title: Republic F-105 Thunderchief

text: The final 143 Thunderchiefs built were of the two-seat F-105F trainer variant. Based on the F-105D, this model was 31 inches (79 cm) longer to provide room for the rear cockpit; otherwise, the aircraft had similar flight performance to the preceding F-105D. A total of 833 F-105s were completed before production ended in 1964. The F-105 had been designed for a short nuclear campaign, leading to shortcomings that became evident in a lengthy conventional war, such as a poor hydraulics layout and fuel tanks that were not self-sealing. Subsequent upgrades improved the reliability and weapons capacity of the existing F-105Ds. In response to the surface-to-air missile (SAM) threat experienced in the skies above Vietnam, dozens of F-105Fs were converted into anti-radar "Wild Weasel" aircraft, culminating with the F-105G.


title: Republic F-105 Thunderchief

text: The F-105 was a mid-wing monoplane with a 45° swept wing and tail surfaces. The single engine was fed by two intakes in the wing roots, leaving the nose free for a radome housing the multi-mode radar. Its fuselage provided room for of fuel and an internal bomb bay. The bomb bay measured by by ; it was originally designed to carry a single nuclear weapon but typically held an additional fuel tank. It featured four under-wing and one centerline pylon; the two inner wing and centerline pylons were capable of accepting fuel from drop tanks. Two outer dry stations were wired for missiles or bombs. One M61 Vulcan (initially designated "T-171E3") 20 mm 6-barrel Gatling-style cannon was installed in the left side of the nose. A short-range AIM-9 Sidewinder air-to-air missile could be carried on each of the outer wing pylons.


title: Republic F-105 Thunderchief

text: The F-105 was designed primarily for low-level interdiction and its low-altitude speed was its greatest asset when dealing with enemy fighters such as the MiG-17/J-5s and MiG-21. The F-105 managed 27.5 air-to-air victories. Based on combat experience, the F-105D was updated with a better ejection seat, additional armor, improved gun sights, and Electronic Counter Measures (ECM) pods on the wings.


title: Republic F-105 Thunderchief

text: Former North American F-86 Sabre pilot Jerry Noel Hoblit recalled being in awe of the F-105's size after seeing it for the first time; he could not manage to reach the air intake lip even with a running jump. The F-105 had a spacious cockpit with good visibility and layout (particularly after the introduction of "tape" instruments); the advanced electronics were easy to learn and operate. Takeoffs and landings were often performed in the range. The spoilers provided good roll control at all speeds and the distinctive four-petal airbrakes (which also opened slightly when the afterburner was engaged to allow for the larger flow of exhaust gases) were highly effective even at supersonic speeds. Loss of control due to a spin or complications of adverse yaw required deliberate effort from the pilot and spontaneous spin recovery was rapid.


title: Republic F-105 Thunderchief

text: The initial reaction of the fighter pilot community to their new aircraft was lukewarm. Between its massive dimensions and troubled early service life, the F-105 had garnered a number of uncomplimentary nicknames. In addition to the aforementioned "Thud", nicknames included the "Squat Bomber", "Lead Sled", and the "Hyper Hog" and/or "Ultra Hog". The latter two names arose from the F-105's predecessors, the Republic F-84 Thunderjet and F-84F Thunderstreak, nicknamed "Hog" and "Super Hog", respectively. According to F-105 pilots and crews, the "Thud" nickname was inspired by the character "Chief Thunderthud" from the "Howdy Doody" television series.


title: Republic F-105 Thunderchief

text: The aircraft's offensive capabilities were sarcastically referred to as a "Triple Threat"—it could bomb you, strafe you, or fall on you. Positive aspects, such as the F-105's responsive controls, strong performance at high speed and low altitude, and its outfit of electronics won over some pilots. For some, "Thud" was a term of endearment; retroactively the RF-84F Thunderflash became known as "Thud's Mother". F-105 pilot Colonel Jack Broughton said of the nickname: "The Thud has justified herself, and the name that was originally spoken with a sneer has become one of utmost respect through the air fraternity".


title: Republic F-105 Thunderchief

text: The rear cockpits of several two-seat F-105Fs were modified under project "Commando Nail" with an R-14A radar and a radar scope that offered high resolution. These aircraft were used for all-weather and night low-level strikes against especially dangerous targets by a unit from the 13th Tactical Fighter Squadron (1966–1975) dubbed "Ryan's Raiders" starting in April 1967. Some of these aircraft were later converted to the Wild Weasel III standard.


title: Republic F-105 Thunderchief

text: In an effort to thwart MiG attacks, several F-105Fs were also fitted with Hallicrafters QRC-128 communication jamming system under project "Combat Martin". The North Vietnamese interceptor force followed Soviet air-defense doctrine, with pilots under rigid direction of ground controllers over radio links. The QRC-128, nicknamed "Colonel Computer", filled up the rear cockpit of the F-105F. It bounced voice communications over the radio channel back out after a delay, resulting in an obnoxious garble. However, the first time the Combat Martin was used, the US National Security Agency (NSA), in charge of US strategic signals intelligence, ordered the Air Force to cease and desist immediately, since the NSA believed that the intelligence obtained by monitoring the channels outweighed the benefits of jamming them.


title: Republic F-105 Thunderchief

text: Experience in Vietnam demonstrated the need for a better visual and blind bombing capability. In March 1968, the Air Force ordered development of an upgraded bombing/navigation system, incorporating a Singer-General Precision inertial navigation system, improvements to the AN/APN-131 navigation radar, and solid-state circuitry for the R-14A radar, which was redesignated R-14K. Furthermore, the digital AN/ARN-92 long-range navigation receiver replaced the problematic AN/ARN-85 receiver. The additional avionics were housed in a long, raised dorsal spine. The modified bombing/navigation system was known as "Thunderstick II". F-105s with this system could achieve a bombing circular error of probability (CEP) of from an altitude of . Although the first Thunderstick II aircraft flew in 1969, they were not used in Vietnam. A total of 30 F-105Ds received this modification.


title: Republic F-105 Thunderchief

text: In 1965, the USAF began operating two-seat North American F-100F Super Sabres specially equipped for Suppression of Enemy Air Defenses (SEAD) missions in Vietnam. Nicknamed the Wild Weasel, these aircraft achieved a number of victories against North Vietnamese surface-to-air missile radars. The second crew member was a Navigator trained as an Electronic Warfare Officer (EWO) to decipher sensor information and guide the pilot towards the targets. However, the F-100F was an interim solution, since its limited payload often required multiple aircraft to conduct a successful strike; it also lacked the speed and endurance to effectively protect the F-105.


title: Republic F-105 Thunderchief

text: The resulting EF-105F Wild Weasel III (the EF designation was popularly used but unofficial) supplemented its sensors and electronic jamming equipment with AGM-45 Shrike anti-radiation missiles and conventional bombs, giving it an offensive capability lacking in the F-100F. The first of these aircraft flew on 15 January 1966 and they began arriving in Southeast Asia in May, flying their first mission on 6 June 1966, with five assigned to the 13th TFS at Korat RTAFB and six more to the 354th TFS at Takhli RTAFB.


title: Republic F-105 Thunderchief

text: In a typical early mission, a single EF-105F would accompany one or two flights of F-105Ds to provide protection from enemy ground fire. While this strategy was effective in reducing F-105D losses, the Weasel aircraft suffered heavy casualties with five of the first 11 lost in July and August 1966. Attacks into high-risk environments saw the Weasels operating in "Iron Hand" hunter-killer flights of mixed single-seat and two-seat Thunderchiefs, suppressing sites during attacks by the strike force and attacking others en route. In the fall of 1967, EF-105Fs began to be upgraded to the definitive Wild Weasel Thunderchief, the F-105G.


title: Republic F-105 Thunderchief

text: The F-105G incorporated a considerable amount of new SEAD-specific avionics, including an upgraded Radar Homing and Warning (RHAW) system which required a redesign of the wingtips. To free outboard hardpoints for additional weapons, the Westinghouse AN/ALQ-105 electronic countermeasures were permanently installed in two long blisters on the underside of the fuselage. Thirty aircraft were fitted with pylons to carry the AGM-78 Standard anti-radiation missile. On a typical mission, the F-105G carried two Shrikes on outboard pylons, a single Standard on an inboard pylon balanced by a fuel tank on the other side, and a centerline fuel tank.


title: Republic F-105 Thunderchief

text: Notes: "The costs above are in approximately 1960 United States dollars and have not been adjusted for inflation."


title: Republic F-105 Thunderchief

text: The F-105B entered USAF service with the Tactical Air Command's 335th Tactical Fighter Squadron of the 4th Tactical Fighter Wing in August 1958, although the squadron did not become fully operational until 1959. On 11 December 1959, an F-105B piloted by Brig Gen Joseph Moore (commander of the 4th Tactical Fighter Wing) set a world record of over a circuit. Difficulties with its avionics and the MA-8 fire-control system were experienced early on; typically the F-105 required 150 hours of maintenance for each flying hour. Most of these problems were addressed under "Project Optimize". The lack of spares resulted in the entire F-105B fleet being briefly grounded in 1960. In 1964, modified F-105Bs with ballast replacing the cannon, fuselage and wing reinforcement for aerobatics, and the addition of a smoke generator, briefly flew with the United States Air Force Thunderbirds demonstration team. After only six shows, a fatal accident from overstressing the airframe led to the reintroduction of the F-100 Super Sabre.


title: Republic F-105 Thunderchief

text: By 1964, the F-105B was relegated to USAF Air National Guard (ANG) squadrons. It was replaced in frontline service by the definitive F-105D whose advanced NASARR R-14A radar and AN/ASG-19 Thunderstick fire-control system gave it all-weather capability. The R-14A radar also added a terrain-avoidance radar capability, while a completely new instrument panel was fitted, replacing dial-type instrument with vertical tape instruments which were easier to read in combat. In order to accommodate the new radar, with a much larger radar dish, the forward fuselage was redesigned, increasing overall length by .


title: Republic F-105 Thunderchief

text: The F-105D entered service with the 335th TFS in September 1960, although it was not fully operational on the F-105D until early 1961. The first overseas F-105 units formed in West Germany in 1961, with the 36th Tactical Fighter Wing at Bitburg Air Base in May and the 49th Tactical Fighter Wing at Spangdahlem Air Base in October. Both wings had a primary tactical nuclear strike role for NATO. The F-105D was also deployed to the Pacific, with the 18th Tactical Fighter Wing at Kadena in Okinawa converting in 1962 and the 8th Tactical Fighter Wing converting from 1963.


