Classification.

Rocks are composed of grains of minerals, which are homogeneous solids formed from a chemical compound arranged in an orderly manner. The aggregate minerals forming the rock are held together by chemical bonds. The types and abundance of minerals in a rock are determined by the manner in which it was formed.  Most rocks contain silicate minerals, compounds that include silicon oxide tetrahedra in their crystal lattice, and account for about one-third of all known mineral species and about 95% of the earth's crust. The proportion of silica in rocks and minerals is a major factor in determining their names and properties.  Rocks are classified according to characteristics such as mineral and chemical composition, permeability, texture of the constituent particles, and particle size. These physical properties are the result of the processes that formed the rocks. Over the course of time, rocks can transform from one type into another, as described by a geological model called the rock cycle. This transformation produces three general classes of rock: igneous, sedimentary and metamorphic.  Those three classes are subdivided into many groups. There are, however, no hard-and-fast boundaries between allied rocks. By increase or decrease in the proportions of their minerals, they pass through gradations from one to the other; the distinctive structures of one kind of rock may thus be traced gradually merging into those of another. Hence the definitions adopted in rock names simply correspond to selected points in a continuously graduated series.

Igneous rock.

Igneous rock (derived from the Latin word "igneus," meaning "of fire," from "ignis" meaning "fire)" is formed through the cooling and solidification of magma or lava. This magma may be derived from partial melts of pre-existing rocks in either a planet's mantle or crust. Typically, the melting of rocks is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition.  Igneous rocks are divided into two main categories:  The chemical abundance and the rate of cooling of magma typically forms a sequence known as Bowen's reaction series. Most major igneous rocks are found along this scale.  About 65% of the Earth's crust by volume consists of igneous rocks, making it the most plentiful category. Of these, 66% are basalt and gabbro, 16% are granite, and 17% granodiorite and diorite. Only 0.6% are syenite and 0.3% are ultramafic. The oceanic crust is 99% basalt, which is an igneous rock of mafic composition. Granite and similar rocks, known as granitoids, dominate the continental crust.

Sedimentary rock.

Sedimentary rocks are formed at the earth's surface by the accumulation and cementation of fragments of earlier rocks, minerals, and organisms or as chemical precipitates and organic growths in water (sedimentation). This process causes clastic sediments (pieces of rock) or organic particles (detritus) to settle and accumulate, or for minerals to chemically precipitate (evaporite) from a solution. The particulate matter then undergoes compaction and cementation at moderate temperatures and pressures (diagenesis).  Before being deposited, sediments are formed by weathering of earlier rocks by erosion in a source area and then transported to the place of deposition by water, wind, ice, mass movement or glaciers (agents of denudation). About 7.9% of the crust by volume is composed of sedimentary rocks, with 82% of those being shales, while the remainder consists of limestone (6%), sandstone and arkoses (12%). Sedimentary rocks often contain fossils. Sedimentary rocks form under the influence of gravity and typically are deposited in horizontal or near horizontal layers or strata, and may be referred to as stratified rocks.

Metamorphic rock.

Metamorphic rocks are formed by subjecting any rock type—sedimentary rock, igneous rock or another older metamorphic rock—to different temperature and pressure conditions than those in which the original rock was formed. This process is called metamorphism, meaning to "change in form". The result is a profound change in physical properties and chemistry of the stone. The original rock, known as the protolith, transforms into other mineral types or other forms of the same minerals, by recrystallization. The temperatures and pressures required for this process are always higher than those found at the Earth's surface: temperatures greater than 150 to 200 °C and pressures of 1500 bars. Metamorphic rocks compose 27.4% of the crust by volume.  The three major classes of metamorphic rock are based upon the formation mechanism. An intrusion of magma that heats the surrounding rock causes contact metamorphism—a temperature-dominated transformation. Pressure metamorphism occurs when sediments are buried deep under the ground; pressure is dominant, and temperature plays a smaller role. This is termed burial metamorphism, and it can result in rocks such as jade. Where both heat and pressure play a role, the mechanism is termed regional metamorphism. This is typically found in mountain-building regions.  Depending on the structure, metamorphic rocks are divided into two general categories. Those that possess a texture are referred to as foliated; the remainders are termed non-foliated. The name of the rock is then determined based on the types of minerals present. Schists are foliated rocks that are primarily composed of lamellar minerals such as micas. A gneiss has visible bands of differing lightness, with a common example being the granite gneiss. Other varieties of foliated rock include slates, phyllites, and mylonite. Familiar examples of non-foliated metamorphic rocks include marble, soapstone, and serpentine. This branch contains quartzite—a metamorphosed form of sandstone—and hornfels.

Human use.

The use of rock has had a huge impact on the cultural and technological development of the human race. Rock has been used by humans and other hominids for at least 2.5 million years. Lithic technology marks some of the oldest and continuously used technologies. The mining of rock for its metal content has been one of the most important factors of human advancement, and has progressed at different rates in different places, in part because of the kind of metals available from the rock of a region.

Mining.

Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock salt, potash, construction aggregate and dimension stone. Mining is required to obtain any material that cannot be grown through agricultural processes, or created artificially in a laboratory or factory. Mining in a wider sense comprises extraction of any resource (e.g. petroleum, natural gas, salt or even water) from the earth.  Mining of rock and metals has been done since prehistoric times. Modern mining processes involve prospecting for mineral deposits, analysis of the profit potential of a proposed mine, extraction of the desired materials, and finally reclamation of the land to prepare it for other uses once mining ceases.  Mining processes may create negative impacts on the environment both during the mining operations and for years after mining has ceased. These potential impacts have led to most of the world's nations adopting regulations to manage negative effects of mining operations.

A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition and the way in which it is formed. Rocks are usually grouped into three main groups: igneous rocks, metamorphic rocks and sedimentary rocks. Rocks form the Earth's outer solid layer, the crust.

Les roches (du latin populaire "rocca") sont des matériaux naturels généralement solides et formés, essentiellement ou en totalité, par un assemblage de minéraux, comportant parfois des fossiles (notamment dans les roches sédimentaires), du verre résultant du refroidissement rapide d'un liquide (volcanisme, friction...) ou des agrégats d'autres roches. Les roches peuvent être formées d'une seule espèce minérale (roches "monominérales") ou de plusieurs (roches "polyminérales") :


Description.

Solar flares affect all layers of the solar atmosphere (photosphere, chromosphere, and corona). The plasma medium is heated to tens of millions of kelvins, while electrons, protons, and heavier ions are accelerated to near the speed of light. Flares produce electromagnetic radiation across the electromagnetic spectrum at all wavelengths, from radio waves to gamma rays. Most of the energy is spread over frequencies outside the visual range and so the majority of the flares are not visible to the naked eye and must be observed with special instruments. Flares occur in active regions around sunspots, where intense magnetic fields penetrate the photosphere to link the corona to the solar interior. Flares are powered by the sudden (timescales of minutes to tens of minutes) release of magnetic energy stored in the corona. The same energy releases may produce coronal mass ejections (CMEs), although the relationship between CMEs and flares is still not well understood.  X-rays and UV radiation emitted by solar flares can affect Earth's ionosphere and disrupt long-range radio communications. Direct radio emission at decimetric wavelengths may disturb the operation of radars and other devices that use those frequencies.  Solar flares were first observed on the Sun by Richard Christopher Carrington and independently by Richard Hodgson in 1859 as localized visible brightenings of small areas within a sunspot group. Stellar flares can be inferred by looking at the lightcurves produced from the telescope or satellite data of variety of other stars.  The frequency of occurrence of solar flares varies, from several per day when the Sun is particularly "active" to less than one every week when the Sun is "dormant", following the 11-year cycle (the solar cycle). Large flares are less frequent than smaller ones.

Cause.

