. They have fleshy, lobed, paired fins, which are joined to the body by a series of bones. The fins of lobe-finned fish differ from those of all other fish in that each is borne on a fleshy, lobe-like, scaly stalk extending from the body. Pectoral and pelvic fins have articulations resembling those of tetrapod limbs. These fins evolved into legs of the first tetrapod land vertebrates (amphibians) in the Devonian Period. Sarcopterygians also possess two dorsal fins with separate bases, as opposed to the single dorsal fin of most ray-finned fish (except some teleosts). The caudal fin is either heterocercal (only fossil taxa) or diphycercal.


title: Fish fin

text: "Latimeria" is a lobe-finned fish which is still extant. There are two species, the West Indian Ocean coelacanth ("Latimeria chalumnae") and the Indonesian coelacanth ("Latimeria menadoensis"). Coelacanths are thought to have evolved into roughly their current form about 408 million years ago, during the early Devonian.


title: Fish fin

text: Locomotion of the coelacanths is unique to their kind. To move around, coelacanths most commonly take advantage of up or downwellings of the current and drift. They use their paired fins to stabilize their movement through the water. While on the ocean floor their paired fins are not used for any kind of movement. Coelacanths can create thrust for quick starts by using their caudal fins. Due to the high number of fins they possess, coelacanths have high maneuverability and can orient their bodies in almost any direction in the water. They have been seen doing headstands and swimming belly up. It is thought that their rostral organ helps give the coelacanth electroperception, which aids in their movement around obstacles.


title: Fish fin

text: Lungfish are also living lobe-finned fish. They occur in Africa ("Protopterus"), Australia ("Neoceratodus"), and South America ("Lepidosiren"). Lungfish evolved during the Devonian Period. Genetic studies and paleontological data confirm that lungfish are the closest living relatives of land vertebrates.


title: Fish fin

text: Fin arrangement and body shape is relatively conservative in lobe-finned fishes. However, there are a few examples from the fossil record that show aberrant morphologies, such as "Allenypterus", "Rebellatrix", "Foreyia" or the tetrapodomorphs.


title: Fish fin

text: Ray-finned fishes form a class of bony fishes called Actinopterygii. Their fins contain spines or rays. A fin may contain only spiny rays, only soft rays, or a combination of both. If both are present, the spiny rays are always anterior. Spines are generally stiff and sharp. Rays are generally soft, flexible, segmented, and may be branched. This segmentation of rays is the main difference that separates them from spines; spines may be flexible in certain species, but they will never be segmented.


title: Fish fin

text: Spines have a variety of uses. In catfish, they are used as a form of defense; many catfish have the ability to lock their spines outwards. Triggerfish also use spines to lock themselves in crevices to prevent them being pulled out.


title: Fish fin

text: Lepidotrichia are usually composed of bone, but in early osteichthyans such as "Cheirolepis", there was also dentine and enamel. They are segmented and appear as a series of disks stacked one on top of another. They may have been derived from dermal scales. The genetic basis for the formation of the fin rays is thought to be genes coded for the production of certain proteins. It has been suggested that the evolution of the tetrapod limb from lobe-finned fishes is related to the loss of these proteins.


title: Fish fin

text: Cartilaginous fishes form a class of fishes called Chondrichthyes. They have skeletons made of cartilage rather than bone. The class includes sharks, rays and chimaeras.


title: Fish fin

text: Shark fin skeletons are elongated and supported with soft and unsegmented rays named ceratotrichia, filaments of elastic protein resembling the horny keratin in hair and feathers. Originally the pectoral and pelvic girdles, which do not contain any dermal elements, did not connect. In later forms, each pair of fins became ventrally connected in the middle when scapulocoracoid and puboischiadic bars evolved. In rays, the pectoral fins have connected to the head and are very flexible. One of the primary characteristics present in most sharks is the heterocercal tail, which aids in locomotion. Most sharks have eight fins. Sharks can only drift away from objects directly in front of them because their fins do not allow them to move in the tail-first direction.


title: Fish fin

text: Unlike modern cartilaginous fish, members of stem chondrichthyan lineages (e.g. the climatiids and the diplacanthids) possessed pectoral dermal plates as well as dermal spines associated with the paired fins. The oldest species demonstrating these features is the acanthodian "Fanjingshania renovata" from the lower Silurian (Aeronian) of China. Fanjingshania possess compound pectoral plates composed of dermal scales fused to a bony plate and fin spines formed entirely of bone. Fin spines associated with the dorsal fins are rare among extant cartilaginous fishes, but are present, for instance, in "Heterodontus" or "Squalus". Dorsal fin spines are typically developed in many fossil groups, such as in Hybodontiformes, Ctenacanthiformes or Xenacanthida. In "Stethacanthus", the first dorsal fin spine was modified, forming a spine-brush complex.


