Plot.

In 1921, an archaeological expedition led by Sir Joseph Whemple (Arthur Byron) finds the mummy of an ancient Egyptian high priest named Imhotep (Boris Karloff). An inspection of the mummy by Whemple's friend Dr. Muller (Edward Van Sloan) reveals that the viscera were not removed, and from the signs of struggling Muller deduces that although Imhotep had been wrapped like a traditional mummy, he had been buried alive. Also buried with Imhotep is a casket with a curse on it. Despite Muller's warning, Sir Joseph's assistant Ralph Norton (Bramwell Fletcher) opens it. He reads aloud an ancient life-giving scroll, the "Scroll of Thoth". Imhotep rises, the sight of which snaps Norton’s mind and causes him to laugh hysterically, as the Mummy shuffles off with the scroll.  Ten years later, Imhotep is masquerading as a modern Egyptian named Ardeth Bay covering himself with makeup. He calls upon Sir Joseph's son Frank (David Manners) and Professor Pearson (Leonard Mudie) and shows them where to dig to find the tomb of the princess Anck-su-namun. After locating the tomb, the archaeologists present its treasures to the Cairo Museum and thank Ardeth Bay for making their discovery possible. It is further revealed that Imhotep's horrific death was punishment for sacrilege: attempting to resurrect his forbidden lover, Princess Anck-su-namun.  Imhotep soon encounters Helen Grosvenor (Zita Johann), a half-Egyptian woman bearing a striking resemblance to the princess. Believing her to be Anck-su-namun's reincarnation, he attempts to kill her, with the intention of mummifying her, resurrecting her, and finally making her his immortal bride. Helen is rescued when she remembers her ancestral past life and prays to the goddess Isis to come to her aid. The statue of Isis raises its arm and emits a flash that sets the Scroll of Thoth on fire. This breaks the spell that had given Imhotep his immortality, causing him to crumble to dust. At the urging of Dr. Muller, Frank calls Helen back to the world of the living while the Scroll of Thoth continues to burn.

Production.

Inspired by the opening of Tutankhamun's tomb in 1922 and the Curse of the Pharaohs, producer Carl Laemmle Jr. commissioned story editor Richard Schayer to find a literary novel to form a basis for an Egyptian-themed horror film, just as the novels "Dracula" and "Frankenstein" informed their 1931 films "Dracula" and "Frankenstein". Schayer found none although the plot bears a strong resemblance to a short story by Arthur Conan Doyle entitled "The Ring of Thoth". Schayer and writer Nina Wilcox Putnam learned about Alessandro Cagliostro and wrote a nine-page treatment entitled "Cagliostro". The story, set in San Francisco, was about a 3,000-year-old magician who survives by injecting nitrates.  Pleased with the Cagliostro concept, Laemmle hired John L. Balderston to write the script. Balderston had contributed to "Dracula" and "Frankenstein", and had covered the opening of Tutankhamun's tomb for "New York World" when he was a journalist so he was more than familiar with the highly popular tomb unearthing. Balderston moved the story to Egypt and renamed the film and its title character Imhotep, after the historical architect. He also changed the story from one of revenge upon all the women who resembled the main character's ex-lover to one where the main character is determined to revive his old love by killing and mummifying her reincarnated self before resurrecting her with the spell of the Scroll of Thoth. Balderston invented the Scroll of Thoth, which gave an aura of authenticity to the story. Thoth was the wisest of the Egyptian gods who, when Osiris died, helped Isis bring her love back from the dead. Thoth is believed to have authored "The Book of the Dead", which may have been the inspiration for Balderston's Scroll of Thoth. Another likely source of inspiration is the fictional "Book of Thoth" that appeared in several ancient Egyptian stories.  Karl Freund, the cinematographer on "Dracula", was hired to direct, making this his first film in the United States as a director. Freund had also been the cinematographer on Fritz Lang's "Metropolis" and later photographed the television series "I Love Lucy". The film was retitled "The Mummy". Freund cast Zita Johann, who believed in reincarnation, and named her character 'Anck-su-namun' after the only wife of Pharaoh Tutankhamun. The real Ankhesenamun's body had not been discovered in the tomb of King Tut and her resting place was unknown. Her name, however, would not have been unknown to the general public.  Filming was scheduled for three weeks. Karloff's first day was spent shooting the Mummy's awakening from his sarcophagus. Make-up artist Jack Pierce had studied photos of Seti I's mummy to design Imhotep; however, Karloff looked nothing like the mummy of Seti I in the film, instead bearing a resemblance to the mummy of Ramesses III. Pierce began transforming Karloff at 11 a.m., applying cotton, collodion and spirit gum to his face; clay to his hair; and wrapping him in linen bandages treated with acid and burnt in an oven, finishing the job at 7 p.m. Karloff finished his scenes at 2 a.m., and another two hours were spent removing the make-up. Karloff found the removal of gum from his face painful, and overall found the day "the most trying ordeal I [had] ever endured". Although the images of Karloff wrapped in bandages are the most iconic taken from the film, Karloff only appears on screen in this make-up for the opening vignette; the rest of the film sees him wearing less elaborate make-up.  A lengthy and detailed flashback sequence was longer than as it presently exists. This sequence showed the various forms Anck-su-namun was reincarnated in over the centuries: Henry Victor is credited in the film as "Saxon Warrior", despite his performance having been deleted. Stills exist of those sequences, but the footage (save for Karloff's appearance and the sacrilegious events leading up to his mummification in ancient Egypt) has been lost.  The piece of classical music heard during the opening credits, taken from the Tchaikovsky ballet "Swan Lake", was previously also used (in the same arrangement) for the opening credits of Universal's "Dracula" (1931) and "Murders in the Rue Morgue" (1932); in 1933 it would be re-used as the title music of the same studio's "Secret of the Blue Room".

Reception.

The film was a success at the box office, particularly in the United Kingdom  The film received positive reviews from critics. Review aggregator website Rotten Tomatoes reports a 93% score, based on 27 reviews, with an average rating of 7.9/10. The site's consensus states: "Relying more on mood and atmosphere than the thrills typical of modern horror fare, Universal's "The Mummy" sets a masterful template for mummy-themed films to follow."

Legacy.

Sequels.

Unlike other Universal Monsters films, "The Mummy" had no official sequels, but rather was reimagined in "The Mummy's Hand" (1940) and its sequels, "The Mummy's Tomb" (1942), "The Mummy's Ghost" (1944), "The Mummy's Curse" (1944), and the studios' comedy-horror crossover movie "Abbott and Costello Meet the Mummy" (1955). These films focus on the titular character named Kharis (Klaris in the Abbott and Costello film). "The Mummy's Hand" recycled footage from the original film for use in the telling of Kharis' origins, where Karloff is clearly visible in several of these recycled scenes but was not credited.

Hammer Film Productions series.

In the late 1950s, British Hammer Film Productions took up the "Mummy" theme, beginning with "The Mummy" (1959), which, rather than being a remake of the 1932 Karloff film, is based on Universal's "The Mummy's Hand" (1940) and "The Mummy's Tomb" (1942). Hammer's follow-ups — "The Curse of The Mummy's Tomb" (1964), "The Mummy's Shroud" (1966) and "Blood from The Mummy's Tomb" (1971) — are unrelated to the first film or even to each other, apart from the appearance of "The Scroll of Life" in "Curse of The Mummy's Tomb" and "Blood from The Mummy's Tomb".

Remake series.

The much later Universal film "The Mummy" (1999) also suggests that it is a remake of the 1932 film, but has a different story line. However, in common with most postmodern remakes of classic horror and science-fiction films, it may be considered as such in that it is produced-distributed by the same studio, its titular character is again named Imhotep, resurrected by the Book of the Dead, and out to find the present-day embodiment of the soul of his beloved Anck-su-namun, and features an Egyptian named Ardeth Bay (in this case, a guard of the city and of Imhotep's tomb). This film spawned two sequels with "The Mummy Returns" (2001) and "" (2008). "The Mummy Returns" also spawned a prequel spin-off of that sequel, "The Scorpion King" (2002), which in turn spawned a prequel, "" (2008), and three sequels, "" (2012), "" (2015) and "" (2018). Also, a short-lived animated series simply titled "The Mummy" ran from 2001 to 2003.

Reboot.

In 2012, Universal announced a reboot of the film, more in-line with the horror films, from the Universal Monsters film franchise. The reboot was directed by Alex Kurtzman. "The Mummy" was planned as the first film in a series of interconnected monster films, as Universal has planned to build a shared universe film series out of its vault of classic monster movies. On January 21, 2016 it was announced that Tom Cruise would be starring in the film. Sofia Boutella was cast to portray Princess Ahmunet / The Mummy for the film, while Russell Crowe would appear as Dr. Henry Jekyll / Mr. Hyde, two roles which had previously been portrayed by Boris Karloff in the studios' previous film franchise. In June 2017, the studio announced the name, logo, theme music (written by Danny Elfman), and upcoming schedule for the shared universe titled Dark Universe. It received negative reviews and is considered a box office bomb scrapping the plans for the upcoming films of the dark universe

Criticism.

"The Mummy" has been decried for "othering" Eastern culture, especially portraying it as being more primitive and superstitious than Western culture. In one scene, Helen Grosvenor longs for the "real" (Classical) Egypt, disparaging that she is in contemporary Islamic Egypt. This is viewed by critic Caroline T. Schroeder as a slight against Islamic culture at the time.  According to Mark A. Hall, of the Perth Museum and Art Gallery, film portrayals of Egypt, especially in Egyptian archaeology, often deal with themes of appropriating and controlling the dangers of non-European cultures, or deal with the past if it relates to legend and superstition. Mummies, Hall says, are a common example of this. While he commended the archaeological wisdom espoused by Sir Joseph Whemple in the film, he writes that "much more is learned from studying bits of broken pottery than from all the sensational finds" and that archaeologists' job is to "increase the sum of human knowledge of the past", and mentions that the archaeological element was only used as a foil for the supernatural elements. As a result, per Hall, what it and similar films offered was a "depiction of archaeology as a colonial imposition by which cultural inheritance is appropriated".