Flares occur when accelerated charged particles, mainly electrons, interact with the plasma medium. Evidence suggests that the phenomenon of magnetic reconnection leads to this copious acceleration of charged particles. On the Sun, magnetic reconnection may happen on solar arcades – a series of closely occurring loops following magnetic lines of force. These lines of force quickly reconnect into a lower arcade of loops leaving a helix of magnetic field unconnected to the rest of the arcade. The sudden release of energy in this reconnection is the origin of the particle acceleration. The unconnected magnetic helical field and the material that it contains may violently expand outwards forming a coronal mass ejection. This also explains why solar flares typically erupt from active regions on the Sun where magnetic fields are much stronger.  Although there is a general agreement on the source of a flare's energy, the mechanisms involved are still not well understood. It's not clear how the magnetic energy is transformed into the kinetic energy of the particles, nor is it known how some particles can be accelerated to the GeV range (10 electron volt) and beyond. There are also some inconsistencies regarding the total number of accelerated particles, which sometimes seems to be greater than the total number in the coronal loop. Scientists are unable to forecast flares.

Classification.

The classification system for solar flares uses the letters A, B, C, M or X, according to the peak flux in watts per square metre (W/m) of X-rays with wavelengths, as measured at the Earth by the GOES spacecraft.  The strength of an event within a class is noted by a numerical suffix ranging from 1 to 9, which is also the factor for that event within the class. Hence, an X2 flare is twice the strength of an X1 flare, an X3 flare is three times as powerful as an X1, and only 50% more powerful than an X2. An X2 is four times more powerful than an M5 flare.

H-alpha classification.

An earlier flare classification was based on Hα spectral observations. The scheme uses both the intensity and emitting surface. The classification in intensity is qualitative, referring to the flares as: faint (f), normal (n) or brilliant (b). The emitting surface is measured in terms of "millionths" of the hemisphere and is described below. (The total hemisphere area "A" = 15.5 × 10 km.)  A flare then is classified taking S or a number that represents its size and a letter that represents its peak intensity, v.g.: Sn is a "normal sunflare".

Hazards.

Solar flares strongly influence the local space weather in the vicinity of the Earth. They can produce streams of highly energetic particles in the solar wind or stellar wind, known as a solar proton event. These particles can impact the Earth's magnetosphere (see main article at geomagnetic storm), and present radiation hazards to spacecraft and astronauts. Additionally, massive solar flares are sometimes accompanied by coronal mass ejections (CMEs) which can trigger geomagnetic storms that have been known to disable satellites and knock out terrestrial electric power grids for extended periods of time.  The soft X-ray flux of X class flares increases the ionization of the upper atmosphere, which can interfere with short-wave radio communication and can heat the outer atmosphere and thus increase the drag on low orbiting satellites, leading to orbital decay. Energetic particles in the magnetosphere contribute to the aurora borealis and aurora australis. Energy in the form of hard x-rays can be damaging to spacecraft electronics and are generally the result of large plasma ejection in the upper chromosphere.  The radiation risks posed by solar flares are a major concern in discussions of a manned mission to Mars, the Moon, or other planets. Energetic protons can pass through the human body, causing biochemical damage, presenting a hazard to astronauts during interplanetary travel. Some kind of physical or magnetic shielding would be required to protect the astronauts. Most proton storms take at least two hours from the time of visual detection to reach Earth's orbit. A solar flare on January 20, 2005 released the highest concentration of protons ever directly measured, giving astronauts as little as 15 minutes to reach shelter.

Observations.

Flares produce radiation across the electromagnetic spectrum, although with different intensity. They are not very intense in visible light, but they can be very bright at particular atomic lines. They normally produce bremsstrahlung in X-rays and synchrotron radiation in radio.

History.

Optical observations.

Richard Carrington observed a flare for the first time on 1 September 1859 projecting the image produced by an optical telescope through a broad-band filter. It was an extraordinarily intense "white light flare". Since flares produce copious amounts of radiation at Hα, adding a narrow ( ≈1 Å) passband filter centered at this wavelength to the optical telescope allows the observation of not very bright flares with small telescopes. For years Hα was the main, if not the only, source of information about solar flares. Other passband filters are also used.

Radio observations.

During World War II, on February 25 and 26, 1942, British radar operators observed radiation that Stanley Hey interpreted as solar emission. Their discovery did not go public until the end of the conflict. The same year Southworth also observed the Sun in radio, but as with Hey, his observations were only known after 1945. In 1943 Grote Reber was the first to report radioastronomical observations of the Sun at 160 MHz. The fast development of radioastronomy revealed new peculiarities of the solar activity like "storms" and "bursts" related to the flares. Today ground-based radiotelescopes observe the Sun from c. 15 MHz up to 400 GHz.

Space telescopes.

Since the beginning of space exploration, telescopes have been sent to space, where they work at wavelengths shorter than UV, which are completely absorbed by the atmosphere, and where flares may be very bright. Since the 1970s, the GOES series of satellites observe the Sun in "soft" X-rays, and their observations became the "standard measure" of flares, diminishing the importance of the Hα classification. "Hard" X-rays were observed by many different instruments, the most important today being the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Nonetheless, UV observations are today the "stars" of solar imaging with their incredible fine details that reveal the complexity of the solar corona. Spacecraft may also bring radio detectors at extremely long wavelengths (as long as a few kilometers) that cannot propagate through the ionosphere.

Space telescopes.

The following spacecraft missions have flares as their main observation target.  In addition to these solar observing facilities, many non-solar astronomical satellites observe flares either intentionally (e.g., NuSTAR), or simply because the penetrating hard radiations coming from a flare can readily penetrate most forms of shielding.

Examples of large solar flares.

The most powerful flare ever observed was the first one to be observed, on September 1, 1859, and was reported by British astronomer Richard Carrington and independently by an observer named Richard Hodgson. The event is named the Solar storm of 1859, or the "Carrington event". The flare was visible to a naked eye (in "white light"), and produced stunning auroras down to tropical latitudes such as Cuba or Hawaii, and set telegraph systems on fire. The flare left a trace in Greenland ice in the form of nitrates and beryllium-10, which allow its strength to be measured today. Cliver and Svalgaard reconstructed the effects of this flare and compared with other events of the last 150 years. In their words: "While the 1859 event has close rivals or superiors in each of the above categories of space weather activity, it is the only documented event of the last ∼150 years that appears at or near the top of all of the lists." The intensity of the flare has been estimated to be around X50.  The ultra-fast coronal mass ejection of August 1972 is suspected of triggering magnetic fuses on naval mines during the Vietnam War, and would have been a life-threatening event to Apollo astronauts if it had occurred during a mission to the Moon.  In modern times, the largest solar flare measured with instruments occurred on November 4, 2003. This event saturated the GOES detectors, and because of this its classification is only approximate. Initially, extrapolating the GOES curve, it was estimated to be X28. Later analysis of the ionospheric effects suggested increasing this estimate to X45. This event produced the first clear evidence of a new spectral component above 100 GHz.  Other large solar flares also occurred on April 2, 2001 (X20), October 28, 2003 (X17.2 and 10), September 7, 2005 (X17), February 17, 2011 (X2), August 9, 2011 (X6.9), March 7, 2012 (X5.4), July 6, 2012 (X1.1). On July 6, 2012, a solar storm hit just after midnight UK time, when an X1.1 solar flare fired out of the AR1515 sunspot. Another X1.4 solar flare from AR 1520 region of the Sun, second in the week, reached the Earth on July 15, 2012 with a geomagnetic storm of G1–G2 level. A X1.8-class flare was recorded on October 24, 2012. There has been major solar flare activity in early 2013, notably within a 48-hour period starting on May 12, 2013, a total of four X-class solar flares were emitted ranging from an X1.2 and upwards of an X3.2, the latter of which was one of the largest year 2013 flares. Departing sunspot complex AR2035-AR2046 erupted on April 25, 2014 at 0032 UT, producing a strong X1.3-class solar flare and an HF communications blackout on the day-side of Earth. NASA's Solar Dynamics Observatory recorded a flash of extreme ultraviolet radiation from the explosion. The Solar Dynamics Observatory recorded an X9.3-class flare at around 1200 UTC on September 6, 2017.