title: Fish fin

text: As with most fish, the tails of sharks provide thrust, making speed and acceleration dependent on tail shape. Caudal fin shapes vary considerably between shark species, due to their evolution in separate environments. Sharks possess a heterocercal caudal fin in which the dorsal portion is usually noticeably larger than the ventral portion. This is because the shark's vertebral column extends into that dorsal portion, providing a greater surface area for muscle attachment. This allows more efficient locomotion among these negatively buoyant cartilaginous fish. By contrast, most bony fish possess a homocercal caudal fin.


title: Fish fin

text: Tiger sharks have a large upper lobe, which allows for slow cruising and sudden bursts of speed. The tiger shark must be able to twist and turn in the water easily when hunting to support its varied diet, whereas the porbeagle shark, which hunts schooling fish such as mackerel and herring, has a large lower lobe to help it keep pace with its fast-swimming prey. Other tail adaptations help sharks catch prey more directly, such as the thresher shark's usage of its powerful, elongated upper lobe to stun fish and squid.


title: Fish fin

text: On the other hand, rays rely on their enlarged pectoral fins for propulsion. Similarly enlarged pectoral fins can be found in the extinct Petalodontiformes (e.g. "Belantsea", "Janassa", "Menaspis"), which belong to Holocephali (ratfish and their fossil relatives), or in "Aquilolamna" (Selachimorpha) and "Squatinactis" (Squatinactiformes). Some cartilaginous fishes have an eel-like locomotion (e.g. "Chlamydoselachus", "Thrinacoselache", "Phoebodus")


title: Fish fin

text: According to the Humane Society International, approximately 100 million sharks are killed each year for their fins, in an act known as shark finning. After the fins are cut off, the mutilated sharks are thrown back in the water and left to die.


title: Fish fin

text: In some countries of Asia, shark fins are a culinary delicacy, such as shark fin soup. Currently, international concerns over the sustainability and welfare of sharks have impacted consumption and availability of shark fin soup worldwide. Shark finning is prohibited in many countries.


title: Fish fin

text: Foil shaped fins generate thrust when moved, the lift of the fin sets water or air in motion and pushes the fin in the opposite direction. Aquatic animals get significant thrust by moving fins back and forth in water. Often the tail fin is used, but some aquatic animals generate thrust from pectoral fins.


title: Fish fin

text: Cavitation occurs when negative pressure causes bubbles (cavities) to form in a liquid, which then promptly and violently collapse. It can cause significant damage and wear. Cavitation damage can occur to the tail fins of powerful swimming marine animals, such as dolphins and tuna. Cavitation is more likely to occur near the surface of the ocean, where the ambient water pressure is relatively low. Even if they have the power to swim faster, dolphins may have to restrict their speed because collapsing cavitation bubbles on their tail are too painful. Cavitation also slows tuna, but for a different reason. Unlike dolphins, these fish do not feel the bubbles, because they have bony fins without nerve endings. Nevertheless, they cannot swim faster because the cavitation bubbles create a vapor film around their fins that limits their speed. Lesions have been found on tuna that are consistent with cavitation damage.


title: Fish fin

text: Scombrid fishes (tuna, mackerel and bonito) are particularly high-performance swimmers. Along the margin at the rear of their bodies is a line of small rayless, non-retractable fins, known as finlets. There has been much speculation about the function of these finlets. Research done in 2000 and 2001 by Nauen and Lauder indicated that "the finlets have a hydrodynamic effect on local flow during steady swimming" and that "the most posterior finlet is oriented to redirect flow into the developing tail vortex, which may increase thrust produced by the tail of swimming mackerel".


title: Fish fin

text: Fish use multiple fins, so it is possible that a given fin can have a hydrodynamic interaction with another fin. In particular, the fins immediately upstream of the caudal (tail) fin may be proximate fins that can directly affect the flow dynamics at the caudal fin. In 2011, researchers using volumetric imaging techniques were able to generate "the first instantaneous three-dimensional views of wake structures as they are produced by freely swimming fishes". They found that "continuous tail beats resulted in the formation of a linked chain of vortex rings" and that "the dorsal and anal fin wakes are rapidly entrained by the caudal fin wake, approximately within the timeframe of a subsequent tail beat".


