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The second Digimon series is direct continuation of the first one, and began airing on April 2, 2000. Three years later, with most of the original DigiDestined now in high school at age fourteen, the Digital World was supposedly secure and peaceful. However, a new evil has appeared in the form of the Digimon Emperor (D... |
The third Digimon series, which began airing on April 1, 2001, is set largely in a "real world" where the Adventure and Adventure 02 series are television shows, and where Digimon game merchandise (based on actual items) become key to providing power boosts to real Digimon which appear in that world. The plot revolves ... |
The fourth Digimon series, which began airing on April 7, 2002, radically departs from the previous three by focusing on a new and very different kind of evolution, Spirit Evolution, in which the human characters use their D-Tectors (this series' Digivice) to transform themselves into special Digimon called Legendary W... |
After a three-year hiatus, a fifth Digimon series began airing on April 2, 2006. Like Frontier, Savers has no connection with the previous installments, and also marks a new start for the Digimon franchise, with a drastic change in character designs and story-line, in order to reach a broader audience. The story focuse... |
Three and a quarter years after the end of the fifth series, a new sixth series was confirmed by Bandai for the Digimon anime, its official name of the series revealed in the June issue of Shueisha's V Jump magazine being Digimon Xros Wars. It began airing in Japan on TV Asahi from July 6, 2010 onwards. Reverting to th... |
On August 17, 2011, Shueisha's V-Jump magazine announced a sequel set one year later, a third arc of Xros Wars subtitled The Young Hunters Who Leapt Through Time, which aired from October 2, 2011 to March 25, 2012, following on from the previous arc. It focuses on a new protagonist, Tagiru Akashi and his partner Gumdra... |
A new Digimon series was announced 30 months after the end of Digimon Fusion at a 15th anniversary concert and theater event for the franchise in August 2014. The series announced the return of the protagonists from the original Digimon Adventure series, most of them now as high school students. A countdown clicking ga... |
The series is set three years after the events of Digimon Adventure 02, when Digimon who turn rogue by a mysterious infection appear to wreak havoc in the Human World. Tai and the other DigiDestined from the original series reunite with their partners and start fighting back with support from the Japanese government, w... |
There have been nine Digimon movies released in Japan. The first seven were directly connected to their respective anime series; Digital Monster X-Evolution originated from the Digimon Chronicle merchandise line. All movies except X-Evolution and Ultimate Power! Activate Burst Mode have been released and distributed in... |
The European publishing company, Panini, approached Digimon in different ways in different countries. While Germany created their own adaptations of episodes, the United Kingdom (UK) reprinted the Dark Horse titles, then translated some of the German adaptations of Adventure 02 episodes. Eventually the UK comics were g... |
The Digimon series has a large number of video games which usually have their own independent storylines with a few sometimes tying into the stories of the anime series or manga series. The games consists of a number of genres including life simulation, adventure, video card game, strategy and racing games, though they... |
In 2011, Bandai posted a countdown on a teaser site. Once the countdown was finished, it revealed a reboot of the Digimon World series titled Digimon World Re:Digitize. An enhanced version of the game released on Nintendo 3DS as Digimon World Re:Digitize Decode in 2013. Another role-playing game by the name Digimon Sto... |
A glacier (US /ˈɡleɪʃər/ or UK /ˈɡlæsiə/) is a persistent body of dense ice that is constantly moving under its own weight; it forms where the accumulation of snow exceeds its ablation (melting and sublimation) over many years, often centuries. Glaciers slowly deform and flow due to stresses induced by their weight, cr... |
On Earth, 99% of glacial ice is contained within vast ice sheets in the polar regions, but glaciers may be found in mountain ranges on every continent except Australia, and on a few high-latitude oceanic islands. Between 35°N and 35°S, glaciers occur only in the Himalayas, Andes, Rocky Mountains, a few high mountains i... |