Flare spray.

Flare sprays are a type of eruption associated with solar flares. They involve faster ejections of material than eruptive prominences, and reach velocities of 20 to 2000 kilometers per second.

Prediction.

Current methods of flare prediction are problematic, and there is no certain indication that an active region on the Sun will produce a flare. However, many properties of sunspots and active regions correlate with flaring. For example, magnetically complex regions (based on line-of-sight magnetic field) called delta spots produce the largest flares. A simple scheme of sunspot classification due to McIntosh, or related to fractal complexity is commonly used as a starting point for flare prediction. Predictions are usually stated in terms of probabilities for occurrence of flares above M or X GOES class within 24 or 48 hours. The U.S. National Oceanic and Atmospheric Administration (NOAA) issues forecasts of this kind. MAG4 was developed at the University of Alabama in Huntsville with support from the Space Radiation Analysis Group at Johnson Space Flight Center (NASA/SRAG) for forecasting M and X class flares, CMEs, fast CME, and Solar Energetic Particle events.

References.

Sources

A solar flare is a sudden flash of increased brightness on the Sun, usually observed near its surface and in close proximity to a sunspot group. Powerful flares are often, but not always, accompanied by a coronal mass ejection. Even the most powerful flares are barely detectable in the total solar irradiance (the "solar constant").

Une éruption solaire ou tempête solaire est un événement primordial de l'activité du Soleil. La variation du nombre d'éruptions solaires permet de définir un cycle solaire d'une période moyenne de 11,2 ans.


History.

Founding.

In January 1994, Yang and Filo were electrical engineering graduate students at Stanford University, when they created a website named "Jerry and David's guide to the World Wide Web". The site was a directory of other websites, organized in a hierarchy, as opposed to a searchable index of pages. In March 1994, "Jerry and David's Guide to the World Wide Web" was renamed "Yahoo!". The human-edited Yahoo! Directory, provided for users to surf through the Internet, became their first product and the company's original purpose. The "yahoo.com" domain was created on January 18, 1995.  The word "yahoo" is a backronym for "Yet Another

Expansion.

Yahoo grew rapidly throughout the 1990s. Yahoo went public in April 1996 and its stock price rose by 600 percent within two years. Like many search engines and web directories, Yahoo added a web portal, putting it in competition with services like Excite, Lycos and America Online. By 1998, Yahoo was the most popular starting point for web users, and the human-edited Yahoo Directory the most popular search engine, receiving 95 million page views per day which was triple the number compared to rival Excite. It also made many high-profile acquisitions. Yahoo began offering free e-mail from October 1997 after the acquisition of RocketMail, which was then renamed to Yahoo! Mail. In 1998, Yahoo decided to

Decline, security breaches, and Verizon purchase.

By the fourth quarter of 2013, the company's share price had more than doubled since Marissa Mayer took over as president in July 2012; however, the share price peaked at about $35 in November 2013. It did go up to $36.04 in the mid-afternoon of December 2, 2015, perhaps on news that the board of directors was meeting to decide on the future of Mayer, whether to sell the struggling Internet business, and whether to continue with the spinoff of its

Altaba Inc..

On June 16, 2017, parts of the original Yahoo Inc, which were not purchased by Verizon Communications, were renamed Altaba Inc. On the United States Securities and Exchange Commission's website, they listed the new company as a "non-diversified, closed-end management investment company."

Products and services.

Yahoo operated a portal that provides the latest news, entertainment, and sports information. The portal also gave users access to other Yahoo services like Yahoo! Search, Yahoo Mail, Yahoo Maps, Yahoo Finance, Yahoo Groups and Yahoo Messenger.

Communication.

Yahoo provided Internet communication services such as Yahoo Messenger and Yahoo Mail. As of May 2007, its e-mail service would offer unlimited storage.  Yahoo provided social networking services and user-generated content, including products such as My Web, Yahoo Personals, Yahoo 360°, Delicious,

Content.

Yahoo partners with numerous content providers in products such as Yahoo Sports, Yahoo Finance, Yahoo Music, Yahoo Movies, Yahoo Weather, Yahoo News, Yahoo! Answers and Yahoo Games to provide news and related

Co-branded Internet services.

Yahoo developed partnerships with broadband providers such as AT&T Inc. (via Prodigy, BellSouth &

Mobile services.

Yahoo Mobile offers services for email, instant messaging, and mobile blogging, as well as information services, searches and alerts. Services for the camera phone include entertainment and ring tones.  Yahoo introduced its Internet search system, called OneSearch, for mobile phones on March 20, 2007. The results include news headlines, images from Flickr, business listings, local weather and links to other sites. Instead of

Commerce.

Yahoo offers shopping services such as Yahoo Shopping, Yahoo Autos, Yahoo Real Estate and Yahoo Travel, which enables users to gather relevant information

Advertising.

Yahoo! Gemini provides services such as Sponsored Search, Local Advertising and Product/Travel/Directory Submit that let different businesses advertise their products and services on the Yahoo network.  Following the closure of a "beta" version on April 30, 2010, the Yahoo Publisher Network was relaunched as an advertising tool that allows online publishers to monetize their websites through the use of site-relevant advertisements.  Yahoo launched its new Internet advertisement sales system in the fourth quarter of 2006, called Panama. It allows advertisers to bid for search terms to trigger their ads on search results pages. The system considers bids, ad quality, clickthrough rates and other

Yahoo Next.

Yahoo Next was an incubation ground for future Yahoo technologies currently undergoing testing.

Yahoo BOSS.

Yahoo Search BOSS is a service that allows developers to build search applications based on Yahoo's search technology. Early Partners in the program include Hakia, Me.dium, Delver, Daylife and Yebol.  In early 2011,

Yahoo Meme.

Yahoo Meme was a beta social service,

Y!Connect.

Y!Connect enables individuals to leave comments in online publication boards by using their Yahoo ID, instead of having to

Yahoo Accessibility.

Yahoo has invested resources to increase and improve

Yahoo Axis.

Yahoo Axis was a desktop web browser extension and mobile browser for iOS devices created and developed by Yahoo. The extension made its public debut

Yahoo SearchMonkey.

Yahoo SearchMonkey (often misspelled Search Monkey) was a Yahoo service which allowed developers and site owners to use structured data to make Yahoo Search results more useful and visually appealing, and drive more relevant traffic to their sites.

Defunct services.

Geocities was a popular web hosting service founded in 1995 and was one of the first services to offer web pages to the public. At one point it was the third-most-browsed site on the World Wide Web. Yahoo purchased GeoCities in 1999 and ten years later the web host was closed, deleting some seven million web pages. A great deal of information was lost but many of those sites and pages were mirrored at the Internet Archive, OOcities.com, and other such databases.  Yahoo Go, a Java-based phone application with access to most of Yahoo services, was closed on January 12, 2010.  Yahoo 360° was a blogging/social networking beta service launched in March 2005 by Yahoo and closed on July 13, 2009. Yahoo Mash beta was another social service closed after one year of operation prior to leaving beta status.  Yahoo Photos was shut down on September 20, 2007, in favor of integration with Flickr. Yahoo Tech was a website that provided product information and setup advice to users. Yahoo launched the

Privacy.

In September 2013, Yahoo's transparency report said the company received 29 thousand requests for information about users from governments in the first six months of 2013. Over 12 thousand of the requests came from the United States.  In October 2013, "The Washington Post" reported that the U.S. National Security Agency intercepted communications between Yahoo's data centers, as part of a program named Muscular.  In late January 2014, Yahoo announced on its company blog that it had detected a "coordinated effort" to hack into possibly millions of Yahoo Mail accounts. The company prompted users to reset their passwords, but did not elaborate on the scope of the possible breach, citing an ongoing federal investigation.  In August 2015, Researchers at Malwarebytes, notified Yahoo about its users getting hacked because of vulnerabilities in Flash. According to them the vulnerability could allow attackers to install "ransomware" on users' computers and lock their files till the customers pay the criminals.