title: Republic F-105 Thunderchief

text: Like the F-105B, the F-105D's early career was plagued with maintenance problems and in-flight failures. The origins of the nickname ""Thud"" were obscure; some claim that it stood for the sound of an F-105 crashing into the ground. The entire F-105D fleet was grounded in December 1961 and then again in June 1962. Many of the issues were worked out during the production run and by 1964, early F-105Ds were upgraded with these fixes under Project "Look Alike", although engine failures and fuel system problems persisted until 1967.


title: Republic F-105 Thunderchief

text: Meanwhile, the USAF was gradually changing the anticipated F-105 mission from nuclear interdiction to conventional bombing. The "Look Alike" upgrades increased the aircraft's capacity from four to 16 conventional bombs on underwing and fuselage centerline hardpoints and added the equipment to launch AGM-12 Bullpup air-to-ground missiles. In June 1961, an F-105D delivered of conventional bombs during a USAF test—at the time a record for a single-engine aircraft with a payload three times heavier than American four-engine heavy bombers of World War II such as the Boeing B-17 Flying Fortress and the Consolidated B-24 Liberator, though aerial refueling would be required for long missions. One of the F-105Ds was named "Memphis Belle II" after the famed World War II B-17.


title: Republic F-105 Thunderchief

text: In spite of a troubled early service life, the F-105 became the dominant attack aircraft early in the Vietnam War. The F-105 could carry more than twice the bomb load farther and faster than the F-100, which was used mostly in South Vietnam. In a foreshadowing of its Wild Weasel role, the first F-105D combat mission of the war involved an attack on 14 August 1964 against an anti-aircraft artillery site on Plaine des Jarres. This mission was carried out by aircraft of the 36th TFS, 6441st Tactical Fighter Wing deployed from Yokota Air Base, Japan to Korat Royal Thai Air Force Base, Thailand. The first Thunderchief lost in the war also occurred during this mission, although the pilot managed to return the aircraft to Korat. The first strike mission took place on 13 January 1965 with the destruction of the Ben Ken bridge in Laos. In early 1965 additional F-105 squadrons were deployed to Korat and Takhli air bases in Thailand. At the start of Operation Rolling Thunder in March 1965, large numbers of F-105Ds were shipped to these bases to participate in intense bombing missions.


title: Republic F-105 Thunderchief

text: On 3 April 1965, a total of 79 aircraft, including 45 F-105 Thunderchiefs, were sent against the Thanh Hoa Bridge, nicknamed "Dragon's Jaw". The next day, enemy MiGs were encountered during a second run upon the bridge; a total of eight MiG-17s faced 46 F-105s escorted by a MiGCAP flight of 21 F-100 Super Sabres. The MiG-17s evaded the escorts using altitude and cloud cover, instead focusing upon the bomb-laden Thunderchiefs. Two Thunderchiefs were lost to the MiG-17s; a third, thought to be lost to ground fire, was later claimed by the North as downed by a MiG-17. One F-105 piloted narrowly escaped. USAF Chief of Staff General John P. McConnell was "hopping mad" to hear that two F-105s had been shot down by Korean War-era subsonic North Vietnamese MiGs. The Thanh Hoa Bridge proved resistant to aerial bombing; multiple missions were flown to damage the bridge both by F-105s and U.S. Navy aircraft.


title: Republic F-105 Thunderchief

text: On 24 July 1965, four U.S. Air Force McDonnell F-4C Phantoms took part in an airstrike against the Dien Ben Phu munitions storage depot and the Lang Chi munitions factory west of Hanoi. One was shot down and three were damaged by SA-2 missiles. After two days, President Johnson gave the order to attack all known SA-2 positions which had been discovered outside the 30-mile exclusion zone. On the morning of 27 July, 48 F-105s participated in the Operation Spring High attack. But the Vietnamese knew U.S. aircraft were coming and set up many 23mm and 37mm anti-aircraft guns at the site. These anti-aircraft guns were lethal at close range and the Vietnamese shot down six aircraft, while more than half of the remaining U.S aircraft suffered damage from ground fire. Both SAM sites were devoid of missiles and equipment, and the Vietnamese had substituted white-painted bundles of bamboo for the real SA-2s. Operation Spring High destroyed two worthless targets at the cost of six aircraft and five pilots.


title: Republic F-105 Thunderchief

text: In December 1966, the Vietnam People's Air Force (VPAF)'s MiG-21 pilots of the 921st Regiment claimed to have downed 14 F-105s without any losses.


title: Republic F-105 Thunderchief

text: On a typical combat mission into North Vietnam, the F-105D carried two wing-mounted fuel tanks, a fuel tank in the bomb bay, and five or six bombs, and required inflight refueling going to and sometimes returning from Hanoi distant. F-105s flying in the vicinity of Hanoi would routinely travel around mountainous terrain nicknamed "Thud Ridge" to evade the air defenses surrounding the city. Colonel Jack Broughton, an F-105 pilot in Vietnam, noted the demands of flying close to Hanoi gave "simply no room for error".


title: Republic F-105 Thunderchief

text: On 11 August 1967, F-105Ds from 335th Tactical Fighter Squadron with support from F-105 Wild Weasels from 338th Tactical Fighter Squadron made the first of many successful attacks on the Paul Doumer bridge over the Red River. Flying low-altitude missions and conducting dive bombings forced the F-105s into range of North Vietnamese anti-aircraft guns, sometimes coming under heavy fire.


title: Republic F-105 Thunderchief

text: USAF F-105s were escorted by F-4s to protect them against enemy fighters. However, the Thunderchief was officially credited with 27.5 air-to-air victories against VPAF aircraft at the cost of 17 aircraft lost to enemy fighters (North Vietnamese pilots claimed to have shot down an additional 23 F-105s but none have been confirmed by USAF). All victories were against MiG-17s. Of these 24.5 were shot down with cannon fire (one victory was shared with an F-4), and three with AIM-9 Sidewinder missiles. One F-105F is unofficially credited with downing three MiGs—one by air-to-air missile, the second by cannon fire and the third by jettisoning the centerline rack full of bombs directly into the path of a surprised MiG.


title: Republic F-105 Thunderchief

text: On 31 May 1968, a dedication ceremony took place at the United States Air Force Academy to honor graduates who had served in Vietnam. An F-105, which had been assembled using parts from ten different F-105s that had seen service in Vietnam, was placed on permanent static display. The ceremony included the entire cadet wing, the superintendent and commandant of cadets of the USAFA, a representative of Republic Aircraft, members of the press, among others. To conclude the ceremony, a flight of four F-105s from McConnell AFB were to fly over in formation at 1,000 feet above the ground and then fly over singly at 250 feet. The formation portion happened as planned. But the flight leader, Lt Col James "Black Matt" Matthews, came back for the single-file pass and exceeded the speed of sound at less than 100 feet. The ensuing sonic boom broke hundreds of windows and fifteen people sustained cuts.


title: Republic F-105 Thunderchief

text: As production of F-105s had ended, the type was replaced in the Vietnam War by other aircraft, primarily the F-4 Phantom II. In October 1970, the 355th Tactical Fighter Wing, which was based at Takhli RTAFB, Thailand, and was the last F-105D unit in Southeast Asia, began to return to the U.S. The F-105G Wild Weasel versions soldiered on until the end of the war. They were gradually replaced by F-4G Wild Weasel IVs.


title: Republic F-105 Thunderchief

text: The Thunderchief was rapidly withdrawn from USAF service after the end of the Vietnam War. Of the 833 F-105s built, a combined 395 F-105s were lost in Southeast Asia, including 334 (296 F-105Ds and 38 two-seaters) lost to enemy action and 61 lost in operational accidents. Following the war the USAF began transferring the remaining aircraft to Air Force Reserve (AFRES) and Air National Guard (ANG) units. By the late 1970s, these aging Thunderchiefs were becoming difficult to maintain. The last F-105Gs with the 128th Tactical Fighter Squadron of the Georgia ANG were retired on 25 May 1983. The last flight of the F-105 Thunderchief was by the AFRES 466th Tactical Fighter Squadron with F-105Ds on 25 February 1984.


title: Tyre, Lebanon

text: Tyre (; ; , Greek "Tyros", Τύρος) is a city in Lebanon, one of the oldest continually inhabited cities in the world, though in medieval times for some centuries by just a tiny population. It was one of the earliest Phoenician metropolises and the legendary birthplace of Europa, her brothers Cadmus and Phoenix, as well as Carthage's founder Dido (Elissa). The city has many ancient sites, including the Tyre Hippodrome, and was added as a whole to UNESCO's list of World Heritage Sites in 1984. The historian Ernest Renan noted that "One can call Tyre a city of ruins, built out of ruins".


title: Tyre, Lebanon

text: Today Tyre is the fourth largest city in Lebanon after Beirut, Tripoli, and Sidon. It is the capital of the Tyre District in the South Governorate. There were approximately 200,000 inhabitants in the Tyre urban area in 2016, including many refugees, as the city hosts three of the twelve Palestinian refugee camps in Lebanon: Burj El Shimali, El Buss, and Rashidieh.


title: Tyre, Lebanon

text: It originally consisted of two distinct urban centres: Tyre itself, which was on an island just offshore, and the associated settlement of Ushu on the adjacent mainland, later called Palaetyrus, meaning "Old Tyre" in Ancient Greek.


title: Tyre, Lebanon

text: Throughout history from prehistoric times onwards, all settlements in the Tyre area profited from the abundance of fresh water supplies, especially from the nearby springs of Rashidieh and Ras Al Ain in the South. In addition there are the springs of Al Bagbog and Ain Ebreen in the North as well as the Litani River, also known as Alqasymieh.


title: Tyre, Lebanon

text: The present city of Tyre covers a large part of the original island and has expanded onto and covers most of the causeway built by Alexander the Great in 332 BCE. This isthmus increased greatly in width over the centuries because of extensive silt depositions on either side. The part of the original island not covered by the modern city of Tyre is mostly of an archaeological site showcasing remains of the city from ancient times.


title: Tyre, Lebanon

text: Four municipalities contribute to Tyre city's 16.7 km built-up area, though none are included in their entirety: Sour municipality contains the heart of the city, excluding the Natural and Coastal Reserve; Burj El Shimali to the East without unpopulated agricultural lands; Abbasiyet Sour to the North without agricultural lands and a dislocated village; and Ain Baal to the South-East, also without agricultural lands and dislocated villages. Tyre's urban area lies on a fertile coastal plain, which explains the fact that as of 2017 about 44% of its territory was used for intra-urban agriculture, while built-up land constituted over 40%.