title: Fish fin

text: The bodies of reef fishes are often shaped differently from open water fishes. Open water fishes are usually built for speed, streamlined like torpedoes to minimise friction as they move through the water. Reef fish operate in the relatively confined spaces and complex underwater landscapes of coral reefs. For this manoeuvrability is more important than straight line speed, so coral reef fish have developed bodies which optimize their ability to dart and change direction. They outwit predators by dodging into fissures in the reef or playing hide and seek around coral heads. The pectoral and pelvic fins of many reef fish, such as butterflyfish, damselfish and angelfish, have evolved so they can act as brakes and allow complex manoeuvres. Many reef fish, such as butterflyfish, damselfish and angelfish, have evolved bodies which are deep and laterally compressed like a pancake, and will fit into fissures in rocks. Their pelvic and pectoral fins have evolved differently, so they act together with the flattened body to optimise manoeuvrability. Some fishes, such as puffer fish, filefish and trunkfish, rely on pectoral fins for swimming and hardly use tail fins at all.


title: Fish fin

text: Male cartilaginous fishes (sharks and rays), as well as the males of some live-bearing ray finned fishes, have fins that have been modified to function as intromittent organs, reproductive appendages which allow internal fertilization. In ray finned fish they are called "gonopodia" or "andropodia", and in cartilaginous fish they are called "claspers".


title: Fish fin

text: "Gonopodia" are found on the males of some species in the Anablepidae and Poeciliidae families. They are anal fins that have been modified to function as movable intromittent organs and are used to impregnate females with milt during mating. The third, fourth and fifth rays of the male's anal fin are formed into a tube-like structure in which the sperm of the fish is ejected. When ready for mating, the gonopodium becomes erect and points forward towards the female. The male shortly inserts the organ into the sex opening of the female, with hook-like adaptations that allow the fish to grip onto the female to ensure impregnation. If a female remains stationary and her partner contacts her vent with his gonopodium, she is fertilized. The sperm is preserved in the female's oviduct. This allows females to fertilize themselves at any time without further assistance from males. In some species, the gonopodium may be half the total body length. Occasionally the fin is too long to be used, as in the "lyretail" breeds of "Xiphophorus helleri". Hormone treated females may develop gonopodia. These are useless for breeding.


title: Fish fin

text: Similar organs with similar characteristics are found in other fishes, for example the "andropodium" in the "Hemirhamphodon" or in the Goodeidae or the "gonopodium" in the Middle Triassic "Saurichthys", the oldest known example of viviparity in a ray-finned fish.


title: Fish fin

text: "Claspers" are found on the males of cartilaginous fishes. They are the posterior part of the pelvic fins that have also been modified to function as intromittent organs, and are used to channel semen into the female's cloaca during copulation. The act of mating in sharks usually includes raising one of the claspers to allow water into a siphon through a specific orifice. The clasper is then inserted into the cloaca, where it opens like an umbrella to anchor its position. The siphon then begins to contract expelling water and sperm.


title: Fish fin

text: Other uses of fins include walking and perching on the sea floor, gliding over water, cooling of body temperature, stunning of prey, display (scaring of predators, courtship), defence (venomous fin spines, locking between corals), luring of prey, and attachment structures.


title: Fish fin

text: The Indo-Pacific sailfish has a prominent dorsal fin. Like scombroids and other billfish, they streamline themselves by retracting their dorsal fins into a groove in their body when they swim. The huge dorsal fin, or sail, of the sailfish is kept retracted most of the time. Sailfish raise them if they want to herd a school of small fish, and also after periods of high activity, presumably to cool down.


title: Fish fin

text: The oriental flying gurnard has large pectoral fins which it normally holds against its body, and expands when threatened to scare predators. Despite its name, it is a demersal fish, not a flying fish, and uses its pelvic fins to walk along the bottom of the ocean.


title: Fish fin

text: Fins can have an adaptive significance as sexual ornaments. During courtship, the female cichlid, "Pelvicachromis taeniatus", displays a large and visually arresting purple pelvic fin. "The researchers found that males clearly preferred females with a larger pelvic fin and that pelvic fins grew in a more disproportionate way than other fins on female fish."


