Etymology.

"Xérxēs" () is the Greek and Latin ("Xerxes", "Xerses") transliteration of the Old Iranian "Xšaya-ṛšā" ("ruling over heroes"), which can be seen by the first part "xšaya", meaning "ruling", and the second "ṛšā", meaning "hero, man". The name of Xerxes was known in Akkadian as "Ḫi-ši-ʾ-ar-šá" and in Aramaic as "ḥšyʾrš". Xerxes would become a popular name amongst the rulers of the Achaemenid Empire.

Historiography.

Much of Xerxes' bad reputation is due to propaganda by the Macedonian king Alexander the Great (), who had him vilified. The modern historian Richard Stoneman regards the portrayal of Xerxes as more nuanced and tragic in the work of the contemporary Greek historian Herodotus. However, many modern historians agree that Herodotus recorded spurious information. Pierre Briant has accused him of presenting a stereotyped and biased portrayal of the Persians. Many Achaemenid-era clay tablets and other reports written in Elamite, Akkadian, Egyptian and Aramaic are frequently contradictory to the reports of classical authors, i.e. Ctesias, Plutarch and Justin.

Early life.

Parentage and birth.

Xerxes' father was Darius the Great (), the incumbent monarch of the Achaemenid Empire, albeit himself not a member of the family of Cyrus the Great, the founder of the empire. His mother was Atossa, a daughter of Cyrus. They had married in 522 BC, with Xerxes being born in.

Upbringing and education.

According to the Greek dialogue First Alcibiades, which describes typical upbringing and education of Persian princes; they were raised by eunuchs. When reaching the age of 7, they learn how to ride and hunt; at age 14, they are looked after by four teachers of aristocratic stock, who teach them how to be "wise, just, prudent and brave." Persian princes were also taught on the basics of the Zoroastrian religion, to be truthful, have self-restraint, and to be courageous. The dialogue further adds that "Fear, for a Persian, is the equivalent of slavery." At the age of 16 or 17, they begin their "national service" for 10 years, which included practicing archery and javelin, competing for prizes, and hunting. Afterwards they serve in the military for around 25 years, and are then elevated to the status of elders and advisers of the king.  This account of education amongst the Persian elite is supported by Xenophon's description of the 5th-century BC Achaemenid prince Cyrus the Younger, whom he was well-acquainted with. Stoneman suggests that this was the type of upbringing and education that Xerxes experienced. It is unknown if Xerxes ever learned to read or write, with the Persians favouring oral history over written literature. Stoneman suggests that Xerxes' upbringing and education was possibly not much different from that of the later Iranian kings, such as Abbas the Great, king of the Safavid Empire in the 17th-century AD. Starting from 498 BC, Xerxes resided in the royal palace of Babylon.

Accession to the throne.

While Darius was preparing for another war against Greece, a revolt spurred in Egypt in 486 BC due to heavy taxes and the deportation of craftsmen to build the royal palaces at Susa and Persepolis. Under Persian law, the king was required to choose a successor before setting out on dangerous expeditions. When Darius decided to leave (487–486 BC), he (Darius) prepared his tomb at Naqsh-e Rustam (five kilometers from his royal palace at Persepolis) and appointed Xerxes, his eldest son by Atossa, as his successor. However, Darius could not lead the campaign due to his failing health and died in October 486 BC at the age of 64.  Artobazan claimed the crown as the eldest of all the children; while Xerxes, on the other hand, argued that he was sprung from Atossa, the daughter of Cyrus, and that it was Cyrus who had won the Persians their freedom. Xerxes was also helped by a Spartan king in exile who was present in Persia at the time, Eurypontid king Demaratus, who also argued that the eldest son does not universally mean they have claim to the crown, as Spartan law states that the first son born while the father is king is the heir to the kingship. Some modern scholars also view the unusual decision of Darius to give the throne to Xerxes to be a result of his consideration of the unique positions that Cyrus the Great and his daughter Atossa enjoyed. Artobazan was born to "Darius the subject", while Xerxes was the eldest son born in the purple after Darius's rise to the throne, and Artobazan's mother was a commoner while Xerxes's mother was the daughter of the founder of the empire.  Xerxes was crowned and succeeded his father in October–December 486 BC when he was about 36 years old. The transition of power to Xerxes was smooth due again in part to the great authority of Atossa and his accession of royal power was not challenged by any person at court or in the Achaemenian family, or any subject nation.

Consolidation of power.

At Xerxes' accession, trouble was brewing in some of his domains. A revolt occurred in Egypt, which seems to have been dangerous enough for Xerxes to personally lead the army to restore order (which also gave him the opportunity to begin his reign with a military campaign). Xerxes suppressed the revolt in January 484 BC, and appointed his full-brother Achaemenes as satrap of the country, replacing the previous satrap Pherendates, who was reportedly killed during the revolt. The suppression of the Egyptian revolt expended the army, which had been mobilized by Darius over the previous three years. Xerxes thus had to raise another army for his expedition into Greece, which would take four years. There was also unrest in Babylon, which revolted at least twice against Xerxes. The first revolt broke out in June or July of 484 BC and was led by a rebel of the name Bel-shimanni. Bel-shimmani's revolt was short-lived, Babylonian documents written during his reign only account for a period of two weeks.  Two years later, Babylon produced another rebel leader, Shamash-eriba. Beginning in the summer of 482 BC, Shamash-eriba seized Babylon itself and other nearby cities, such as Borsippa and Dilbat, and was only defeated in March 481 BC after a lengthy siege of Babylon. The precise cause of the unrest in Babylon is uncertain. It may have been due to tax increase. Prior to these revolts, Babylon had occupied a special position within the Achaemenid Empire, the Achaemenid kings had been titled as "King of Babylon" and "King of the Lands", perceiving Babylonia as a somewhat separate entity within their empire, united with their own kingdom in a personal union. Xerxes dropped "King of Babylon" from his titulature and divided the previously large Babylonian satrapy (accounting for most of the Neo-Babylonian Empire's territory) into smaller sub-units.  Using texts written by classical authors, it is often assumed that Xerxes enacted a brutal vengeance on Babylon following the two revolts. According to ancient writers, Xerxes destroyed Babylon's fortifications and damaged the temples in the city. The Esagila was allegedly exposed to great damage and Xerxes allegedly carried the statue of Marduk away from the city, possibly bringing it to Iran and melting it down (classical authors held that the statue was entirely made of gold, which would have made melting it down possible). Modern historian Amélie Kuhrt considers it unlikely that Xerxes destroyed the temples, but believes that the story of him doing so may derive from an anti-Persian sentiment among the Babylonians. It is doubtful if the statue was removed from Babylon at all and some have even suggested that Xerxes did remove a statue from the city, but that this was the golden statue of a man rather than the statue of the god Marduk. Though mentions of it are lacking considerably compared to earlier periods, contemporary documents suggest that the Babylonian New Year's Festival continued in some form during the Achaemenid period. Because the change in rulership from the Babylonians themselves to the Persians and due to the replacement of the city's elite families by Xerxes following its revolt, it is possible that the festival's traditional rituals and events had changed considerably.

Campaigns.

Invasion of the Greek mainland.

Darius died while in the process of preparing a second army to invade the Greek mainland, leaving to his son the task of punishing the Athenians, Naxians, and Eretrians for their interference in the Ionian Revolt, the burning of Sardis, and their victory over the Persians at Marathon. From 483 BC, Xerxes prepared his expedition: The Xerxes Canal was dug through the isthmus of the peninsula of Mount Athos, provisions were stored in the stations on the road through Thrace, and two pontoon bridges later known as Xerxes' Pontoon Bridges were built across the Hellespont. Soldiers of many nationalities served in the armies of Xerxes from all over his multi-ethnic massive Eurasian-sized empire and beyond, including the Assyrians, Phoenicians, Babylonians, Egyptians, Jews, Macedonians, European Thracians, Paeonians, Achaean Greeks, Ionians, Aegean islanders, Aeolians, Greeks from Pontus, Colchians, Indians and many more.  According to the Greek historian Herodotus, Xerxes's first attempt to bridge the Hellespont ended in failure when a storm destroyed the flax and papyrus cables of the bridges. In retaliation, Xerxes ordered the Hellespont (the strait itself) whipped three hundred times, and had fetters thrown into the water. Xerxes's second attempt to bridge the Hellespont was successful. The Carthaginian invasion of Sicily deprived Greece of the support of the powerful monarchs of Syracuse and Agrigentum; ancient sources assume Xerxes was responsible, modern scholarship is skeptical. Many smaller Greek states, moreover, took the side of the Persians, especially Thessaly, Thebes and Argos. Xerxes was victorious during the initial battles.  Xerxes set out in the spring of 480 BC from Sardis with a fleet and army which Herodotus estimated was roughly one million strong along with 10,000 elite warriors named the Immortals. More recent estimates place the Persian force at around 60,000 combatants.

Battle of Thermopylae and destruction of Athens.

At the Battle of Thermopylae, a small force of Greek warriors led by King Leonidas of Sparta resisted the much larger Persian forces, but were ultimately defeated. According to Herodotus, the Persians broke the Spartan phalanx after a Greek man called Ephialtes betrayed his country by telling the Persians of another pass around the mountains. At Artemisium, large storms had destroyed ships from the Greek side and so the battle stopped prematurely as the Greeks received news of the defeat at Thermopylae and retreated. After Thermopylae, Athens was captured. Most of the Athenians had abandoned the city and fled to the island of Salamis before Xerxes arrived. A small group attempted to defend the Athenian Acropolis, but they were defeated. Xerxes ordered the Destruction of Athens and burnt the city, leaving an archaeologically attested destruction layer, known as the Perserschutt. The Persians thus gained control of all of mainland Greece to the north of the Isthmus of Corinth.