title: Tyre, Lebanon

text: In terms of geomorphology and seismicity, Tyre is close to the Roum Fault and the Yammouneh Fault. Though it has suffered a number of devastating earthquakes over the millennia, the threat level is considered to be low in most places and moderate in a few others. However, a tsunami following an earthquake and subsequent landslides and floods pose major natural risks to the Tyrian population.


title: Tyre, Lebanon

text: Vast reserves of natural gas are estimated to lie beneath Lebanese waters, much of it off Tyre's coast, but exploitation has been delayed by border disputes with Israel.


title: Tyre, Lebanon

text: Early names of Tyre include Akkadian "Ṣurru", Phoenician "Ṣūr" (), and Hebrew "Ṣōr" (). In Semitic languages, the name of the city means "rock" after the rocky formation on which the town was originally built.


title: Tyre, Lebanon

text: The predominant form in Classical Greek was "Týros" (Τύρος), which was first seen in the works of Herodotus but may have been adopted considerably earlier. It gave rise to Latin "Tyrus", which entered English during the Middle English period as "Tyre". The demonym for Tyre is "Tyrian", and the inhabitants are "Tyrians".


title: Tyre, Lebanon

text: Tyre has a Hot-summer mediterranean climate (classified as "Csa" under the Köppen climate classification), characterized by six months of drought from May to October. On average, it has 300 days of sun a year and a yearly temperature of 20.8°C. The average maximum temperature reaches its highest at 30.8 °C in August and the average minimum temperature its lowest at 10 °C in January. On average, the mean annual precipitation reaches up to 645 mm. The temperature of the sea water reaches a minimum of 17 °C in February and a maximum of 32 °C in August. At a depth of 70 m it is constantly at 17–18 °C.


title: Tyre, Lebanon

text: Meanwhile, rising sea levels due to global warming threaten coastal erosion to Tyre's peninsula and bay areas.


title: Tyre, Lebanon

text: Roman historian Justin wrote that the original founders arrived from the nearby city of Sidon in the quest to establish a new harbor. Doric Greek historian Herodotus (c. 484–425 BC), born in the city of Halicarnassus under the Achaemenid Empire, visited Tyre around 450 BCE at the end of the Greco-Persian Wars (499–449 BC), and wrote in his "Histories" that according to the priests there, the city was founded around 2750 BCE, as a walled place upon the mainland, now known as "Paleotyre" (Old Tyre). Archaeological evidence has corroborated this timing.


title: Tyre, Lebanon

text: Tyre enjoys a reputation of having some of the cleanest beaches and waters of Lebanon. However, a UN HABITAT profile found that "seawater is also polluted due to waste water discharge especially in the port area". There is still also considerable pollution by solid waste.


title: Tyre, Lebanon

text: The Tyre Coast Nature Reserve (TCNR) was decreed in 1998 by the Ministry of Public Works. It is long and covers over . The TCNR is within the best preserved stretch of sandy coastline in southern Lebanon and divided into two section zones: a 1.8-km sand lined beach, 1.8 km long and 500 meters wide-ranging from the Tyre Rest House in the north to the Rashidieh Refugee Camp in the South, and a stretch of 2 km with agriculture lands of small family farms and the springs of Ras El Ain with three constantly flowing artesian wells, ranging from Rashidieh to the village of Chaetiyeh in the South.


title: Tyre, Lebanon

text: The former is divided into two zones: one for tourism that features a public beach of some 900 m and restaurant tents during the summer season hosting up to 20,000 visitors on a busy day, and another 900 m of conservation zone as a sanctuary for sea turtles and migrating birds.


title: Tyre, Lebanon

text: Due to its diverse flora and fauna, the reserve was designated a Ramsar Site in 1999 according to the international treaty for the conservation and sustainable use of Wetlands, since it is considered "the last bio-geographic ecosystem in Lebanon". It is an important nesting site for migratory birds, the endangered Loggerhead and green sea turtle, the Arabian spiny mouse and many other creatures (including wall lizards, common pipistrelle, and European badger). Also, there are frequent sighting of dolphins in the waters off Tyre. Altogether, the TCNR includes


title: Tyre, Lebanon

text: 275 species distributed over 50 families. In addition, the reserve is home to seven regionally and nationally threatened species, 4 endemic and 10 rare species, whilst 59 species are restricted to the Eastern Mediterranean area. It is also worthy to indicate that, several bio-indicator species as well as 25 medicinal species were recognized. TCNR encloses flora species belonging to the various habitats: the sandy shore, rocky shore, littoral and Freshwater ecosystems. A wide number of Gramineae, Fabaceae, Asteraceae and Umbellifereae families dominate the floristic resources.


title: Tyre, Lebanon

text: However, the biodiversity of the TCNR is threatened as shown by a strong decrease in the numbers of the caspian terrapin Mauremys caspica, the green toad Bufo viridis and the tree frog Hyla savigny. Also, since the 2000s, the North American camphorweed "Heterotheca subaxillaris" has invaded the TCNR as a neophyte from Haifa across the Blue Line.


title: Tyre, Lebanon

text: The oil spill which devastated the coast north of Ashkelon in February 2021 also contaminated Tyre's beaches.


title: Tyre, Lebanon

text: Arguably the most lasting Phoenician legacy for the Tyrian population has been the linguistic mark that the Syriac and Akkadian languages have left on the Arabic spoken in the region of Tyre. Most notably, the widely used term "Ba'ali" – which is used especially to describe vegetables and fruits from rain-fed, untreated agricultural production – originates from the Baal religion. The Tyrian municipality of Ain Baal is apparently also named after the Phoenician deity. The most visible part of ancient and medieval history on the other side have been the archaeological sites though:


title: Tyre, Lebanon

text: The first archaeological excavations were by Ernest Renan in 1860 and 1861. He was followed in the 1870s by Johannes Nepemuk Sepp. His most notable work was excavating at the cathedral in an attempt to find the bones of Frederick Barbarossa. More work was undertaken in 1903 by the Greek archaeologist Theodore Makridi, curator of the Imperial Museum at Constantinople. Important findings like fragments of marble sarcophagi were sent to the Ottoman capital.


title: Tyre, Lebanon

text: In 1921, an archaeological survey of Tyre was done by a French team under the leadership of Denyse Le Lasseur in 1921. It was followed by another mission between 1934 and 1936 that included aerial surveys and diving expeditions. It was led by the Jesuit missionary Antoine Poidebard, a pioneer of aerial archaeology.


title: Tyre, Lebanon

text: Large-scale excavations started in 1946 under the leadership of Emir Maurice Chéhab (1904-1994), "the father of modern Lebanese archaeology" who for decades headed the Antiquities Service in Lebanon and was the curator of the National Museum of Beirut. His teams uncovered most remains in the Al Bass/Hippodrome and the City Site/Roman baths.


title: Tyre, Lebanon

text: During the 1960s, Honor Frost (1917–2010) – the Cyprus-born pioneer of underwater archaeology initiated several investigations "aimed at identifying and documenting the significant archaeological potential for harbour facilities within coastal Tyre". Based on the results, she suggested that the Al Mobarakee Tower may actually date back to Hellenistic times.


title: Tyre, Lebanon

text: All those works stopped though soon after the 1975 beginning of the Civil War and many records were lost.


title: Tyre, Lebanon

text: In 1984, the United Nations Educational, Scientific and Cultural Organisation (UNESCO) declared Tyre a World Heritage Site in an attempt to halt the damage being done to the archaeological sites by the armed conflict and by anarchic urban development.


title: Tyre, Lebanon

text: In the late 1980s, "clandestine excavations" took place in the Al-Bass cemetery which "flooded the antiquities market".


title: Tyre, Lebanon

text: Regular excavation activities only started again in 1995 under the supervision of Ali Khalil Badawi. Shortly afterwards, an Israeli bomb destroyed an apartment block in the city and evidence for an early church was revealed underneath the rubble. Its unusual design suggests that this was the site of the Cathedral of Paulinus which had been inaugurated in 315 CE.


title: Tyre, Lebanon

text: In 1997, the first Phoenician cremation cemetery was uncovered in the Al Bass site, near the Roman necropolis. Meanwhile, Honor Frost mentored local Lebanese archaeologists to conduct further underwater investigations, which in 2001 confirmed the existence of a man-made structure within the northern harbour area of Tyre.


title: Tyre, Lebanon

text: In 2003, Randa Berri, president of the National Association for the Preservation of South Lebanon’s Archaeology and Heritage and wife of Nabih Berri, veteran leader of the Amal Movement and longtime Speaker of the Parliament of Lebanon, patronized a plan to renovate Khan Sour / Khan Al Askaar, the former Ma'ani palace, and convert it into a museum. As of 2019, nothing was done in that regard and the ruins have kept on crumbling.


title: Tyre, Lebanon

text: The hostilities of the 2006 Lebanon War put the ancient structures of Tyre at risk. This prompted UNESCO's Director-General to launch a "Heritage Alert" for the site. Following the cessation of hostilities in September 2006, a visit by conservation experts to Lebanon observed no direct damage to the ancient city of Tyre. However, the bombardment had damaged frescoes in a Roman funerary cave at the Tyre Necropolis. Additional site degradation was also noted, including "the lack of maintenance, the decay of exposed structures due to lack of rainwater regulation and the decay of porous and soft stones".


title: Tyre, Lebanon

text: Since 2008, a Lebanese-French team under the direction by Pierre-Louis Gatier of the University of Lyon has been conducting archaeological and topographical work. When international archeological missions in Syria came to a halt after 2012 due to the war there, some of them instead started excavations in Tyre, amongst them a team headed by Leila Badre, director of the Archeological Museum of the American University of Beirut (AUB), and Belgian archaeologists.


title: Tyre, Lebanon

text: Threats to Tyre's ancient cultural heritage include development pressures and the illegal antiquities trade. A highway, planned for 2011, was expected to be built in areas that are deemed archaeologically sensitive. A small-scale geophysical survey indicated the presence of archaeological remains at proposed construction sites. The sites have not been investigated. Despite the relocation of a proposed traffic interchange, the lack of precise site boundaries confuses the issue of site preservation.