title: Fish fin

text: There are two prevailing hypotheses that have been historically debated as models for the evolution of paired fins in fish: the gill arch theory and the lateral fin-fold theory. The former, commonly referred to as the “Gegenbaur hypothesis,” was posited in 1870 and proposes that the “paired fins are derived from gill structures”. This fell out of popularity in favor of the lateral fin-fold theory, first suggested in 1877, which proposes that paired fins budded from longitudinal, lateral folds along the epidermis just behind the gills. There is weak support for both hypotheses in the fossil record and in embryology. However, recent insights from developmental patterning have prompted reconsideration of both theories in order to better elucidate the origins of paired fins.


title: Fish fin

text: Karl Gegenbaur's concept of the “Archipterygium” was introduced in 1876. It was described as a gill ray, or “joined cartilaginous stem,” that extended from the gill arch. Additional rays arose from along the arch and from the central gill ray. Gegenbaur suggested a model of transformative homology – that all vertebrate paired fins and limbs were transformations of the Archipterygium. Based on this theory, paired appendages such as pectoral and pelvic fins would have differentiated from the branchial arches and migrated posteriorly. However, there has been limited support for this hypothesis in the fossil record both morphologically and phylogenically. In addition, there was little to no evidence of an anterior-posterior migration of pelvic fins. Such shortcomings of the gill-arch theory led to its early demise in favor of the lateral fin-fold theory proposed by St. George Jackson Mivart, Francis Balfour, and James Kingsley Thacher.


title: Fish fin

text: The lateral fin-fold theory hypothesized that paired fins developed from lateral folds along the body wall of the fish. Just as segmentation and budding of the median fin fold gave rise to the median fins, a similar mechanism of fin bud segmentation and elongation from a lateral fin fold was proposed to have given rise to the paired pectoral and pelvic fins. However, there was little evidence of a lateral fold-to-fin transition in the fossil record. In addition, it was later demonstrated phylogenically that pectoral and pelvic fins arise from distinct evolutionary and mechanistic origins.


title: Fish fin

text: Recent studies in the ontogeny and evolution of paired appendages have compared finless vertebrates – such as lampreys – with chondricthyes, the most basal living vertebrate with paired fins. In 2006, researchers found that the same genetic programming involved in the segmentation and development of median fins was found in the development of paired appendages in catsharks. Although these findings do not directly support the lateral fin-fold hypothesis, the original concept of a shared median-paired fin evolutionary developmental mechanism remains relevant.


title: Fish fin

text: A similar renovation of an old theory may be found in the developmental programming of chondricthyan gill arches and paired appendages. In 2009, researchers at the University of Chicago demonstrated that there are shared molecular patterning mechanisms in the early development of the chondricthyan gill arch and paired fins. Findings such as these have prompted reconsideration of the once-debunked gill-arch theory.


title: Fish fin

text: Fish are the ancestors of all mammals, reptiles, birds and amphibians. In particular, terrestrial tetrapods (four-legged animals) evolved from fish and made their first forays onto land 400 million years ago. They used paired pectoral and pelvic fins for locomotion. The pectoral fins developed into forelegs (arms in the case of humans) and the pelvic fins developed into hind legs. Much of the genetic machinery that builds a walking limb in a tetrapod is already present in the swimming fin of a fish.


title: Fish fin

text: In 2011, researchers at Monash University in Australia used primitive but still living lungfish "to trace the evolution of pelvic fin muscles to find out how the load-bearing hind limbs of the tetrapods evolved." Further research at the University of Chicago found bottom-walking lungfishes had already evolved characteristics of the walking gaits of terrestrial tetrapods.


title: Fish fin

text: In a classic example of convergent evolution, the pectoral limbs of pterosaurs, birds and bats further evolved along independent paths into flying wings. Even with flying wings there are many similarities with walking legs, and core aspects of the genetic blueprint of the pectoral fin have been retained.


title: Fish fin

text: The first mammals appeared during the Permian period (between 298.9 and 252.17 million years ago). Several groups of these mammals started returning to the sea, including the cetaceans (whales, dolphins and porpoises). Recent DNA analysis suggests that cetaceans evolved from within the even-toed ungulates, and that they share a common ancestor with the hippopotamus. About 23 million years ago another group of bearlike land mammals started returning to the sea. These were the seals. What had become walking limbs in cetaceans and seals evolved independently into new forms of swimming fins. The forelimbs became flippers, while the hindlimbs were either lost (cetaceans) or also modified into flipper (pinnipeds). In cetaceans, the tail gained two fins at the end, called a fluke. Fish tails are usually vertical and move from side to side. Cetacean flukes are horizontal and move up and down, because cetacean spines bend the same way as in other mammals.