Glacial ice is the largest reservoir of freshwater on Earth. Many glaciers from temperate, alpine and seasonal polar climates store water as ice during the colder seasons and release it later in the form of meltwater as warmer summer temperatures cause the glacier to melt, creating a water source that is especially imp... |
Glacial bodies larger than 50,000 km2 (19,000 sq mi) are called ice sheets or continental glaciers. Several kilometers deep, they obscure the underlying topography. Only nunataks protrude from their surfaces. The only extant ice sheets are the two that cover most of Antarctica and Greenland. They contain vast quantitie... |
Tidewater glaciers are glaciers that terminate in the sea, including most glaciers flowing from Greenland, Antarctica, Baffin and Ellesmere Islands in Canada, Southeast Alaska, and the Northern and Southern Patagonian Ice Fields. As the ice reaches the sea, pieces break off, or calve, forming icebergs. Most tidewater g... |
Thermally, a temperate glacier is at melting point throughout the year, from its surface to its base. The ice of a polar glacier is always below freezing point from the surface to its base, although the surface snowpack may experience seasonal melting. A sub-polar glacier includes both temperate and polar ice, dependin... |
Glaciers form where the accumulation of snow and ice exceeds ablation. The area in which a glacier forms is called a cirque (corrie or cwm) - a typically armchair-shaped geological feature (such as a depression between mountains enclosed by arêtes) - which collects and compresses through gravity the snow which falls in... |
Glaciers are broken into zones based on surface snowpack and melt conditions. The ablation zone is the region where there is a net loss in glacier mass. The equilibrium line separates the ablation zone and the accumulation zone; it is the altitude where the amount of new snow gained by accumulation is equal to the amou... |
The top 50 m (160 ft) of a glacier are rigid because they are under low pressure. This upper section is known as the fracture zone and moves mostly as a single unit over the plastically flowing lower section. When a glacier moves through irregular terrain, cracks called crevasses develop in the fracture zone. Crevasses... |
Crevasses can form in several different ways. Transverse crevasses are transverse to flow and form where steeper slopes cause a glacier to accelerate. Longitudinal crevasses form semi-parallel to flow where a glacier expands laterally. Marginal crevasses form from the edge of the glacier, due to the reduction in speed ... |
Mean speeds vary greatly, but is typically around 1 m (3 ft) per day. There may be no motion in stagnant areas; for example, in parts of Alaska, trees can establish themselves on surface sediment deposits. In other cases, glaciers can move as fast as 20–30 m (70–100 ft) per day, such as in Greenland's Jakobshavn Isbræ ... |
A few glaciers have periods of very rapid advancement called surges. These glaciers exhibit normal movement until suddenly they accelerate, then return to their previous state. During these surges, the glacier may reach velocities far greater than normal speed. These surges may be caused by failure of the underlying be... |
In glaciated areas where the glacier moves faster than one km per year, glacial earthquakes occur. These are large scale temblors that have seismic magnitudes as high as 6.1. The number of glacial earthquakes in Greenland peaks every year in July, August and September and is increasing over time. In a study using data ... |
Ogives are alternating wave crests and valleys that appear as dark and light bands of ice on glacier surfaces. They are linked to seasonal motion of glaciers; the width of one dark and one light band generally equals the annual movement of the glacier. Ogives are formed when ice from an icefall is severely broken up, i... |
Glaciers are present on every continent and approximately fifty countries, excluding those (Australia, South Africa) that have glaciers only on distant subantarctic island territories. Extensive glaciers are found in Antarctica, Chile, Canada, Alaska, Greenland and Iceland. Mountain glaciers are widespread, especially ... |
The permanent snow cover necessary for glacier formation is affected by factors such as the degree of slope on the land, amount of snowfall and the winds. Glaciers can be found in all latitudes except from 20° to 27° north and south of the equator where the presence of the descending limb of the Hadley circulation lowe... |
Even at high latitudes, glacier formation is not inevitable. Areas of the Arctic, such as Banks Island, and the McMurdo Dry Valleys in Antarctica are considered polar deserts where glaciers cannot form because they receive little snowfall despite the bitter cold. Cold air, unlike warm air, is unable to transport much w... |