Storing personal information and tracking usage.

Working with comScore, "The New York Times" found that Yahoo was able to collect far more data about users than its competitors from its Web sites and advertising network. By one measure, on average Yahoo had the potential in December 2007 to build a profile of 2,500 records per month about each of its visitors. Yahoo retains search requests for a period of 13 months. However, in response to European regulators, Yahoo obfuscates the IP address of users after three months by deleting its last eight bits.  On March 29, 2012, Yahoo

Criticism.

In 2000, Yahoo was taken to court in France by parties seeking to prevent French citizens from purchasing memorabilia relating to the Nazi Party. In March 2004, Yahoo launched a paid inclusion program whereby commercial websites were guaranteed listings on the Yahoo search engine. Yahoo discontinued the program at the end of 2009. Yahoo was criticized for providing ads via the Yahoo ad network to companies who display them through spyware and adware.  Yahoo, as well as other search engines, cooperated with the Chinese government in censoring search results. In April 2005, dissident Shi Tao was sentenced to 10 years in prison for "providing state secrets to foreign entities" as a result of being identified by IP address by Yahoo. Human rights organizations and the company's general counsel disputed the extent of Yahoo's foreknowledge of Shi's fate. Human rights groups also accuse Yahoo of aiding authorities in the arrest of dissidents Li Zhi and Jiang Lijun. In April 2017, Yahoo was sued for failing to uphold settlement agreements in this case. Yahoo pledged to give support to the families of those arrested and create a relief fund for those persecuted for expressing their views online with Yahoo

Management.

Chief Executive Officers.

Former chief operating officer Henrique de Castro departed from the company in January 2014 after Mayer, who initially

Yahoo International.

Yahoo offers a multi-lingual interface. The site is available in over 20 languages. The official directory for all of the Yahoo International sites is "world.yahoo.com". The company's international sites are wholly owned by Yahoo, with the exception of its Japan and China sites.  Yahoo holds a 34.75% minority stake in Yahoo! Japan, while SoftBank holds 35.45%, Yahoo!Xtra in New Zealand, which Yahoo!7 have 51% of and 49% belongs to Telecom New Zealand, and Yahoo!7 in Australia, which is a 50–50 agreement between Yahoo and the Seven Network. Historically, Yahoo entered into joint venture agreements with SoftBank for the major European sites (UK, France and Germany) and well as South Korea and Japan. In November 2005, Yahoo purchased the minority interests that SoftBank owned in Europe and Korea.  Yahoo used to hold a

Logos and themes.

Yahoo got its first logo during its establishment in 1994—it consists of the "Yahoo" wordmark which is coloured black and are using the Times New Roman font, but it were later changed.  In March 1995, when the company changed its name to Yahoo, it introduced another logo which is briefly changed to a more elaborate text that includes an exclamation point at the end, but it were short-lived for only 5 months.  Later, in August 1995, that same year, Yahoo changed its logo again and it became an stylized yellow jumping "Y" figurine on a blue circle while the "Yahoo!" wordmark is written below, but the logo were also short-lived for 4 months until December 1995.  On January 1, 1996, Yahoo introduced a simplified new logo that included the text "Yahoo" and an exclamation mark, both in red with a slight shadow behind the text. By May 2009, Yahoo tweaked the logo by recoloring it from red to purple and removing the logo's outline and shadow. At the time, the purple logo was accompanied by a new slogan, "It's Y!ou." A shortened variant of the logo, consisting of only the letter "Y" and an exclamation point, was also used.  On August 7, 2013, at around midnight EDT, Yahoo announced that the final version of the new logo would be revealed on September 5, 2013 at 4:00 a.m. UTC. In the period leading up to the unveiling of the new logo, the "30 Days of Change" campaign was introduced, whereby a variation of the logo was published every day for the 30 days following the announcement. The new logo was eventually launched with an accompanying video that showed its digital construction, and Mayer published a personalized description of the design process on her Tumblr page. Mayer explains:  So, one weekend this summer, I rolled up my sleeves and dove into the trenches with our logo design team... We spent the majority of Saturday and Sunday designing the logo from start to finish, and we had a ton of fun weighing every minute detail. We knew we wanted a logo that reflected Yahoo – whimsical, yet sophisticated. Modern and fresh, with a nod to our history. Having a human touch, personal. Proud.  On September 19, 2013, Yahoo launched a new version of the "My Yahoo" personalized homepage. The redesign allows users to tailor a homepage with widgets that access features such as email accounts, calendars, Flickr and other Yahoo content, and Internet content. Users can also select "theme packs" that represent artists such as Polly Apfelbaum and Alec Monopoly, and bands such as Empire of the Sun. Mayer then explained at a conference in late September 2013 that the logo change was the result of feedback from both external parties and employees.  In September 2019 saw another logo change for Yahoo, which the company claims is a "refreshed brand identity [that] is simpler and more flexible, and looks back to the original, quirky 1996 logo." The logo is white text set against a purple background, with both the “y” and “!” of the logo reportedly set at an angle of 22.5 degrees.

Yahoo! () is an American web services provider headquartered in Sunnyvale, California, and owned by Verizon Media. The original Yahoo! company was founded by Jerry Yang and David Filo in January 1994 and was incorporated on March 2, 1995. Yahoo was one of the pioneers of the early Internet era in the 1990s.

Yahoo! est une société américaine de service web appartenant depuis 2017 à Verizon Media. Son siège social est situé à Sunnyvale en Californie.


Foundations.

Precursors.

The concept of data communication – transmitting data between two different places through an electromagnetic medium such as radio or an electric wire – pre-dates the introduction of the first computers. Such communication systems were typically limited to point to point communication between two end devices. Semaphore lines, telegraph systems and telex machines can be considered early precursors of this kind of communication. The telegraph in the late 19th century was the first fully

Information theory.

Fundamental theoretical work in data transmission and information theory was developed by Claude Shannon, Harry Nyquist, and Ralph Hartley in the early

Semiconductor technology.

The development of transistor technology was fundamental to a new generation of electronic devices that later effected almost every aspect of the human experience. The long-sought realization of the field-effect transistor, in form of the MOS transistor (MOSFET), by Mohamed Atalla and Dawon Kahng at Bell Labs in

Development of wide area networking.

With limited exceptions, the earliest computers were connected directly to terminals used by individual users, typically in the same building or site.  Wide area networks (WANs) emerged during the 1950s and became established during the 1960s.

Inspiration.

Christopher Strachey, who became Oxford University's first professor of computation, filed a patent application for time-sharing in February 1959. In June that year, he gave a paper "Time Sharing in Large Fast Computers" at the UNESCO Information Processing Conference in Paris where he passed the concept on to J. C. R. Licklider. Licklider, Vice President at Bolt Beranek and Newman, Inc., discussed a computer network in his January 1960 paper "Man-Computer Symbiosis":  In August 1962, Licklider and Welden Clark published the paper "On-Line Man-Computer Communication" which was one of the first

Development of packet switching.

The issue of connecting separate physical networks to form one logical network was the first of many problems. Early networks used message switched systems that required rigid routing structures prone to single point of failure. In the 1960s, Paul Baran of the RAND Corporation produced a study of survivable networks for the U.S. military in the event of nuclear war. Information transmitted across Baran's network would be divided into what he called "message blocks". Independently, Donald Davies

Software.

The software for establishing links between network sites in the ARPANET was the Network Control Program (NCP), completed in c. 1970. Further development in the early 1970s by Robert E. Kahn and Vint Cerf let to the formulation of the "Transmission Control Program", and its specification

Networks that led to the Internet.