title: Fish fin

text: Ichthyosaurs are ancient reptiles that resembled dolphins. They first appeared about 245 million years ago and disappeared about 90 million years ago.


title: Fish fin

text: "This sea-going reptile with terrestrial ancestors converged so strongly on fishes that it actually evolved a dorsal fin and tail fin for improved aquatic locomotion. These structures are all the more remarkable because they evolved from nothing — the ancestral terrestrial reptile had no hump on its back or blade on its tail to serve as a precursor."


title: Fish fin

text: The biologist Stephen Jay Gould said the ichthyosaur was his favorite example of convergent evolution.


title: Fish fin

text: Fins or flippers of varying forms and at varying locations (limbs, body, tail) have also evolved in a number of other tetrapod groups, including diving birds such as penguins (modified from wings), sea turtles (forelimbs modified into flippers), mosasaurs (limbs modified into flippers), and sea snakes (vertically expanded, flattened tail fin).


title: Fish fin

text: The use of fins for the propulsion of aquatic animals can be remarkably effective. It has been calculated that some fish can achieve a propulsive efficiency greater than 90%. Fish can accelerate and maneuver much more effectively than boats or submarine, and produce less water disturbance and noise. This has led to biomimetic studies of underwater robots which attempt to emulate the locomotion of aquatic animals. An example is the Robot Tuna built by the Institute of Field Robotics, to analyze and mathematically model thunniform motion. In 2005, the Sea Life London Aquarium displayed three robotic fish created by the computer science department at the University of Essex. The fish were designed to be autonomous, swimming around and avoiding obstacles like real fish. Their creator claimed that he was trying to combine "the speed of tuna, acceleration of a pike, and the navigating skills of an eel."


title: Fish fin

text: The "AquaPenguin", developed by Festo of Germany, copies the streamlined shape and propulsion by front flippers of penguins. Festo also developed "AquaRay", "AquaJelly" and "AiraCuda", respectively emulating the locomotion of manta rays, jellyfish and barracuda.


title: Fish fin

text: In 2004, Hugh Herr at MIT prototyped a biomechatronic robotic fish with a living actuator by surgically transplanting muscles from frog legs to the robot and then making the robot swim by pulsing the muscle fibers with electricity.


title: Fish fin

text: Robotic fish offer some research advantages, such as the ability to examine an individual part of a fish design in isolation from the rest of the fish. However, this risks oversimplifying the biology so key aspects of the animal design are overlooked. Robotic fish also allow researchers to vary a single parameter, such as flexibility or a specific motion control. Researchers can directly measure forces, which is not easy to do in live fish. "Robotic devices also facilitate three-dimensional kinematic studies and correlated hydrodynamic analyses, as the location of the locomotor surface can be known accurately. And, individual components of a natural motion (such as outstroke vs. instroke of a flapping appendage) can be programmed separately, which is certainly difficult to achieve when working with a live animal."


title: Sare Jahan se Accha

text: "Sare Jahan se Accha" (Urdu: ; "Sāre Jahāṉ se Acchā"), formally known as "Tarānah-e-Hindi" (Urdu: , "Anthem of the People of Hindustan"), is an Urdu language patriotic song for children written by poet Allama Muhammad Iqbal in the ghazal style of Urdu poetry. The poem was published in the weekly journal "Ittehad" on 16 August 1904. Publicly recited by Iqbal the following year at Government College, Lahore, British India (now in Pakistan) it quickly became an anthem of opposition to the British Raj. The song, an ode to Hindustan—the land comprising present-day Bangladesh, India and Pakistan, was later published in 1924 in the Urdu book Bang-i-Dara.


title: Sare Jahan se Accha

text: The song has remained popular, but only in India. An abridged version is sung and played frequently as a patriotic song and as a marching song of the Indian Armed Forces.


title: Sare Jahan se Accha

text: Iqbal was a lecturer at the Government College, Lahore at that time, and was invited by a student Lala Har Dayal to preside over a function. Instead of delivering a speech, Iqbal sang "Saare Jahan Se Achcha". The song, in addition to embodying yearning and attachment to the land of Hindustan, expressed "cultural memory" and had an elegiac quality. In 1905, the 27-year-old Iqbal viewed the future society of the subcontinent as both a pluralistic and composite Hindu-Muslim culture. Later that year he left for Europe for a three-year sojourn that was to transform him into an Islamic philosopher and a visionary of a future Islamic society.