Historical accuracy.

The Scroll of Thoth is a fictional artifact, though likely based on the "Book of the Dead". Thoth, the Egyptian god of knowledge, is said to be the inventor of hieroglyphs and the author of the "Book of the Dead". The film also makes reference to the Egyptian myth of the goddess Isis resurrecting Osiris after his murder by his brother Set.  Conspirators were caught in a plot to assassinate Pharaoh Ramesses III around 1151 B.C.E. Papyrus trial transcripts reveal that the conspirators were prescribed ‘great punishments of death’, and archaeological evidence led to the suggestion that at least one of them may have been buried alive. Although such punishment was not common practice, this discovery probably influenced the film’s screenplay.  There is no evidence to suggest that the ancient Egyptians believed in or considered the possibility of reanimated mummies. Mummification was a sacred process meant to prepare a dead body to carry the soul through the afterlife, not for being reincarnated and living again on Earth. While it is possible that some individuals were mummified by being buried alive, it is unlikely that ancient Egyptians would think resurrection was possible because they were very aware of the fact that all the necessary organs had been removed and the body would be of little use on Earth anymore. However, Egyptologist Stuart Tyson Smith notes that ‘the idea of mobile mummies was not entirely alien to ancient Egypt’, citing one of the Hellenistic-era stories of Setna Khaemwas, which features both the animated mummy of Naneferkaptah and a fictional "Book of Thoth" and may have inspired screenwriter John Balderston.

The Mummy is a 1932 American pre-Code horror film directed by Karl Freund. The screenplay by John L. Balderston was from a story by Nina Wilcox Putnam and Richard Schayer. Released by Universal Studios, the film stars Boris Karloff, Zita Johann, David Manners, Edward Van Sloan and Arthur Byron. The film is about an ancient Egyptian mummy named Imhotep who is discovered by a team of archaeologists and inadvertently brought back to life through a magic scroll. Disguised as a modern Egyptian, the mummy searches for his lost love, whom he believes has been reincarnated into a modern girl.

La Momie ("The Mummy") est un film d'horreur américain réalisé par Karl Freund, sorti en 1932. "La Momie" est un classique du cinéma hollywoodien d'horreur des années 1930. Réalisé par pour le compte des studios Universal, ce film - quoiqu'il n'ait pas été pionnier en la matière - a largement contribué à populariser la figure de la Momie, qui sera repris dans de nombreux films. Il connaîtra quatre suite sorties entre 1940 et 1944. Il fait partie de la série des "Universal Monsters".


Carrier Sense Multiple Access with Collision Detection

Procedure.

The following procedure is used to initiate a transmission. The procedure is complete when the frame is transmitted successfully or a collision is detected during transmission.  The following procedure is used to resolve a detected collision. The procedure is complete when retransmission is initiated or the retransmission is aborted due to numerous collisions.  Methods for collision detection are media dependent. On a shared, electrical bus such as 10BASE5 or 10BASE2, collisions can be detected by comparing transmitted data with received data or by recognizing a higher than normal signal amplitude on the bus. On all other media, a carrier sensed on the receive channel while transmitting triggers a collision event. Repeaters or hubs detect collisions on their own and propagate jam signals.  The collision recovery procedure can be likened to what happens at a dinner party, where all the guests talk to each other through a common medium (the air). Before speaking, each guest politely waits for the current speaker to finish. If two guests start speaking at the same time, both stop and wait for short, random periods of time (in Ethernet, this time is measured in microseconds). The hope is that by each choosing a random period of time, both guests will not choose the same time to try to speak again, thus avoiding another collision.

Jam signal.

The jam signal or jamming signal is a signal that carries a 32-bit binary pattern sent by a data station to inform the other stations of the collision and that they must not transmit. The maximum jam-time is calculated as follows: The maximum allowed diameter of an Ethernet installation is limited to 232 bits. This makes a round-trip-time of 464 bits. As the slot time in Ethernet is 512 bits, the difference between slot time and round-trip-time is 48 bits (6 bytes), which is the maximum "jam-time".  This in turn means: A station noting a collision has occurred is sending a 4 to 6 byte long pattern composed of 16 1-0 bit combinations. Note: The size of this jam signal is clearly above the minimum allowed frame-size of 64 bytes.  The purpose of this is to ensure that any other node which may currently be receiving a frame will receive the jam signal in place of the correct 32-bit MAC CRC, this causes the other receivers to discard the frame due to a CRC error.

Late collision.

A late collision is a type of collision that happens further into the packet than is allowed for by the protocol standard in question. In 10 megabit shared medium Ethernet, if a collision error occurs after the first 512 bits of data are transmitted by the transmitting station, a late collision is said to have occurred. Importantly, late collisions are not re-sent by the NIC unlike collisions occurring before the first 64 octets; it is left for the upper layers of the protocol stack to determine that there was loss of data.  As a correctly set up CSMA/CD network link should not have late collisions, the usual possible causes are full-duplex/half-duplex mismatch, exceeded Ethernet cable length limits, or defective hardware such as incorrect cabling, non-compliant number of hubs in the network, or a bad NIC.

Local collision.

A local collision is a collision that occurs at the NIC as opposed to on the wire. A NIC cannot detect a local collisions without attempting to send information.  On UTP cable, a local collision is detected on the local segment only when a station detects a signal on the RX pair at the same time it is sending on the TX pair. Since the two signals are on different pairs there is no characteristic change in the signal. Collisions are only recognized on UTP when the station is operating in half-duplex. The only functional difference between half and full-duplex operation in this regard is whether or not the transmit and receive pairs are permitted to be used simultaneously.

Channel capture effect.

The channel capture effect is a phenomenon where one user of a shared medium "captures" the medium for a significant time. During this period (usually 16 frames), other users are denied use of the medium. This effect was first seen in networks using CSMA/CD on Ethernet. Because of this effect, the most data-intense connection dominates the multiple-access wireless channel. This happens in Ethernet links because of the way nodes "back off" from the link and attempt to re-access it. In the Ethernet protocol, when a communication collision happens (when two users of the medium try to send at the same time), each user waits for a random period of time before re-accessing the link. However, a user will wait ("back off") for a random amount of time proportional to the number of times it has successively tried to access the link. The channel capture effect happens when one user continues to "win" the link.  For example, user A and user B both try to access a quiet link at the same time. Since they detect a collision, user A waits for a random time between 0 and 1 time units and so does user B. Let's say user A chooses a lower back-off time. User A then begins to use the link and B allows it to finish sending its frame. If user A still has more to send, then user A and user B will cause another data collision. A will once again choose a random back-off time between 0 and 1, but user B will choose a back-off time between 0 and 3 – because this is B's second time colliding in a row. Chances are A will "win" this one again. If this continues, A will most likely win all the collision battles, and after 16 collisions (the number of tries before a user backs down for an extended period of time), user A will have "captured" the channel.  The ability of one node to capture the entire medium is decreased as the number of nodes increases. This is because as the number of nodes increases, there is a higher probability that one of the "other" nodes will have a lower back-off time than the capturing node.  The channel capture effect creates a situation where one station is able to transmit while others are continually backing off, thus leading to a situation of short-term unfairness. Yet, the situation is long-term fair because every station has the opportunity to "capture" the medium once one station is done transmitting. The efficiency of the channel is increased when one node has captured the channel.  A negative side effect of the capture effect would be the idle time created due to stations backing off. Once one station is finished transmitting on the medium, large idle times are present because all other stations were continually backing off. In some instances, back-off can occur for so long that some stations actually discard packets because maximum attempt limits have been reached.

Applications.

CSMA/CD was used in now-obsolete shared media Ethernet variants (10BASE5, 10BASE2) and in the early versions of twisted-pair Ethernet which used repeater hubs. Modern Ethernet networks, built with switches and full-duplex connections, no longer need to use CSMA/CD because each Ethernet segment, or collision domain, is now isolated. CSMA/CD is still supported for backwards compatibility and for half-duplex connections. The IEEE 802.3 standard, which defines all Ethernet variants, for historical reasons still bore the title "Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications" until 802.3-2008, which uses new name "IEEE Standard for Ethernet".

Carrier-sense multiple access with collision detection (CSMA/CD) is a media access control (MAC) method used most notably in early Ethernet technology for local area networking. It uses carrier-sensing to defer transmissions until no other stations are transmitting. This is used in combination with collision detection in which a transmitting station detects collisions by sensing transmissions from other stations while it is transmitting a frame. When this collision condition is detected, the station stops transmitting that frame, transmits a jam signal, and then waits for a random time interval before trying to resend the frame.

Cette méthode permet à une station d'écouter le support physique de liaison (câble ou fibre) pour déterminer si une autre station transmet une trame de données (niveau déterminé de tension électrique ou de lumière). Si tel n'est pas le cas (donc s'il n'y a pas eu de signal), elle suppose qu'elle peut émettre.


Geology and geography.

Parnassus is one of the largest mountainous regions of Mainland Greece and one of the highest Greek mountains. It spreads over three municipalities, namely of Boeotia, Phthiotis and Phocis, where its largest part lies. Its altitude is 2,457 meters and its highest peak is Liakouras. To the Northeast it is connected to Giona and to the south with Kirphe. Its name is due to the homonymous hero of the Greek mythology, son of Cleopompus (or Poseidon) and Cleodora, who had built on the mountain a city which was destroyed in the Deluge of Deukalion. Etymological analysis, however, shows a prehellenic origin of the name, relating it to the Pelasgians, and it appears to be from the Anatolian language Luwian. The mountain is delimited to the east by the valley of the Boeotian Kephissus and to the West by the valley of Amfissa. The geological particularity of Parnassus is its rich deposits of bauxite, which has led to their systematic mining since the end of the 1930s, resulting in ecological damage to part of the mountain.

Mythology.