Glacial abrasion is commonly characterized by glacial striations. Glaciers produce these when they contain large boulders that carve long scratches in the bedrock. By mapping the direction of the striations, researchers can determine the direction of the glacier's movement. Similar to striations are chatter marks, line... |
Glacial moraines are formed by the deposition of material from a glacier and are exposed after the glacier has retreated. They usually appear as linear mounds of till, a non-sorted mixture of rock, gravel and boulders within a matrix of a fine powdery material. Terminal or end moraines are formed at the foot or termina... |
Before glaciation, mountain valleys have a characteristic "V" shape, produced by eroding water. During glaciation, these valleys are widened, deepened, and smoothed, forming a "U"-shaped glacial valley. The erosion that creates glacial valleys eliminates the spurs of earth that extend across mountain valleys, creating ... |
At the start of a classic valley glacier is a bowl-shaped cirque, which has escarped walls on three sides but is open on the side that descends into the valley. Cirques are where ice begins to accumulate in a glacier. Two glacial cirques may form back to back and erode their backwalls until only a narrow ridge, called ... |
Some rock formations in the path of a glacier are sculpted into small hills called roche moutonnée, or "sheepback" rock. Roche moutonnée are elongated, rounded, and asymmetrical bedrock knobs that can be produced by glacier erosion. They range in length from less than a meter to several hundred meters long. Roche mouto... |
Large masses, such as ice sheets or glaciers, can depress the crust of the Earth into the mantle. The depression usually totals a third of the ice sheet or glacier's thickness. After the ice sheet or glacier melts, the mantle begins to flow back to its original position, pushing the crust back up. This post-glacial reb... |
First recognized in 1900 by Max Planck, it was originally the proportionality constant between the minimal increment of energy, E, of a hypothetical electrically charged oscillator in a cavity that contained black body radiation, and the frequency, f, of its associated electromagnetic wave. In 1905 the value E, the min... |
Classical statistical mechanics requires the existence of h (but does not define its value). Eventually, following upon Planck's discovery, it was recognized that physical action cannot take on an arbitrary value. Instead, it must be some multiple of a very small quantity, the "quantum of action", now called the Planck... |
Equivalently, the smallness of the Planck constant reflects the fact that everyday objects and systems are made of a large number of particles. For example, green light with a wavelength of 555 nanometres (the approximate wavelength to which human eyes are most sensitive) has a frequency of 7014540000000000000♠540 THz ... |
In the last years of the nineteenth century, Planck was investigating the problem of black-body radiation first posed by Kirchhoff some forty years earlier. It is well known that hot objects glow, and that hotter objects glow brighter than cooler ones. The electromagnetic field obeys laws of motion similarly to a mass ... |
The assumption that black-body radiation is thermal leads to an accurate prediction: the total amount of emitted energy goes up with the temperature according to a definite rule, the Stefan–Boltzmann law (1879–84). But it was also known that the colour of the light given off by a hot object changes with the temperature... |
Prior to Planck's work, it had been assumed that the energy of a body could take on any value whatsoever – that it was a continuous variable. The Rayleigh–Jeans law makes close predictions for a narrow range of values at one limit of temperatures, but the results diverge more and more strongly as temperatures increase.... |
The black-body problem was revisited in 1905, when Rayleigh and Jeans (on the one hand) and Einstein (on the other hand) independently proved that classical electromagnetism could never account for the observed spectrum. These proofs are commonly known as the "ultraviolet catastrophe", a name coined by Paul Ehrenfest i... |
The photoelectric effect is the emission of electrons (called "photoelectrons") from a surface when light is shone on it. It was first observed by Alexandre Edmond Becquerel in 1839, although credit is usually reserved for Heinrich Hertz, who published the first thorough investigation in 1887. Another particularly thor... |