Battles of Salamis and Plataea.

Xerxes was induced, by the message of Themistocles (against the advice of Artemisia of Halicarnassus), to attack the Greek fleet under unfavourable conditions, rather than sending a part of his ships to the Peloponnesus and awaiting the dissolution of the Greek armies. The Battle of Salamis (September, 480 BC) was won by the Greek fleet, after which Xerxes set up a winter camp in Thessaly.  According to Herodotus, fearing that the Greeks might attack the bridges across the Hellespont and trap his army in Europe, Xerxes decided to retreat back to Asia, taking the greater part of the army with him. Another cause of the retreat might have been that the continued unrest in Babylon, a key province of the empire, required the king's personal attention. He left behind a contingent in Greece to finish the campaign under Mardonius, who according to Herodotus had suggested the retreat in the first place. This force was defeated the following year at Plataea by the combined forces of the Greek city states, ending the Persian offensive on Greece for good.

Construction projects.

After the military blunders in Greece, Xerxes returned to Persia and oversaw the completion of the many construction projects left unfinished by his father at Susa and Persepolis. He oversaw the building of the Gate of All Nations and the Hall of a Hundred Columns at Persepolis, which are the largest and most imposing structures of the palace. He oversaw the completion of the Apadana, the Tachara (Palace of Darius) and the Treasury, all started by Darius, as well as having his own palace built which was twice the size of his father's. His taste in architecture was similar to that of Darius, though on an even more gigantic scale. He had colorful enameled brick laid on the exterior face of the Apadana. He also maintained the Royal Road built by his father and completed the Susa Gate and built a palace in Susa.

Death.

In August 465 BC, Artabanus, the commander of the royal bodyguard and the most powerful official in the Persian court, assassinated Xerxes with the help of a eunuch, Aspamitres. Although Artabanus bore the same name as the famed uncle of Xerxes, a Hyrcanian, his rise to prominence was due to his popularity in religious quarters of the court and harem intrigues. He put his seven sons in key positions and had a plan to dethrone the Achaemenids.  Greek historians give contradicting accounts of events. According to Ctesias (in Persica 20), Artabanus then accused the Crown Prince Darius, Xerxes's eldest son, of the murder and persuaded another of Xerxes's sons, Artaxerxes, to avenge the patricide by killing Darius. But according to Aristotle (in Politics 5.1311b), Artabanus killed Darius first and then killed Xerxes. After Artaxerxes discovered the murder, he killed Artabanus and his sons. Participating in these intrigues was the general Megabyzus, whose decision to switch sides probably saved the Achaemenids from losing their control of the Persian throne.

Government.

Religion.

While there is no general consensus in scholarship whether Xerxes and his predecessors had been influenced by Zoroastrianism, it is well established that Xerxes was a firm believer in Ahura Mazda, whom he saw as the supreme deity. However, Ahura Mazda was also worshipped by adherents of the (Indo-)Iranian religious tradition. On his treatment of other religions, Xerxes followed the same policy as his predecessors; he appealed to local religious scholars, made sacrifices to local deities, and destroyed temples in cities and countries that caused disorder.

Wives and children.

By queen Amestris:  By unknown wives or mistresses:

Cultural depictions.

Xerxes is the central character of the Aeschylus play "The Persians". Xerxes is the protagonist of the opera "Serse" by the German-English Baroque composer George Frideric Handel. It was first performed in the King's Theatre London on 15 April 1738. The famous aria "Ombra mai fù" opens the opera.  The murder of Xerxes by Artabanus ("Artabano"), execution of crown prince Darius ("Dario"), revolt by Megabyzus ("Megabise"), and subsequent succession of Artaxerxes I is romanticised by the Italian poet Metastasio in his opera libretto "Artaserse", which was first set to music by Leonardo Vinci, and subsequently by other composers such as Johann Adolf Hasse and Johann Christian Bach.  The historical novel "Xerxes of de Hoogmoed" (1919) by Dutch writer Louis Couperus describes the Persian wars from the perspective of Xerxes. Though the account is fictionalised, Couperus nevertheless based himself on an extensive study of Herodotus. The English translation "Arrogance: The Conquests of Xerxes" by Frederick H. Martens appeared in 1930. Later generations' fascination with ancient Sparta, particularly the Battle of Thermopylae, has led to Xerxes' portrayal in works of popular culture. He was played by David Farrar in the fictional film "The 300 Spartans" (1962), where he is portrayed as a cruel, power-crazed despot and an inept commander. He also features prominently in the graphic novels "300" and "" by Frank Miller, as well as the film adaptation "300" (2007) and its sequel "" (2014), as portrayed by Brazilian actor Rodrigo Santoro, in which he is represented as a giant man with androgynous qualities, who claims to be a god-king. This portrayal attracted controversy, especially in Iran. Ken Davitian plays Xerxes in "Meet the Spartans", a parody of the first "300" movie replete with sophomoric humour and deliberate anachronisms.  Other works dealing with the Persian Empire or the Biblical story of Esther have also featured or alluded to Xerxes, such as the video game "Assassin's Creed II" and the film "One Night with the King" (2006), in which Ahasuerus (Xerxes) was portrayed by British actor Luke Goss. He is the leader of the Persian Empire in the video game "Civilization II" and "III" (along with Scheherazade), although "Civilization IV" replaces him with Cyrus the Great and Darius I. Gore Vidal, in his historical fiction novel "Creation" (1981), describes at length the rise of the Achemenids, especially Darius I, and presents the life and death circumstances of Xerxes. Vidal's version of the Persian Wars, which diverges from the orthodoxy of the Greek histories, is told through the invented character of Cyrus Spitama, a half-Greek, half-Persian, and grandson of the prophet Zoroaster. Thanks to his family connection, Cyrus is brought up in the Persian court after the murder of Zoroaster, becoming the boyhood friend of Xerxes, and later a diplomat who is sent to India, and later to Greece, and who is thereby able to gain privileged access to many leading historical figures of the period.  Xerxes (Ahasuerus) is portrayed by Richard Egan in the 1960 film "Esther and the King" and by Joel Smallbone in the 2013 film, "The Book of Esther". In at least one of these films, the events of the Book of Esther are depicted as taking place upon Xerxes' return from Greece.  Xerxes plays an important background role (never making an appearance) in two short works of alternate history taking place generations after his complete victory over Greece. These are: "Counting Potsherds" by Harry Turtledove in his anthology "Departures" and "The Craft of War" by Lois Tilton in "Alternate Generals" volume 1 (edited by Turtledove).

Xerxes I (; – August 465 BC), commonly known as Xerxes the Great, was the fourth King of Kings of the Achaemenid Empire, ruling from 486 to 465 BC. He was the son and successor of Darius the Great () and his mother was Atossa, a daughter of Cyrus the Great (), the first Achaemenid king. Like his father and predecessor Darius I, he ruled the empire at its territorial apex. He ruled from 486 BC until his assassination in 465 BC at the hands of Artabanus, the commander of the royal bodyguard.

Xerxés I. (řecky "Ξέρξης", staropersky "Chšajáršá" [ ]; 519–465 př. n. l.) byl perský velkokrál z rodu Achaimenovců vládnoucí od listopadu 486 do srpna 465 př. n. l. Jeho jméno ve staré perštině znamená „vládce hrdinů“. Pojednává o něm biblická kniha Ester, jež ho označuje jménem Achašveróš (hebrejsky אֲחַשְׁוֵרוֹשׁ). V hebrejském textu Bible je o něm též zmínka v knize Ezdráš a v knize Daniel.


Medical uses.

Oral glucosamine is a dietary supplement and is not a prescription drug. It is illegal in the United States to market any dietary supplement as a treatment for any disease or condition. Glucosamine is marketed as a supplement to support the structure and function of joints, and the marketing is targeted to people suffering from osteoarthritis.  Commonly sold forms of glucosamine are glucosamine sulfate, glucosamine chondroitin, glucosamine hydrochloride, and "N"-acetylglucosamine. Of the three commonly available forms of glucosamine, only glucosamine sulfate is given a "likely effective" rating for treating osteoarthritis. Glucosamine is often sold in combination with other supplements such as chondroitin sulfate and methylsulfonylmethane.  Glucosamine, along with commonly used chondroitin, is not routinely prescribed to treat people who have symptomatic osteoarthritis of the knee, as there is insufficient evidence that this treatment is helpful.  As is common with heavily promoted dietary supplements, the claimed benefits of glucosamine are based principally on clinical and laboratory studies. Clinical studies on glucosamine efficacy are divided, with some reporting relief from arthritic pain and stiffness, while higher quality studies report no benefit above placebo. , there is no evidence that consumption of glucosamine by sport participants prevents or limits joint damage after injury. In a randomized placebo-controlled trial, glucosamine supplementation had no additional effect on any rehabilitation outcome when given to athletes after anterior cruciate ligament (ACL) reconstruction.

Adverse effects and drug interactions.