Mount Parnassus is named after Parnassos, the son of the nymph Kleodora and the man Kleopompus. A city, of which Parnassos was leader, was flooded by torrential rains. The citizens ran from the flood, following wolves' howling, up the mountain slope. There the survivors built another city, and called it Lykoreia, which in Greek means "the howling of the wolves." While Orpheus was living with his mother and his eight beautiful aunts on Parnassus, he met Apollo who was courting the laughing muse Thalia. Apollo became fond of Orpheus and gave him a little golden lyre, and taught him to play it. Orpheus's mother taught him to make verses for singing. As the Oracle of Delphi was sacred to the god Apollo, so did the mountain itself become associated with Apollo. According to some traditions, Parnassus was the site of the fountain Castalia and the home of the Muses; according to other traditions, that honor fell to Mount Helicon, another mountain in the same range. As the home of the Muses, Parnassus became known as the home of poetry, music, and learning.  Parnassus was also the site of several unrelated minor events in Greek mythology.  Parnassus was also the home of Pegasus, the winged horse of Bellerophon.

As metaphor.

This relation of the mountain to the Muses offered an instigation to its more recent "mystification", with the poetic-artistic trend of the 19th century called "Parnassism". The Parnassic movement was established in France in the decade 1866–1876 as a reaction to Romanticism with a return to some classicistic elements and belief in the doctrine "Art for the Art", first expressed by Theophile Gautier. The periodical "Modern Parnassus" issued for the first time by Catul Mendes and Xavier Ricard contained direct references to Mt. Parnassus and its mythological feature as habitation of the Muses. The Parnassists, who did not exceed a group of twenty poets, exercised a relatively strong influence on the cultural life of Paris, particularly due to their tenacity on perfection of rhyme and vocabulary. Parnassism influenced several French poets, but it also exercised an influence on Modern Greek poets, particularly Kostis Palamas and Gryparis. The name of the mountain (Mont Parnasse) was also given to a quarter of Paris on the left bank of the Seine, where artists and poets used to gather and recite their poems in public. Montparnasse is nowadays one of the most renowned quarters of the city and in its cemetery many personalities of the arts and culture are buried.  Parnassus figures earlier in Jonathan Swift's "The Battle of the Books" (1697) as the site of an ideological war between the ancients and the moderns.

Cultural Change.

In 1995, Roland S. Moore, a representative from the Prevention Research Center in the US, conducted a study in this region on how the advent of tourism enacted cultural change in the region. Primarily, the research centered around how the climate surrounding alcohol use had changed, as well as the structure of the household. Prior to the 1970s and the boom of Greek tourism, residents of Mount Parnassus largely consumed only beers, wines, and distilled spirits, and even then it was primarily men drinking. As time went on, more and more liquors became common alongside female consumption. Since hospitality careers are more conducive for women and children, the familial structure of the patriarchal breadwinner also fell out of popularity, replaced by a more democratic familial structure.

National Park.

The significant biodiversity, both in flora and in fauna, led the authorities to the establishment of the National Park of Parnassus in 1938, the year when the systematic mining of bauxite started. The Park comprises a landscape of spreading on the mountainous region between Delphi, Arachova and Agoriani. Among the endemic flora species under protection are the Cephalonian fir tree and the Parnassian peony ("Paeonia parnassica"). In the Park sojourn prey birds and wolves, boars, badgers and weasels.

Parnassos Ski Resort.

The slopes of Mount Parnassus are composed of two ski sections, Kellaria and Fterolakka, which together make up the largest ski center in Greece. A smaller ski center (only two drag lifts) called Gerontovrahos is across a ridge from Kellaria. Parnassus is mined for its abundant supply of bauxite which is converted to aluminium oxide and then to aluminium.  The construction of the ski resort started in 1975 and was completed in 1976, when the first two drag lifts operated in Fterolaka. In 1981 the construction of a new ski area was completed in Kelaria, while in winter season 1987–1988 the chair lift Hermes started operating and connected the two ski areas. Both ski resorts continued expanding and in 1993 the first high-speed quad in Greece was installed, named Hercules. In 2014–2015 two new hybrid lifts were installed along with a new eight-seater, replacing the old infrastructure.  Today the Ski Center operates with 16 lifts, two hybrid ski lifts which combine an eight-seater Cabin and a six-seater chair, an eight-seater Cabin, a 4-seater chair lift, a 2-seater chair lift, 6 drag lifts and four baby lifts. The ski center boasts 25 marked ski runs and about 15 ski routes of total length while the longest run is.

Mount Parnassus (;, "Parnassos") is a mountain of limestone in central Greece that towers above Delphi, north of the Gulf of Corinth, and offers scenic views of the surrounding olive groves and countryside. According to Greek mythology, this mountain was sacred to Dionysus and the Dionysian mysteries; it was also sacred to Apollo and the Corycian nymphs, and it was the home of the Muses. The mountain was also favored by the Dorians. It is suggested that the name derives from "parnassas", the possessive adjective of the Luwian word "parna" meaning "house", or specifically "temple", so the name effectively means the "mountain of the house of the god".

Le mont Parnasse (ou simplement Parnasse, du grec ancien / ) est une montagne du centre de la Grèce, qui surplombe la cité de Delphes, à proximité d'Aráchova. Particulièrement vénéré dans l'Antiquité, il était consacré à la fois au dieu Apollon et aux neuf Muses, dont il était l'une des deux résidences avec le mont Hélicon. Il fait partie des dix parcs nationaux de Grèce. Le Parnasse accueille le principal domaine skiable de Grèce.


History.

In the era of the electrical telegraph, its principal users were post offices, railway stations, the more important governmental centers (ministries), stock exchanges, very few nationally distributed newspapers, the largest internationally important corporations, and wealthy individuals. Despite the fact that telephone devices existed before the invention of the telephone exchange, their success and economical operation would have been impossible on the same schema and structure of the contemporary telegraph, as prior to the invention of the telephone exchange switchboard, early telephones were hardwired to and communicated with only a single other telephone (such as from an individual's home to the person's business).  A telephone exchange is a telephone system located at service centers (central offices) responsible for a small geographic area that provided the switching or interconnection of two or more individual subscriber lines for calls made between them, rather than requiring direct lines between subscriber stations. This made it possible for subscribers to call each other at homes, businesses, or public spaces. These made telephony an available and comfortable communication tool for everyday use, and it gave the impetus for the creation of a whole new industrial sector.  As with the invention of the telephone itself, the honor of "first telephone exchange" has several claimants. One of the first to propose a telephone exchange was Hungarian Tivadar Puskás in 1877 while he was working for Thomas Edison. The first experimental telephone exchange was based on the ideas of Puskás, and it was built by the Bell Telephone Company in Boston in 1877. The world's first state-administered telephone exchange opened on November 12, 1877 in Friedrichsberg close to Berlin under the direction of Heinrich von Stephan. George W. Coy designed and built the first commercial US telephone exchange which opened in New Haven, Connecticut in January, 1878. The switchboard was built from "carriage bolts, handles from teapot lids and bustle wire" and could handle two simultaneous conversations. Charles Glidden is also credited with establishing an exchange in Lowell, MA. with 50 subscribers in 1878.  In Europe other early telephone exchanges were based in London and Manchester, both of which opened under Bell patents in 1879. Belgium had its first International Bell exchange (in Antwerp) a year later.  In 1887 Puskás introduced the multiplex switchboard..  Later exchanges consisted of one to several hundred plug boards staffed by switchboard operators. Each operator sat in front of a vertical panel containing banks of 1⁄4-inch tip-ring-sleeve (3-conductor)

Technologies.

Many terms used in telecommunication technology differ in meaning and usage among the various English speaking regions. For the purpose of this article the following definitions are made:  "Central office" originally referred to switching equipment and its operators, it is also used generally for the building that houses switching and related inside plant equipment. In United States telecommunication jargon, a central office (C.O.) is a common carrier switching center Class 5 telephone switch in which trunks and local loops are terminated and switched. In the UK, a "telephone exchange" means an exchange building, and is also the name for a telephone switch.

Manual service exchanges.

With manual service, the customer lifts the receiver off-hook and asks the operator to connect the call to a requested number. Provided that the number is in the same central office, and located on the operator's switchboard, the operator connects the call by plugging the ringing cord into the jack corresponding to the called customer's line. If the called party's line is on a different switchboard in the same office, or in a different central office, the operator plugs into the trunk for the destination switchboard or office and asks the operator answering (known as the "B" operator) to connect the call.

Early automatic exchanges.

Automatic exchanges, or dial service, came into existence in the early 20th century. Their purpose was to eliminate the need for human switchboard operators who completed the connections required for a telephone call. Automation replaced human operators with electromechanical systems and telephones were equipped with a dial by which a caller transmitted the destination telephone number to the automatic switching system.  A telephone exchange automatically senses an off-hook condition of the telephone when the user removes the handset from the switchhook or cradle. The exchange provides dial tone at that time to indicate to the user that the exchange is ready to receive dialed digits. The pulses or DTMF

Electromechanical signaling.

Circuits interconnecting switches are called "trunks". Before Signalling System 7, Bell System electromechanical switches in the United States originally communicated with one another over trunks using a variety of DC voltages and signaling tones, replaced today by digital signals.  Some signaling communicated dialed digits. An early form called Panel Call Indicator Pulsing used quaternary pulses to set up calls between a panel switch and a manual switchboard. Probably the most common form of communicating dialed digits between electromechanical switches was sending dial pulses, equivalent to a rotary dial's pulsing, but sent over trunk circuits between switches.  In Bell System trunks, it was common to use 20 pulse-per-second

Sounds.

A characteristic of electromechanical switching equipment is that the maintenance staff could hear the mechanical clattering of Strowgers, panel switches or crossbar relays. Most Bell System central offices were housed in reinforced concrete buildings with concrete ceilings and floors.  In rural areas some smaller switching facilities, such as community dial offices (CDOs), were housed in prefabricated metal buildings. These facilities almost always had concrete floors. The hard surfaces reflected sounds.  During heavy use periods, it could be difficult to converse in a central office switch room due to the clatter of calls being processed in a large switch. For example, on Mother's

Maintenance tasks.