title: Sare Jahan se Accha

text: In 1910, Iqbal wrote another song for children, "Tarana-e-Milli" (Anthem of the Religious Community), which was composed in the same metre and rhyme scheme as "Saare Jahan Se Achcha", but which renounced much of the sentiment of the earlier song. The sixth stanza of "Saare Jahan Se Achcha" (1904), which is often quoted as proof of Iqbal's secular outlook:


title: Sare Jahan se Accha

text: Iqbal's world view had now changed; it had become both global and Islamic. Instead of singing of Hindustan, "our homeland," the new song proclaimed that "our homeland is the whole world." Two decades later, in his presidential address to the Muslim League annual conference in Allahabad in 1930, he supported a separate nation-state in the Muslim majority areas of the sub-continent, an idea that inspired the creation of Pakistan.


title: T wave

text: In electrocardiography, the T wave represents the repolarization of the ventricles. The interval from the beginning of the QRS complex to the apex of the T wave is referred to as the "absolute refractory period". The last half of the T wave is referred to as the "relative refractory period" or "vulnerable period". The T wave contains more information than the QT interval. The T wave can be described by its symmetry, skewness, slope of ascending and descending limbs, amplitude and subintervals like the T–T interval.


title: T wave

text: In most leads, the T wave is positive. This is due to the repolarization of the membrane. During ventricle contraction (QRS complex), the heart depolarizes. Repolarization of the ventricle happens in the opposite direction of depolarization and is negative current, signifying the relaxation of the cardiac muscle of the ventricles. But this negative flow causes a positive T wave; although the cell becomes more negatively charged, the net effect is in the positive direction, and the ECG reports this as a positive spike. However, a negative T wave is normal in lead aVR. Lead V1 generally have a negative T wave. In addition, it is not uncommon to have a negative T wave in lead III, aVL, or aVF. A periodic beat-to-beat variation in the amplitude or shape of the T wave may be termed T wave alternans.


title: T wave

text: The refractory period of cardiac muscle is distinct from that of skeletal muscle. Nerves that innervate skeletal muscle have an extremely short refractory period after being subjected to an action potential (of the order of 1 ms). This can lead to sustained or tetanic contraction. In the heart, contractions must be spaced to maintain a rhythm. Unlike in muscle, repolarization occurs at a slow rate (100 ms). This prevents the heart from undergoing sustained contractions because it forces the refractory period and cardiac action potential firing to be of the same length of time.


title: T wave

text: Repolarization depends on the charges of ions and their flow across membranes. In skeletal muscle cells, repolarization is simple. First, sodium ions flow into the cell to depolarize it and cause skeletal muscle contraction. Once the action potential is over, potassium ions flow out of the cell due to increased cell membrane permeability to those ions. This high permeability contributes to the rapid repolarization of the membrane potential. This repolarization occurs quickly enough that another action potential can cause depolarization before the last action potential has dissipated. Cardiac muscle differs in that there are more calcium channels that counteract the potassium channels. While potassium quickly flows out of the cell, calcium slowly flows into the cell. This causes the repolarization to occur more slowly, making the refractory period as long as the action potential, preventing sustained contractions.


title: T wave

text: The T wave is representative of the repolarization of the membrane. In an EKG reading, the T wave is notable because it must be present before the next depolarization. An absent or strangely shaped T wave may signify disruption in repolarization or another segment of the heartbeat.


title: T wave

text: Normally, T waves are upright in all leads, except aVR, aVL, III and V1 leads. Highest amplitude of T wave is found at V2 and V3 leads. The shape of the T wave is usually asymmetrical with a rounded peak. T wave inversions from V2 to V4 leads are frequently found and normal in children. In normal adults, T wave inversions from from V2 to V3 are less commonly found but can be normal. The depth of the T wave also becomes progressively shallow from one to the next lead. The height of the T wave should not exceed 5 mm in limb leads and more than 10 mm in precordial leads.


title: T wave

text: Both the abnormalities of the ST segment and T wave represents the abnormalities of the ventricular repolarization or secondary to abnormalities in ventricular depolarisation.