One clinical study over three years showed that glucosamine in doses of 1500 mg per day is safe to use.  Glucosamine with or without chondroitin elevates the international normalized ratio (INR) in individuals who are taking the blood thinner, warfarin. It may also interfere with the efficacy of chemotherapy for treating cancer symptoms.  Adverse effects may include stomach upset, constipation, diarrhea, headache, and rash. There are case reports of people who have chronic liver disease and a worsening of their condition with glucosamine supplementation. More high-quality clinical research is needed before recommending glucosamine in pregnancy.  Since glucosamine is usually derived from the shells of shellfish, it may be unsafe for those with shellfish allergy. However, many manufacturers of glucosamine derived from shellfish include a warning that those with a seafood allergy should consult a healthcare professional before taking the product. Alternative, non-shellfish-derived forms of glucosamine are available.  Another concern has been that the extra glucosamine could contribute to diabetes by interfering with the normal regulation of the hexosamine biosynthesis pathway, but several investigations found no evidence that this occurs. Other studies conducted in lean or obese subjects concluded that oral glucosamine at standard doses does not affect insulin resistance.

Biochemistry.

Glucosamine is naturally present in the shells of shellfish, animal bones, bone marrow, and fungi. -Glucosamine is made naturally in the form of glucosamine-6-phosphate, and is the biochemical precursor of all nitrogen-containing sugars. Specifically in humans, glucosamine-6-phosphate is synthesized from fructose 6-phosphate and glutamine by glutamine—fructose-6-phosphate transaminase as the first step of the hexosamine biosynthesis pathway. The end-product of this pathway is uridine diphosphate "N"-acetylglucosamine (UDP-GlcNAc), which is then used for making glycosaminoglycans, proteoglycans, and glycolipids.  As the formation of glucosamine-6-phosphate is the first step for the synthesis of these products, glucosamine may be important in regulating their production; however, the way that the hexosamine biosynthesis pathway is actually regulated, and whether this could be involved in contributing to human disease remains unclear.

Manufacturing.

Most glucosamine is manufactured by processing chitin from the shells of shellfish including shrimp, lobsters, and crabs. To meet the demands of vegetarians and others with objections to shellfish, manufacturers have brought glucosamine products to market made using fungus "Aspergillus niger" and from fermenting corn.

History.

Glucosamine was first prepared in 1876 by Georg Ledderhose by the hydrolysis of chitin with concentrated hydrochloric acid. The stereochemistry was not fully determined until the 1939 work of Walter Haworth.

Legal status.

United States.

In the United States, glucosamine is not approved by the Food and Drug Administration (FDA) for medical use in humans. Since glucosamine is classified as a dietary supplement in the United States, evidence of safety is required by FDA regulations, but evidence of efficacy is not required so long as it is not advertised as a treatment for a medical condition.  In 2004, the FDA declared there was insufficient evidence for supplement manufacturers to state that glucosamine was effective for treating arthritis, joint degeneration, or cartilage deterioration, a position remaining in effect as of 2018.

Europe.

In most of Europe, glucosamine is approved as a medical drug and is sold in the form of glucosamine sulfate. In this case, evidence of safety and efficacy is required for the medical use of glucosamine and several guidelines have recommended its use as an effective and safe therapy for osteoarthritis.  The Task Force of the European League Against Rheumatism (EULAR) committee has granted glucosamine sulfate a level of toxicity of 5 in a 0-100 scale, and recent OARSI (Osteoarthritis Research Society International) guidelines for hip and knee osteoarthritis indicate an acceptable safety profile. By 2014, the OARSI did not recommend glucosamine for disease modification, and considered it "uncertain" for symptom relief, in knee osteoarthritis.

Class-action lawsuits.

In 2013, without admitting fault, manufacturer Rexall Sundown and NBTY agreed to pay up to to settle consumer claims related to the wording of certain claims on the packaging of glucosamine bottles sold at Costco under the Kirkland label.  In August 2012, a class-action lawsuit was filed in New York claiming that 21st Century Healthcare, Inc. had falsely advertised that its "Glucosamine 750 Chondroitin 600 Triple Strength" dietary supplements would restore lost cartilage. In April 2013, a San Diego man launched a proposed class-action lawsuit in California Federal Court accusing Nutramax Laboratories, Walmart and Rite Aid of falsely advertising the effectiveness of glucosamine.

Research.

Humans.

Since glucosamine is a precursor for glycosaminoglycans, and glycosaminoglycans are a major component of cartilage, research has focused on the potential for supplemental glucosamine to beneficially influence cartilage structure and alleviate arthritis. Although its use as a supplement appears safe, the evidence does not support it being universally effective, as clinical trials have not provided results that support its efficacy in 100% of human subjects.

Bioavailability.

Two studies measured the concentrations of glucosamine in the synovial fluid and plasma after oral administration of glucosamine sulfate to both healthy volunteers and people with osteoarthritis.  In the first study, glucosamine sulfate was given to healthy volunteers in doses of 750, 1500, or 3000 mg once daily. In the second study, oral glucosamine sulfate capsules (1500 mg) were given daily for two weeks to 12 people with osteoarthritis. Glucosamine concentrations in plasma and synovial fluid increased significantly from baseline levels and the levels in the two fluids were highly correlated. The authors interpreted that these levels could be biologically advantageous to articular cartilage, but the levels are still ten- to a hundredfold lower than required to positively affect the cartilage (chondrocytes) to build new tissue. Glucosamine sulfate uptake in synovial fluid may be as much as 20%, or could be negligible, indicating no biological significance.

Veterinary medicine.

Dogs.

Some studies have shown efficacy of glucosamine supplementation for dogs with osteoarthritis pain, particularly in combination with other nutraceuticals like chondroitin while others have not. A trial of oral combination capsules (glucosamine, chondroitin, manganese ascorbate) in dogs with osteoarthritis found no benefit on either gait analysis or subjective assessments by the veterinarian or owner.

Horses.

The use of glucosamine in equine medicine exists, but one meta-analysis judged extant research too flawed to be of value in guiding treatment of horses.  A number of studies have measured the bioavailability of glucosamine after oral administration to horses. When given as a single oral dose (9 g) with or without chondroitin sulfate (3 g) to ten horses, glucosamine (hydrochloride) was detected in the blood with a maximum level of at two hours after dosing. Another study examined both the serum and the joint synovial fluid after nasogastric (oral) or intravenous administration of 20 mg/kg glucosamine hydrochloride to eight adult horses. Although joint fluid concentrations of glucosamine reached 9–15 μmol/L following intravenous dosing, it was only 0.3–0.7 μmol/L with nasogastric dosing. The authors calculated that these glucosamine synovial fluid levels achieved by the oral route were 500 times lower than that required to have a positive effect on the metabolism of cartilage cells. A follow up study by the same research group compared glucosamine sulfate with glucosamine hydrochloride at the same dose (20 mg/kg) in eight horses and found a higher fluid concentration with the sulfate preparation (158 ng/mL compared to 89 ng/mL one hour post oral dose). They concluded that these higher synovial fluid levels obtained with the sulfate derivative were still too low to have a relevant biological effect on articular cartilage.  A three-month trial of an oral dosage regime of a commercial preparation of glucosamine sulfate, chondroitin sulfate and methylsulfonylmethane was performed in veteran horses with no effect on gait stiffness, with exercise alone in the control group being effective. The intravenous use of a combination of "N"-acetylglucosamine, pentosan polysulfate and sodium hyaluronate in horses with surgically-induced osteoarthritis saw improvements in X-ray changes to the cartilage but not histologically or in biochemical outcomes, suggesting more evidence is needed for this combination and route of administration.

Glucosamine (CHNO) is an amino sugar and a prominent precursor in the biochemical synthesis of glycosylated proteins and lipids. Glucosamine is part of the structure of the polysaccharides, chitosan, and chitin. Glucosamine is one of the most abundant monosaccharides. Produced commercially by the hydrolysis of shellfish exoskeletons or, less commonly, by fermentation of a grain such as corn or wheat, glucosamine has many names depending on country.

Glukosamin (řidčeji také glukozamin) (CHNO) je tělu vlastní, bazická sloučenina, která vzniká z glukózy náhradou hydroxylové skupiny (–OH) v poloze 2 za skupinu –NH. Zabudovává se do polysacharidů (glykosaminoglykanů – GAG), které mají v organismu různé funkce, např. chondroitinsulfát je jednou z hlavních složek kloubních chrupavek, kde váže vodu a propůjčuje pružnost.


Etymology.

The word "talc" derives from Medieval Latin "talcum", which in turn originates from "ṭalq" which, derives from "tālk". In ancient times, the word was used for various related minerals, including talc, mica, and selenite.

Formation.

Talc dominantly forms from the metamorphism of magnesian minerals such as serpentine, pyroxene, amphibole, and olivine, in the presence of carbon dioxide and water. This is known as "talc carbonation" or "steatization" and produces a suite of rocks known as talc carbonates.  Talc is primarily formed by hydration and carbonation by this reaction:  Talc can also be formed via a reaction between dolomite and silica, which is typical of skarnification of dolomites by silica-flooding in contact metamorphic aureoles:  Talc can also be formed from magnesian chlorite and quartz in blueschist and eclogite metamorphism by the following metamorphic reaction:  Talc is also found as a diagenetic mineral in sedimentary rocks where it can form from the transformation of metastable hydrated magnesium-clay precursors such as kerolite, sepiolite, or stevensite that can precipitate from marine and lake water in certain conditions.  In this reaction, the ratio of talc and kyanite depends on aluminium content, with more aluminous rocks favoring production of kyanite. This is typically associated with high-pressure, low-temperature minerals such as phengite, garnet, and glaucophane within the lower blueschist facies. Such rocks are typically white, friable, and fibrous, and are known as whiteschist.  Talc is a trioctahedral layered mineral; its structure is similar to pyrophyllite, but with magnesium in the octahedral sites of the composite layers.

Occurrence.