Electromechanical switching systems required sources of electricity in form of direct current (DC), as well as alternating ring current (AC), which were generated on-site with mechanical generators. In addition, telephone switches required adjustment of many mechanical parts. Unlike modern switches, a circuit connecting a dialed call through an electromechanical switch had DC continuity within the local exchange area via metallic conductors.  The design and maintenance procedures of all systems involved methods to avoid that subscribers experienced undue changes in the quality of the service or that they noticed failures. A variety of tools referred to as "make-busy"s were plugged into electromechanical switch elements upon failure and during repairs. A make-busy identified the part being worked on as in-use, causing

Electronic switches.

Electronic switching systems gradually evolved in stages from electromechanical hybrids with stored program control to the fully digital systems. Early systems used reed relay-switched metallic paths under digital control. Equipment testing, phone numbers reassignments, circuit lockouts and similar tasks were accomplished by data entry on a terminal.  Examples of these systems included the Western Electric 1ESS switch, Northern Telecom SP1, Ericsson AXE, Philips PRX/A, ITT Metaconta, British GPO/BT TXE series and several other designs were similar. Ericsson also developed a fully computerized version of

Digital switches.

Digital switches work by connecting two or more digital circuits, according to a dialed telephone number or other instruction. Calls are set up between switches. In modern networks, this is usually controlled using the Signalling System 7 (SS7) protocol, or one of its variants. Many networks around the world are now transitioning to voice over IP technologies which use Internet-based protocols such as the Session Initiation Protocol (SIP). These may have superseded TDM and SS7 based technologies in some networks.  The concepts of digital switching

The switch's place in the system.

Telephone switches are a small component of a large network. A major part, in terms of expense, maintenance, and logistics of the telephone system is outside plant, which is the wiring outside the central office. While many subscribers were served with party-lines in the middle of the 20th century, it was the goal that each subscriber telephone station were connected to an individual pair of wires from the switching system.  A typical central office may have tens of thousands of pairs of wires that appear on terminal blocks called the main distribution frame (MDF). A component of the MDF is protection: fuses or other devices that protect the switch from lightning, shorts with electric power lines, or other foreign voltages. In a typical telephone company, a large database tracks information about each subscriber pair and the status of each jumper. Before computerization of Bell System records in the 1980s, this information was handwritten in pencil in accounting ledger books.  To reduce the expense of outside plant, some companies use "pair gain" devices to provide telephone service to subscribers. These devices are used to

Switch design.

Long-distance switches may use a slower, more efficient switch-allocation algorithm than local central offices, because they have near 100% utilization of their input and output channels. Central offices have more than 90% of their channel capacity unused.  Traditional telephone switches connected physical circuits (e.g., wire pairs) while modern telephone switches use a combination of space- and time-division switching. In other words, each voice channel is represented by a time slot (say 1 or 2) on a physical wire pair (A or B). In order to connect two voice channels (say A1 and B2) together, the telephone switch interchanges the information between A1 and B2. It switches both the time slot and physical connection. To do this, it exchanges data

Switch control algorithms.

Fully connected mesh network.

One way is to have enough switching fabric to assure that the pairwise allocation will always

Clos's nonblocking switch algorithm.

The connections between layers of subswitches of telephone switching system are

Fault tolerance.

Composite switches are inherently fault-tolerant. If a subswitch fails, the controlling computer can sense it during a periodic test. The computer marks all the connections to the subswitch as "in use". This prevents new calls, and does not interrupt old calls that remain working. As calls in progress end, the subswitch becomes unused, and new calls avoid the subswitch because it's already "in use."

Fire and disaster recovery.

The central exchange, due to the system's design, is almost always a single point of failure for local calls. As the capacity of individual switches and the optical fibre which interconnects them increases, potential disruption caused by destruction of one local office will only be magnified. Multiple fibre connections can be used to provide redundancy to voice and data connections between switching centres, but careful network design is required to avoid situations where a main fibre and its backup both go through the same damaged central office as a potential common mode failure.

A telephone exchange or telephone switch is a telecommunications system used in the public switched telephone network or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital systems to establish telephone calls between subscribers.

Dans le réseau téléphonique commuté, un commutateur téléphonique met en relation deux correspondants suivant des règles fondées sur le numéro composé par l'appelant. Plusieurs commutateurs peuvent s'enchaîner entre l'appelant et le destinataire.


Names.

"Salvia officinalis" has numerous common names. Some of the best-known are sage, common sage, garden sage, golden sage, kitchen sage, true sage, culinary sage, Dalmatian sage, and broadleaf sage. Cultivated forms include purple sage and red sage. The specific epithet "officinalis" refers to plants with a well-established medicinal or culinary value.

Taxonomy.

"Salvia officinalis" was described by Carl Linnaeus in 1753. It has been grown for centuries in the Old World for its food and healing properties, and was often described in old herbals for the many miraculous properties attributed to it. The specific epithet, "officinalis", refers to the plant's medicinal use—the "officina" was the traditional storeroom of a monastery where herbs and medicines were stored. "S. officinalis" has been classified under many other scientific names over the years, including six different names since 1940 alone. It is the type species for the genus "Salvia".  The second most commonly used species of sage is "Salvia lavandulaefolia", which shares a similar composition with "Salvia officinalis", with the exception that lavandulaefolia contains very little of the potentially toxic GABA receptor-antagonizing monoterpenoid thujone.

Description.

Cultivars are quite variable in size, leaf and flower color, and foliage pattern, with many variegated leaf types. The Old World type grows to approximately tall and wide, with lavender flowers most common, though they can also be white, pink, or purple. The plant flowers in late spring or summer. The leaves are oblong, ranging in size up to long by wide. Leaves are grey-green, rugose on the upper side, and nearly white underneath due to the many short soft hairs. Modern cultivars include leaves with purple, rose, cream, and yellow in many variegated combinations.

History.

"Salvia officinalis" has been used since ancient times for warding off evil, snakebites, increasing women's fertility, and more. The Romans referred to sage as the "holy herb," and employed it in their religious rituals. Theophrastus wrote about two different sages, a wild undershrub he called "sphakos", and a similar cultivated plant he called "elelisphakos". Pliny the Elder said the latter plant was called "salvia" by the Romans, and used as a diuretic, a local anesthetic for the skin, a styptic, and for other uses. Charlemagne recommended the plant for cultivation in the early Middle Ages, and during the Carolingian Empire, it was cultivated in monastery gardens. Walafrid Strabo described it in his poem "Hortulus" as having a sweet scent and being useful for many human ailments—he went back to the Greek root for the name and called it "lelifagus".  The plant had a high reputation throughout the Middle Ages, with many sayings referring to its healing properties and value. It was sometimes called "S. salvatrix" (sage the savior). Dioscorides, Pliny, and Galen all recommended sage as a diuretic, hemostatic, emmenagogue, and tonic. Le Menagier de Paris, in addition to recommending cold sage soup and sage sauce for poultry, recommends infusion of sage for washing hands at table. John Gerard's "Herball" (1597) states that sage "is singularly good for the head and brain, it quickeneth the senses and memory, strengtheneth the sinews, restoreth health to those that have the palsy, and taketh away shakey trembling of the members." Gervase Markham's The English Huswife (1615) gives a recipe for a tooth-powder of sage and salt. It appears in recipes for Four Thieves Vinegar, a blend of herbs which was supposed to ward off the plague. In past centuries, it was also used for hair care, insect bites and wasp stings, nervous conditions, mental conditions, oral preparations for inflammation of the mouth, tongue and throat, and also to reduce fevers.

Uses.

Culinary use.

In Britain, sage has for generations been listed as one of the essential herbs, along with parsley, rosemary, and thyme (as in the folk song "Scarborough Fair"). It has a savory, slightly peppery flavor. Sage appears in the 14th and 15th centuries in a "Cold Sage Sauce", known in French, English and Lombard cuisine, probably traceable to its appearance in "Le Viandier de Taillevent". It appears in many European cuisines, notably Italian, Balkan and Middle Eastern cookery. In Italian cuisine, it is an essential condiment for saltimbocca and other dishes, favored with fish. In British and American cooking, it is traditionally served as sage and onion stuffing, an accompaniment to roast turkey or chicken at Christmas or Thanksgiving Day. Other dishes include pork casserole, Sage Derby cheese and Lincolnshire sausages. Despite the common use of traditional and available herbs in French cuisine, sage never found favor there.  In the Levant and Egypt it is commonly used as a flavor for hot black tea, or boiled and served as an herbal drink in its own right.

Essential oil.

Common sage is grown in parts of Europe for distillation of an essential oil, although other species such as "Salvia fruticosa" may also be harvested and distilled with it. The essential oil contains cineole, borneol, and thujone. Sage leaf contains tannic acid, oleic acid, ursolic acid, carnosol, carnosic acid, fumaric acid, chlorogenic acid, caffeic acid, niacin, nicotinamide, flavones, flavonoid glycosides, and estrogenic substances.

Medical research.

Some research has suggested certain extracts of "salvia officinalis" may have positive effects on human brain function, but due to significant methodological problems, no firm conclusions can be drawn. The thujone present in "Salvia" extracts may be neurotoxic.

Cultivars.

In favorable conditions in the garden, "S. officinalis" can grow to a substantial size (1 square metre or more), but a number of cultivars are more compact. As such they are valued as small ornamental flowering shrubs, rather than for their herbal properties. Some provide low ground cover, especially in sunny dry environments. Like many herbs they can be killed by a cold wet winter, especially if the soil is not well drained. But they are easily propagated from summer cuttings, and some cultivars are produced from seeds.  Named cultivars include: 'Icterina' and 'Purpurascens' have gained the Royal Horticultural Society's Award of Garden Merit.