Prior to Einstein's paper, electromagnetic radiation such as visible light was considered to behave as a wave: hence the use of the terms "frequency" and "wavelength" to characterise different types of radiation. The energy transferred by a wave in a given time is called its intensity. The light from a theatre spotligh... |
The "photoelectrons" emitted as a result of the photoelectric effect have a certain kinetic energy, which can be measured. This kinetic energy (for each photoelectron) is independent of the intensity of the light, but depends linearly on the frequency; and if the frequency is too low (corresponding to a photon energy t... |
Niels Bohr introduced the first quantized model of the atom in 1913, in an attempt to overcome a major shortcoming of Rutherford's classical model. In classical electrodynamics, a charge moving in a circle should radiate electromagnetic radiation. If that charge were to be an electron orbiting a nucleus, the radiation ... |
Bohr also introduced the quantity , now known as the reduced Planck constant, as the quantum of angular momentum. At first, Bohr thought that this was the angular momentum of each electron in an atom: this proved incorrect and, despite developments by Sommerfeld and others, an accurate description of the electron angul... |
where the uncertainty is given as the standard deviation of the measured value from its expected value. There are a number of other such pairs of physically measurable values which obey a similar rule. One example is time vs. energy. The either-or nature of uncertainty forces measurement attempts to choose between trad... |
The Bohr magneton and the nuclear magneton are units which are used to describe the magnetic properties of the electron and atomic nuclei respectively. The Bohr magneton is the magnetic moment which would be expected for an electron if it behaved as a spinning charge according to classical electrodynamics. It is define... |
In principle, the Planck constant could be determined by examining the spectrum of a black-body radiator or the kinetic energy of photoelectrons, and this is how its value was first calculated in the early twentieth century. In practice, these are no longer the most accurate methods. The CODATA value quoted here is bas... |
There are both practical and theoretical difficulties in determining h. The practical difficulties can be illustrated by the fact that the two most accurate methods, the watt balance and the X-ray crystal density method, do not appear to agree with one another. The most likely reason is that the measurement uncertainty... |
The theoretical difficulties arise from the fact that all of the methods except the X-ray crystal density method rely on the theoretical basis of the Josephson effect and the quantum Hall effect. If these theories are slightly inaccurate – though there is no evidence at present to suggest they are – the methods would n... |
A watt balance is an instrument for comparing two powers, one of which is measured in SI watts and the other of which is measured in conventional electrical units. From the definition of the conventional watt W90, this gives a measure of the product KJ2RK in SI units, where RK is the von Klitzing constant which appears... |
The gyromagnetic ratio γ is the constant of proportionality between the frequency ν of nuclear magnetic resonance (or electron paramagnetic resonance for electrons) and the applied magnetic field B: ν = γB. It is difficult to measure gyromagnetic ratios precisely because of the difficulties in precisely measuring B, bu... |
A further complication is that the measurement of γ′p involves the measurement of an electric current: this is invariably measured in conventional amperes rather than in SI amperes, so a conversion factor is required. The symbol Γ′p-90 is used for the measured gyromagnetic ratio using conventional electrical units. In ... |
The Faraday constant F is the charge of one mole of electrons, equal to the Avogadro constant NA multiplied by the elementary charge e. It can be determined by careful electrolysis experiments, measuring the amount of silver dissolved from an electrode in a given time and for a given electric current. In practice, it i... |
The X-ray crystal density method is primarily a method for determining the Avogadro constant NA but as the Avogadro constant is related to the Planck constant it also determines a value for h. The principle behind the method is to determine NA as the ratio between the volume of the unit cell of a crystal, measured by X... |