Talc is a common metamorphic mineral in metamorphic belts that contain ultramafic rocks, such as soapstone (a high-talc rock), and within whiteschist and blueschist metamorphic terranes. Prime examples of whiteschists include the Franciscan Metamorphic Belt of the western United States, the western European Alps especially in Italy, certain areas of the Musgrave Block, and some collisional orogens such as the Himalayas, which stretch along Pakistan, India, Nepal, and Bhutan.  Talc carbonate ultramafics are typical of many areas of the Archaean cratons, notably the komatiite belts of the Yilgarn Craton in Western Australia. Talc-carbonate ultramafics are also known from the Lachlan Fold Belt, eastern Australia, from Brazil, the Guiana Shield, and from the ophiolite belts of Turkey, Oman, and the Middle East.  China is the key world talc and steatite producing country with an output of about 2.2M tonnes(2016), which accounts for 30% of total global output. The other major producers are Brazil (12%), India (11%), the U.S. (9%), France (6%), Finland (4%), Italy, Russia, Canada, and Austria (2%, each).  Notable economic talc occurrences include the Mount Seabrook talc mine, Western Australia, formed upon a polydeformed, layered ultramafic intrusion. The France-based Luzenac Group is the world's largest supplier of mined talc. Its largest talc mine at Trimouns near Luzenac in southern France produces 400,000 tonnes of talc per year.

Conflict mineral.

Extraction in disputed areas of Nangarhar province, Afghanistan, has led the international monitoring group Global Witness to declare talc a conflict mineral, as the profits are used to fund armed confrontation between the Taliban and Islamic State.

Uses.

Talc is used in many industries, including paper making, plastic, paint and coatings, rubber, food, electric cable, pharmaceuticals, cosmetics, and ceramics. A coarse grayish-green high-talc rock is soapstone or steatite, used for stoves, sinks, electrical switchboards, etc. It is often used for surfaces of laboratory table tops and electrical switchboards because of its resistance to heat, electricity and acids. In finely ground form, talc finds use as a cosmetic (talcum powder), as a lubricant, and as a filler in paper manufacture. It is used to coat the insides of inner tubes and rubber gloves during manufacture to keep the surfaces from sticking. Talcum powder, with heavy refinement, has been used in baby powder, an astringent powder used to prevent diaper rash. The American Academy of Pediatrics recommends that parents not use baby powder because it poses a risk of respiratory problems, including breathing trouble and serious lung damage if the baby inhales it. The small size of the particles makes it difficult to keep them out of the air while applying the powder. Zinc oxide-based ointments are a much safer alternative.  It is also often used in basketball to keep a player's hands dry. Most tailor's chalk, or French chalk, is talc, as is the chalk often used for welding or metalworking.  Talc is also used as food additive or in pharmaceutical products as a glidant. In medicine, talc is used as a pleurodesis agent to prevent recurrent pleural effusion or pneumothorax. In the European Union, the additive number is E553b. <br> Talc may be used in the processing of white rice as a buffing agent in the polishing stage.  Due to its low shear strength, talc is one of the oldest known solid lubricants. Also a limited use of talc as friction-reducing additive in lubricating oils is made.  Talc is widely used in the ceramics industry in both bodies and glazes. In low-fire art-ware bodies, it imparts whiteness and increases thermal expansion to resist crazing. In stonewares, small percentages of talc are used to flux the body and therefore improve strength and vitrification. It is a source of MgO flux in high-temperature glazes (to control melting temperature). It is also employed as a matting agent in earthenware glazes and can be used to produce magnesia mattes at high temperatures.  ISO standard for quality (ISO 3262)  Patents are pending on the use of magnesium silicate as a cement substitute. Its production requirements are less energy-intensive than ordinary Portland cement (at a heating requirement of around 650 °C for talc compared to 1500 °C for limestone to produce Portland cement), while it absorbs far more carbon dioxide as it hardens. This results in a negative carbon footprint overall, as the cement substitute removes 0.6 tonnes of CO per tonne used. This contrasts with a positive carbon footprint of 0.4 tonne per tonne of conventional cement.  Talc is used in the production of the materials that are widely used in the building interiors such as base content paints in wall coatings. Other areas that use talc to a great extent are organic agriculture, food industry, cosmetics, and hygiene products such as baby powder and detergent powder.  Talc is sometimes used as an adulterant to illegal heroin, to expand volume and weight and thereby increase its street value. With intravenous use, it may lead to pulmonary talcosis, a granulomatous inflammation in the lungs.

Sterile talc powder.

Sterile talc powder (NDC 63256-200-05) is a sclerosing agent used in the procedure of pleurodesis. This can be helpful as a cancer treatment to prevent pleural effusions (an abnormal collection of fluid in the space between the lungs and the thoracic wall). It is inserted into the space via a chest tube, causing it to close up, so fluid cannot collect there. The finished product has been sterilized by gamma irradiation.

Safety.

Suspicions have been raised that talc use contributes to certain types of disease, mainly cancers of the ovaries and lungs. Talc containing asbestos is classified as a group 1 agent (carcinogenic to humans), talc use in the perineal classified as group 2B (possibly carcinogenic to humans) and talc not containing asbestos is classified as group 3 (unclassifiable as to carcinogenicity in humans)(all in the IARC listing). Reviews by Cancer Research UK and the American Cancer Society conclude that some studies have found a link, but other studies have not.  The studies discuss pulmonary issues, lung cancer, and ovarian cancer. One of these, published in 1993, was a US National Toxicology Program report, which found that cosmetic grade talc containing no asbestos-like fibres was correlated with tumor formation in rats forced to inhale talc for 6 hours a day, five days a week over at least 113 weeks. A 1971 paper found particles of talc embedded in 75% of the ovarian tumors studied. Research published in 1995 and 2000 concluded that it was plausible that talc could cause ovarian cancer, but no conclusive evidence was shown. The Cosmetic Ingredient Review Expert Panel concluded in 2015 that talc, in the concentrations currently used in cosmetics, is safe.. In 2018, Health Canada issued a warning, advising against inhaling talcum powder or using it in the female perianal area.

Industrial grade.

In the United States, the Occupational Safety and Health Administration and National Institute for Occupational Safety and Health have set occupational exposure limits to respirable talc dusts at 2 mg/m over an eight-hour workday. At levels of 1000 mg/m, inhalation of talc is considered immediately dangerous to life and health.

Food grade.

The United States Food and Drug Administration considers talc (magnesium silicate) generally recognized as safe (GRAS) to use as an anticaking agent in table salt in concentrations smaller than 2%.

Association with asbestos.

One particular issue with commercial use of talc is its frequent co-location in underground deposits with asbestos ore. Asbestos is a general term for different types of fibrous silicate minerals, desirable in construction for their heat resistant properties. There are six varieties of asbestos; the most common variety in manufacturing, white asbestos, is in the serpentine family. Serpentine minerals are sheet silicates; although not in the serpentine family, talc is also a sheet silicate, with two sheets connected by magnesium cations. The frequent co-location of talc deposits with asbestos may result in contamination of mined talc with white asbestos, which poses serious health risks when dispersed into the air and inhaled. Stringent quality control since 1976, including separating cosmetic- and food-grade talc from "industrial"-grade talc, has largely eliminated this issue, but it remains a potential hazard requiring mitigation in the mining and processing of talc. A 2010 US FDA survey failed to find asbestos in a variety of talc-containing products. A 2018 Reuters investigation asserted that pharmaceuticals company Johnson & Johnson knew for decades that there was asbestos in its baby powder, and in 2020 the company stopped selling its baby powder in the USA and Canada.

Litigation.

In 2006 the International Agency for Research on Cancer classified talcum powder as a possible human carcinogen if used in the female genital area. Yet no federal agency in the US acted to remove talcum powder from the market or add warnings.  In February 2016, as the result of a lawsuit against Johnson & Johnson (J&J), a St. Louis jury awarded $72 million to the family of an Alabama woman who died from ovarian cancer. The family claimed that the use of talcum powder was responsible for her cancer.  In May 2016, a South Dakota woman was awarded $55 million as the result of another lawsuit against J&J. The woman had used Johnson & Johnson's Baby Powder for more than 35 years before being diagnosed with ovarian cancer in 2011.  In October 2016, a St. Louis jury awarded $70.1 million to a Californian woman with ovarian cancer who had used Johnson's Baby Powder for 45 years.  In August 2017, a Los Angeles jury awarded $417 million to a Californian woman, Eva Echeverria, who developed ovarian cancer as a "proximate result of the unreasonably dangerous and defective nature of talcum powder", her lawsuit against Johnson & Johnson stated. On 20 October 2017, Los Angeles Superior Court judge Maren Nelson dismissed the verdict. The judge stated that Echeverria proved there is "an ongoing debate in the scientific and medical community about whether talc more probably than not causes ovarian cancer and thus (gives) rise to a duty to warn", but not enough to sustain the jury's imposition of liability against Johnson & Johnson stated, and concluded that Echeverria did not adequately establish that talc causes ovarian cancer.  In July 2018, a court in St. Louis awarded a $4.7bn claim ($4.14bn in punitive damages and $550m in compensatory damages) against J&J to 22 claimant women, concluding that the company had suppressed evidence of asbestos in its products for more than four decades.  At least 1,200 to 2,000 other talcum powder-related lawsuits are pending.

Talc is a clay mineral composed of hydrated magnesium silicate with the chemical formula MgSiO(OH). Talc in powdered form, often in combination with corn starch, is widely used as baby powder. This mineral is used as a thickening agent and lubricant, is an ingredient in ceramics, paint and roofing material, and is also one of the main ingredients in many cosmetic products. It occurs as foliated to fibrous masses, and in an exceptionally rare crystal form. It has a perfect basal cleavage, uneven flat fracture and it is foliated with a two dimensional platy form.