title: Tyre, Lebanon

text: A 2018 study of Mediterranean world heritage sites found that Tyre's City site has "the highest risk of coastal erosion under current climatic conditions, in addition to 'moderate' risk from extreme sea levels."


title: Tyre, Lebanon

text: Like many of the cities in the Levant and in Lebanon, the architecture since the Lebanese Civil War in the 1970s has been of poor quality, which tend to threaten the cultural heritage in the built environment before the war. Meanwhile, historical buildings from the Ottoman period like Khan Rabu and Khan Sour / Khan Ashkar have partly collapsed after decades of total neglect and lack of any maintenance whatsoever.


title: Tyre, Lebanon

text: In 2013, the International Association to Save Tyre (IAST) made headlines when it launched an online raffle in association with Sotheby's to fund the artisans' village Les Ateliers de Tyr at the outskirts of the city. Participants could purchase tickets for 100 euros to win the 1914 "Man with Opera Hat" painting by Pablo Picasso. The proceeds totaled US$5.26 million. The painting was won by a 25-year-old fire-safety official from Pennsylvania. IAST president Maha al-Khalil Chalabi is a daughter of feudal lord and politician Kazem el-Khalil. In September 2017, she opened "Les Atelier", which is located in the middle of an orangen grove covering an area of 7.300 m at the northeastern outskirts of Tyre.


title: Tyre, Lebanon

text: The first cinema in Tyre opened in the late 1930s when a café owner established makeshift film screenings. Hamid Istanbouli – a fisherman by profession, who was also a traditional storyteller ("hakawati") and thus interested in cinema – projected films on the wall of a Turkish hammam. In 1939 the Roxy opened, followed in 1942 by the "Empire".


title: Tyre, Lebanon

text: By the mid-1950s there were four cinemas in Tyre, and four more soon opened in nearby Nabatieh. Many also hosted live performances by famous actors and musicians, serving as community spaces where people from different backgrounds came together.


title: Tyre, Lebanon

text: In 1959, the "Cinema Rivoli of Tyre" opened and quickly became one of the prime movie theatres of the country. According to UNIFIL, it was visited "by celebrity who's whos of the time, including Jean Marais, Brigitte Bardot, Rushdi Abaza and Omar Hariri." In 1964, the "Dunia" opened, two years later followed by the "Al Hamra Cinema", which became a venue for some of the Arab world's most famous performers, like Mahmoud Darwish, Sheikh Imam, Ahmed Fouad Negm, Wadih el-Safi, and Marcel Khalife.


title: Tyre, Lebanon

text: Meanwhile, two Tyrian artists had a major impact on the development of Lebanese music: Halim el-Roumi (1919–1983) and Ghazi Kahwaji (1945–2017). Some sources claim that the famous musician, composer, singer and actor el-Roumi was born in Tyre to Lebanese parents. However, others suggest that he was born in Nazareth and moved to Tyre from Palestine. For some time, he worked as a teacher at the Jafariya High School there. In 1950 he became director of Radio Lebanon's music department, where he discovered the singer Fairuz and introduced her to the Rahbani brothers. Roumi composed music for and with them in close collaborations.


title: Tyre, Lebanon

text: Kahwaji was Lebanon's first scenographer and for three decades the artistic general director for the Rahbani brothers and Fairuz. He used this prominent position to promote "against confessionalism and fundamentalism". Kahwaji, who was also a professor at the Lebanese University (LU) and the Saint Joseph University in Beirut, published between 2008 and 2010 the sarcastic three-volume book series "Kahwajiyat" about social injustice in the Arab world.


title: Tyre, Lebanon

text: By then, cultural life in Tyre had been severely affected by armed conflict as well. In 1975, the commercial "Festivals de Tyr" – organised by Maha al-Khalil Chalabi, the daughter of feudal landlord and politician Kazem al-Khalil – were supposed to debut but stopped at the outbreak of the Civil War.


title: Tyre, Lebanon

text: Some cinemas were damaged by Israeli bombardment in 1982 and all of them eventually closed down, the last ones in 1989: the Hamra and the AK2000.


title: Tyre, Lebanon

text: In the mid-nineties though, first the idea of a commercial Tyre International Festival was revived. It has been organised since then annually in the ancient site of the Roman hippodrome, featuring international artists like Elton John and Sarah Brightman, as well as Lebanese stars Wadih El Safi, Demis Roussos, Kadim Al-Saher, Melhem Barakat, Julia Boutros, and Majida El Roumi, the daughter of Halim el-Roumi.


title: Tyre, Lebanon

text: The pop singer, folk music entertainer, sound-lyric poet, concert dancer, fit model and Muslim humanitarian Layal Abboud (born 1982) was born and raised in the Tyrian village of Kniseh. She has returned occasionally to perform in Tyre as well.


title: Tyre, Lebanon

text: In 2006, the "Centre de Lecture et d’Animation Culturelle" (C.L.A.C.) was opened by Tyre's municipality as the first public library of the city, with support from the Lebanese Ministry of Culture and the French Embassy in Beirut. It is located in the historical building of the "Beit Daoud" next to the "Beit El Medina", the former Mamluk House, in the old town.


title: Tyre, Lebanon

text: In 2014, the NGO Tiro Association for Arts rehabilitated the defunct cinema Al Hamra under the leadership of "Palestinian-Lebanese street theater performer, actor, comedian, and theater director" (*1986). His grandfather was one of the founders of cinema in Tyre and his father used to repair cinema projectors. The Tiro Association launched the Lebanese International Theater Festival (alternating for storytelling, contemporary dance, and women monodrama), the Lebanese International Short film Festival, the Tyre International Music Festival, the Palestinian Culture Festival, Tiro Arts Festival, and a number of other festivals.


title: Tyre, Lebanon

text: In 2018, the Istanbouli Theatre troupe rehabilitated and moved to the Rivoli Cinema, which had been closed since 1988, to establish the non-commercial Lebanese National Theater as a free cultural space with free entrance and a special focus on training children and youth in arts. It also runs the "Mobile Peace Bus", which is decorated with graffiti of Lebanese cultural icons, to promote arts in the villages of the neighbouring countryside. Istanbouli has argued:


title: Tyre, Lebanon

text: In Tyre, we have 400 shops for shisha, one library, and one theatre. But if there are places, people will come.


title: Tyre, Lebanon

text: In 2019, the film "Manara" (Arabic for "lighthouse") by Lebanese director Zayn Alexander, who shot the movie at the Al Fanar resort in Tyre, won the Laguna Sud Award for Best Short Film at the Venice Days Strand festival.


title: Tyre, Lebanon

text: The Jafariya School was founded in 1938 by Imam Abdul Hussein Sharafeddin. It soon expanded thanks mainly to donations from rich émigrés and thus was upgraded in 1946 to be a Secondary School, the first in Southern Lebanon (see above). It has remained one of the main schools in Tyre ever since.


title: Tyre, Lebanon

text: An important role in the Tyrian education landscape is played by the charity organisation of the vanished Imam Musa al-Sadr, which has been headed since his disappearance in 1978 by his sister Rabab al-Sadr. While the foundation operates in various parts of the country, its main base is a compound on the southern entry of the Tyre peninsula close to the sea. A major focus are its Orphanages, but it also runs adult educational and vocational training programmes, especially for young women, in addition to health and development projects.


title: Tyre, Lebanon

text: Musa Sadr also laid the groundwork for establishing the Islamic University of Lebanon (IUL) which was finally licensed in 1996 and opened a branch on the seafront,in Tyre. Its board of trustees is dominated by representatives of the Supreme Shiite Council, founded by Sadr in 1967.


title: Tyre, Lebanon

text: The Lebanese Evangelical School in Tyre with a history of more than 150 years is arguably the largest school in town. Collège Élite, a French international school opened in 1996, is another one of a host of private schools in Tyre. The Cadmous College - a pre-kindergarten to grade 12 school, run by the Maronite missionaries - has about 10% Christian and 90% Muslim pupils.


title: Tyre, Lebanon

text: In August 2019, the 17-year-old Ismail Ajjawi – a Palestinian resident of Tyre and graduate of the UNRWA Deir Yassin High School in the El Bass refugee camp – made global headlines when he scored top-results to earn a scholarship to study at Harvard, but was deported upon arrival in Boston despite valid visa. He was readmitted ten days later to start his studies in time.


title: Tyre, Lebanon

text: An accurate statistical accounting is not possible, since the government of Lebanon has released only rough estimates of population numbers since 1932. However, a 2016 calculation by UN HABITAT estimated a figure of 201,208 inhabitants, many of them refugees:


title: Tyre, Lebanon

text: The Lebanese nationality population of Tyre is predominantly Shia Muslim with a small but noticeable Christian community. In 2010, it was estimated that Christians accounted for 15% of Tyre's population. In 2017, the Maronite Catholic Archeparchy of Tyre counted about 42,500 members. Most of them live in the mountains of Southern Lebanon, while there are just some 500 Maronites in Tyre itself. The Melkite Greek Catholic Archeparchy of Tyre – which not only covers the District of Tyre in the South Governorate but also neighbouring areas in the Nabatieh Governorate – registered 2,857 members in that year.


title: Tyre, Lebanon

text: The city of Tyre has become home to more than 60,000 Palestinian refugees who are mainly Sunni Muslims with some Christian families. Tyre hosted Shias from the seven villages that were depopulated in 1948, they settled in suburbs like Shabriha. As of June 2018, there were 12,281 registered persons in the Al Buss camp, 24,929 in Burj El Shimali and 34,584 in Rashidieh. In the ramshackle "gathering" of Jal Al Bahar next to the coastal highway, the number of residents was estimated to be around 2,500 in 2015. Many Palestinians contributed to the society in Tyre especially in the education field, photography and trading.


title: Tyre, Lebanon

text: In all camps, the number of refugees from Syria and Palestinian refugees from Syria increased in recent years. Tensions developed since these new arrivals would often accept work in the citrus and banana groves "for half the daily wage" that local Palestinian refugees used to earn.


title: Tyre, Lebanon

text: In early 2019, some 1,500 Syrian refugees were evicted from their informal settlements around the Litani river for allegedly polluting the waters which are already heavily contaminated.


title: Tyre, Lebanon

text: Tyre is known as "Little West Africa". Many families in Tyre have relatives in the Western Africa diaspora, especially in Senegal, Sierra Leone, Liberia, Ivory Coast and Nigeria. In Senegal, most immigrants originated from Tyre. Member of the Tyrian communities there are "primarily second-, third-, and fourth-generation migrants, many of whom have never been to Lebanon." One of Tyre's main promenades is called "Avenue du Senegal".