title: T wave

text: Inverted T wave is considered abnormal if inversion is deeper than 1.0 mm. Inverted T waves found in leads other than the V1 to V4 leads is associated with increased cardiac deaths. Inverted T waves associated with cardiac signs and symptoms (chest pain and cardiac murmur) are highly suggestive of myocardial ischaemia. Other ECG changes associate with myocardial ischaemia are: ST segment depression with an upright T wave; ST segment depression with biphasic T wave or inverted T wave with negative QRS complex; T wave symmetrically inverted with a pointed apex, while the ST segment is either bowed upwards or horizontally depressed, or not deviated; and ST segment depression progressing to abnormal T wave during ischaemia free intervals. However, ST segment depression is not suggestive of ischaemic location of the heart. ST segment depression in eight or more leads, associated with ST segment elevation in aVR and V1 are associated with left main coronary artery disease or three-vessel disease (blockage of all three major branches of coronary arteries). ST segment depression most prominent from V1 to V3 is suggestive of posterior infarction. Furthermore, tall or wide QRS complex with an upright T wave is further suggestive of the posterior infarction.


title: T wave

text: Wellens' syndrome is caused by the injury or blockage of the left anterior descending artery, therefore resulting in symmetrical T wave inversions from V2 to V4 with depth more than 5 mm in 75% of the cases. Meanwhile, the remaining 25% of the cases shows biphasic T wave morphology. ST segments remains neutral in this syndrome. Those who were treated without angiography will develop anterior wall myocardial infarction in a mean period of 9 days. An episode of chest pain in Wellens' syndrome is associated with ST elevation or depression and later progressed to T wave abnormality after chest pain subsided. T wave inversion less than 5 mm may still represents myocardial ischaemia, but is less severe than Wellens' syndrome.


title: T wave

text: Hypertrophic cardiomyopathy is the thickening of the left ventricle, occasionally right ventricle. It may be associated with left ventricular outflow tract obstruction or may not be associated with it in 75% of the cases. ECG would be abnormal in 75 to 95% of the patients. Characteristic ECG changes would be large QRS complex associated with giant T wave inversion in lateral leads I, aVL, V5, and V6, together with ST segment depression in left ventricular thickening. For right ventricular thickening, T waves are inverted from V2 to V3 leads. ST and T waves changes may not be apparent in hypertrophic cardiomyopathy, but if there is presence of ST and T waves changes indicates severe hypertrophy or ventricular systolic dysfunction. According to Sokolow-Lyon criterion, the height of R wave in V5 or V6 + the height of S wave in V1 more than 35 mm would be suggestive of left ventricular hypertrophy.


title: T wave

text: Both right and left bundle branch blocks are associated with similar ST and T wave changes as in hypertrophic cardiomyopathy, but are opposite to the direction of the QRS complex.


title: T wave

text: In pulmonary embolism, T wave can be symmetrically inverted at V2 to V4 leads but sinus tachycardia is usually the more common finding. T wave inversion is only present in 19% of mild pulmonary embolism, but the T inversion can be present in 85% of the cases in severe pulmonary embolism. Besides, T inversion can also exists in leads III and aVF.


title: T wave

text: Inversion of T waves in most of the ECG leads except aVR indicates many causes most commonly myocardial ischaemia and intracranial haemorrhage. Others include: hypertrophic cardiomyopathy, Takotsubo cardiomyopathy (stress-induced cardiomyopathy), cocaine abuse, pericarditis, pulmonary embolism, and advanced or complete atrioventricular block.


title: T wave

text: As the name suggests, Biphasic T waves move in opposite directions. The two main causes of these waves are myocardial ischemia and hypokalemia.


title: T wave

text: Wellens' Syndrome is a pattern of biphasic T waves in V2–3. It is generally present in patients with ischemic chest pain.


title: T wave

text: T wave is considered flat when the wave varies from -1.0 mm to + 1.0 mm in height. Hypokalemia or digitalis therapy can cause flattened T wave with a prominent U wave. As hypokalemia progressively worsens, T wave becomes more flatten while U wave becomes more prominent, with progressively deeper ST segment depression. For digitalis toxicity, there will be sagging QT interval, flattened T wave, and prominent U wave with a shortened QT interval.


title: T wave

text: These T waves may be seen in patients displaying Prinzmetal angina. Additionally, patients exhibiting the early stages of STEMI may display these broad and disproportional waves.


title: T wave

text: The name of these T waves suggests the shape it exhibits (double peaks). Since these T wave abnormalities may arise from different events, ie hypothermia and severe brain damage, they have been deemed as nonspecific, making them much more difficult to interpret.


title: E-commerce payment system

text: An e-commerce payment system (or an electronic payment system) facilitates the acceptance of electronic payment for offline transfer, also known as a subcomponent of electronic data interchange (EDI), e-commerce payment systems have become increasingly popular due to the widespread use of the internet-based shopping and banking.