Mastek (talek, steatit, klouzek), chemický vzorec MgSiO(OH), je jednoklonný minerál. Český název podle vlastnosti – je na omak mastný, jinak z arabského slova "talq" – talek


History.

See also "American Banjo Museum"

Early origins.

The modern banjo derives from instruments that have been speculated to be used in the Caribbean since the 17th century by enslaved people taken from West Africa. Written references to the banjo in North America appear in the 18th century, and the instrument became increasingly available commercially from around the second quarter of the 19th century. Since many slaves of South America were brought there by the Portuguese, they might have brought the idea of the instrument with them.  Several claims as to the etymology of the name "banjo" have been made. It may derive from the Kimbundu word "mbanza", which is an African string instrument modeled after the Portuguese "banza": a "vihuela" with five two-string courses and a further two short strings. The Oxford English Dictionary states that it comes from a dialectal pronunciation of Portuguese "bandore" or from an early anglicisation of Spanish "bandurria". The name may also derive from a traditional Afro-Caribbean folk dance called "banya", which incorporates several cultural elements

Minstrel era, 1830s–1870s.

In the antebellum South, many black slaves played the banjo and taught their masters how to play. For example, in his memoir "With Sabre and Scalpel: The Autobiography of a Soldier and Surgeon", the Confederate veteran and surgeon John Allan Wyeth recalls learning to play the banjo as a child from a slave on his family plantation. Another man who learned to play from African-Americans, probably in the 1820s, was Joel Walker Sweeney, a minstrel performer from Appomattox Court House, Virginia.. Sweeney has been credited with adding a string to the four-string African-American banjo, and popularizing the five-string

Classic era, 1880s-1910s.

The term "classic banjo" is used today to talk about a bare-finger "guitar style" that was widely in use among banjo players of the late 19th to early 20th century. It is still used by banjoists today. The term also differentiates that style of playing from the fingerpicking bluegrass banjo styles, such as the Scruggs style and Keith style.  The "Briggs Banjo Method", considered to be the first banjo method and which taught the "stroke style" of playing, also mentioned the existence of another way of playing, the "guitar style." Alternatively known as "finger style",

Ragtime era (1895–1919) and Jazz Age era (1910s–1930s).

In the early 1900s, new banjos began to spread, four-string models, played with a plectrum rather than with the minstrel-banjo clawhammer stroke or the classic-banjo fingerpicking style. The new banjos were a result of changing musical tastes. New music spurred the creation of "evolutionary variations" of the banjo, from the five-string model current since the 1830s to newer four-string plectrum and tenor banjos.  The instruments became ornately decorated in the 1920s to be visually dynamic to a theater audience. The instruments were increasingly modified or made in a new style – necks that were shortened to handle the four steel (not fiber as before) strings, strings that were sounded with a pick instead of fingers, four strings instead

Modern era.

In the Post World War 2 years, the banjo experienced a resurgence, played by music stars such as Earl Scruggs (bluegrass), Bela Fleck (jazz, rock, world music), Gerry O'Connor (Celtic and Irish music), Perry Bechtel (jazz, big band), Pete Seeger (folk), and Otis Taylor (African-American roots, blues, jazz).  Among these, Pete Seeger and Earl Scruggs were instrumental in turning the situation around.  Pete Seeger "was a major force behind a new national interest in folk music." Learning to play a fingerstyle in the Appalachians from musicians who never stopped playing the banjo, he wrote the book, "How To Play The Five-String Banjo", which was the only banjo method

Technique.

Two techniques closely associated with the five-string banjo are rolls and drones. Rolls are right hand accompanimental fingering pattern[s] that consist of eight (eighth) notes that subdivide each measure. Drone notes are quick little notes [typically eighth notes], usually played on the 5th (short) string to fill in around the melody notes [typically eighth notes]. These techniques are both idiomatic to the banjo in all styles, and their sound is characteristic of bluegrass.  Historically, the banjo was played in the claw-hammer style by the Africans who brought their version of the banjo with them. Several other styles of play

Modern banjo.

The modern banjo comes in a variety of forms, including four- and five-string versions. A six-string version, tuned and played similarly to a guitar, has gained popularity. In almost all of its forms, banjo playing is characterized by a fast arpeggiated plucking, though many different playing styles exist.  The body, or "pot", of a modern banjo typically consists of a circular rim (generally made of wood, though metal was also common on older banjos) and a tensioned head, similar to a drum head. Traditionally, the head was made from animal skin, but today is often made of various synthetic materials. Most modern banjos also have a metal "tone ring" assembly that helps further clarify and project the sound, but many older banjos do not include a tone ring.  The banjo is usually tuned with friction tuning pegs or planetary gear tuners, rather than the worm gear machine head used on guitars. Frets have become standard since the late 19th century, though fretless banjos are still manufactured and played by those wishing to execute glissando, play quarter tones, or otherwise achieve the sound and feeling of early playing styles.  Modern banjos are typically strung with metal strings. Usually, the fourth string is wound with either steel or bronze-phosphor alloy. Some players may string their banjos with nylon or gut strings to achieve a more mellow, old-time tone.

Open-back and resonator.

Some banjos have a separate resonator plate on the back of the pot to project the sound forward and give the instrument more volume. This type of banjo is usually used in bluegrass music, though resonator banjos

Five-string banjo.

The modern five-string banjo is a variation on Sweeney's original design. The fifth string is usually the same gauge as the first, but starts from the fifth fret, three-quarters the length of the other strings. This lets the string be tuned to a higher open pitch than possible for the full-length strings. Because of the short fifth string, the five-string banjo uses a reentrant tuning—the string pitches do not proceed lowest to highest across the fingerboard. Instead, the fourth string is lowest, then third, second, first, and the fifth string is highest.  The short fifth string presents special problems for a capo. For small changes (going up or down one or two semitones, for example), retuning the fifth string simply is possible. Otherwise, various devices called "fifth-string capos" effectively shorten the vibrating part of the string. Many banjo players use model-railroad spikes or titanium spikes (usually installed at the seventh fret and sometimes at others), under which they hook the string to press it down on the fret.  Five-string banjo players use many tunings. (Tunings are given in left-to-right order, as viewed from the front of the instrument with the neck pointing up.) Probably the most common, particularly in bluegrass, is the Open-G tuning G4 D3 G3 B3 D4. In earlier times, the tuning G4 C3 G3 B3 D4 was commonly used, instead, and this is still the preferred tuning for some types of folk music and for classic banjo. Other tunings found in old-time music include double C (G4 C3 G3 C4 D4), "sawmill" (G4 D3 G3 C4 D4) also called "mountain modal" and open D (F#4D3 F#3 A3 D4). These tunings are often taken up a tone, either by tuning up or using a capo. For example, "double-D" tuning (A4 D3 A3 D4 E4) – commonly reached by tuning up from double C – is often played to accompany fiddle tunes in the key of D and Open-A (A4 E3 A3 C#4 E4) is usually used for playing tunes in the key of A. Dozens of other banjo tunings are used, mostly in old-time music. These tunings are used to make playing specific tunes easier, usually fiddle tunes or groups of fiddle tunes.  The size of the five-string banjo is largely standardized, but smaller and larger sizes exist, including the long-neck or "Seeger neck" variation designed by Pete Seeger. Petite variations on the five-string banjo have been available since the 1890s. S.S. Stewart introduced the banjeaurine, tuned one fourth above a standard five-string. Piccolo banjos are smaller, and tuned one octave above a standard banjo. Between these sizes and standard lies the A-scale banjo, which is two frets shorter and usually tuned one full step above standard tunings. Many makers have produced banjos of other scale lengths, and with various innovations.  American old-time music typically uses the five-string, open-back banjo. It is played in a number of different styles, the most common being clawhammer or frailing, characterized by the use of a downward rather than upward stroke when striking the strings with a fingernail. Frailing techniques use the thumb to catch the fifth string for a drone after most strums or after each stroke ("double thumbing"), or to pick out additional melody notes in what is known as drop-thumb. Pete Seeger popularized a folk style by combining clawhammer with up picking, usually without the use of fingerpicks. Another common style of old-time banjo playing is fingerpicking banjo or classic banjo. This style is based upon parlor-style guitar.  Bluegrass music, which uses the five-string resonator banjo almost exclusively, is played in several common styles. These include Scruggs style, named after Earl Scruggs; melodic, or Keith style, named for Bill Keith; and three-finger style with single-string work, also called Reno style after Don Reno. In these styles, the emphasis is on arpeggiated figures played in a continuous eighth-note rhythm, known as rolls. All of these styles are typically played with fingerpicks.  The first five-string, electric, solid-body banjo was developed by Charles Wilburn (Buck) Trent, Harold "Shot" Jackson, and David Jackson in 1960.

Four-string banjos.

Four-string banjos, both plectrum and tenor, can be used for chordal accompaniment (as in early jazz), for single-string melody playing (as in Irish traditional music), in "chord melody" style (a succession of chords in which the highest notes carry the melody), in tremolo style (both on chords and single strings), and a mixed technique called duo style that combines single-string tremolo and rhythm chords.

Plectrum banjo.

The plectrum banjo is a standard banjo without the short drone string. It usually has 22 frets on the neck and a scale length of 26 to 28 inches, and was originally tuned C3 G3 B3 D4. It can also be tuned like the top four strings of a guitar, which is known as "Chicago tuning". As the name suggests, it is usually played with a guitar-style pick (that is, a single one held between thumb and forefinger), unlike the five-string banjo,

Tenor banjo.