title: Tyre, Lebanon

text: As there were an estimated 250,000 foreign workers – mostly female Ethiopians – under the discriminatory Kafala system of sponsorship in Lebanon by 2019, there is also a large community of African migrants in Tyre. They are mainly Ethiopian women who work as domestic servants. Some of them celebrate church service at the Greek-Catholic Cathedral of Saint Thomas, which has devoted a chapel on its compound to Tyre-born Saint Frumentius, the first bishop of the Ethiopian Orthodox Tewahedo Church. In April 2014 one Ethiopian made sad headlines in an apparent suicide in Tyre:


title: Tyre, Lebanon

text: Media reports said the woman had fled last week from her employer's home. Security forces later detained the Ethiopian and returned her to her employer


title: Tyre, Lebanon

text: The economy of urban Tyre mostly depends on tourism, contracting services, the construction sector, and remittances from Tyrians in the diaspora, especially in West Africa.


title: Tyre, Lebanon

text: UNIFIL contributes greatly to the purchasing power in the Tyrian economy as well, both through spending by its individual members as well as through "quick-impact projects" like gravelling road, rehabilitating public places etc.


title: Tyre, Lebanon

text: As of 2016, Olive trees were reported to comprise 38% of Tyre's agricultural land, but producers lacked a collective marketing strategy. While Citrus reportedly comprised 25% of the agricultural land, 20% of its harvest ended up wasted.


title: Tyre, Lebanon

text: Tyre houses one of the nation's major ports, though much smaller than the ports of Beirut, Tripoli, and also Sidon/Saida. Its cargo traffic has been limited to the periodical import of used cars. One day after the 2020 Beirut explosion which devastated the Port of Beirut and much of the national capital on 4 August the national government reportedly decided to use the Port of Tyre as a back-up for the Port of Tripoli.


title: Tyre, Lebanon

text: In the harbour area, the Barbour family of shipbuilders continues to build wooden boats. Tyre is thus one of only a few cities in the Mediterranean that has kept this ancient tradition, although the Barbour business has been struggling to survive as well. By 2004, there were "over 600 fishermen [..] striving to make ends meet in Tyre alone".


title: Tyre, Lebanon

text: Lebanon's General Directorate of Land Registry and Cadastre (GDLRC) recorded for Tyre a 4.4 percent growth rate for land transactions between 2014 and 2018, the highest rate in the country during that period. This increase in real estate prices has been largely attributed to the inflow of remittances from diaspora Tyrians.


title: Tyre, Lebanon

text: Off the Tyrian coast, block 9 has been awarded for deepwater drilling of natural gas to a consortium of French company TotalEnergies, Italy-based Eni, and Russian Novatek.


title: Tyre, Lebanon

text: Tadamon Sour Sporting Club, or simply Tadamon (meaning "Solidarity"), nicknamed "The Ambassador of the South", was founded in 1946 and is thus the historically most established football club of Tyre. They play their home matches at the Tyre Municipal Stadium, and have won one Lebanese FA Cup (2000–01) and two Lebanese Challenge Cups (2013 and 2018). Tadamon's traditional rivals, Salam Sour Sports Club, are also based in Tyre.


title: Tyre, Lebanon

text: According to BBC reports, Tadamon SC was stripped of its Lebanese Premier League championship title in 2001 following match-fixing allegations.


title: Tyre, Lebanon

text: In the same year the club scored arguably one of its biggest transfers when Roda Antar from its own youth teams was loaned to Germany's Hamburger SV for two seasons. After eight years in Germany with Hamburg, SC Freiburg and 1. FC Köln he played another six years in the Chinese Super League and then returned to Tadamon for one final season before retirement.


title: Tyre, Lebanon

text: A number of Lebanese Premier League professional footballers, who have also played for the Lebanon national team, originate from Tyre, namely Rabih Ataya, and Nassar Nassar.


title: Tyre, Lebanon

text: A multi-ring structured region on Europa, the smallest of the four Galilean moons orbiting Jupiter, is named after Tyre, the legendary birthplace of princess Europa. Originally called "Tyre Macula", it is some 140 kilometers in diameter (about the size of the island of Hawaii) and thought to be the site where an asteroid or comet impacted Europa's ice crust.


title: Tyre, Lebanon

text: The asteroid 209 Dido is named after the legendary Tyrian-Carthaginian princess. It is a very large main-belt asteroid, classified as a C-type asteroid which is probably composed of carbonaceous materials. 209 Dido was discovered in 1879 by C. H. F. Peters.


title: Microscope

text: A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisible to the eye unless aided by a microscope.


title: Microscope

text: There are many types of microscopes, and they may be grouped in different ways. One way is to describe the method an instrument uses to interact with a sample and produce images, either by sending a beam of light or electrons through a sample in its optical path, by detecting photon emissions from a sample, or by scanning across and a short distance from the surface of a sample using a probe. The most common microscope (and the first to be invented) is the optical microscope, which uses lenses to refract visible light that passed through a thinly sectioned sample to produce an observable image. Other major types of microscopes are the fluorescence microscope, electron microscope (both the transmission electron microscope and the scanning electron microscope) and various types of scanning probe microscopes.


title: Microscope

text: Although objects resembling lenses date back 4,000 years and there are Greek accounts of the optical properties of water-filled spheres (5th century BC) followed by many centuries of writings on optics, the earliest known use of simple microscopes (magnifying glasses) dates back to the widespread use of lenses in eyeglasses in the 13th century. The earliest known examples of compound microscopes, which combine an objective lens near the specimen with an eyepiece to view a real image, appeared in Europe around 1620. The inventor is unknown, even though many claims have been made over the years. Several revolve around the spectacle-making centers in the Netherlands, including claims it was invented in 1590 by Zacharias Janssen (claim made by his son) or Zacharias' father, Hans Martens, or both, claims it was invented by their neighbor and rival spectacle maker, Hans Lippershey (who applied for the first telescope patent in 1608), and claims it was invented by expatriate Cornelis Drebbel, who was noted to have a version in London in 1619. Galileo Galilei (also sometimes cited as compound microscope inventor) seems to have found after 1610 that he could close focus his telescope to view small objects and, after seeing a compound microscope built by Drebbel exhibited in Rome in 1624, built his own improved version. Giovanni Faber coined the name "microscope" for the compound microscope Galileo submitted to the Accademia dei Lincei in 1625 (Galileo had called it the "occhiolino" 'little eye').


title: Microscope

text: The first detailed account of the microscopic anatomy of organic tissue based on the use of a microscope did not appear until 1644, in Giambattista Odierna's "L'occhio della mosca", or "The Fly's Eye".


title: Microscope

text: The microscope was still largely a novelty until the 1660s and 1670s when naturalists in Italy, the Netherlands and England began using them to study biology. Italian scientist Marcello Malpighi, called the father of histology by some historians of biology, began his analysis of biological structures with the lungs. The publication in 1665 of Robert Hooke's "Micrographia" had a huge impact, largely because of its impressive illustrations. A significant contribution came from Antonie van Leeuwenhoek who achieved up to 300 times magnification using a simple single lens microscope. He sandwiched a very small glass ball lens between the holes in two metal plates riveted together, and with an adjustable-by-screws needle attached to mount the specimen. Then, Van Leeuwenhoek re-discovered red blood cells (after Jan Swammerdam) and spermatozoa, and helped popularise the use of microscopes to view biological ultrastructure. On 9 October 1676, van Leeuwenhoek reported the discovery of micro-organisms.


title: Microscope

text: The performance of a light microscope depends on the quality and correct use of the condensor lens system to focus light on the specimen and the objective lens to capture the light from the specimen and form an image. Early instruments were limited until this principle was fully appreciated and developed from the late 19th to very early 20th century, and until electric lamps were available as light sources. In 1893 August Köhler developed a key principle of sample illumination, Köhler illumination, which is central to achieving the theoretical limits of resolution for the light microscope. This method of sample illumination produces even lighting and overcomes the limited contrast and resolution imposed by early techniques of sample illumination. Further developments in sample illumination came from the discovery of phase contrast by Frits Zernike in 1953, and differential interference contrast illumination by Georges Nomarski in 1955; both of which allow imaging of unstained, transparent samples.


title: Microscope

text: In the early 20th century a significant alternative to the light microscope was developed, an instrument that uses a beam of electrons rather than light to generate an image. The German physicist, Ernst Ruska, working with electrical engineer Max Knoll, developed the first prototype electron microscope in 1931, a transmission electron microscope (TEM). The transmission electron microscope works on similar principles to an optical microscope but uses electrons in the place of light and electromagnets in the place of glass lenses. Use of electrons, instead of light, allows for much higher resolution.


title: Microscope

text: Development of the transmission electron microscope was quickly followed in 1935 by the development of the scanning electron microscope by Max Knoll. Although TEMs were being used for research before WWII, and became popular afterwards, the SEM was not commercially available until 1965.


title: Microscope

text: Transmission electron microscopes became popular following the Second World War. Ernst Ruska, working at Siemens, developed the first commercial transmission electron microscope and, in the 1950s, major scientific conferences on electron microscopy started being held. In 1965, the first commercial scanning electron microscope was developed by Professor Sir Charles Oatley and his postgraduate student Gary Stewart, and marketed by the Cambridge Instrument Company as the "Stereoscan".


title: Microscope

text: One of the latest discoveries made about using an electron microscope is the ability to identify a virus. Since this microscope produces a visible, clear image of small organelles, in an electron microscope there is no need for reagents to see the virus or harmful cells, resulting in a more efficient way to detect pathogens.


title: Microscope

text: From 1981 to 1983 Gerd Binnig and Heinrich Rohrer worked at IBM in Zurich, Switzerland to study the quantum tunnelling phenomenon. They created a practical instrument, a scanning probe microscope from quantum tunnelling theory, that read very small forces exchanged between a probe and the surface of a sample. The probe approaches the surface so closely that electrons can flow continuously between probe and sample, making a current from surface to probe. The microscope was not initially well received due to the complex nature of the underlying theoretical explanations. In 1984 Jerry Tersoff and D.R. Hamann, while at AT&T's Bell Laboratories in Murray Hill, New Jersey began publishing articles that tied theory to the experimental results obtained by the instrument. This was closely followed in 1985 with functioning commercial instruments, and in 1986 with Gerd Binnig, Quate, and Gerber's invention of the atomic force microscope, then Binnig's and Rohrer's Nobel Prize in Physics for the SPM.