Salvia officinalis (sage, also called garden sage, common sage, or culinary sage) is a perennial, evergreen subshrub, with woody stems, grayish leaves, and blue to purplish flowers. It is a member of the mint family Lamiaceae and native to the Mediterranean region, though it has naturalized in many places throughout the world. It has a long history of medicinal and culinary use, and in modern times as an ornamental garden plant. The common name "sage" is also used for a number of related and unrelated species.

La sauge officinale ("Salvia officinalis") est un sous-arbrisseau de la famille des Lamiacées, souvent cultivé dans les jardins comme plante condimentaire et officinale ou tout simplement pour la beauté de son feuillage et de ses fleurs. On l'appelle aussi "herbe sacrée" ou "thé d'Europe" (à ne pas confondre avec le thé effectivement cultivé en Europe; voir Cha Gorreana).


Description.

"Lonicera japonica" is a twining vine able to climb up to high or more in trees, with opposite, simple oval leaves long and broad. When its stems are young, they are slightly red in color and may be fuzzy. Older stems are brown with peeling bark, and are often hollow on the inside. The flowers are double-tongued, opening white and fading to yellow, and sweetly vanilla scented. The fruit, which is produced in fall, is a black spherical berry diameter containing a few seeds. While the nectar from the flowers can be safely consumed by humans, all other parts of the plant have the potential to be toxic.

Subspecies.

There are three species of "Lonicera japonica":

Cultivation, management, and uses.

This species is often sold by American nurseries as the cultivar 'Hall's Prolific' ("Lonicera japonica" var. "halliana"), and in the UK as the cultivar 'Halliana'. The cultivar is also known as Hall's Japanese honeysuckle. It is an effective groundcover and has pleasant, strong-smelling flowers. It can be cultivated by seed, cuttings, or layering. In addition, it will spread itself via shoots if given enough space to grow. The variety "L. japonica" var. "repens" has gained the Royal Horticultural Society's Award of Garden Merit.  Japanese honeysuckle flowers are edible to humans and appreciated for their sweet-tasting nectar. The flowers can also be a significant source of food for deer, rabbits, hummingbirds, and other wildlife.

Herbal medicine.

In traditional Chinese medicine, "Lonicera japonica" is called "rěn dōng téng" (); literally "winter enduring vine") or "jīn yín huā" (; literally "gold-silver flower"). Alternative Chinese names include "er hua" (二花) and "shuang hua" (雙花), meaning "double-[color] flowers". In Korean, it is called "geumeunhwa".  The dried leaves and flowers (Flos Lonicerae Japonicae) are employed in traditional Chinese medicine, being used to treat fever, cold-related headache, cough, thirst, certain inflammation including sore throat, skin infection, and tumor necrosis.

As an invasive species.

Japanese honeysuckle has become naturalized in Argentina, Australia, Brazil, Mexico, New Zealand, and much of the US, including Hawaii, as well as a number of Pacific and Caribbean islands. It is classified as a noxious weed in Texas, Illinois, and Virginia, and is banned in Indiana and New Hampshire. It is listed on the New Zealand National Pest Plant Accord as an unwanted organism.  "Lonicera japonica" was initially brought to the United States from Japan in the early 1900s as an ornamental plant. It is still deliberately planted in the United States for reasons such as erosion control or forage for deer, but has become invasive in many areas. It prefers to invade areas that have been disturbed, such as roadsides or floodplains. It will generally only invade forests when the canopy has been opened by logging or fallen trees, as it grows less vigorously in the shade. Once it has invaded an area, "Lonicera japonica" grows rapidly and outcompetes native plants for sunlight and nutrients. It proliferates using both sexual and vegetative reproduction, producing seeds that are spread by animals and expanding locally via rhizomes. Eventually, it will form a dense thicket which prevents other plant species from germinating in that area. Due to its suppression of germination in the understory, "Lonicera japonica" also prevents the regeneration of trees.  Management of invasive "Lonicera japonica" has been achieved through a variety of means. Small patches can be removed by hand, or using simple digging tools, but all plant parts including roots and rhizomes must be removed to prevent resprouting. Larger patches can be removed through repeated mowing, but application of herbicide is also recommended to prevent regrowth. There has been some study of using controlled burns to remove "Lonicera japonica", but the underground portion of the plant is usually able to survive and resprout, limiting the effectiveness of this method. Browsing by herbivores may limit its growth, but is unlikely to fully eliminate it. There is currently no known biological control for "Lonicera japonica".

Chemistry.

"Lonicera japonica" contains methyl caffeate, 3,4-di-O-caffeoylquinic acid, methyl 3,4-di-O-caffeoylquinate, protocatechuic acid, methyl chlorogenic acid, and luteolin. The two biflavonoids, 3′-O-methyl loniflavone and loniflavone, along with luteolin and chrysin, can be isolated from the leaves. Other phenolic compounds present in the plant are hyperoside, chlorogenic acid, and caffeic acid. The two secoiridoid glycosides, loniceracetalides A and B, can be isolated, together with 10 known iridoid glycosides, from the flower buds. The plant also contains the saponins loniceroside A and B and the antiinflammatory loniceroside C.

Lonicera japonica, known as Japanese honeysuckle and golden-and-silver honeysuckle, is a species of honeysuckle native to eastern Asia. It is often grown as an ornamental plant, but has become an invasive species in a number of countries. Japanese honeysuckle is used in traditional Chinese medicine.

Le chèvrefeuille du Japon ("Lonicera japonica") est une liane arbustive de la famille des Caprifoliacées originaire de Chine, de Corée et du Japon. La variété 'Chinensis' dont les boutons floraux et le revers de la corolle sont pourpres, est vendue en jardinerie sous le nom de chèvrefeuille de Chine.


History.

The various types of "ad hominem" arguments have been known in the West since at least the ancient Greeks. Aristotle, in his work "Sophistical Refutations", detailed the fallaciousness of putting the questioner but not the argument under scrutiny. Many examples of ancient non-fallacious "ad hominem" arguments are preserved in the works of the Pyrrhonist philosopher Sextus Empiricus. In these arguments, the concepts and assumptions of the opponents are used as part of a dialectical strategy against the opponents to demonstrate the unsoundness of their own arguments and assumptions. In this way, the arguments are to the person ("ad hominem"), but without attacking the properties of the individuals making the arguments. This kind of argument is also known as "argument from commitment". Italian polymath Galileo Galilei and British philosopher John Locke also examined the argument from commitment, a form of the "ad hominem" argument, meaning examining an argument on the basis of whether it stands true to the principles of the person carrying the argument. In the mid-19th century, the modern understanding of the term "ad hominem" started to take shape, with the broad definition given by English logician Richard Whately. According to Whately, "ad hominem" arguments were "addressed to the peculiar circumstances, character, avowed opinions, or past conduct of the individual". Over time, the term acquired a different meaning; by the beginning of the 20th century, it was linked to a logical fallacy, in which a debater, instead of disproving an argument, attacked their opponent. This approach was also popularized in philosophical textbooks of the mid-20th century, and it was challenged by Australian philosopher Charles Leonard Hamblin in the second half of the 20th century. In a detailed work, he suggested that the inclusion of a statement against a person in an argument does not necessarily make it a fallacious argument since that particular phrase is not a premise that leads to a conclusion. While Hablin's criticism was not widely accepted, Canadian philosopher Douglas N. Walton examined the fallaciousness of the "ad hominem" argument even further. Nowadays, except within specialized philosophical usages, the usage of the term "ad hominem" signifies a straight attack at the character and ethos of a person, in an attempt to refute their argument.

Terminology.

The Latin phase "argumentum ad hominem" stands for "argument against the person". "Ad" corresponds to "against" but it could also mean "to" or "towards".  The terms "ad mulierem" and "ad feminam" have been used specifically when the person receiving the criticism is female.

Types of ad hominem arguments.

Fallacious "ad hominem" reasoning is categorized among informal fallacies, more precisely as a genetic fallacy, a subcategory of fallacies of irrelevance.  "Ad hominem" fallacies can be separated in various different types, among others are "tu quoque", circumstantial, guilt by association, and abusive "ad hominem". All of them are similar to the general scheme of "ad hominem" argument, that is instead of dealing with the essence of someones argument or trying to refute it, the interlocutor is attacking the character of the proponent of the argument and concluding that it is a sufficient reason to drop the initial argument.

"Tu quoque".

"Ad hominem tu quoque" (literally: "You also") is a response to a personal attack (or "ad hominem" argument) that itself is a personal attack.  "Tu quoque" appears as:  Here is an example given by philosophy professor George Wrisley to illustrate the above: A businessman and politician is giving a lecture at a University about how good his company is and how nicely the system works. A student asks him "Is it true that you and your company are selling weapons to third world rulers who use those arms against their own people?" and the businessman replies "is it true that your university gets funding by the same company you are claiming it is selling guns to those countries? You are not a white dove either". The "ad hominem" accusation of the student is relevant to the narrative the businessman tries to project thus not fallacious. On the other hand, the attack on the student (that is, the student being inconsistent) is irrelevant to the opening narrative. So the businessman's "tu quoque" response is fallacious.  Canadian philosopher Christopher Tindale approaches somewhat different the "tu quoque" fallacy. According to Tindale, a "tu quoque" fallacy appears when a response to an argument is made on the history of the arguer. This argument is also invalid because it does not disprove the premise; if the premise is true, then source A may be a hypocrite or even changed their mind, but this does not make the statement less credible from a logical perspective. A common example, given by Tindale, is when a doctor advises a patient to lose weight, but the patient argues that there is no need for him to go on a diet because the doctor is also overweight.

Circumstantial.