The shorter-necked, tenor banjo, with 17 ("short scale") or 19 frets, is also typically played with a plectrum. It became a popular instrument after about 1910. Early models used for melodic picking typically had 17 frets on the neck and a scale length of 19 to 21 inches. By the mid-1920s, when the instrument was used primarily for strummed chordal accompaniment, 19-fret necks with a scale length of 21 to 23 inches became standard. The usual tuning is the all-fifths tuning C3 G3 D4 A4, in which exactly seven semitones (a perfect fifth) occur between the open notes of consecutive strings. Other players (particularly in Irish traditional music) tune the banjo G2 D3 A3 E4 like an octave mandolin, which lets the banjoist duplicate fiddle and mandolin fingering. The popularization of this tuning is usually attributed to the late Barney McKenna, banjoist with The Dubliners. Fingerstyle on tenor banjo retuned to open G tuning dgd'g' or

Low banjos.

In the late 19th and early 20th centuries, in vogue in plucked-string instrument ensembles—guitar orchestras, mandolin orchestras, banjo orchestras—was when the instrumentation was made to parallel that of the string section in symphony orchestras. Thus, "violin, viola, 'cello, bass" became "mandolin, mandola, mandocello, mandobass", or in the case of banjos, "banjolin, banjola, banjo cello, bass banjo". Because the range of pluck-stringed instrument generally is not as great as that of comparably sized bowed-string instruments, other instruments were often added to these plucked orchestras to extend the range of the ensemble upwards and downwards.

Cello banjo.

Rarer than either the tenor or plectrum banjo is the cello banjo (also "banjo cello"). It is normally tuned C2-G2-D3-A3, one octave below the tenor banjo like the cello

Bass and contrabass banjo.

Bass banjos have been produced in both upright bass formats and with standard, horizontally carried banjo bodies. Contrabass banjos with either three or four strings have also been made; some of these had headstocks similar to those of bass violins. Tuning varies on these large instruments, with four-string models sometimes being tuned in 4ths like a bass violin—E1-A1-D2-G2, and sometimes in 5ths, like a four-string cello banjo, one octave lower—C1-G1-D2-A2. Other variants are also used.

Six-string banjos.

The six-string banjo began as a British innovation by William Temlet, one of England's earliest banjo makers. He opened a shop in London in 1846, and sold banjos with closed backs and up to seven strings. He marketed these as "zither" banjos from his 1869 patent. American Alfred Davis Cammeyer (1862–1949), a young violinist-turned banjo concert player, devised the five- or six-string zither banjo around 1880. It had a wood resonator and metal "wire" strings (the first and second melody strings and fifth "thumb" string. The third melody string was gut, and the fourth was silk covered), as well as frets and guitar-style tuning machines.  A zither banjo usually has a closed back and sides with the drum body (usually metal) and skin tensioning system suspended inside the wooden rim/back, the neck and string tailpiece was mounted on the wooden outer rim, the short string usually led through a tube in the neck so that the tuning peg could be mounted on the peg head. They were often made by builders who used guitar tuners that came in banks of three, so if five-stringed had a redundant tuner. The banjos could also be somewhat easily converted over to a six-string banjo.

Banjo hybrids and variants.

A number of hybrid instruments exist, crossing the banjo with other stringed instruments. Most of these use the body of a banjo, often with a resonator, and the neck of the other instrument. Examples include the Banjo Mandolin (first patented in 1882) and the banjo ukulele or banjolele, most famously played by the English comedian George Formby. These were especially popular in the early decades of the 20th century, and were probably a result of a desire either to allow players of other instruments to jump on the banjo bandwagon at the height of its popularity, or to get the natural amplification benefits of the banjo resonator in an age before electric amplification.  The six-string banjo guitar basically consists of a six-string guitar neck attached to a bluegrass or plectrum banjo body. This was the instrument of the early jazz great Johnny St. Cyr, jazzmen Django Reinhardt, Danny Barker, Papa Charlie Jackson and Clancy Hayes, as well as the blues and gospel singer The Reverend Gary Davis. Nowadays, it appears under various names such as guitanjo, guitjoe, ganjo, banjitar, or bantar. Today, musicians as diverse as Keith Urban, Rod Stewart, Taj Mahal, Joe Satriani, David Hidalgo, Larry Lalonde and Doc Watson play the six-string guitar banjo. Rhythm guitarist Dave Day of 1960s proto-punks The Monks replaced his guitar with a six-string, gut-strung guitar banjo on which he played guitar chords. This instrument sounds much more metallic, scratchy and wiry than a standard electric guitar, due to its amplification by a small microphone stuck inside the banjo's body.  Instruments that have a five-string banjo neck on a wooden body (for example, a guitar, bouzouki, or dobro body) have also been made, such as the banjola. A 20th-century Turkish instrument similar to the banjo is called the "cümbüş". At the end of the 20th century, a development of the five-string banjo was the BanSitar. This features a bone bridge, giving the instrument a sitar-like resonance. A recent innovation is the patented Banjo-Tam, invented by Frank Abrams of Asheville, North Carolina, combining a traditional five-string banjo neck with a tambourine as a rim or pot.

The banjo is a stringed instrument with a thin membrane stretched over a frame or cavity to form a resonator. The membrane is typically circular, and usually made of plastic, or occasionally animal skin. Early forms of the instrument were fashioned by African Americans in the United States, adapted from African instruments of similar design. The banjo is frequently associated with folk and country music. Banjo can also be used in some rock songs. Many rock bands, such as The Eagles, Led Zeppelin, and The Allman Brothers, have used the five-string banjo in some of their songs. Historically, the banjo occupied a central place in African-American traditional music and the folk culture of rural whites before entering the mainstream via the minstrel shows of the 19th century. Along with the fiddle, the banjo is a mainstay of American old-time music. It is also very frequently used in traditional ("trad") jazz.

Banjo (zřídka bendžo či benžo) je drnkací čtyř-, pěti- nebo šestistrunný nástroj. Tón vzniká podobně jako u kytary rozechvěním struny mezi nultým pražcem a kobylkou. Pomocí hmatníku je možné struny zkracovat a tím zvyšovat jejich tón.


Description.

As a microkernel-based OS, QNX is based on the idea of running most of the operating system kernel in the form of a number of small tasks, named Resource Managers. This differs from the more traditional monolithic kernel, in which the operating system kernel is one very large program composed of a huge number of parts, with special abilities. In the case of QNX, the use of a microkernel allows users (developers) to turn off any functions they do not need without having to change the OS. Instead, such services will simply not run.  The system is quite small, with earlier versions fitting on one 1.44 MB floppy disk.  QNX Neutrino (2001) has been ported to a number of platforms and now runs on practically any modern central processing unit (CPU) family that is used in the embedded market. This includes the PowerPC, x86, MIPS, SH-4, and the closely interrelated of ARM, StrongARM, and XScale.  QNX offers a license for noncommercial and academic users.  The BlackBerry PlayBook tablet computer designed by BlackBerry uses a version of QNX as the primary operating system. Devices from BlackBerry running the BlackBerry 10 operating system are also based on QNX.  QNX is also used in car infotainment systems with many major car makers offering variants that include an embedded QNX architecture. It is supported by popular SSL/TLS libraries such as wolfSSL.

History.

Gordon Bell and Dan Dodge, both students at the University of Waterloo in 1980, took a course (CS452) in real-time operating systems, in which the students constructed a basic real-time microkernel and user programs. Both were convinced there was a commercial need for such a system, and moved to the high-tech planned community Kanata, Ontario, to start Quantum Software Systems that year. In 1982, the first version of QUNIX was released for the Intel 8088 CPU. In 1984, Quantum Software Systems renamed QUNIX to QNX in an effort to avoid any trademark infringement challenges.  One of the first widespread uses of the QNX real-time OS (RTOS) was in the nonembedded world when it was selected as the operating system for the Ontario education system's own computer design, the Unisys ICON. Over the years QNX was used mostly for larger projects, as its 44k kernel was too large to fit inside the one-chip computers of the era. The system garnered a reputation for reliability and became used in running machinery in many industrial applications.  In the late-1980s, Quantum realized that the market was rapidly moving towards the Portable Operating System Interface (POSIX) model and decided to rewrite the kernel to be much more compatible at a low level. The result was QNX 4. During this time Patrick Hayden, while working as an intern, along with Robin Burgener (a full-time employee at the time), developed a new windowing system. This patented concept was developed into the embeddable graphical user interface (GUI) named the QNX Photon microGUI. QNX also provided a version of the X Window System.  Toward the end of the 1990s, the company (now called QNX Software Systems) began work on a new version of QNX, designed from the ground up to be symmetric multiprocessing (SMP) capable, and to support all current POSIX application programming interfaces (APIs) and any new POSIX APIs that could be anticipated while still retaining the microkernel architecture. This resulted in QNX Neutrino, released in 2001.  Along with the Neutrino kernel, QNX Software Systems became a founding member of the Eclipse consortium. The company released a suite of Eclipse plug-ins packaged with the Eclipse workbench in 2002, and named QNX Momentics Tool Suite.  In 2004, the company announced it had been sold to Harman International Industries. Before this acquisition, QNX software was already widely used in the automotive industry for telematics systems. Since the purchase by Harman, QNX software has been designed into over 200 different automobile makes and models, in telematics systems and in infotainment and navigation units. The QNX CAR Application Platform was running in over 20 million vehicles as of mid-2011. The company has since released several middleware products including the QNX Aviage Multimedia Suite, the QNX Aviage Acoustic Processing Suite and the QNX HMI Suite.  The microkernels of Cisco Systems' IOS-XR (ultra high availability IOS, introduced 2004) and IOS Software Modularity (introduced 2006) are based upon QNX.  In September 2007, QNX Software Systems announced the availability of some of its source code.  On April 9, 2010, Research In Motion announced they would acquire QNX Software Systems from Harman International Industries. On the same day, QNX source code access was restricted from the public and hobbyists.  In September 2010, the company announced a tablet computer, the BlackBerry PlayBook, and a new operating system BlackBerry Tablet OS based on QNX to run on the tablet.  On October 18, 2011, Research In Motion announced "BBX", which was later renamed to BlackBerry 10, in December 2011. Blackberry 10 devices build upon the BlackBerry PlayBook QNX based operating system for touch devices, but adapt the user interface for smartphones using the Qt based Cascades Native User-Interface framework.  At the Geneva Motor Show, Apple demonstrated CarPlay which provides an iOS-like user interface to head units in compatible vehicles. Once configured by the automaker, QNX can be programmed to hand off its display and some functions to an Apple CarPlay device.  On December 11, 2014, Ford Motor Company stated the company would be replacing Microsoft Auto with QNX.  In January 2017, QNX announced the upcoming release of its SDP 7.0, with support for Intel and ARM 32- and 64-bit platforms, and support for C++14; it was released in March 2017.