There are a number of proposals to redefine certain of the SI base units in terms of fundamental physical constants. This has already been done for the metre, which is defined in terms of a fixed value of the speed of light. The most urgent unit on the list for redefinition is the kilogram, whose value has been fixed f... |
The legal process to change the definition of the kilogram is already underway, but it had been decided that no final decision would be made before the next meeting of the General Conference on Weights and Measures in 2011. (For more detailed information, see kilogram definitions.) The Planck constant is a leading cont... |
Comcast Corporation, formerly registered as Comcast Holdings,[note 1] is an American multinational mass media company and is the largest broadcasting and largest cable company in the world by revenue. It is the second largest pay-TV company after the AT&T-DirecTV acquisition, largest cable TV company and largest home I... |
Comcast operates multiple cable-only channels (including E! Entertainment Television, the Golf Channel, and NBCSN), over-the-air national broadcast network channels (NBC and Telemundo), the film production studio Universal Pictures, and Universal Parks & Resorts, with a global total of nearly 200 family entertainment l... |
Comcast has been criticized for multiple reasons. The company's customer satisfaction often ranks among the lowest in the cable industry. Comcast has violated net neutrality practices in the past; and, despite Comcast's commitment to a narrow definition of net neutrality, critics advocate a definition of which preclude... |
Comcast is sometimes described as a family business. Brian L. Roberts, Chairman, President, and CEO of Comcast, is son of co-founder Ralph Roberts. Roberts owns or controls just over 1% of all Comcast shares but all of the Class B supervoting shares, which gives him an "undilutable 33% voting power over the company". L... |
The company is often criticized by both the media and its own staff for its less upstanding policies regarding employee relations. A 2012 Reddit post written by an anonymous Comcast call center employee eager to share their negative experiences with the public received attention from publications including The Huffingt... |
Comcast has also earned a reputation for being anti-union. According to one of the company's training manuals, "Comcast does not feel union representation is in the best interest of its employees, customers, or shareholders". A dispute in 2004 with CWA, a labor union that represented many employees at Comcast's offices... |
Despite these criticisms, Comcast has appeared on multiple "top places to work" lists. In 2009, it was included on CableFAX magazine's "Top 10 Places to Work in Cable", which cited its "scale, savvy and vision". Similarly, the Philadelphia Business Journal awarded Comcast the silver medal among extra-large companies in... |
The book value of the company nearly doubled from $8.19 a share in 1999 to $15 a share in 2009. Revenues grew sixfold from 1999's $6 billion to almost $36 billion in 2009. Net profit margin rose from 4.2% in 1999 to 8.4% in 2009, with operating margins improving 31 percent and return on equity doubling to 6.7 percent i... |
With $18.8 million spent in 2013, Comcast has the seventh largest lobbying budget of any individual company or organization in the United States. Comcast employs multiple former US Congressmen as lobbyists. The National Cable & Telecommunications Association, which has multiple Comcast executives on its board, also rep... |
In 1963, Ralph J. Roberts in conjunction with his two business partners, Daniel Aaron and Julian A. Brodsky, purchased American Cable Systems as a corporate spin-off from its parent, Jerrold Electronics, for US $500,000. At the time, American Cable was a small cable operator in Tupelo, Mississippi, with five channels a... |
In 1994, Comcast became the third largest cable operator in the United States with around 3.5 million subscribers following its purchase of Maclean-Hunter's American division for $1.27 billion. The company's UK branch, Comcast UK Cable Partners, goes public while constructing a cable telecommunications network. With fi... |
Comcast sold Comcast Cellular to SBC Communications in 1999 for $400 million, releasing them from $1.27 billion in debt. Comcast acquired Greater Philadelphia Cablevision in 1999. In March 1999, Comcast offered to buy MediaOne for $60 billion. However, MediaOne decided to accept AT&T Corporation's offer of $62 billion ... |
