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SUMMARY / RELATED TOPICS

Adaptive immune system

The adaptive immune system known as the acquired immune system or, more as the specific immune system, is a subsystem of the overall immune system, composed of specialized, systemic cells and processes that eliminate pathogens or prevent their growth. The acquired immune system is one of the two main immunity strategies found in vertebrates. Acquired immunity creates immunological memory after an initial response to a specific pathogen, leads to an enhanced response to subsequent encounters with that pathogen; this process of acquired immunity is the basis of vaccination. Like the innate system, the acquired system includes both humoral immunity components and cell-mediated immunity components. Unlike the innate immune system, the acquired immune system is specific to a particular pathogen. Acquired immunity can provide long-lasting protection. In other cases it does not provide lifetime protection; the acquired system response destroys invading pathogens and any toxic molecules they produce. Sometimes the acquired system is unable to distinguish harmful from harmless foreign molecules.

Antigens are any substances. The cells that carry out the acquired immune response are white blood cells known as lymphocytes. Two main broad classes—antibody responses and cell mediated immune response—are carried by two different lymphocytes. In antibody responses, B cells are activated to secrete antibodies, which are proteins known as immunoglobulins. Antibodies travel through the bloodstream and bind to the foreign antigen causing it to inactivate, which does not allow the antigen to bind to the host. In acquired immunity, pathogen-specific receptors are "acquired" during the lifetime of the organism; the acquired response is called "adaptive" because it prepares the body's immune system for future challenges. The system is adaptable because of somatic hypermutation, VJ recombination; this mechanism allows a small number of genes to generate a vast number of different antigen receptors, which are uniquely expressed on each individual lymphocyte. Since the gene rearrangement leads to an irreversible change in the DNA of each cell, all progeny of that cell inherit genes that encode the same receptor specificity, including the memory B cells and memory T cells that are the keys to long-lived specific immunity.

A theoretical framework explaining the workings of the acquired immune system is provided by immune network theory. This theory, which builds on established concepts of clonal selection, is being applied in the search for an HIV vaccine; the term "adaptive" was first used by Robert Good in reference to antibody responses in frogs as a synonym for "acquired immune response" in 1964. Good acknowledged he used the terms as synonyms but explained only that he "preferred" to use the term "adaptive", he might have been thinking of the not implausible theory of antibody formation in which antibodies were plastic and could adapt themselves to the molecular shape of antigens, and/or to the concept of "adaptive enzymes" as described by Monod in bacteria, that is, enzymes whose expression could be induced by their substrates. The phrase was used exclusively by Good and his students and a few other immunologists working with marginal organisms until the 1990s when it became used in tandem with the term "innate immunity" which became a popular subject after the discovery of the Toll receptor system in Drosophila, a marginal organism for the study of immunology.

The term "adaptive" as used in immunology is problematic as acquired immune responses can be both adaptive and maladaptive in the physiological sense. Indeed, both acquired and innate immune responses can be both adaptive and maladaptive in the evolutionary sense. Most textbooks today, following the early use by Janeway, use "adaptive" exclusively and noting in glossaries that the term is synonymous with "acquired"; the classic sense of "acquired immunity" came to mean, since Tonegawas's discovery, "antigen-specific immunity mediated by somatic gene rearrangements that create clone-defining antigen receptors". In the last decade, the term "adaptive" has been applied to another class of immune response not so-far associated with somatic gene rearrangements; these include expansion of natural killer cells with so-far unexplained specificity for antigens, expansion of NK cells expressing germ-line encoded receptors, activation of other innate immune cells to an activated state that confers a short-term "immune memory".