Technology.

The QNX kernel, codice_1, contains only CPU scheduling, interprocess communication, interrupt redirection and timers. Everything else runs as a user process, including a special process known as codice_2 which performs process creation and memory management by operating in conjunction with the microkernel. This is made possible by two key mechanisms: subroutine-call type interprocess communication, and a boot loader which can load an image containing the kernel and any desired set of user programs and shared libraries. There are no device drivers in the kernel. The network stack is based on NetBSD code. Along with its support for its own, native, device drivers, QNX supports its legacy, "io-net manager" server, and the network drivers ported from NetBSD.  QNX interprocess communication consists of sending a message from one process to another and waiting for a reply. This is a single operation, called codice_3. The message is copied, by the kernel, from the address space of the sending process to that of the receiving process. If the receiving process is waiting for the message, control of the CPU is transferred at the same time, without a pass through the CPU scheduler. Thus, sending a message to another process and waiting for a reply does not result in "losing one's turn" for the CPU. This tight integration between message passing and CPU scheduling is one of the key mechanisms that makes QNX message passing broadly usable. Most Unix and Linux interprocess communication mechanisms lack this tight integration, although a user space implementation of QNX-type messaging for Linux does exist. Mishandling of this subtle issue is a primary reason for the disappointing performance of some other microkernel systems such as early versions of Mach. The recipient process need not be on the same physical machine.  All I/O operations, file system operations, and network operations were meant to work through this mechanism, and the data transferred was copied during message passing. Later versions of QNX reduce the number of separate processes and integrate the network stack and other function blocks into single applications for performance reasons.  Message handling is prioritized by thread priority. Since I/O requests are performed using message passing, high priority threads receive I/O service before low priority threads, an essential feature in a hard real-time system.  The boot loader is the other key component of the minimal microkernel system. Because user programs can be built into the boot image, the set of device drivers and support libraries needed for startup need not be, and are not, in the kernel. Even such functions as program loading are not in the kernel, but instead are in shared user-space libraries loaded as part of the boot image. It is possible to put an entire boot image into ROM, which is used for diskless embedded systems.  Neutrino supports symmetric multiprocessing and processor affinity, called bound multiprocessing (BMP) in QNX terminology. BMP is used to improve cache hitting and to ease the migration of non-SMP safe applications to multi-processor computers.  Neutrino supports strict priority-preemptive scheduling and adaptive partition scheduling (APS). APS guarantees minimum CPU percentages to selected groups of threads, even though others may have higher priority. The adaptive partition scheduler is still strictly priority-preemptive when the system is underloaded. It can also be configured to run a selected set of critical threads strictly real time, even when the system is overloaded.

QNX RTOS Release history.

QNX RTOS History

QNX/Neutrino Release history.

QNX/Neutrino Microkernel history -- Forked from QNX 4.24 in 1996.

Transparent Distributed Processing.

Due to its microkernel architecture QNX is also a distributed operating system. Dan Dodge and Peter van der Veen hold based on the QNX operating system's distributed processing features known commercially as Transparent Distributed Processing. This allows the QNX kernels on separate devices to access each other's system services using effectively the same communication mechanism as is used to access local services.

Forums.

OpenQNX is a QNX Community Portal established and run independently. An IRC channel and Newsgroups access via web is available. Diverse industries are represented by the developers on the site.  Foundry27 is a web-based QNX community established by the company. It serves as a hub to QNX Neutrino development where developers can register, choose the license, and get the source code and related toolkit of the RTOS.

Reception.

"PC Magazine" stated in April 1983 that QNX was "an extraordinary piece of software". Citing its multitasking, the review concluded that "QNX gives you the power to maximize utilization of the PC's resources".

QNX ( or ) is a commercial Unix-like real-time operating system, aimed primarily at the embedded systems market. QNX was one of the first commercially successful microkernel operating systems., it is used in a variety of devices including cars and mobile phones.

QNX (výslovnost ) je název operačního systému, který od začátku 80. let 20. století vyvíjela kanadská firma "Quantum Software Systems". QNX je komerční operační systém reálného času unixového typu používající mikrojádro. Operační systém je unixového typu, včetně shellu a externích programů, kompatibilní s normou POSIX. Je používán v různých zařízeních včetně automobilů a mobilních telefonů. Firma byla nejprve přejmenovaná na QNX Software Systems a v roce 2010 byla převzata firmou BlackBerry Limited.


Etymology.

Herbivore is the anglicized form of a modern Latin coinage, "herbivora," cited in Charles Lyell's 1830 "Principles of Geology." Richard Owen employed the anglicized term in an 1854 work on fossil teeth and skeletons. "Herbivora" is derived from the Latin "herba" meaning a small plant or herb, and "vora," from "vorare," to eat or devour.

Definition and related terms.

Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in general are known as primary consumers. Herbivory is usually limited to animals that eat plants. Fungi, bacteria and protists that feed on living plants are usually termed plant pathogens (plant diseases), while fungi and microbes that feed on dead plants are described as saprotrophs. Flowering plants that obtain nutrition from other living plants are usually termed parasitic plants. There is, however, no single exclusive and definitive ecological classification of consumption patterns; each textbook has its own variations on the theme.

Evolution of herbivory.

The understanding of herbivory in geological time comes from three sources: fossilized plants, which may preserve evidence of defence (such as spines), or herbivory-related damage; the observation of plant debris in fossilised animal faeces; and the construction of herbivore mouthparts.  Although herbivory was long thought to be a Mesozoic phenomenon, fossils have shown that within less than 20 million years after the first land plants evolved, plants were being consumed by arthropods. Insects fed on the spores of early Devonian plants, and the Rhynie chert also provides evidence that organisms fed on plants using a "pierce and suck" technique.  During the next 75 million years, plants evolved a range of more complex organs, such as roots and seeds. There is no evidence of any organism being fed upon until the middle-late Mississippian,. There was a gap of 50 to 100 million years between the time each organ evolved and the time organisms evolved to feed upon them; this may be due to the low levels of oxygen during this period, which may have suppressed evolution. Further than their arthropod status, the identity of these early herbivores is uncertain. Hole feeding and skeletonisation are recorded in the early Permian, with surface fluid feeding evolving by the end of that period.  Herbivory among four-limbed terrestrial vertebrates, the tetrapods developed in the Late Carboniferous (307 – 299 million years ago). Early tetrapods were large amphibious piscivores. While amphibians continued to feed on fish and insects, some reptiles began exploring two new food types, tetrapods (carnivory) and plants (herbivory). The entire dinosaur order ornithischia was composed with herbivores dinosaurs. Carnivory was a natural transition from insectivory for medium and large tetrapods, requiring minimal adaptation. In contrast, a complex set of adaptations was necessary for feeding on highly fibrous plant materials.  Arthropods evolved herbivory in four phases, changing their approach to it in response to changing plant communities. Tetrapod herbivores made their first appearance in the fossil record of their jaws near the Permio-Carboniferous boundary, approximately 300 million years ago. The earliest evidence of their herbivory has been attributed to dental occlusion, the process in which teeth from the upper jaw come in contact with teeth in the lower jaw is present. The evolution of dental occlusion led to a drastic increase in plant food processing and provides evidence about feeding strategies based on tooth wear patterns. Examination of phylogenetic frameworks of tooth and jaw morphologes has revealed that dental occlusion developed independently in several lineages tetrapod herbivores. This suggests that evolution and spread occurred simultaneously within various lineages.

Food chain.

Herbivores form an important link in the food chain because they consume plants in order to digest the carbohydrates photosynthetically produced by a plant. Carnivores in turn consume herbivores for the same reason, while omnivores can obtain their nutrients from either plants or animals. Due to a herbivore's ability to survive solely on tough and fibrous plant matter, they are termed the primary consumers in the food cycle (chain). Herbivory, carnivory, and omnivory can be regarded as special cases of consumer–resource interactions.

Feeding strategies.