"Circumstantial ad hominem" points out that someone is in circumstances (for instance, their job, wealth, property, or relations) such that they are disposed to take a particular position. It constitutes an attack on the bias of a source. As with other types of "ad hominem" attack, circumstantial attack could be fallacious or not. It could be fallacious because a disposition to make a certain argument does not make the argument invalid; this overlaps with the genetic fallacy (an argument that a claim is incorrect due to its source). But it also may be a sound argument, if the premises are correct and the bias is relevant to the argument.  A simple example is: a father may tell his daughter not to start smoking because she will damage her health, and she may point out that he is or was a smoker. This does not alter the fact that smoking might cause various diseases. Her father's inconsistency is not a proper reason to reject his claim.  Philosopher and pundit on informal fallacies Douglas N. Walton argues that a circumstantial "ad hominem" argument can be non-fallacious. This could be the case when someone (A) attacks the personality of another person (B), making an argument (a) while the personality of B is relevant to argument a, i.e. B talks as an authority figure. To illustrate this reasoning, Walton gives the example of a witness at a trial: if he had been caught lying and cheating in his own life, should the jury take his word for granted? No, according to Walton.

Guilt by association.

Guilt by association, that is accusing an arguer because of his alleged connection with a discredited person or group, can sometimes also be a type of "ad hominem" fallacy when the argument attacks a source because of the similarity between the views of someone making an argument and other proponents of the argument.  This form of the argument is as follows:  Academic Leigh Kolb gives as an example that the 2008 US vice‐presidential candidate Sarah Palin attacked Barack Obama for having worked with Bill Ayers, who had been a leader in the Weather Underground terrorist group in the 1960s. Despite Obama denouncing every act of terrorism, he was still associated by his opponents with terrorism.  Guilt by association is frequently found in social and political debates. It also appears after major events (such as scandals and terrorism) linked to a specific group. An example, given also by Leigh Kolb, is the peak of attacks against Muslims in the US after the September 11 attacks.

Abusive "ad hominem".

Abusive "ad hominem" argument (or direct "ad hominem") is associated with an attack to the character of the person carrying an argument. This kind of argument, besides usually being fallacious, is also counterproductive, as a proper dialogue is hard to achieve after such an attack.  Key issues in examining an argument to determine whether it is an "ad hominem" fallacy or not are whether the accusation against the person stands true or not, and whether the accusation is relevant to the argument. An example is a dialogue at the court, where the attorney cross-examines an eyewitness, bringing to light the fact that the witness was convicted in the past for lying. If the attorney's conclusion is that the witness is lying, that would be wrong. But if his argument would be that the witness should not be trusted, that would not be a fallacy.

Argument from commitment.

An "ad hominem" argument from commitment is a type of valid argument that employs, as a dialectical strategy, the exclusive utilization of the beliefs, convictions, and assumptions of those holding the position being argued against, i.e., arguments constructed on the basis of what other people hold to be true. This usage is generally only encountered in specialist philosophical usage or in pre-20th century usages. This type of argument is also known as the "ex concessis" argument (Latin for "from what has been conceded already").

Usage in debates.

"Ad hominem" fallacies are considered to be uncivil and do not help creating a constructive atmosphere for dialogue to flourish. An "ad hominem" attack is an attack on the character of the target who tends to feel the necessity to defend himself or herself from the accusation of being hypocritical. Walton has noted that it is so powerful of an argument that it is employed in many political debates. Since it is associated with negativity and dirty tricks, it has gained a bad fame, of being always fallacious.  Author Eithan Orkibi, having studied the Israeli politics prior to elections, described two other forms of "ad hominem" attacks that are common during election periods. They both depend on the collective memory shared by both proponents and the audience. The first is the "precedent ad hominem", according to which the previous history of someone means that they do not fit for the office. It goes like this: "My opponent was (allegedly) wrong in the past, therefore he is wrong now". The second one is a behavioral "ad hominem": "my opponent was not decent in his arguments in the past, so he is not now either". These kinds of attacks are based on the inability of the audience to have a clear view of the amount of false statements by both parts of the debate.

Criticism as a fallacy.

Walton has argued that "ad hominem" reasoning is not always fallacious, and that in some instances, questions of personal conduct, character, motives, etc., are legitimate and relevant to the issue, as when it directly involves hypocrisy, or actions contradicting the subject's words.  The philosopher Charles Taylor has argued that "ad hominem" reasoning (discussing facts about the speaker or author relative to the value of his statements) is essential to understanding certain moral issues due to the connection between individual persons and morality (or moral claims), and contrasts this sort of reasoning with the apodictic reasoning (involving facts beyond dispute or clearly established) of philosophical naturalism.

Ad hominem (), short for argumentum ad hominem, is a term that is applied to several different types of arguments, most of which are fallacious. Typically it refers to a fallacious argumentative strategy whereby genuine discussion of the topic at hand is avoided by instead attacking the character, motive, or other attribute of the person making the argument, or persons associated with the argument, rather than attacking the substance of the argument itself. The most common form of this fallacy is "A makes a claim "a", B asserts that A holds a property that is unwelcome, and hence B concludes that argument "a" is wrong".

La locution latine sert à désigner un argument de rhétorique qui consiste à confondre un adversaire en lui opposant ses propres paroles ou ses propres actes. Cette locution latine ne doit pas être confondue avec une attaque ou un "argumentum ad personam" qui est fréquemment considéré comme une manœuvre déloyale visant à discréditer son adversaire sans lui répondre sur le fond. Une réplique's'oppose donc, en attaquant la personne, à une argumentation'qui s'attacherait aux faits.


History.

In prehistoric times the area was used for agriculture by the Hän-speaking people of the Tr’ondëk Hwëch’in and their forebears. The heart of their homeland was Tr'ochëk, a fishing camp at the confluence of the Klondike River and Yukon River, now a National Historic Site of Canada, just across the Klondike River from modern Dawson City. This site was also an important summer gathering spot and a base for moose-hunting on the Klondike Valley.  The current settlement was founded by Joseph Ladue and named in January 1897 after noted Canadian geologist George M. Dawson, who had explored and mapped the region in 1887. It served as Yukon's capital from the territory's founding in 1898 until 1952, when the seat was moved to Whitehorse. Dawson City was the centre of the Klondike Gold Rush. It began in 1896 and changed the First Nations camp into a thriving city of 40,000 by 1898. By 1899, the gold rush had ended and the town's population plummeted as all but 8,000 people left. When Dawson was incorporated as a city in 1902, the population was under 5,000. St. Paul's Anglican Church, also built that same year, is a National Historic Site.  The population dropped after World War II when the Alaska Highway bypassed it to the south. The economic damage to Dawson City was such that Whitehorse, the highway's hub, replaced it as territorial capital in 1953. Dawson City's population languished around the 600–900 mark through the 1960s and 1970s, but has risen and held stable since then. The high price of gold has made modern placer mining operations profitable, and the growth of the tourism industry has encouraged development of facilities. In the early 1950s, Dawson was linked by road to Alaska, and in fall 1955, with Whitehorse along a road that now forms part of the Klondike Highway.  In 1978, another kind of buried treasure was discovered when a construction excavation inadvertently uncovered a forgotten collection of more than 500 discarded films on highly flammable nitrate film stock from the early 20th century that were buried in (and preserved by) the permafrost. These silent-era film reels, dating from "between 1903 and 1929, were uncovered in the rubble beneath [an] old hockey rink". (See Dawson Film Find.) Owing to its dangerous chemical volatility, the historical find was moved by military transport to Library and Archives Canada and the U.S. Library of Congress for both transfer to safety film and storage. A documentary about the find, "" was released in 2016.  The City of Dawson and the nearby ghost town of Forty Mile are featured prominently in the novels and short stories of American author Jack London, including "The Call of the Wild". London lived in the Dawson area from October 1897 to June 1898. Other writers who lived in and wrote of Dawson City include Pierre Berton and the poet Robert Service. The childhood home of the former is now used as a retreat for professional writers administered by the Writers' Trust of Canada.

Geography.

Dawson City lies on the Tintina Fault. This fault has created the Tintina Trench and continues eastward for several hundred kilometres. Erosional remnants of lava flows form outcrops immediately north and west of Dawson City.

Climate.

Dawson City has a dry-summer subarctic climate (Köppen climate classification: Dsc), similar to the territory capital of Whitehorse. The average temperature in July is and in January is. The highest temperature ever recorded is on 9 July 1899 and 18 June 1950. The lowest temperature ever recorded is on 3 February 1947. It experiences a wide range of temperatures surpassing in most summers and dropping below in winter. Because of its northerly location, June is a warmer month than August.  The community is at an elevation of and the average rainfall in July is and the average snowfall in January is. Dawson has an average total annual snowfall of and averages 70 frost free days per year. The town is built on a layer of frozen earth, which may pose a threat to the town's infrastructure in the future if the permafrost melts.

City or town.

Dawson was incorporated as a city in 1902 when it met the criteria for "city" status under the municipal act of that time. It retained the incorporation even as the population plummeted. When a new municipal act was adopted in the 1980s, Dawson met the criteria of "town", and was incorporated as such although with a special provision to allow it to continue to use the word "City", partially for historical reasons and partially to distinguish it from Dawson Creek, a small city in northeastern British Columbia. Dawson Creek is also named in honour of George M. Dawson. This led the territorial government to post the following signs at the boundaries of the town: "Welcome to the Town of the City of Dawson".

Law and government.

In 2004, the Yukon government removed the mayor and the town council, as a result of the town going bankrupt. The territorial government accepted a large portion of the responsibility for this situation in March 2006, writing off $3.43 million of the debt and leaving the town with $1.5 million still to pay off. Elections were set for June 15, 2006. John Steins, a local artist and one of the leaders of the movement to restore democracy to Dawson, was acclaimed as mayor, while 13 residents ran for the four council seats. Steins was succeeded in office by former mayor Peter Jenkins, who in turn was succeeded by the current mayor, Wayne Potoroka.  Other past mayors of Dawson City have included Art Webster, Colin Mayes, Yolanda Burkhard, Mike Comadain and Vi Campbell.  In the Legislative Assembly of Yukon, Dawson City is in the electoral district of Klondike, currently represented by Sandy Silver of the Yukon Liberal Party.  The government of Tr’ondëk Hwëch’in, now a self-governing First Nation, is also located in Dawson.

Industry.