In this sense, "adaptive immunity" more resembles the concept of "activated state" or "heterostasis", thus returning in sense to the physiological sense of "adaptation" to environmental changes. Acquired immunity is triggered in vertebrates when a pathogen evades the innate immune system and generates a threshold level of antigen and generates "stranger" or "danger" signals activating dendritic cells; the major functions of the acquired immune system include: Recognition of specific "non-self" antigens in the presence of "self", during the process of antigen presentation. Generation of responses that are tailored to maximally eliminate specific pathoge

Sumayhan Al-Nabit

Sumayhan Al-Nabit is a Saudi Arabian professional footballer who plays as a winger for Pro League side Al-Taawoun. Al-Nabit began his career at his local club Al-Lewaa in Baqaa. On 14 August 2011, he joined the youth team of Al-Ahli, he represented the team at every level besides the first team. On 18 July 2017, he signed a 2-year contract with Medina based club Ohod. On 7 January 2019, Al-Nabit signed a 6-month contract with Abha. Following Abha's promotion to the Pro League, Al-Nabit renewed his contract for a further year. On 2 January 2020, Al-Nabit signed a pre-contract agreement with Al-Taawoun and was set to join them following the expiry of his contract. On 1 February 2020, Al-Taawoun announced; as of match played 1 February 2020 Sumayhan Al-Nabit at Soccerway

Fire Museum of Greater Cincinnati

The Fire Museum of Greater Cincinnati known as the Cincinnati Fire Museum and exhibits Greater Cincinnati, Ohio's firefighting artifacts and honors firefighters, both past and present. Over 200 years of firefighting history is on display in the Fire Museum of Greater Cincinnati. Exhibits include examples of early leather fire buckets, an 1808 fire drum, the oldest surviving fire engine in Cincinnati, an 1836 hand pumper; the museum features and interactive exhibit that allows visitors to experience a modern Emergency-One fire engine cab by wailing the siren, ringing the bell, flashing the lights. The fire museum is housed in the restored 1907 Court Street Firehouse at 315 West Court Street; the firehouse was part of the Cincinnati Fire Department. The Court Street Firehouse is a registered historic building, listed in the National Register on July 18, 1974. Media related to Fire Museum of Greater Cincinnati at Wikimedia Commons Fire Museum of Greater Cincinnati - official site Documentation from the University of Cincinnati

Client (computing)

A client is a piece of computer hardware or software that accesses a service made available by a server. The server is on another computer system, in which case the client accesses the service by way of a network. A client is a computer or a program that, as part of its operation, relies on sending a request to another program or a computer hardware or software that accesses a service made available by a server. For example, web browsers are clients that connect to web servers and retrieve web pages for display. Email clients retrieve email from mail servers. Online chat uses a variety of clients. Multiplayer video games or online video games may run as a client on each computer; the term "client" may be applied to computers or devices that run the client software or users that use the client software. A client is part of a client–server model, still used today. Clients and servers may be computer programs run on the same machine and connect via inter-process communication techniques. Combined with Internet sockets, programs may connect to a service operating on a remote system through the Internet protocol suite.

Servers wait for potential clients to initiate connections. The term was first applied to devices that were not capable of running their own stand-alone programs, but could interact with remote computers via a network; these computer terminals were clients of the time-sharing mainframe computer. In one classification, client computers and devices are either thick clients, thin clients, or hybrid clients. A Thick client known as a rich client or fat client, is a client that performs the bulk of any data processing operations itself, does not rely on the server; the personal computer is a common example of a fat client, because of its large set of features and capabilities and its light reliance upon a server. For example, a computer running an Art program that shares the result of its work on a network is a thick client. A computer that runs entirely as a standalone machine save to send or receive files via a network is by standard called a workstation. A thin client is a minimal sort of client.

Thin clients use the resources of the host computer. A thin client only presents processed data provided by an application server, which performs the bulk of any required data processing. A device using web application is a thin client. A hybrid client is a mixture of the above two client models. Similar to a fat client, it relies on the server for storing persistent data; this approach offers features from both the thin client. A device running an online version of the video game Diablo III is an example of hybrid client