Two herbivore feeding strategies are grazing (e.g. cows) and browsing (herbivory) (e.g. moose). For a terrestrial mammal to be called a grazer, at least 90% of the forage has to be grass, and for a browser at least 90% tree leaves and/or twigs. An intermediate feeding strategy is called "mixed-feeding". In their daily need to take up energy from forage, herbivores of different body mass may be selective in choosing their food. "Selective" means that herbivores may choose their forage source depending on, e.g., season or food availability, but also that they may choose high quality (and consequently highly nutritious) forage before lower quality. The latter especially is determined by the body mass of the herbivore, with small herbivores selecting for high quality forage, and with increasing body mass animals are less selective. Several theories attempt to explain and quantify the relationship between animals and their food, such as Kleiber's law, Holling's disk equation and the marginal value theorem (see below).  Kleiber's law describes the relationship between an animal's size and its feeding strategy, saying that larger animals need to eat less food per unit weight than smaller animals. Kleiber's law states that the metabolic rate (q) of an animal is the mass of the animal (M) raised to the 3/4 power: q=M Therefore, the mass of the animal increases at a faster rate than the metabolic rate.  Herbivores employ numerous types of feeding strategies. Many herbivores do not fall into one specific feeding strategy, but employ several strategies and eat a variety of plant parts.  Optimal Foraging Theory is a model for predicting animal behavior while looking for food or other resource, such as shelter or water. This model assesses both individual movement, such as animal behavior while looking for food, and distribution within a habitat, such as dynamics at the population and community level. For example, the model would be used to look at the browsing behavior of a deer while looking for food, as well as that deer's specific location and movement within the forested habitat and its interaction with other deer while in that habitat.  This model has been criticized as circular and untestable. Critics have pointed out that its proponents use examples that fit the theory, but do not use the model when it does not fit the reality. Other critics point out that animals do not have the ability to assess and maximize their potential gains, therefore the optimal foraging theory is irrelevant and derived to explain trends that do not exist in nature.  Holling's disk equation models the efficiency at which predators consume prey. The model predicts that as the number of prey increases, the amount of time predators spend handling prey also increases and therefore the efficiency of the predator decreases. In 1959, S. Holling proposed an equation to model the rate of return for an optimal diet: Rate (R )=Energy gained in foraging (Ef)/(time searching (Ts) + time handling (Th)) formula_1 Where s=cost of search per unit time f=rate of encounter with items, h=handling time, e=energy gained per encounter In effect, this would indicate that a herbivore in a dense forest would spend more time handling (eating) the vegetation because there was so much vegetation around than a herbivore in a sparse forest, who could easily browse through the forest vegetation. According to the Holling's disk equation, a herbivore in the sparse forest would be more efficient at eating than the herbivore in the dense forest.  The marginal value theorem describes the balance between eating all the food in a patch for immediate energy, or moving to a new patch and leaving the plants in the first patch to regenerate for future use. The theory predicts that absent complicating factors, an animal should leave a resource patch when the rate of payoff (amount of food) falls below the average rate of payoff for the entire area. According to this theory, locus should move to a new patch of food when the patch they are currently feeding on requires more energy to obtain food than an average patch. Within this theory, two subsequent parameters emerge, the Giving Up Density (GUD) and the Giving Up Time (GUT). The Giving Up Density (GUD) quantifies the amount of food that remains in a patch when a forager moves to a new patch. The Giving Up Time (GUT) is used when an animal continuously assesses the patch quality.

Attacks and counter-attacks.

Herbivore offense.

The myriad defenses displayed by plants means that their herbivores need a variety of skills to overcome these defenses and obtain food. These allow herbivores to increase their feeding and use of a host plant. Herbivores have three primary strategies for dealing with plant defenses: choice, herbivore modification, and plant modification.  Feeding choice involves which plants a herbivore chooses to consume. It has been suggested that many herbivores feed on a variety of plants to balance their nutrient uptake and to avoid consuming too much of any one type of defensive chemical. This involves a tradeoff however, between foraging on many plant species to avoid toxins or specializing on one type of plant that can be detoxified.  Herbivore modification is when various adaptations to body or digestive systems of the herbivore allow them to overcome plant defenses. This might include detoxifying secondary metabolites, sequestering toxins unaltered, or avoiding toxins, such as through the production of large amounts of saliva to reduce effectiveness of defenses. Herbivores may also utilize symbionts to evade plant defences. For example, some aphids use bacteria in their gut to provide essential amino acids lacking in their sap diet.  Plant modification occurs when herbivores manipulate their plant prey to increase feeding. For example, some caterpillars roll leaves to reduce the effectiveness of plant defenses activated by sunlight.

Plant defense.

A plant defense is a trait that increases plant fitness when faced with herbivory. This is measured relative to another plant that lacks the defensive trait. Plant defenses increase survival and/or reproduction (fitness) of plants under pressure of predation from herbivores.  Defense can be divided into two main categories, tolerance and resistance. Tolerance is the ability of a plant to withstand damage without a reduction in fitness. This can occur by diverting herbivory to non-essential plant parts, resource allocation, compensatory growth, or by rapid regrowth and recovery from herbivory. Resistance refers to the ability of a plant to reduce the amount of damage it receives from herbivores. This can occur via avoidance in space or time, physical defenses, or chemical defenses. Defenses can either be constitutive, always present in the plant, or induced, produced or translocated by the plant following damage or stress.  Physical, or mechanical, defenses are barriers or structures designed to deter herbivores or reduce intake rates, lowering overall herbivory. Thorns such as those found on roses or acacia trees are one example, as are the spines on a cactus. Smaller hairs known as trichomes may cover leaves or stems and are especially effective against invertebrate herbivores. In addition, some plants have waxes or resins that alter their texture, making them difficult to eat. Also the incorporation of silica into cell walls is analogous to that of the role of lignin in that it is a compression-resistant structural component of cell walls; so that plants with their cell walls impregnated with silica are thereby afforded a measure of protection against herbivory.  Chemical defenses are secondary metabolites produced by the plant that deter herbivory. There are a wide variety of these in nature and a single plant can have hundreds of different chemical defenses. Chemical defenses can be divided into two main groups, carbon-based defenses and nitrogen-based defenses.  Plants have also changed features that enhance the probability of attracting natural enemies to herbivores. Some emit semiochemicals, odors that attract natural enemies, while others provide food and housing to maintain the natural enemies' presence, e.g. ants that reduce herbivory. A given plant species often has many types of defensive mechanisms, mechanical or chemical, constitutive or induced, which allow it to escape from herbivores.

Herbivore–plant interactions per predator–prey theory.

According to the theory of predator–prey interactions, the relationship between herbivores and plants is cyclic. When prey (plants) are numerous their predators (herbivores) increase in numbers, reducing the prey population, which in turn causes predator number to decline. The prey population eventually recovers, starting a new cycle. This suggests that the population of the herbivore fluctuates around the carrying capacity of the food source, in this case the plant.  Several factors play into these fluctuating populations and help stabilize predator–prey dynamics. For example, spatial heterogeneity is maintained, which means there will always be pockets of plants not found by herbivores. This stabilizing dynamic plays an especially important role for specialist herbivores that feed on one species of plant and prevents these specialists from wiping out their food source. Prey defenses also help stabilize predator–prey dynamics, and for more information on these relationships see the section on Plant Defenses. Eating a second prey type helps herbivores' populations stabilize. Alternating between two or more plant types provides population stability for the herbivore, while the populations of the plants oscillate. This plays an important role for generalist herbivores that eat a variety of plants. Keystone herbivores keep vegetation populations in check and allow for a greater diversity of both herbivores and plants. When an invasive herbivore or plant enters the system, the balance is thrown off and the diversity can collapse to a monotaxon system.  The back and forth relationship of plant defense and herbivore offense drives coevolution between plants and herbivores, resulting in a "coevolutionary arms race". The escape and radiation mechanisms for coevolution, presents the idea that adaptations in herbivores and their host plants, has been the driving force behind speciation.  While much of the interaction of herbivory and plant defense is negative, with one individual reducing the fitness of the other, some is actually beneficial. This beneficial herbivory takes the form of mutualisms in which both partners benefit in some way from the interaction. Seed dispersal by herbivores and pollination are two forms of mutualistic herbivory in which the herbivore receives a food resource and the plant is aided in reproduction.

Impacts.

Herbivorous fish and marine animals are indispensable parts of the coral reef ecosystem. Since algae and seaweeds grow much faster than corals, they can occupy spaces where corals could have settled. They can outgrow and thus outcompete corals on bare surfaces. In the absence of plant-eating fish, seaweeds deprive corals of sunlight.  Herbivory can have impacts on both economics and ecology. For example, environmental degradation from white-tailed deer ("Odocoileus virginianus") in the US alone has the potential to both change vegetative communities through over-browsing and cost forest restoration projects upwards of $750 million annually. Agricultural crop damage by the same species totals approximately $100 million every year. Insect crop damages also contribute largely to annual crop losses in the U.S. Herbivores affect economics through the revenue generated by hunting and ecotourism. For example, the hunting of herbivorous game species such as white-tailed deer, cottontail rabbits, antelope, and elk in the U.S. contributes greatly to the billion-dollar annually, hunting industry. Ecotourism is a major source of revenue, particularly in Africa, where many large mammalian herbivores such as elephants, zebras, and giraffes help to bring in the equivalent of millions of US dollars to various nations annually.

A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthparts adapted to rasping or grinding. Horses and other herbivores have wide flat teeth that are adapted to grinding grass, tree bark, and other tough plant material.

Býložravec (herbivor) je živočich, který pojídá pouze či téměř výhradně rostliny nebo části rostlin. Býložravost se odborně nazývá herbivorie. Ve srovnání s masožravci mají býložravci zpravidla delší a složitější trávicí soustavu, v níž zpravidla žije značné množství symbiontů napomáhajících trávení celulózy (některé druhy bakterií a kvasinek). Trávicí soustava obsahuje také široké spektrum enzymů, jež umožňují trávení potravy.