In 2001, Comcast announced it would acquire the assets of the largest cable television operator at the time, AT&T Broadband, for US$44.5 billion. The proposed name for the merged company was "AT&T Comcast", but the companies ultimately decided to keep only the Comcast name. In 2002, Comcast acquired all assets of AT&T ... |
On February 11, 2004, Comcast announced a $54 billion bid for The Walt Disney Company, as well as taking on $12 billion of Disney's debt. The deal would have made Comcast the largest media conglomerate in the world. However, after rejection by Disney and uncertain response from investors, the bid was abandoned in April... |
On April 8, 2005, a partnership led by Comcast and Sony Pictures Entertainment finalized a deal to acquire MGM and its affiliate studio, United Artists, and create an additional outlet to carry MGM/UA's material for cable and Internet distribution. On October 31, 2005, Comcast officially announced that it had acquired ... |
Comcast announced in May 2007 and launched in September 2008 a dashboard called SmartZone. Hewlett-Packard led "design, creation and management". Collaboration and unified messaging technology came from open-source vendor Zimbra. "SmartZone users will be able to send and receive e-mail, listen to their voicemail messag... |
In April 2005, Comcast and Time Warner Cable announced plans to buy the assets of bankrupted Adelphia Cable. The two companies paid a total of $17.6 billion in the deal that was finalized in the second quarter of 2006—after the U.S. Federal Communications Commission (FCC) completed a seven-month investigation without r... |
Media outlets began reporting in late September 2009 that Comcast was in talks to buy NBCUniversal. Comcast denied the rumors at first, while NBC would not comment on them. However, CNBC itself reported on October 1 that General Electric was considering spinning NBCUniversal off into a separate company that would merge... |
Following a tentative agreement on by December 1, on December 3, 2009, the parties announced that Comcast would buy a controlling 51% stake in NBCUniversal for $6.5 billion in cash and $7.3 billion in programming. GE would take over the remaining 49% stake in NBCUniversal, using $5.8 billion to buy out Vivendi's 20% mi... |
On February 12, 2014, the Los Angeles Times reported that Comcast sought to acquire Time Warner Cable in a deal valued at $45.2 billion. On February 13, it was reported that Time Warner Cable agreed to the acquisition. This was to add several metropolitan areas to the Comcast portfolio, such as New York City, Los Angel... |
Critics noted in 2013 that Tom Wheeler, the head of the FCC, which has to approve the deal, is the former head of both the largest cable lobbying organization, the National Cable & Telecommunications Association, and as largest wireless lobby, CTIA – The Wireless Association. According to Politico, Comcast "donated to ... |
Comcast delivers third-party television programming content to its own customers, and also produces its own first-party content both for subscribers and customers of other competing television services. Fully or partially owned Comcast programming includes Comcast Newsmakers, Comcast Network, Comcast SportsNet, SportsN... |
Comcast also owns many local channels. Comcast also has a variety network known as Comcast Network, available exclusively to Comcast and Cablevision subscribers. The channel shows news, sports, and entertainment and places emphasis in Philadelphia and the Baltimore/Washington, D.C. areas, though the channel is also ava... |
In 1996, Comcast bought a controlling stake in Spectacor from the company's founder, Ed Snider. Comcast-Spectacor holdings now include the Philadelphia Flyers NHL hockey team, the Philadelphia 76ers National Basketball Association basketball team and two large multipurpose arenas in Philadelphia. Over a number of years... |
In 2004 and 2007, the American Customer Satisfaction Index (ACSI) survey found that Comcast had the worst customer satisfaction rating of any company or government agency in the country, including the Internal Revenue Service. The ACSI indicates that almost half of all cable customers (regardless of company) have regis... |
Comcast was given an "F" for its corporate governance practices in 2010, by Corporate Library, an independent shareholder-research organization. According to Corporate Library, Comcast's board of directors ability to oversee and control management was severely compromised (at least in 2010) by the fact that several of ... |
In January 2015, a customer named Ricardo Brown received a bill from Comcast with his name changed to "Asshole Brown". Brown's wife, Lisa, believed a Comcast employee changed the name in response to the Browns' request to cancel their cable service, an incident in which she was refused a cancellation unless she paid a ... |