title: Microscope

text: New types of scanning probe microscope have continued to be developed as the ability to machine ultra-fine probes and tips has advanced.


title: Microscope

text: The most recent developments in light microscope largely centre on the rise of fluorescence microscopy in biology. During the last decades of the 20th century, particularly in the post-genomic era, many techniques for fluorescent staining of cellular structures were developed. The main groups of techniques involve targeted chemical staining of particular cell structures, for example, the chemical compound DAPI to label DNA, use of antibodies conjugated to fluorescent reporters, see


title: Microscope

text: immunofluorescence, and fluorescent proteins, such as green fluorescent protein. These techniques use these different fluorophores for analysis of cell structure at a molecular level in both live and fixed samples.


title: Microscope

text: The rise of fluorescence microscopy drove the development of a major modern microscope design, the confocal microscope. The principle was patented in 1957 by Marvin Minsky, although laser technology limited practical application of the technique. It was not until 1978 when Thomas and Christoph Cremer developed the first practical confocal laser scanning microscope and the technique rapidly gained popularity through the 1980s.


title: Microscope

text: Much current research (in the early 21st century) on optical microscope techniques is focused on development of superresolution analysis of fluorescently labelled samples. Structured illumination can improve resolution by around two to four times and techniques like stimulated emission depletion (STED) microscopy are approaching the resolution of electron microscopes. This occurs because the diffraction limit is occurred from light or excitation, which makes the resolution must be doubled to become super saturated. Stefan Hell was awarded the 2014 Nobel Prize in Chemistry for the development of the STED technique, along with Eric Betzig and William Moerner who adapted fluorescence microscopy for single-molecule visualization.


title: Microscope

text: X-ray microscopes are instruments that use electromagnetic radiation usually in the soft X-ray band to image objects. Technological advances in X-ray lens optics in the early 1970s made the instrument a viable imaging choice. They are often used in tomography (see micro-computed tomography) to produce three dimensional images of objects, including biological materials that have not been chemically fixed. Currently research is being done to improve optics for hard X-rays which have greater penetrating power.


title: Microscope

text: Microscopes can be separated into several different classes. One grouping is based on what interacts with the sample to generate the image, i.e., light or photons (optical microscopes), electrons (electron microscopes) or a probe (scanning probe microscopes). Alternatively, microscopes can be classified based on whether they analyze the sample via a scanning point (confocal optical microscopes, scanning electron microscopes and scanning probe microscopes) or analyze the sample all at once (wide field optical microscopes and transmission electron microscopes).


title: Microscope

text: Wide field optical microscopes and transmission electron microscopes both use the theory of lenses (optics for light microscopes and electromagnet lenses for electron microscopes) in order to magnify the image generated by the passage of a wave transmitted through the sample, or reflected by the sample. The waves used are electromagnetic (in optical microscopes) or electron beams (in electron microscopes). Resolution in these microscopes is limited by the wavelength of the radiation used to image the sample, where shorter wavelengths allow for a higher resolution.


title: Microscope

text: Scanning optical and electron microscopes, like the confocal microscope and scanning electron microscope, use lenses to focus a spot of light or electrons onto the sample then analyze the signals generated by the beam interacting with the sample. The point is then scanned over the sample to analyze a rectangular region. Magnification of the image is achieved by displaying the data from scanning a physically small sample area on a relatively large screen. These microscopes have the same resolution limit as wide field optical, probe, and electron microscopes.


title: Microscope

text: Scanning probe microscopes also analyze a single point in the sample and then scan the probe over a rectangular sample region to build up an image. As these microscopes do not use electromagnetic or electron radiation for imaging they are not subject to the same resolution limit as the optical and electron microscopes described above.


title: Microscope

text: The most common type of microscope (and the first invented) is the optical microscope. This is an optical instrument containing one or more lenses producing an enlarged image of a sample placed in the focal plane. Optical microscopes have refractive glass (occasionally plastic or quartz), to focus light on the eye or on to another light detector. Mirror-based optical microscopes operate in the same manner. Typical magnification of a light microscope, assuming visible range light, is up to 1,250× with a theoretical resolution limit of around 0.250 micrometres or 250 nanometres. This limits practical magnification to ~1,500×. Specialized techniques (e.g., scanning confocal microscopy, Vertico SMI) may exceed this magnification but the resolution is diffraction limited. The use of shorter wavelengths of light, such as ultraviolet, is one way to improve the spatial resolution of the optical microscope, as are devices such as the near-field scanning optical microscope.


title: Microscope

text: Sarfus is a recent optical technique that increases the sensitivity of a standard optical microscope to a point where it is possible to directly visualize nanometric films (down to 0.3 nanometre) and isolated nano-objects (down to 2 nm-diameter). The technique is based on the use of non-reflecting substrates for cross-polarized reflected light microscopy.


title: Microscope

text: Ultraviolet light enables the resolution of microscopic features as well as the imaging of samples that are transparent to the eye. Near infrared light can be used to visualize circuitry embedded in bonded silicon devices, since silicon is transparent in this region of wavelengths.


title: Microscope

text: In fluorescence microscopy many wavelengths of light ranging from the ultraviolet to the visible can be used to cause samples to fluoresce, which allows viewing by eye or with specifically sensitive cameras.


title: Microscope

text: Phase-contrast microscopy is an optical microscopic illumination technique in which small phase shifts in the light passing through a transparent specimen are converted into amplitude or contrast changes in the image. The use of phase contrast does not require staining to view the slide. This microscope technique made it possible to study the cell cycle in live cells.


title: Microscope

text: The traditional optical microscope has more recently evolved into the digital microscope. In addition to, or instead of, directly viewing the object through the eyepieces, a type of sensor similar to those used in a digital camera is used to obtain an image, which is then displayed on a computer monitor. These sensors may use CMOS or charge-coupled device (CCD) technology, depending on the application.


title: Microscope

text: Digital microscopy with very low light levels to avoid damage to vulnerable biological samples is available using sensitive photon-counting digital cameras. It has been demonstrated that a light source providing pairs of entangled photons may minimize the risk of damage to the most light-sensitive samples. In this application of ghost imaging to photon-sparse microscopy, the sample is illuminated with infrared photons, each of which is spatially correlated with an entangled partner in the visible band for efficient imaging by a photon-counting camera.


title: Microscope

text: The two major types of electron microscopes are transmission electron microscopes (TEMs) and scanning electron microscopes (SEMs). They both have series of electromagnetic and electrostatic lenses to focus a high energy beam of electrons on a sample. In a TEM the electrons pass through the sample, analogous to basic optical microscopy. This requires careful sample preparation, since electrons are scattered strongly by most materials. The samples must also be very thin (below 100 nm) in order for the electrons to pass through it. Cross-sections of cells stained with osmium and heavy metals reveal clear organelle membranes and proteins such as ribosomes. With a 0.1 nm level of resolution, detailed views of viruses (20 – 300 nm) and a strand of DNA (2 nm in width) can be obtained. In contrast, the SEM has raster coils to scan the surface of bulk objects with a fine electron beam. Therefore, the specimen do not necessarily need to be sectioned, but coating with a nanometric metal or carbon layer may be needed for nonconductive samples. SEM allows fast surface imaging of samples, possibly in thin water vapor to prevent drying.


title: Microscope

text: The different types of scanning probe microscopes arise from the many different types of interactions that occur when a small probe is scanned over and interacts with a specimen. These interactions or modes can be recorded or mapped as function of location on the surface to form a characterization map. The three most common types of scanning probe microscopes are atomic force microscopes (AFM), near-field scanning optical microscopes (MSOM or SNOM, scanning near-field optical microscopy), and scanning tunneling microscopes (STM). An atomic force microscope has a fine probe, usually of silicon or silicon nitride, attached to a cantilever; the probe is scanned over the surface of the sample, and the forces that cause an interaction between the probe and the surface of the sample are measured and mapped. A near-field scanning optical microscope is similar to an AFM but its probe consists of a light source in an optical fiber covered with a tip that has usually an aperture for the light to pass through. The microscope can capture either transmitted or reflected light to measure very localized optical properties of the surface, commonly of a biological specimen. Scanning tunneling microscopes have a metal tip with a single apical atom; the tip is attached to a tube through which a current flows. The tip is scanned over the surface of a conductive sample until a tunneling current flows; the current is kept constant by computer movement of the tip and an image is formed by the recorded movements of the tip.


title: Microscope

text: Scanning acoustic microscopes use sound waves to measure variations in acoustic impedance. Similar to Sonar in principle, they are used for such jobs as detecting defects in the subsurfaces of materials including those found in integrated circuits. On February 4, 2013, Australian engineers built a "quantum microscope" which provides unparalleled precision.


title: Microscope

text: Mobile app microscopes can optionally be used as optical microscope when the flashlight is activated. However, mobile app microscopes are harder to use due to visual noise, are often limited to 40x, and the resolution limits of the camera lens itself.


title: Information theory

text: Information theory is the scientific study of the quantification, storage, and communication of information. The field was originally established by the works of Harry Nyquist and Ralph Hartley, in the 1920s, and Claude Shannon in the 1940s. The field is at the intersection of probability theory, statistics, computer science, statistical mechanics, information engineering, and electrical engineering.


title: Information theory

text: A key measure in information theory is entropy. Entropy quantifies the amount of uncertainty involved in the value of a random variable or the outcome of a random process. For example, identifying the outcome of a fair coin flip (with two equally likely outcomes) provides less information (lower entropy) than specifying the outcome from a roll of a die (with six equally likely outcomes). Some other important measures in information theory are mutual information, channel capacity, error exponents, and relative entropy. Important sub-fields of information theory include source coding, algorithmic complexity theory, algorithmic information theory and information-theoretic security.


title: Information theory

text: Applications of fundamental topics of information theory include source coding/data compression (e.g. for ZIP files), and channel coding/error detection and correction (e.g. for DSL). Its impact has been crucial to the success of the Voyager missions to deep space, the invention of the compact disc, the feasibility of mobile phones and the development of the Internet. The theory has also found applications in other areas, including statistical inference, cryptography, neurobiology, perception, linguistics, the evolution and function of molecular codes (bioinformatics), thermal physics, molecular dynamics, quantum computing, black holes, information retrieval, intelligence gathering, plagiarism detection, pattern recognition, anomaly detection and even art creation.