NPL network.

Following discussions with J. C. R. Licklider in 1965, Donald Davies became interested in data communications for computer networks. Later that year, at the National Physical Laboratory (United Kingdom), Davies designed and proposed a national data network based on packet switching. The following year, he described the use of an "Interface computer" to act as a router. The proposal was not taken up nationally but by 1967, a pilot experiment had demonstrated

ARPANET.

Robert Taylor was promoted to the head of the Information Processing Techniques Office (IPTO) at Defense Advanced Research Projects Agency (DARPA) in 1966. He intended to realize Licklider's ideas of an interconnected networking system. As part of the IPTO's role, three network terminals had been installed: one for System Development Corporation in Santa Monica, one for Project Genie at University of California, Berkeley, and one for the Compatible Time-Sharing System project at Massachusetts Institute of Technology (MIT). Taylor's identified need for networking became obvious from the waste of resources apparent to him.  Bringing in Larry Roberts from MIT, he initiated a project to build such a network. Roberts and Thomas Merrill had been researching computer time-sharing over wide area networks. At the first ACM Symposium on Operating Systems Principles in October 1967, Roberts presented a proposal for the "ARPA net", based on Wesley Clark's proposal for using Interface Message Processors to create a message switching network. At the conference, Roger Scantlebury presented Donald Davies' work on packet switching for data communications and mentioned the work of Paul Baran at RAND. Roberts incorporated the packet switching concepts into the ARPANET design and upgraded the

Merit Network.

The Merit Network was formed in 1966 as the Michigan Educational Research Information Triad to explore computer networking between three of Michigan's public universities as a means to help the state's educational and economic development. With initial support from the State of Michigan and the National Science Foundation (NSF), the packet-switched network was first demonstrated in December 1971 when an interactive host to host connection was made between the IBM mainframe computer systems at the University of

CYCLADES.

The CYCLADES packet switching network was a French research network designed and directed by Louis Pouzin. First demonstrated in 1973, it was developed to explore alternatives to the early

X.25 and public data networks.

Based on international research initiatives, particularly the contributions of Rémi Després, packet switching network standards were developed by the International Telegraph and Telephone Consultative Committee (ITU-T) in the form of X.25 and related standards. X.25 is built on the concept of virtual circuits emulating traditional telephone connections. In 1974, X.25 formed the basis for the SERCnet network between British academic and research sites, which later became JANET. The initial ITU Standard on X.25 was approved in March 1976.  The British Post Office, Western Union International and Tymnet collaborated to create the first international packet switched network, referred to as the International Packet Switched Service (IPSS), in 1978. This network grew from Europe and the US to cover

UUCP and Usenet.

In 1979, two students at Duke University, Tom Truscott and Jim Ellis, originated the idea of using Bourne shell scripts to transfer news and messages on a serial line UUCP connection with nearby University of North Carolina at Chapel Hill. Following public release of the software in 1980, the mesh of UUCP hosts forwarding on the Usenet news rapidly expanded. UUCPnet, as it would later be named, also created gateways and links between FidoNet and dial-up BBS hosts.

Merging the networks and creating the Internet (1973–95).

TCP/IP.

With so many different network methods, something was needed to unify them. Robert E. Kahn of DARPA and ARPANET recruited Vinton Cerf of Stanford University to work with him on the problem. By 1973, they had worked out a fundamental reformulation, where the differences between network protocols were hidden by using a common internetwork protocol, and instead of the network being responsible for reliability, as in the ARPANET, the hosts became responsible. Cerf credits Hubert Zimmermann and Louis Pouzin (designer of the CYCLADES network), and his graduate students Judy Estrin, Richard Karp, Yogen Dalal and Carl Sunshine with important work on this design. Concurrently, an International Networking Working Group formed in 1972, led by Cerf; active members included Alex McKenzie, Donald Davies, Roger Scantlebury, Louis Pouzin and Hubert Zimmermann.  The specification of the resulting protocol, the Transmission Control Protocol (TCP), was published as by the Network Working Group in December 1974. It contains the first attested use of the term "internet", as a shorthand for "internetwork".  Between 1976 and 1977, Yogen Dalal proposed separating TCP's routing and transmission control functions into two discrete layers, which led to the splitting of TCP into the TCP

From ARPANET to NSFNET.

After the ARPANET had been up and running for several years, ARPA looked for another agency to hand off the network to; ARPA's primary mission was funding cutting edge research and development, not running a communications utility. Eventually, in July 1975, the network had been turned over to the Defense Communications Agency, also part of the Department of Defense. In 1983, the U.S. military portion of the ARPANET was broken off as a separate network, the MILNET. MILNET subsequently became the unclassified but military-only NIPRNET, in parallel with the SECRET-level

Transition towards the Internet.

The term "internet" was reflected in the first RFC published on the TCP protocol (RFC 675: Internet Transmission Control Program, December 1974) as a short form of "internetworking", when the two terms were used interchangeably. In general, an internet was a collection of networks linked by a common protocol. In the time period when the ARPANET was connected to the newly formed NSFNET project in the late 1980s, the term was used as the name of the network, Internet, being the large and global TCP/IP network.  As interest in networking grew by needs of collaboration, exchange of data, and access of remote computing resources, the TCP/IP technologies spread throughout the rest of

TCP/IP goes global (1980s).

CERN, the European Internet, the link to the Pacific and beyond.

In 1982, NORSAR and Peter Kirstein's group at University College London (UCL) left the ARPANET and began to use TCP/IP over satellite links. UCL provided access between the Internet and academic networks in the UK.  Between 1984 and 1988 CERN began installation and operation of TCP/IP to interconnect its major internal computer systems, workstations, PCs and an accelerator control system. CERN continued to operate a limited self-developed system (CERNET) internally and several incompatible (typically proprietary) network protocols externally. There was considerable resistance in Europe towards more widespread use of TCP/IP, and

The early global "digital divide" emerges.

While developed countries with technological infrastructures were joining the Internet, developing countries began to experience a digital divide separating them from the Internet. On an essentially continental basis, they are building organizations for Internet resource administration and sharing operational experience, as more and more transmission facilities go into place.

Rise of the global Internet (late 1980s/early 1990s onward).

Initially, as with its predecessor networks, the system that would evolve into the Internet was primarily for government and government body use.  However, interest in commercial use of the Internet quickly became a commonly debated topic. Although commercial use was forbidden, the exact definition of commercial use was unclear and subjective. UUCPNet and the X.25 IPSS had no such restrictions, which would eventually see the official barring of UUCPNet use of ARPANET and NSFNET connections. (Some UUCP links still remained connecting to these networks however, as administrators cast a blind eye to their operation.) As a result, during the late 1980s, the first Internet service provider (ISP) companies were formed. Companies like PSINet, UUNET, Netcom, and Portal Software were formed to provide service to the regional research networks and provide alternate network access, UUCP-based email and Usenet News to the public. The first commercial dialup ISP in the United States was The World, which opened in 1989.  In 1992, the U.S. Congress passed

Networking in outer space.

The first Internet link into low earth orbit was established on January 22, 2010 when astronaut T. J. Creamer posted the first unassisted update to his Twitter account from the International Space Station, marking the extension of the Internet into space. (Astronauts at the ISS had used email and Twitter before, but these messages had been relayed to the ground through a NASA data link before being posted by a human proxy.) This personal Web access, which NASA calls the Crew Support LAN, uses the space station's high-speed Ku band microwave link. To surf the Web, astronauts can use a station laptop computer to control a desktop computer on Earth, and they can talk to their families and friends on Earth using Voice over IP equipment.  Communication with spacecraft beyond earth orbit has traditionally been

Internet governance.