Tuberculosis (TB) is an infectious disease usually caused by the bacterium Mycobacterium tuberculosis (MTB). Tuberculosis generally affects the lungs, but can also affect other parts of the body. Most infections do not have symptoms, known as latent tuberculosis. About 10% of latent infections progress to active diseas... |
One-third of the world's population is thought to be infected with TB. New infections occur in about 1% of the population each year. In 2014, there were 9.6 million cases of active TB which resulted in 1.5 million deaths. More than 95% of deaths occurred in developing countries. The number of new cases each year has de... |
If a tuberculosis infection does become active, it most commonly involves the lungs (in about 90% of cases). Symptoms may include chest pain and a prolonged cough producing sputum. About 25% of people may not have any symptoms (i.e. they remain "asymptomatic"). Occasionally, people may cough up blood in small amounts, ... |
In 15–20% of active cases, the infection spreads outside the lungs, causing other kinds of TB. These are collectively denoted as "extrapulmonary tuberculosis". Extrapulmonary TB occurs more commonly in immunosuppressed persons and young children. In those with HIV, this occurs in more than 50% of cases. Notable extrapu... |
The main cause of TB is Mycobacterium tuberculosis, a small, aerobic, nonmotile bacillus. The high lipid content of this pathogen accounts for many of its unique clinical characteristics. It divides every 16 to 20 hours, which is an extremely slow rate compared with other bacteria, which usually divide in less than an ... |
Using histological stains on expectorated samples from phlegm (also called "sputum"), scientists can identify MTB under a microscope. Since MTB retains certain stains even after being treated with acidic solution, it is classified as an acid-fast bacillus. The most common acid-fast staining techniques are the Ziehl–Nee... |
The M. tuberculosis complex (MTBC) includes four other TB-causing mycobacteria: M. bovis, M. africanum, M. canetti, and M. microti. M. africanum is not widespread, but it is a significant cause of tuberculosis in parts of Africa. M. bovis was once a common cause of tuberculosis, but the introduction of pasteurized milk... |
People with prolonged, frequent, or close contact with people with TB are at particularly high risk of becoming infected, with an estimated 22% infection rate. A person with active but untreated tuberculosis may infect 10–15 (or more) other people per year. Transmission should occur from only people with active TB – th... |
TB infection begins when the mycobacteria reach the pulmonary alveoli, where they invade and replicate within endosomes of alveolar macrophages. Macrophages identify the bacterium as foreign and attempt to eliminate it by phagocytosis. During this process, the bacterium is enveloped by the macrophage and stored tempora... |
The primary site of infection in the lungs, known as the "Ghon focus", is generally located in either the upper part of the lower lobe, or the lower part of the upper lobe. Tuberculosis of the lungs may also occur via infection from the blood stream. This is known as a Simon focus and is typically found in the top of t... |
Tuberculosis is classified as one of the granulomatous inflammatory diseases. Macrophages, T lymphocytes, B lymphocytes, and fibroblasts aggregate to form granulomas, with lymphocytes surrounding the infected macrophages. When other macrophages attack the infected macrophage, they fuse together to form a giant multinuc... |
In many people, the infection waxes and wanes. Tissue destruction and necrosis are often balanced by healing and fibrosis. Affected tissue is replaced by scarring and cavities filled with caseous necrotic material. During active disease, some of these cavities are joined to the air passages bronchi and this material ca... |
Diagnosing active tuberculosis based only on signs and symptoms is difficult, as is diagnosing the disease in those who are immunosuppressed. A diagnosis of TB should, however, be considered in those with signs of lung disease or constitutional symptoms lasting longer than two weeks. A chest X-ray and multiple sputum c... |
The Mantoux tuberculin skin test is often used to screen people at high risk for TB. Those who have been previously immunized may have a false-positive test result. The test may be falsely negative in those with sarcoidosis, Hodgkin's lymphoma, malnutrition, and most notably, active tuberculosis. Interferon gamma relea... |
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