title: Information theory

text: Information theory studies the transmission, processing, extraction, and utilization of information. Abstractly, information can be thought of as the resolution of uncertainty. In the case of communication of information over a noisy channel, this abstract concept was formalized in 1948 by Claude Shannon in a paper entitled "A Mathematical Theory of Communication", in which information is thought of as a set of possible messages, and the goal is to send these messages over a noisy channel, and to have the receiver reconstruct the message with low probability of error, in spite of the channel noise. Shannon's main result, the noisy-channel coding theorem showed that, in the limit of many channel uses, the rate of information that is asymptotically achievable is equal to the channel capacity, a quantity dependent merely on the statistics of the channel over which the messages are sent.


title: Information theory

text: Coding theory is concerned with finding explicit methods, called "codes", for increasing the efficiency and reducing the error rate of data communication over noisy channels to near the channel capacity. These codes can be roughly subdivided into data compression (source coding) and error-correction (channel coding) techniques. In the latter case, it took many years to find the methods Shannon's work proved were possible.


title: Information theory

text: A third class of information theory codes are cryptographic algorithms (both codes and ciphers). Concepts, methods and results from coding theory and information theory are widely used in cryptography and cryptanalysis. "See the article ban (unit) for a historical application."


title: Information theory

text: The landmark event "establishing" the discipline of information theory and bringing it to immediate worldwide attention was the publication of Claude E. Shannon's classic paper "A Mathematical Theory of Communication" in the "Bell System Technical Journal" in July and October 1948.


title: Information theory

text: Prior to this paper, limited information-theoretic ideas had been developed at Bell Labs, all implicitly assuming events of equal probability. Harry Nyquist's 1924 paper, "Certain Factors Affecting Telegraph Speed", contains a theoretical section quantifying "intelligence" and the "line speed" at which it can be transmitted by a communication system, giving the relation (recalling the Boltzmann constant), where "W" is the speed of transmission of intelligence, "m" is the number of different voltage levels to choose from at each time step, and "K" is a constant. Ralph Hartley's 1928 paper, "Transmission of Information", uses the word "information" as a measurable quantity, reflecting the receiver's ability to distinguish one sequence of symbols from any other, thus quantifying information as , where "S" was the number of possible symbols, and "n" the number of symbols in a transmission. The unit of information was therefore the decimal digit, which since has sometimes been called the hartley in his honor as a unit or scale or measure of information. Alan Turing in 1940 used similar ideas as part of the statistical analysis of the breaking of the German second world war Enigma ciphers.


title: Information theory

text: Much of the mathematics behind information theory with events of different probabilities were developed for the field of thermodynamics by Ludwig Boltzmann and J. Willard Gibbs. Connections between information-theoretic entropy and thermodynamic entropy, including the important contributions by Rolf Landauer in the 1960s, are explored in "Entropy in thermodynamics and information theory".


title: Information theory

text: In Shannon's revolutionary and groundbreaking paper, the work for which had been substantially completed at Bell Labs by the end of 1944, Shannon for the first time introduced the qualitative and quantitative model of communication as a statistical process underlying information theory, opening with the assertion:


title: Information theory

text: Information theory is based on probability theory and statistics, where quantified information is usually described in terms of bits. Information theory often concerns itself with measures of information of the distributions associated with random variables. One of the most important measures is called entropy, which forms the building block of many other measures. Entropy allows quantification of measure of information in a single random variable. Another useful concept is mutual information defined on two random variables, which describes the measure of information in common between those variables, which can be used to describe their correlation. The former quantity is a property of the probability distribution of a random variable and gives a limit on the rate at which data generated by independent samples with the given distribution can be reliably compressed. The latter is a property of the joint distribution of two random variables, and is the maximum rate of reliable communication across a noisy channel in the limit of long block lengths, when the channel statistics are determined by the joint distribution.


title: Information theory

text: The choice of logarithmic base in the following formulae determines the unit of information entropy that is used. A common unit of information is the bit, based on the binary logarithm. Other units include the nat, which is based on the natural logarithm, and the decimal digit, which is based on the common logarithm.


title: Information theory

text: In what follows, an expression of the form is considered by convention to be equal to zero whenever . This is justified because formula_1 for any logarithmic base.


title: Information theory

text: Based on the probability mass function of each source symbol to be communicated, the Shannon entropy , in units of bits (per symbol), is given by


title: Information theory

text: where is the probability of occurrence of the -th possible value of the source symbol. This equation gives the entropy in the units of "bits" (per symbol) because it uses a logarithm of base 2, and this base-2 measure of entropy has sometimes been called the shannon in his honor. Entropy is also commonly computed using the natural logarithm (base , where is Euler's number), which produces a measurement of entropy in nats per symbol and sometimes simplifies the analysis by avoiding the need to include extra constants in the formulas. Other bases are also possible, but less commonly used. For example, a logarithm of base will produce a measurement in bytes per symbol, and a logarithm of base 10 will produce a measurement in decimal digits (or hartleys) per symbol.


title: Information theory

text: Intuitively, the entropy of a discrete random variable is a measure of the amount of "uncertainty" associated with the value of when only its distribution is known.


title: Information theory

text: The entropy of a source that emits a sequence of symbols that are independent and identically distributed (iid) is bits (per message of symbols). If the source data symbols are identically distributed but not independent, the entropy of a message of length will be less than .


title: Information theory

text: If one transmits 1000 bits (0s and 1s), and the value of each of these bits is known to the receiver (has a specific value with certainty) ahead of transmission, it is clear that no information is transmitted. If, however, each bit is independently equally likely to be 0 or 1, 1000 shannons of information (more often called bits) have been transmitted. Between these two extremes, information can be quantified as follows. If formula_3 is the set of all messages that could be, and is the probability of some formula_4, then the entropy, , of is defined:


title: Information theory

text: (Here, is the self-information, which is the entropy contribution of an individual message, and formula_6 is the expected value.) A property of entropy is that it is maximized when all the messages in the message space are equiprobable ; i.e., most unpredictable, in which case .


title: Information theory

text: The special case of information entropy for a random variable with two outcomes is the binary entropy function, usually taken to the logarithmic base 2, thus having the shannon (Sh) as unit:


title: Information theory

text: The of two discrete random variables and is merely the entropy of their pairing: . This implies that if and are independent, then their joint entropy is the sum of their individual entropies.


title: Information theory

text: For example, if represents the position of a chess piece— the row and the column, then the joint entropy of the row of the piece and the column of the piece will be the entropy of the position of the piece.


title: Information theory

text: The or "conditional uncertainty" of given random variable (also called the "equivocation" of about ) is the average conditional entropy over :


title: Information theory

text: Because entropy can be conditioned on a random variable or on that random variable being a certain value, care should be taken not to confuse these two definitions of conditional entropy, the former of which is in more common use. A basic property of this form of conditional entropy is that:


title: Information theory

text: "Mutual information" measures the amount of information that can be obtained about one random variable by observing another. It is important in communication where it can be used to maximize the amount of information shared between sent and received signals. The mutual information of relative to is given by:


title: Information theory

text: Mutual information can be expressed as the average Kullback–Leibler divergence (information gain) between the posterior probability distribution of "X" given the value of "Y" and the prior distribution on "X":


title: Information theory

text: In other words, this is a measure of how much, on the average, the probability distribution on "X" will change if we are given the value of "Y". This is often recalculated as the divergence from the product of the marginal distributions to the actual joint distribution:


title: Information theory

text: Mutual information is closely related to the log-likelihood ratio test in the context of contingency tables and the multinomial distribution and to Pearson's χ test: mutual information can be considered a statistic for assessing independence between a pair of variables, and has a well-specified asymptotic distribution.


title: Information theory

text: The "Kullback–Leibler divergence" (or "information divergence", "information gain", or "relative entropy") is a way of comparing two distributions: a "true" probability distribution , and an arbitrary probability distribution . If we compress data in a manner that assumes is the distribution underlying some data, when, in reality, is the correct distribution, the Kullback–Leibler divergence is the number of average additional bits per datum necessary for compression. It is thus defined


title: Information theory

text: Although it is sometimes used as a 'distance metric', KL divergence is not a true metric since it is not symmetric and does not satisfy the triangle inequality (making it a semi-quasimetric).


title: Information theory

text: Another interpretation of the KL divergence is the "unnecessary surprise" introduced by a prior from the truth: suppose a number "X" is about to be drawn randomly from a discrete set with probability distribution . If Alice knows the true distribution , while Bob believes (has a prior) that the distribution is , then Bob will be more surprised than Alice, on average, upon seeing the value of "X". The KL divergence is the (objective) expected value of Bob's (subjective) surprisal minus Alice's surprisal, measured in bits if the "log" is in base 2. In this way, the extent to which Bob's prior is "wrong" can be quantified in terms of how "unnecessarily surprised" it is expected to make him.


title: Information theory

text: Directed information, formula_17, is an information theory measure that quantifies the information flow from the random process formula_18 to the random process formula_19. The term "directed information" was coined by James Massey and is defined as


title: Information theory

text: Differently from the Mutual informaion, the dircted information is not symmetric. The formula_17 measures the information bits that are transmitted caussaly from formula_24 to formula_25. The Directed information has many applications in problems where causality plays an important role such as capacity of channel with feedback, capacity of discrete memoryless networks with feedback, gambling with causal side information, compression with causal side information,


title: Information theory

text: Other important information theoretic quantities include Rényi entropy (a generalization of entropy), differential entropy (a generalization of quantities of information to continuous distributions), and the conditional mutual information.


title: Information theory

text: Coding theory is one of the most important and direct applications of information theory. It can be subdivided into source coding theory and channel coding theory. Using a statistical description for data, information theory quantifies the number of bits needed to describe the data, which is the information entropy of the source.


title: Information theory

text: This division of coding theory into compression and transmission is justified by the information transmission theorems, or source–channel separation theorems that justify the use of bits as the universal currency for information in many contexts. However, these theorems only hold in the situation where one transmitting user wishes to communicate to one receiving user. In scenarios with more than one transmitter (the multiple-access channel), more than one receiver (the broadcast channel) or intermediary "helpers" (the relay channel), or more general networks, compression followed by transmission may no longer be optimal.


title: Information theory

text: Any process that generates successive messages can be considered a of information. A memoryless source is one in which each message is an independent identically distributed random variable, whereas the properties of ergodicity and stationarity impose less restrictive constraints. All such sources are stochastic. These terms are well studied in their own right outside information theory.