As a globally distributed network of voluntarily interconnected autonomous networks, the Internet operates without a central governing body. Each constituent network chooses the technologies and protocols it deploys from the technical standards that are developed by the Internet Engineering Task Force (IETF). However, successful interoperation of many networks requires certain parameters that must be common throughout the network. For managing such parameters, the Internet Assigned Numbers Authority (IANA) oversees the allocation and assignment of various technical identifiers. In addition, the Internet Corporation for Assigned Names and Numbers (ICANN) provides oversight and coordination for the two principal name spaces in the Internet, the Internet Protocol address space and the Domain Name System.

NIC, InterNIC, IANA, and ICANN.

The IANA function was originally performed by USC Information Sciences Institute (ISI), and it delegated portions of this responsibility with respect to numeric network and autonomous system identifiers to the Network Information Center (NIC) at Stanford Research Institute (SRI International) in Menlo Park, California. ISI's Jonathan Postel managed the IANA, served as RFC Editor and performed other key roles until his premature death in 1998.  As the early ARPANET grew, hosts were referred to by names, and a HOSTS.TXT file would be distributed from SRI International to each host on the network. As the network grew, this became cumbersome. A technical solution came in the form of the Domain Name System,

Internet Engineering Task Force.

The Internet Engineering Task Force (IETF) is the largest and most visible of several loosely related ad-hoc groups that provide technical direction for the Internet, including the Internet Architecture Board (IAB), the Internet Engineering Steering Group (IESG), and the Internet Research Task Force (IRTF).  The IETF is a loosely self-organized group of international volunteers who contribute to the engineering and evolution of Internet technologies. It is the principal body engaged in the development of new Internet standard specifications. Much of the work of the IETF is organized into "Working Groups". Standardization efforts of the Working Groups are often adopted by the Internet community, but the IETF does not control or patrol the Internet.  The IETF grew out of quarterly meeting of U.S. government-funded researchers, starting in January 1986. Non-government representatives were invited by the fourth IETF meeting in October 1986. The concept of Working

Request for Comments.

Request for Comments (RFCs) are the main documentation for the work of the IAB, IESG, IETF, and IRTF. RFC 1, "Host Software", was written by Steve Crocker at UCLA in April 1969, well before the IETF was created. Originally they were technical memos documenting aspects of ARPANET development and were edited by Jon Postel, the first RFC Editor.  RFCs cover a wide range of information from proposed standards, draft standards, full standards, best practices, experimental protocols, history, and other informational topics. RFCs can be written by individuals or informal groups of individuals, but many are the product of a more formal Working Group. Drafts are submitted to the IESG either by individuals or by the Working Group Chair. An RFC Editor, appointed by the IAB, separate from IANA, and working in conjunction with the IESG, receives drafts from the IESG and edits, formats, and publishes them. Once an RFC is published, it is never revised. If the standard it describes changes or its information becomes obsolete, the revised standard or updated information will be re-published as a new RFC that "obsoletes" the original.

The Internet Society.

The Internet Society (ISOC) is an international, nonprofit organization founded during 1992 "to assure the open development, evolution and use of the Internet for the benefit of all people throughout the world". With offices near Washington, DC, USA, and in Geneva, Switzerland, ISOC has a membership base comprising more than 80 organizational and more than 50,000 individual members.

Globalization and Internet governance in the 21st century.

Since the 1990s, the Internet's governance and organization has been of global importance to governments, commerce, civil society, and individuals. The organizations which held control of certain technical aspects of the Internet were the successors of the old ARPANET oversight and the current decision-makers in the day-to-day technical aspects of the network. While recognized as the administrators of certain aspects of the Internet, their roles and their decision-making authority are limited and subject to increasing international scrutiny and increasing objections. These objections have led to the ICANN removing themselves from relationships with first the University of Southern California in 2000, and in September 2009, gaining autonomy from the US government by the ending of its longstanding agreements, although some contractual obligations with the U.S. Department of Commerce continued. Finally, on October 1, 2016 ICANN ended its contract with the United States Department of Commerce National Telecommunications and Information Administration (NTIA), allowing oversight to pass to the global Internet community.  The IETF, with

Politicization of the Internet.

Due to its prominence and immediacy as an effective means of mass communication, the Internet has also become more politicized as it has grown. This has led in turn, to discourses and activities that would once have taken place in other ways, migrating to being mediated by internet.  Examples include political activities such as public protest and canvassing of support and votes, but also:

Net neutrality.

On April 23, 2014, the Federal Communications Commission (FCC) was reported to be considering a new rule that would permit Internet service providers to offer content providers a faster track to send content, thus reversing their earlier net neutrality position. A possible solution to net neutrality concerns may be municipal broadband, according to Professor Susan Crawford, a legal and technology expert at Harvard Law School. On May 15, 2014, the FCC decided to consider two options regarding Internet services: first, permit fast and slow broadband lanes, thereby compromising net neutrality; and second, reclassify broadband as a telecommunication service, thereby preserving net neutrality. On November 10, 2014, President Obama recommended the FCC reclassify broadband Internet service as a telecommunications service in order to preserve net neutrality. On January 16, 2015, Republicans presented legislation, in the form of a U.S. Congress HR discussion draft bill, that makes concessions to net neutrality but

Use and culture.

Email and Usenet.

E-mail has often been called the killer application of the Internet. It predates the Internet, and was a crucial tool in creating it. Email started in 1965 as a way for multiple users of a time-sharing mainframe computer to communicate. Although the history is undocumented, among the first systems to have such a facility were the System Development Corporation (SDC) Q32 and the Compatible Time-Sharing System (CTSS) at MIT.  The ARPANET computer network made a large contribution to the evolution of electronic mail. An experimental inter-system transferred mail on the ARPANET shortly after its creation. In 1971 Ray Tomlinson created what was to become the standard Internet electronic mail addressing format, using the @ sign to separate mailbox names from host names.  A number of protocols were developed to deliver messages among groups of time-sharing computers over alternative transmission systems, such as UUCP and IBM's VNET email system. Email could be passed this way between a number

From Gopher to the WWW.

As the Internet grew through the 1980s and early 1990s, many people realized the increasing need to be able to find and organize files and information. Projects such as Archie, Gopher, WAIS, and the FTP Archive list attempted to create ways to organize distributed data. In the early 1990s, Gopher, invented by Mark P. McCahill offered a viable alternative to the World Wide Web. However, in 1993 the World Wide Web saw many advances to indexing and ease of access through search engines, which often neglected Gopher and

Search engines.

Even before the World Wide Web, there were search engines that attempted to organize the Internet. The first of these was the Archie search engine from McGill University in 1990, followed in 1991 by WAIS and Gopher. All three of those systems predated the invention of the World Wide Web but all continued to index the Web and the rest of the Internet for several years after the Web appeared. There are still Gopher servers as of 2006, although there are a great many more web servers.  As the Web grew, search engines and Web directories were created to track pages on the Web and allow people to find things. The first full-text Web search engine was WebCrawler in 1994. Before WebCrawler, only Web page titles were searched. Another early search engine, Lycos, was created in 1993 as a university project, and was the first to achieve commercial success. During the late 1990s, both Web directories and Web search engines were popular—Yahoo! (founded

File sharing.

Resource or file sharing has been an important activity on computer networks from well before the Internet was established and was supported in a variety of ways including bulletin board systems (1978), Usenet (1980), Kermit (1981), and many others. The File Transfer Protocol (FTP) for use on the Internet was standardized in 1985 and is still in use today. A variety of tools were developed to aid the use of FTP by helping users discover files they might want to transfer, including the Wide Area Information Server (WAIS) in 1991, Gopher in 1991, Archie in 1991, Veronica in 1992, Jughead in 1993, Internet Relay Chat (IRC) in 1988, and eventually the World Wide Web (WWW) in 1991 with Web directories and Web search engines.  In

Dot-com bubble.