Today, Dawson City's main industries are tourism and gold mining.

Energy.

Electricity is provided by Yukon Energy Corporation (YEC). Most of the grid power is hydroelectric power through the north-south grid from dams near Mayo, Whitehorse and Aishihik Lake. After the local hydroelectric power plant for the gold dredges was shut down in 1966, YEC provided electrical power from local diesel generators. In 2004 YEC connected Dawson to its grid system. Since then the diesel generators function as a backup to the grid.

Gold mining.

Gold mining started in 1896 with the Bonanza (Rabbit) Creek discovery by George Carmack, Dawson Charlie and Skookum Jim Mason (Keish). The area's creeks were quickly staked and most of the thousands who arrived in the spring of 1898 for the Klondike Gold Rush found that there was very little opportunity to benefit directly from gold mining. Many instead became entrepreneurs to provide services to miners. Starting approximately 10 years later, large gold dredges began an industrial mining operation, scooping huge amounts of gold out of the creeks, and completely reworking the landscape, altering the locations of rivers and creeks and leaving tailing piles in their wake. A network of canals and dams were built to the north to produce hydroelectric power for the dredges. The dredges shut down for the winter, but one built for "Klondike Joe Boyle" was designed to operate year-round, and Boyle had it operate all through one winter. That dredge (Dredge No. 4) is open as a National Historic Site of Canada on Bonanza Creek.  The last dredge shut down in 1966, and the hydroelectric facility, at North Fork, was closed when the City of Dawson declined an offer to purchase it. Since then, placer miners returned to the status of being the primary mining operators in the region until recently. In 2016, Goldcorp announced a takeover of Kaminak Gold's Coffee Project south of Dawson. This marked a shift in the region, drawing the interest of the major gold mining companies in the Yukon. In 2017, Newmont Mining Corporation, Barrick Gold and Agnico Eagle Mines Limited have all committed significant investment, engaging in the exploration of properties across the Central Yukon.

Tourism.

There are eight National Historic Sites of Canada located in Dawson, including the "Dawson Historical Complex", a National Historic Site encompassing the historic core of the town.  The Downtown Hotel at Second Avenue and Queen Street has garnered media attention for its unusual "Sourtoe Cocktail", which features a real mummified human toe. The hotel and the toe received increased attention in June 2017 after the toe was stolen; it was soon returned to the hotel by mail along with a written apology.  Bonanza Creek has two National Historic Sites; the Discovery Claim and the Dredge No. 4.  Tr'ochëk is the site of a traditional Han fishing camp on the flats at the confluence of the Klondike River and Yukon River. The site is owned and managed by the Tr’ondëk Hwëch’in First Nation. In addition to the fishing camp remains, the site includes traditional plant harvesting areas and lookout points.  Diamond Tooth Gertie's Gambling Hall puts on nightly vaudeville shows during tourist season, from May to September.

Education.

Yukon School of Visual Arts, a university level accredited art program, is based in Dawson City.  Robert Service School, Dawson City's only grade school is named in honour of British-Canadian poet and writer Robert William Service (January 16, 1874 – September 11, 1958). The Robert Service School offers Kindergarten - Grade 12, and is one of only 28 schools in the Yukon Territory.

Sports.

Every February, Dawson City acts as the halfway mark for the Yukon Quest International Sled Dog Race. Mushers entered in the event have a mandatory 36-hour layover in Dawson City while getting their rest and preparing for the second half of the world's toughest sled dog race.  Dawson City also hosts a softball tournament which brings teams from Inuvik in late summer. Furthermore, a volleyball tournament is held annually at the end of October and is attended by various high schools across Yukon.  The city was home to the Dawson City Nuggets hockey team, which in 1905 challenged the Ottawa Silver Seven for the Stanley Cup. Travelling to Ottawa by dog sled, ship, and train, the team lost the most lopsided series in Stanley Cup history, losing two games by the combined score of 32 to 4.

Transport and communications.

Media.

Television Radio  Print

Dawson City, officially the Town of the City of Dawson, is a town in the Canadian territory of Yukon. It is inseparably linked to the Klondike Gold Rush (1896–99). Its population was 1,375 as of the 2016 census, making it the second largest town of Yukon.

La Cité de Dawson, couramment appelée Dawson par les francophones, (Dawson City"' en anglais) est un village ("town") situé dans le territoire canadien du Yukon. Au recensement de 2011, Statistique Canada y a dénombré une population de.


Mandate.

The Commission had a broader mandate, more power and greater resources than the Auditor General, and most importantly could look beyond government to the advertising agencies that had received the Sponsorship dollars. The terms of reference allowed the commissioner to question witnesses, hire experts and adopt any procedures or methods that he considers expedient for the proper conduct of the inquiry. The purpose given was to "investigate and report on questions raised, directly or indirectly" by the Auditor General's report. However, as is typically the case in commissions of inquiry, he was specifically directed not to make any conclusions or recommendations on criminal charges or civil liability.  Commissioner Gomery was given a two part mandate with power issued to him under the Inquiries Act. The first part of the mandate was investigate and report on questions and concerns addressed in the 2003 Report of the Auditor General of Canada relating to the sponsorship program and advertising activities of the Government of Canada. These concerns included the program’s creation, the selection of agencies, the program’s management and activities, the receiving and use of funds and disbursement of commissions, and anything else that Gomery feels relevant.  The second part of the mandate was for Gomery to make any recommendations that he considers advisable, based on his findings. Specifically requested of Gomery were the following: to prevent mismanagement of sponsorship or advertising programs in the future, taking into account legislation to protect "whistleblowers"; to recommend changes to legislation to change the governance of Crown corporations to ensure that audit committees are strengthened, that public access to information is increased, that there is a consistent application of the provisions for each organization, that compliance and enforcement be enhanced, and finally that respective responsibilities and accountabilities of Ministers and public servants as recommended by the Auditor General of Canada.

Proceedings and testimonies.

The Commission began in Ottawa, meeting in the Old City Hall. The hearing opened in September 2004. The first to testify was Auditor General Sheila Fraser who reported the findings of her earlier investigations. The first part of its investigation was of the political direction of the project. Most of the top officials involved were called to testify. In an unprecedented event, the inquiry saw the testimony of two Prime Ministers in February 2005: Paul Martin and Jean Chrétien. The testimony of Chrétien was much anticipated. In December 2004, Chrétien's lawyers had moved to expel Justice Gomery due to comments he had made to a "National Post" reporter that the lawyers argued showed that Gomery was biased against Chrétien. These included Gomery commenting that golf balls marked with Chrétien's name, which had been paid for by the sponsorship program, were "small town cheap." Gomery rejected the calls to recuse himself setting up a confrontation between him and Chrétien. At the end of his day of testimony Chrétien closed his statement by pulling out a series of golf balls bearing the name of American presidents and the law firm Ogilvie Renault (which at the time employed former Prime Minister Brian Mulroney, Gomery commission counsel Bernard Roy and Gomery's own daughter) asking whether each of them was "small town cheap". The stunt was the focus of all the media reports.  After the prime ministers testified, the hearings moved to Montreal to investigate where the money had gone. The hearings in Ottawa had uncovered little more than what was in the Auditor General's report. The AG did not have the authority to investigate outside of the government, and the look into the advertising companies in Montreal uncovered a great deal of new and explosive allegations. The most important of these were by Groupaction executive Jean Brault who recounted a series of crimes committed to direct government money to Liberal party supporters. These caused a sharp fall in the support for the governing Liberals, and put their government in jeopardy.

Phase I Report.

On November 1, 2005, Gomery released the Phase I Report. Gomery criticized Chrétien and his chief of staff Jean Pelletier but cleared them of direct involvement in kickback schemes. While people such as Alfonso Gagliano, Chuck Guité and Jacques Corriveau took advantage of the programme, Gomery argued that abuses would not have occurred had Chrétien set the programme with safeguards in place. Gomery said that Pelletier "failed to take the most elementary precautions against mismanagement – and Mr. Chrétien was responsible for him."  Gomery also exonerated Prime Minister Paul Martin, the minister of finance during most of the sponsorship programme. Gomery specifically said that Martin "is entitled, like other ministers from the Quebec caucus, to be exonerated from any blame for carelessness or misconduct", as the Department of Finance's role was not oversight, but setting the "fiscal framework".

Phase II Report.

On February 1, 2006, Gomery released his final report consisting mostly of recommendations for changes to the civil service and its relation to government.  The recommendations suggested include:  Shortly after Justice Gomery held a press conference, Prime Minister-designate Stephen Harper, elected on January 23, 2006, told the press that some of the Commission's recommendations matched his proposed first bill, the Federal Accountability Act. Other recommendations went further than what Harper promised, while some other recommendations (dealing with the public service) would not be enacted in the short term.

Criticisms.

Many commentators criticized the report for various reasons: alleged bias on the part of the commission, the terms of reference with which it was set up, and the use of evidence in the report. Several, including former Prime Minister Jean Chrétien, Warren Kinsella, and former cabinet minister Sheila Copps, criticized the commission as being little more than an extension of Liberal party infighting.  Gomery was accused by some as being friendly to Paul Martin, and hostile toward Chrétien, and Chrétien's lawyers attempted unsuccessfully to have Gomery removed due to his alleged bias. The two men had long represented a power struggle within the party. Subsequent to the release of the first report, Chrétien took action in Federal Court to review the commission report on the grounds that Gomery showed a "reasonable apprehension of bias", and that some conclusions didn't have an "evidentiary" basis.  Jean Chrétien's lawyers stated that Gomery has made many comments which indicate he had a bias going into the investigation such as comments Gomery made calling Chrétien "small town cheap", referring to the management of the sponsorship program as "catastrophically bad," and calling Chuck Guité a "charming scamp".  Other allegations of bias concern the commission's chief counsel, Bernard Roy, a former chief of staff to former Progressive Conservative Prime Minister Brian Mulroney. Roy is also a partner in Mulroney's law firm where Gomery's daughter works. Chrétien's lawyers stated that the appointment is a conflict of interest. Roy is a longtime personal friend of the former prime-minister's. Brian Mulroney and Jean Chrétien have had an adversarial personal relationship in recent years since the Airbus affair. The choice of counsel may account for the failure to call some Chrétien friendly witnesses.  During spring 2005, Chrétien legal team made a request to have Gomery removed but it was denied.  Conservative leader Stephen Harper was sympathetic to Chrétien's complaints of bias, stating that the main problem was that the commission's terms of reference did not allow it to investigate Paul Martin's contracting habits as finance minister. Other criticisms concern the lack of powers the commission had to investigate criminal matters, which were being investigated by the RCMP.  Chrétien's lawyers have indicated they are concerned about conclusions which are not based on evidence, but mere extrapolation. Jean Chrétien, on the day the report was tabled in the House of Commons, objected to the findings of the Commission, commenting that Gomery believed the wrong witnesses. "Personally, I believe Jean Pelletier, a man who dedicated his life to the service of his city, his province and his country," said the former Prime Minister, dismissing's Chuck Guité's testimony. Chrétien believes that Gomery's conclusion that the programme was run out of the prime minister's office is wrong.