Japanese cruiser Tsukushi

Tsukushi was an early unprotected cruiser, serving in the fledgling Imperial Japanese Navy. Its name is a traditional name for Kyūshū island, its sister ships Chaoyong and Yangwei were acquired by the Chinese Beiyang Fleet. The design for Tsukushi was advertised by its designer British naval architect Sir George Wightwick Rendel at the Armstrong Whitworth shipyards at Newcastle upon Tyne in England as an example of a low-cost cruiser able to withstand larger Ironclad warships. In theory, the ship would rely on its small size and higher speed, along with a higher muzzle velocity main battery to attack larger, more cumbersome foes – similar to the principles of Jeune Ecole, as promoted by French naval architect Émile Bertin. However, the British Admiralty was skeptical of the idea, had concerns over the seaworthiness of the design in the North Sea, did not order any of the design for the Royal Navy. Armstrong Whitworth turned to overseas clients instead. Tsukushi had an all-steel construction with waterproof bulkheads, a single smokestack, twin masts, which could be used for sails.

The prow was reinforced for ramming. The power plant was a double expansion reciprocating steam engine with four cylindrical boilers driving twin screws; the ship had a number of technical innovations, including a hydraulic steering system and electrical incandescent light fixtures. The ship’s main armament were two breech-loading 10-inch Armstrong Whitworth cannons, one on the bow and one on the stern, mounted in stationary gun shields; the ship had four 5.1-inch guns, two 57-mm long guns, one Gatling gun, as well as two torpedo tubes. Tsukushi was laid down as Arturo Prat on 10 February 1879 for the Chilean Navy and launched on 11 August 1880. However, in the middle of construction, the Chilean-Peruvian War ended, Chile cancelled the order; the Imperial Japanese Navy picked up the contract for the semi-completed vessel. Tsukushi arrived in Japan after its shakedown cruise from England on 16 June 1883. Tsukushi did not see combat in the First Sino-Japanese War, but was used for patrolling between Korea and Weihaiwei in a reserve capacity in the Western Fleet.

It was assigned as a flagship for gunboat squadrons used to support ground troops, in this capacity led the gunboats Banjō, Chōkai up the Taedong River in Korea in September 1894 to provide support for the Battle of Pyongyang. After the war, Tsukushi was designated a first-class gunboat; the ship was rearmed in 1898, with its Armstrong cannon replaced by four 120 mm quick-firing guns, its lighter weaponry replaced by one 76-mm, two 27-mm guns, two machine guns. During the Boxer Rebellion of 1900 Tsukushi was stationed at Amoy and Shanghai to protect Japanese civilians and interests at the Japanese concessions. During the Russo-Japanese War, Tsukushi served as a guard ship patrolling the Tsushima Straits between Korea and Kyūshū, as an escort vessel covering the transport of Japanese troops to the Korean Peninsula, it was present as the Battle of Tsushima. Afterwards, Tsukushi was assigned to the Kure Naval District and served as a guard ship at the Port of Kobe. After the war, Tsukushi was used as a torpedo training vessel, was struck from the navy list on 25 May 1906.

It was scrapped in 1910. Chesneau and Eugene M. Kolesnik, Conway's All The World's Fighting Ships 1860–1905, Conway Maritime Press, 1979 reprinted 2002, ISBN 0-85177-133-5 Jentsura, Hansgeorg. Warships of the Imperial Japanese Navy, 1869–1945. Naval Institute Press. ISBN 0-87021-893-X. Nishida, Hiroshi. "Tsukushi gunboat". Imperial Japanese Navy. Retrieved 3 August 2007

Sentry Island

Sentry Island is one of several Canadian arctic islands in Nunavut, Canada within western Hudson Bay. The closest community is 13.7 km to the west. The island forms part of the Arvia'juaq and Qikiqtaarjuk National Historic Site and a Paallirmiut Inuit summer camp site. Sentry Island is a popular place for hunting; the island served as a rest stop for Henry Hudson and his crew during his ill-fated journeys to find the Northwest Passage in 1610 - 1611. On July 3, 2018, a man from Arviat was killed in a rare polar bear attack on the island; the man was on the island with his children when the polar bear approached them and attacked, killing 31-year-old Aaron Gibbons. The bear was killed by two others who were living in the area