Suddenly the low price of reaching millions worldwide, and the possibility of selling to or hearing from those people at the same moment when they were reached, promised to overturn established business dogma in advertising, mail-order sales, customer relationship management, and many more areas. The web was a new killer app—it could bring together unrelated buyers and sellers in seamless and low-cost ways. Entrepreneurs around the world developed new business models, and ran to their nearest venture capitalist. While some of the new entrepreneurs had experience in business and economics, the majority were simply people with ideas, and did not manage the capital influx prudently. Additionally,

Mobile phones and the Internet.

The first mobile phone with Internet connectivity was the Nokia 9000 Communicator, launched in Finland in 1996. The viability of Internet services access on mobile phones was limited until prices came down from that model, and network providers started to develop systems and services conveniently accessible on phones. NTT DoCoMo in Japan launched the first mobile Internet service, i-mode, in 1999 and this is considered the birth of the mobile phone Internet services. In 2001, the mobile phone email system by Research in Motion (now BlackBerry Limited) for their BlackBerry product was launched in America. To make efficient use of the small screen and tiny keypad and one-handed operation typical of mobile phones,

Web technologies.

Web pages were initially conceived as structured documents based upon Hypertext Markup Language (HTML) which can allow access to images, video, and other content. Hyperlinks in the page permit users to navigate to other pages. In the earliest browsers,

Historiography.

There are nearly insurmountable problems in supplying a historiography of the Internet's development. The process of digitization represents a twofold challenge both for historiography in general and, in particular, for historical communication research. A sense of the difficulty in documenting early developments that led to the internet can be gathered from the quote:

The history of the Internet has its origin in the efforts to build and interconnect computer networks that arose from research and development in the United States and involved international collaboration, particularly with researchers in the United Kingdom and France.

L’histoire d'Internet remonte au développement des premiers réseaux de télécommunication. L’idée d’un réseau informatique, permettant aux utilisateurs de différents ordinateurs de communiquer, se développa par de nombreuses étapes successives. La somme de tous ces développements conduisit au « réseau des réseaux » () que nous connaissons aujourd’hui en tant qu'Internet. Il est le fruit à la fois de développements technologiques et du regroupement d’infrastructures réseau existantes et de systèmes de télécommunications.


Geography.

The southern half of the Barents Sea, including the ports of Murmansk (Russia) and Vardø (Norway) remain ice-free year round due to the warm North Atlantic drift. In September, the entire Barents Sea is more or less completely ice-free. Until the Winter War (1939–40), Finland's territory also reached to the Barents Sea. Its harbor at Petsamo was Finland's only ice-free winter harbor.  There are three main types of water masses in the Barents Sea: Warm, salty Atlantic water (temperature >3 °C, salinity >35) from the North Atlantic drift; cold Arctic water (temperature <0 °C, salinity <35) from the north; and warm, but not very salty, coastal water (temperature >3 °C, salinity <34.7). Between the Atlantic and Polar waters, a front called the Polar Front is formed. In the western parts of the sea (close to Bear Island), this front is determined by the bottom topography and is therefore relatively sharp and stable from year to year, while in the east (towards Novaya Zemlya), it can be quite diffuse and its position can vary markedly between years.  The lands of Novaya Zemlya attained most of their early Holocene coastal deglaciation approximately 10,000 years before present.

Extent.

The International Hydrographic Organization defines the limits of the "Barentsz Sea" as follows:  Other islands in the Barents Sea include Chaichy and Timanets.

Geology.

The Barents Sea was originally formed from two major continental collisions: the Caledonian orogeny, in which the Baltica and Laurentia collided to form Laurasia, and a subsequent collision between Laurasia and Western Siberia. Most of its geological history is dominated by extensional tectonics, caused by the collapse of the Caledonian and Uralian orogenic belts and the break-up of Pangaea. These events created the major rift basins that dominate the Barents Shelf, along with various platforms and structural highs. The later geological history of the Barents Sea is dominated by Late Cenozoic uplift, particularly that caused by Quaternary glaciation, which has resulted in erosion and deposition of significant sediment.

Ecology.

Due to the North Atlantic drift, the Barents Sea has a high biological production compared to other oceans of similar latitude. The spring bloom of phytoplankton can start quite early near the ice edge, because the fresh water from the melting ice makes up a stable water layer on top of the sea water. The phytoplankton bloom feeds zooplankton such as "Calanus finmarchicus", "Calanus glacialis", "Calanus hyperboreus", "Oithona" spp., and krill. The zooplankton feeders include young cod, capelin, polar cod, whales, and little auk. The capelin is a key food for top predators such as the north-east Arctic cod, harp seals, and seabirds such as common guillemot and Brunnich's guillemot. The fisheries of the Barents Sea, in particular the cod fisheries, are of great importance for both Norway and Russia.  SIZEX-89 was an international winter experiment in 1989 for which the main objectives were to perform sensor signature studies of different ice types in order to develop SAR algorithms for ice variables, such as ice types, ice concentrations and ice kinematics. Although previous research suggested that predation by whales may be the cause of depleting fish stocks, more recent research suggests that marine mammal consumption has only a trivial influence on fisheries. A model assessing the effects of fisheries and climate was far more accurate at describing trends in fish abundance. There is a genetically distinct polar bear population associated with the Barents Sea.

History.

Name.

The Barents Sea was formerly known to Russians as Murmanskoye More, or the "Sea of Murmans" (i.e., their term for Norwegians). It appears with this name in sixteenth-century maps, including Gerard Mercator's "Map of the Arctic" published in his 1595 atlas. Its eastern corner, in the region of the Pechora River's estuary, has been known as Pechorskoye Morye, that is, Pechora Sea.  This sea was given its present name by Europeans in honor of Willem Barentsz, a Dutch navigator and explorer. Barentsz was the leader of early expeditions to the far north, at the end of the sixteenth century.  The Barents Sea has been called by sailors ""The Devil's Dance Floor"" due to its unpredictability and difficulty level.  Ocean rowers call it ""Devil's Jaw"". In 2017, after the first recorded complete man-powered crossing of the Barents Sea from Tromsø to Longyearbyen in a row boat by Polar Row expedition, captain Fiann Paul was asked by Norwegian TV2 how a rower would name the Barents Sea. Fiann responded that he would name it "Devil's Jaw", adding that the winds you constantly battle are like breath from the devil's nostrils while he holds you in his jaws.

Modern era.

Seabed mapping was completed in 1933; the first full map was produced by Russian marine geologist Maria Klenova.  The Barents Sea was the site of a notable World War II engagement, a German surface raiding attack on a British merchant convoy, which later became known as the Battle of the Barents Sea. Under the command of Oskar Kummetz, the German warships sank minelayer HMS "Bramble" and destroyer, but lost destroyer, and was severely damaged by British gunfire. The Germans later retreated and the British convoy arrived safely at Murmansk shortly afterwards.  During the Cold War, the Soviet Red Banner Northern Fleet used the southern reaches of the sea as a ballistic missile submarine bastion, a strategy that Russia continues. Nuclear contamination from dumped Russian naval reactors is an environmental concern in the Barents Sea.

Economy.

Political status.

For decades there was a boundary dispute between Norway and Russia regarding the position of the boundary between their respective claims to the Barents Sea. The Norwegians favoured a median line, based on the Geneva Convention of 1958, whereas the Russians favoured a meridian- based sector line, based on a Soviet decision of 1926. A neutral "grey" zone between the competing claims had an area of 175,000 sq.km, which is approximately 12% of the total area of the Barents Sea. The two countries started negotiations on the location of the boundary in 1974, and agreed to a moratorium on hydrocarbon exploration in 1976.  Twenty years after the fall of the Soviet Union, in 2010 Norway and Russia signed an agreement that placed the boundary equidistant from their competing claims. This was ratified and went into force on 7 July 2011, opening the grey zone for hydrocarbon exploration.

Oil and gas.