Appeal to Federal Court.

Subsequent to the release of the first report, Chrétien's lawyers took action in Federal Court to invalidate the report and clear his name. They want the court to review the commission report on the grounds that Gomery showed a "reasonable apprehension of bias", and that some conclusions didn't have an "evidentiary" basis.  On June 26, 2008, the Federal Court quashed the Gomery inquiry's conclusions that Chrétien and Pelletier bore responsibility for the sponsorship scandal. Justice Max Teitelbaum criticized Gomery for having a preoccupation with the media spotlight that led him to give interviews he should have eschewed, making comments that indicated he judged issues before all evidence was heard, exhibited bias against Mr. Chrétien, and trivialized the inquiry proceedings. For instance, Teitelbaum pointed out that Gomery's remark halfway through the hearings that "juicy stuff" was yet to come made it appear that evidence of wrongdoing was expected before it was heard. The federal judge also ruled that Gomery's comments on "small town cheap" amounted to a personal insult against Chrétien. The federal government was ordered to pay Chrétien's legal costs. Chrétien and his aides have described it as vindication. Justice Teitelbaum's decision was appealed to the Federal Court of Appeal where it was upheld.

The Gomery Commission, formally the Commission of Inquiry into the Sponsorship Program and Advertising Activities, was a federal Canadian Royal Commission headed by Justice John Gomery for the purpose of investigating the sponsorship scandal, which involved allegations of corruption within the Canadian government.

La Commission d'enquête sur le programme de commandites et les activités publicitaires, appelée couramment Commission Gomery du nom de son président, le juge québécois John Gomery, est une commission d'enquête canadienne créée en 2004 chargée de faire la lumière sur le scandale des commandites.


Signs and symptoms.

Since oxygen is carried to tissues in the blood, insufficient blood supply causes tissue to become starved of oxygen. In the highly metabolically active tissues of the heart and brain, irreversible damage to tissues can occur in as little as 3–4 minutes at body temperature. The kidneys are also quickly damaged by loss of blood flow (renal ischemia). Tissues with slower metabolic rates may undergo irreversible damage after 20 minutes.  Clinical manifestations of acute limb ischemia (which can be summarized as the "six P's") include pain, pallor, pulseless, paresthesia, paralysis, and poikilothermia.  Without immediate intervention, ischemia may progress quickly to tissue necrosis and gangrene within a few hours. Paralysis is a very late sign of acute arterial ischemia and signals the death of nerves supplying the extremity. Foot drop may occur as a result of nerve damage. Because nerves are extremely sensitive to hypoxia, limb paralysis or ischemic neuropathy may persist after revascularization and may be permanent.

Cardiac ischemia.

Cardiac ischemia may be asymptomatic or may cause chest pain, known as angina pectoris. It occurs when the heart muscle, or myocardium, receives insufficient blood flow. This most frequently results from atherosclerosis, which is the long-term accumulation of cholesterol-rich plaques in the coronary arteries. Ischemic heart disease is the most common cause of death in most Western countries and a major cause of hospital admissions.

Bowel.

Both large and small bowel can be affected by ischemia. Ischemia of the large intestine may result in an inflammatory process known as ischemic colitis. Ischemia of the small bowel is called mesenteric ischemia.

Brain.

Brain ischemia is insufficient blood flow to the brain, and can be acute or chronic. Acute ischemic stroke is a neurologic emergency that may be reversible if treated rapidly. Chronic ischemia of the brain may result in a form of dementia called vascular dementia. A brief episode of ischemia affecting the brain is called a transient ischemic attack (TIA), often called a mini-stroke. 10% of TIAs will develop into a stroke within 90 days, half of which will occur in the first two days following the TIA.

Limb.

Lack of blood flow to a limb results in acute limb ischemia.

Cutaneous.

Reduced blood flow to the skin layers may result in mottling or uneven, patchy discoloration of the skin

Causes.

Ischemia is a vascular disease involving an interruption in the arterial blood supply to a tissue, organ, or extremity that, if untreated, can lead to tissue death. It can be caused by embolism, thrombosis of an atherosclerotic artery, or trauma. Venous problems like venous outflow obstruction and low-flow states can cause acute arterial ischemia. An aneurysm is one of the most frequent causes of acute arterial ischemia. Other causes are heart conditions including myocardial infarction, mitral valve disease, chronic atrial fibrillation, cardiomyopathies, and prosthesis, in all of which thrombi are prone to develop.

Occlusion.

The thrombi may dislodge and may travel anywhere in the circulatory system, where they may lead to pulmonary embolus, an acute arterial occlusion causing the oxygen and blood supply distal to the embolus to decrease suddenly. The degree and extent of symptoms depend on the size and location of the obstruction, the occurrence of clot fragmentation with embolism to smaller vessels, and the degree of peripheral arterial disease (PAD).

Trauma.

Traumatic injury to an extremity may produce partial or total occlusion of a vessel from compression, shearing, or laceration. Acute arterial occlusion may develop as a result of arterial dissection in the carotid artery or aorta or as a result of iatrogenic arterial injury (e.g., after angiography).

Other.

An inadequate flow of blood to a part of the body may be caused by any of the following:

Pathophysiology.

Ischemia results in tissue damage in a process known as ischemic cascade. The damage is the result of the build-up of metabolic waste products, inability to maintain cell membranes, mitochondrial damage, and eventual leakage of autolyzing proteolytic enzymes into the cell and surrounding tissues.  Restoration of blood supply to ischemic tissues can cause additional damage known as reperfusion injury that can be more damaging than the initial ischemia. Reintroduction of blood flow brings oxygen back to the tissues, causing a greater production of free radicals and reactive oxygen species that damage cells. It also brings more calcium ions to the tissues causing further calcium overloading and can result in potentially fatal cardiac arrhythmias and also accelerates cellular self-destruction. The restored blood flow also exaggerates the inflammation response of damaged tissues, causing white blood cells to destroy damaged cells that may otherwise still be viable.

Treatment.

Early treatment is essential to keep the affected limb viable. The treatment options include injection of an anticoagulant, thrombolysis, embolectomy, surgical revascularisation, or partial amputation. Anticoagulant therapy is initiated to prevent further enlargement of the thrombus. Continuous IV unfractionated heparin has been the traditional agent of choice.  If the condition of the ischemic limb is stabilized with anticoagulation, recently formed emboli may be treated with catheter-directed thrombolysis using intra-arterial infusion of a thrombolytic agent (e.g., recombinant tissue plasminogen activator (tPA), streptokinase, or urokinase). A percutaneous catheter inserted into the femoral artery and threaded to the site of the clot is used to infuse the drug. Unlike anticoagulants, thrombolytic agents work directly to resolve the clot over a period of 24 to 48 hours.  Direct arteriotomy may be necessary to remove the clot. Surgical revascularization may be used in the setting of trauma (e.g., laceration of the artery). Amputation is reserved for cases where limb salvage is not possible. If the patient continues to have a risk of further embolization from some persistent source, such as chronic atrial fibrillation, treatment includes long-term oral anticoagulation to prevent further acute arterial ischemic episodes.  Decrease in body temperature reduces the aerobic metabolic rate of the affected cells, reducing the immediate effects of hypoxia. Reduction of body temperature also reduces the inflammation response and reperfusion injury. For frostbite injuries, limiting thawing and warming of tissues until warmer temperatures can be sustained may reduce reperfusion injury.  Ischemic stroke is at times treated with various levels of statin therapy at hospital discharge, followed by home time, in an attempt to lower the risk of adverse events.

Society and culture.

The Infarct Combat Project (ICP) is an international nonprofit organization founded in 1998 to fight ischemic heart diseases through education and research.

Etymology and pronunciation.

The word "ischemia" () is from Greek ἴσχαιμος "iskhaimos", "staunching blood" from ἴσχω "iskhο", "keep back, restrain" and αἷμα "haima", "blood".

Ischemia or ischaemia is a restriction in blood supply to tissues, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems with blood vessels, with resultant damage to or dysfunction of tissue. It also means local anemia in a given part of a body sometimes resulting from constriction (such as vasoconstriction, thrombosis or embolism). Ischemia comprises not only insufficiency of oxygen, but also reduced availability of nutrients and inadequate removal of metabolic wastes. Ischemia can be partial (poor perfusion) or total.

Une ischémie (prononcer ; du grec ancien ἴσχω, "ískhô" (« tenir ») et αἷμα, "haîma" (« sang »)) est la diminution de l'apport sanguin artériel à un organe. Cette diminution entraîne essentiellement une baisse de l'oxygénation des tissus de l'organe en dessous de ses besoins ("hypoxie") et la perturbation, voire l'arrêt, de sa fonction. L’ischémie est l’interruption à la fois de l’apport d’oxygène et de l’élimination des molécules toxiques résultant du métabolisme anaérobique.