title: Information theory

text: Information "rate" is the average entropy per symbol. For memoryless sources, this is merely the entropy of each symbol, while, in the case of a stationary stochastic process, it is


title: Information theory

text: that is, the conditional entropy of a symbol given all the previous symbols generated. For the more general case of a process that is not necessarily stationary, the "average rate" is


title: Information theory

text: that is, the limit of the joint entropy per symbol. For stationary sources, these two expressions give the same result.


title: Information theory

text: It is common in information theory to speak of the "rate" or "entropy" of a language. This is appropriate, for example, when the source of information is English prose. The rate of a source of information is related to its redundancy and how well it can be compressed, the subject of .


title: Information theory

text: Communications over a channel is the primary motivation of information theory. However, channels often fail to produce exact reconstruction of a signal; noise, periods of silence, and other forms of signal corruption often degrade quality.


title: Information theory

text: Consider the communications process over a discrete channel. A simple model of the process is shown below:


title: Information theory

text: Here "X" represents the space of messages transmitted, and "Y" the space of messages received during a unit time over our channel. Let be the conditional probability distribution function of "Y" given "X". We will consider to be an inherent fixed property of our communications channel (representing the nature of the "noise" of our channel). Then the joint distribution of "X" and "Y" is completely determined by our channel and by our choice of , the marginal distribution of messages we choose to send over the channel. Under these constraints, we would like to maximize the rate of information, or the "signal", we can communicate over the channel. The appropriate measure for this is the mutual information, and this maximum mutual information is called the and is given by:


title: Information theory

text: This capacity has the following property related to communicating at information rate "R" (where "R" is usually bits per symbol). For any information rate "R" < "C" and coding error "ε" > 0, for large enough "N", there exists a code of length "N" and rate ≥ R and a decoding algorithm, such that the maximal probability of block error is ≤ "ε"; that is, it is always possible to transmit with arbitrarily small block error. In addition, for any rate "R" > "C", it is impossible to transmit with arbitrarily small block error.


title: Information theory

text: "Channel coding" is concerned with finding such nearly optimal codes that can be used to transmit data over a noisy channel with a small coding error at a rate near the channel capacity.


title: Information theory

text: In practice many channels have memory. Namely, at time formula_31 the channel is given by the conditional probability formula_32.


title: Information theory

text: In such a case the capacity is given by the mutual information rate when there is no feedback available and the Directed information rate in the case that either there is feedback or not (if there is no feedback the directed information equals the mutual information).


title: Information theory

text: Information theoretic concepts apply to cryptography and cryptanalysis. Turing's information unit, the ban, was used in the Ultra project, breaking the German Enigma machine code and hastening the end of World War II in Europe. Shannon himself defined an important concept now called the unicity distance. Based on the redundancy of the plaintext, it attempts to give a minimum amount of ciphertext necessary to ensure unique decipherability.


title: Information theory

text: Information theory leads us to believe it is much more difficult to keep secrets than it might first appear. A brute force attack can break systems based on asymmetric key algorithms or on most commonly used methods of symmetric key algorithms (sometimes called secret key algorithms), such as block ciphers. The security of all such methods currently comes from the assumption that no known attack can break them in a practical amount of time.


title: Information theory

text: Information theoretic security refers to methods such as the one-time pad that are not vulnerable to such brute force attacks. In such cases, the positive conditional mutual information between the plaintext and ciphertext (conditioned on the key) can ensure proper transmission, while the unconditional mutual information between the plaintext and ciphertext remains zero, resulting in absolutely secure communications. In other words, an eavesdropper would not be able to improve his or her guess of the plaintext by gaining knowledge of the ciphertext but not of the key. However, as in any other cryptographic system, care must be used to correctly apply even information-theoretically secure methods; the Venona project was able to crack the one-time pads of the Soviet Union due to their improper reuse of key material.


title: Information theory

text: Pseudorandom number generators are widely available in computer language libraries and application programs. They are, almost universally, unsuited to cryptographic use as they do not evade the deterministic nature of modern computer equipment and software. A class of improved random number generators is termed cryptographically secure pseudorandom number generators, but even they require random seeds external to the software to work as intended. These can be obtained via extractors, if done carefully. The measure of sufficient randomness in extractors is min-entropy, a value related to Shannon entropy through Rényi entropy; Rényi entropy is also used in evaluating randomness in cryptographic systems. Although related, the distinctions among these measures mean that a random variable with high Shannon entropy is not necessarily satisfactory for use in an extractor and so for cryptography uses.


title: Information theory

text: One early commercial application of information theory was in the field of seismic oil exploration. Work in this field made it possible to strip off and separate the unwanted noise from the desired seismic signal. Information theory and digital signal processing offer a major improvement of resolution and image clarity over previous analog methods.


title: Information theory

text: Semioticians and Winfried Nöth both considered Charles Sanders Peirce as having created a theory of information in his works on semiotics. Nauta defined semiotic information theory as the study of "the internal processes of coding, filtering, and information processing."


title: Information theory

text: Concepts from information theory such as redundancy and code control have been used by semioticians such as Umberto Eco and to explain ideology as a form of message transmission whereby a dominant social class emits its message by using signs that exhibit a high degree of redundancy such that only one message is decoded among a selection of competing ones.


title: Information theory

text: Quantitative information theoretic methods have been applied in cognitive science to analyze the integrated process organization of neural information in the context of the binding problem in cognitive neuroscience. In this context, either an information-theoretical measure, such as (Gerald Edelman and Giulio Tononi's functional clustering model and dynamic core hypothesis (DCH)) or (Tononi's integrated information theory (IIT) of consciousness), is defined (on the basis of a reentrant process organization, i.e. the synchronization of neurophysiological activity between groups of neuronal populations), or the measure of the minimization of free energy on the basis of statistical methods (Karl J. Friston's free energy principle (FEP), an information-theoretical measure which states that every adaptive change in a self-organized system leads to a minimization of free energy, and the Bayesian brain hypothesis).


title: Chunky Panday

text: Suyash Panday (born 26 September 1962), better known by his stage name Chunky Panday, is an Indian actor who works in Bollywood films. He has appeared in over 100 films in a career that has spanned over three decades.


title: Chunky Panday

text: His most successful films in Hindi were in the period 1987-1994. After the failure of his Hindi films as lead hero since 1994, his career in Hindi films faded away. He then worked in Bangladeshi cinema from 1995 and most of his films in Bangladesh were successful. He has been acting as a character actor since 2003 in Hindi films.


title: Chunky Panday

text: Panday worked as an instructor in acting school in 1986. He used to be senior to many junior budding artists such as Akshay Kumar.


title: Chunky Panday

text: Panday debuted his acting career with the 1987 multi-starer film "Aag Hi Aag" opposite Neelam Kothari. Film producer Pahlaj Nihalani gave Panday his first break in 1987 by signing him up for two films, his debut film and Paap Ki Duniya. His second successful film was "Paap Ki Duniya" with Sunny Deol and Neelam. Subsequently, Panday appeared in many multi-hero films from 1987 to 1993. In 1988, Panday was appreciated for his supporting role in N. Chandra's film "Tezaab" featuring Anil Kapoor and Madhuri Dixit. Panday played the character of Babban, Munna's (Anil Kapoor) friend. For his performance in "Tezaab", Panday was nominated for the Filmfare Award for the Best Supporting Actor.


title: Chunky Panday

text: Since then he has appeared in many films with mixed success throughout the late 1980s and 1990s. Most of his films where he had the leading role did not fare well at the box office from 1992. In most films, he was cast in supporting roles to senior actors like Rajesh Khanna, Dharmendra, Jeetendra, Sunny Deol and Sanjay Dutt. Some of those hit films with him in second lead, are "Paap Ki Duniya" (1988), "Khatron Ke Khiladi" (1988), "Ghar Ka Chiraag" (1989), "Nakabandi", "Zahreelay" (1990), "Rupaye Dus Karod", "Vishwatma" (1992), "Lootere" (1993) and "Aankhen" (1993) . His solo hit was "Parda Hai Parda" (1992).


title: Chunky Panday

text: The advent of the 1990s saw a new wave of actors like Aamir Khan, Salman Khan and Shah Rukh Khan taking on roles as "romantic heroes", while Akshay Kumar, Suniel Shetty and Ajay Devgan grabbed the "action hero" roles. Panday found it difficult to slot himself in either category. In addition, by the late nineties, solo-hero films were back in vogue instead of the multi-hero films in which Panday was generally cast and Panday was not seen as a marketable hero for solo hero films.


title: Chunky Panday

text: Panday grew increasingly tired of playing second fiddle to more prominent actors, but had difficulty being seen as marketable, other than supporting household names. "I was offered hero ke bhai ka (lead actor's brother) roles," he said. "I (told them), 'Boss, not happening.'" He moved to act as hero in Bangladesh films. In 1995, he was offered his first films as the lead hero in Bangladeshi films. He acted in six films between 1995 and 1997 as hero in Bangladesh and all of them were successful. Between 1997 and 2002, he received minimal work in Bollywood, playing supporting roles in low-budget films like "Tirchhi Topiwale", "Yeh Hai Mumbai Meri Jaan", "Kaun Rokega Mujhe" and "Jwalamukhi".


title: Chunky Panday

text: Panday returned to Bollywood in 2003 playing minor supporting roles in "", "Elaan", "" and "Apna Sapna Money Money".


title: Chunky Panday

text: In 2005, he played an underworld gangster in the Ram Gopal Varma film "D – Underworld Badshah". Later, director Ram Gopal Varma roped him in for "Darwaaza Bandh Rakho", a dark comedy thriller in which he played one of four robbers who hold a family hostage.


title: Chunky Panday

text: Panday played the role of the Indo-Italian "Aakhiri Pasta" in the 2010 comedy hit "Housefull" followed by his reprised roles in the sequels "Housefull 2" in 2012, "Housefull 3" in 2016 and in "Housefull 4" in 2019.


title: Chunky Panday

text: In regards to his film selection since returning to acting in Bollywood, Panday has stated that he prefers not to play a hero nowadays because there is less pressure on him if the film fails and it's much more fun playing interesting characters and showing his range.


title: Chunky Panday

text: While Panday's second stint in Bollywood has mainly consisted of starring as a character actor, he doesn't want to be pigeonholed into only doing comic roles. "I don't think I am restricting myself to doing only comedy. I am hoping that someone offers me something else... It requires a lot of guts for someone to cast me in something else. I am just hoping that someone sees something else in me other than comedy."