title: E-commerce payment system

text: Credit cards remain the most common forms of payment for e-commerce transactions. As of 2008, in North America, almost 90% of online retail transactions were made with this payment type. It is difficult for an online retailer to operate without supporting credit and debit cards due to their widespread use. Online merchants must comply with stringent rules stipulated by the credit and debit card issuers (e.g. Visa and Mastercard) in accordance with a bank and financial regulation in the countries where the debit/credit service conducts business.


title: E-commerce payment system

text: E-commerce payment system often use B2B mode. The security of customer information, business information, and payment information base is a concern during the payment process of transactions under the conventional B2B e-commerce model.


title: E-commerce payment system

text: For the vast majority of payment systems accessible on the public Internet, baseline authentication (of the financial institution on the receiving end), data integrity, and confidentiality of the electronic information exchanged over the public network involves obtaining a certificate from an authorized certificate authority (CA) who provides public-key infrastructure (PKI). Even with transport layer security (TLS) in place to safeguard the portion of the transaction conducted over public networks—especially with payment systems—the customer-facing website itself must be coded with great care, so as not to leak credentials and expose customers to subsequent identity theft.


title: E-commerce payment system

text: Despite widespread use in North America, there are still many countries such as China and India that have some problems to overcome in regard to credit card security. Increased security measures include use of the card verification number (CVN) which detects fraud by comparing the verification number printed on the signature strip on the back of the card with the information on file with the cardholder's issuing bank.


title: E-commerce payment system

text: There are companies that specialize in financial transaction over the Internet, such as Stripe for credit cards processing, Smartpay for direct online bank payments and PayPal for alternative payment methods at checkout. Many of the mediaries permit consumers to establish an account quickly, and to transfer funds between their on-line accounts and traditional bank accounts, typically via automated clearing house (ACH) transactions.


title: E-commerce payment system

text: The speed and simplicity with which cyber-mediary accounts can be established and used have contributed to their widespread use, despite the risk of theft, abuse, and the typically arduous process of seeking recourse when things go wrong. The inherent information asymmetry of large financial institutions maintaining information safeguards provides the end-user with little insight into the system when the system mishandles funds, leaving disgruntled users frequently accusing the mediaries of sloppy or wrongful behavior; trust between the public and the banking corporations is not improved when large financial institutions are revealed to have taken flagrant advantage of their asymmetric power, such as the 2016 Wells Fargo account fraud scandal.


title: E-commerce payment system

text: There are varied types of electronic payment methods such as online credit card transactions, e-wallets, e-cash and wireless payment system. Credit cards constitute a popular method of online payment but can be expensive for the merchant to accept because of transaction fees primarily. Debit cards constitute an excellent alternative with similar security but usually much cheaper charges. Besides card-based payments, alternative payment methods have emerged and sometimes even claimed market leadership.


title: E-commerce payment system

text: This is a system that does not involve any sort of physical card. It is used by customers who have accounts enabled with Internet banking. Instead of entering card details on the purchaser's site, in this system the payment gateway allows one to specify which bank they wish to pay from. Then the user is redirected to the bank's website, where one can authenticate oneself and then approve the payment. Typically there will also be some form of two-factor authentication.


title: E-commerce payment system

text: It is typically seen as being safer than using credit cards, as it is much more difficult for hackers to gain login credentials compared to credit card numbers. For many eCommerce merchants, offering an option for customers to pay with the cash in their bank account reduces cart abandonment as it enables a way to complete a transaction without credit cards.


title: E-commerce payment system

text: In some developing countries, many people do not have access to banking facilities, especially in tier II and tier III cities. Taking the example of India, there are more mobile phone users than there are people with active bank accounts. Telecom operators, in such locations, have started offering mobile money wallets which allow adding funds easily through their existing mobile subscription number, by visiting physical recharge points close to their homes and offices and converting their cash into mobile wallet currency. This can be used for online transaction and eCommerce purchases.


title: Dominion: Prequel to the Exorcist

text: Dominion: Prequel to the Exorcist is a 2005 American supernatural horror film directed by Paul Schrader and written by William Wisher Jr. and Caleb Carr. The film serves as an alternative prequel to "The Exorcist" (1973) and is the fifth installment in "The Exorcist" series. The film stars Stellan Skarsgård, Clara Bellar, Gabriel Mann and Billy Crawford.