Encouraged by the success of oil exploration and production in the North Sea in the 1960s, Norway began hydrocarbon exploration in the Barents Sea in 1969. They acquired seismic reflection surveys through the following years, which were analysed to understand the location of the main sedimentary basins. NorskHydro drilled the first well in 1980, which was a dry hole, and the first discoveries were made the following year: the Alke and Askeladden gas fields. Several more discoveries were made on the Norwegian side of the Barents Sea throughout the 1980s, including the important Snøhvit field.  But, interest in the area began to wane due to a succession of dry holes, wells containing only gas (which was cheap at the time), and the prohibitive costs of developing wells in such a remote area. Interest in the area was reignited in the late 2000s, after the Snovhit field was finally brought into production and two new large discoveries were made.  The Russians began exploration in their territory around the same time, encouraged by their success in the Timan-Pechora Basin. They drilled their first wells in the early 1980s, and some very large gas fields were discovered throughout this decade. The Shtokman field was discovered in 1988 and is classed as a giant gas field: currently the 5th-largest gas field in the world. Similar practical difficulties Barents Sea resulted in a decline in Russian exploration, aggravated by the nation's political instability of the 1990s.

Fishing.

The Barents Sea contains the world's largest remaining cod population, as well as important stocks of haddock and capelin. Fishing is managed jointly by Russia and Norway in the form of the Joint Norwegian–Russian Fisheries Commission, established in 1976, in an attempt to keep track of how many fish are leaving the ecosystem due to fishing. The Joint Norwegian-Russian Fisheries Commission sets Total Allowable Catches (TACs) for multiple species throughout their migratory tracks. Through the Commission, Norway and Russia also exchange fishing quotas and catch statistics to ensure the TACs are not being violated.  But there are problems with reporting under this system, and researchers believe that they do not have accurate data for the effects of fishing on the Barents Sea ecosystem. Cod is one of the major catches. A large portion of catches are not reported when the fishing boats land, in order to account for profits that are being lost to high taxes and fees. Since many fishermen do not strictly follow the TACs and rules set forth by the Commission, the amount of fish being extracted annually from the Barents Sea is underestimated.

Barents Sea biodiversity and marine bioprospecting.

The Barents Sea, where temperate waters from the Gulf Stream and cold waters from the Arctic meet, is home to an enormous diversity of organisms, which are well adapted to the extreme conditions of their marine habitats. This makes these arctic species very attractive for marine bioprospecting. Marine bioprospecting may be defined as the search for bioactive molecules and compounds from marine sources having new, unique properties and the potential for commercial applications. Amongst others, applications include medicines, food and feed, textiles, cosmetics and the process industry.  The Norwegian government strategically supports the development of marine bioprospecting as it has the potential to contribute to new and sustainable wealth creation. Tromsø and the northern areas of Norway play a central role in this strategy. They have excellent access to unique Arctic marine organisms, existing marine industries, and R&D competence and infrastructure in this region. Since 2007, science and industry have cooperated closely on bioprospecting, and the development and commercialization of new products.

Institutions and industry supporting marine bioprospecting in Barents Sea.

MabCent-SFI is one of fourteen Research-Based Innovation Centers initiated by the Research Council of Norway. It is the only one within the field of “bioactive compounds and drug discovery” that is based on bioactives from marine organisms. MabCent-SFI maintains a focus on bioactives from Arctic and sub-Arctic organisms. By the end of 2011, MabCent had tested about 200,000 extracts, finding several hundred "hits". Through further research and development, some of these hits will become valuable "leads", i.e. characterized compounds known to possess biological effects of interest.  The commercial partners in MabCent-SFI are Biotec Pharmacon ASA and its subsidiary ArcticZymes AS, ABC BioScience AS, Lytix Biopharma AS and Pronova BioPharma ASA. ArcticZymes is also a partner in MARZymes, a project financed by the Research Council of Norway to find marine enzymes which are adapted to the extreme conditions in the Arctic. The science partners in MabCent-SFI are Marbank, a national marine biobank located in Tromsø; Marbio, a medium/high-throughput platform for screening and identification of bioactive compounds; and Norstruct, a protein structure determination platform. Mabcent-SFI is hosted by the University of Tromsø.  BioTech North is an emerging biotechnology cluster of enterprises and R&D organizations, which cooperate closely with regional funding and development actors (triple helix). As bioactive molecules and compounds from Arctic marine resources form the basis of activities for the majority of the cluster members, BioTech North serves as a marine biotech cluster. The majority of BioTech North’s enterprises are active within life science applications and markets. To date the cluster contains around thirty organizations from both the private and public sector. It has received Arena status and is funded through the [ Arena] programme financed by Innovation Norway, SIVA and The Research Council of Norway. Stakeholders of BioTech North include Barents BioCentre Lab, BioStruct, Marbank, Norut, Nofima, Mabcent-SFI, University of Tromsø, Unilab, Barentzymes AS, Trofi, Scandiderma AS, Prophylix Pharma AS, Olivita, Marealis, ProCelo, Probio, Lytix Biopharma, Integorgen, d'Liver, Genøk, Cognis, Clare AS, Chitinor, Calanus AS, Biotec Betaglucans, Ayanda, ArcticZymes AS, ABC Bioscience, Akvaplanniva.

The Barents Sea (, ;, ; ) is a marginal sea of the Arctic Ocean, located off the northern coasts of Norway and Russia and divided between Norwegian and Russian territorial waters. Known among Russians in the Middle Ages as the Murman Sea ("Norwegian Sea"), the current name of the sea is after the historical Dutch navigator Willem Barentsz.

La mer de Barents (ou plus rarement de Barentz ou de Barentsz) est une mer de l'océan Arctique située au nord de la Norvège (Finnmark) et de la Russie occidentale (oblast de Mourmansk et district autonome de Nénétsie). Elle s'étend jusqu'au Spitzberg au nord-ouest et à la terre François-Joseph au nord-nord-est, tandis qu'elle est limitée à l'est par la Nouvelle-Zemble.


Education and early life.

Born on 13 May 1753 in the village of Nolay, Côte-d'Or, Carnot was the son of local judge and royal notary, Claude Carnot and his wife, Marguerite Pothier. He was the second oldest of seven children. At the age of fourteen, Lazare and his brother were enrolled at the Collège d'Autun, in Burgundy where he focused on the study of philosophy and the classics. He held a strong belief in stoic philosophy and was deeply influenced by Roman civilization. When he turned fifteen, he left the Collège d'Autun to strengthen his philosophical knowledge and study under the Society of the Priests of Saint Sulpice. During his short time with them, he studied logic, mathematics and theology under the Abbe Bison. After being impressed with Lazare’s work as a scholar, the Duke D’Aumont (Marquis de Nolay) recommended a military career for the young one. Carnot was soon sent by his father to the Aumont residence to further his education. Here, he was enrolled in M. de Longpres pension school in 1770 until he was ready to enter one of two prestigious engineering and artillery schools in Paris. A year later, in February 1771, he was ranked the third highest among twelve who were chosen out of his class of more than one hundred who took the entrance exams. It was at this point when he entered the École royale du génie de Mézières, appointed as a second lieutenant. Studies at the Mézières included geometry, mechanics, geometrical designing, geography, hydraulics and material preparation. On 1 January 1773 he graduated the school, ranked as a first lieutenant. He was eighteen years old.  It was here where he met and studied with Benjamin Franklin at the age of twenty. He obtained commission as a lieutenant in Louis Joseph, Prince of Condé’s engineer corps. At this moment, he made a name for himself both in the line of (physics) theoretical engineering and in his work in the field of fortifications. While in the army, he continued his study of mathematics. In 1784 he published his first work "Essay on Machines," which contained a statement that foreshadowed the principle of energy as applied to a falling weight, and the earliest proof that kinetic energy is lost in the collision of imperfectly elastic bodies. This publication earned him the honor of admittance to a literary society. Another turning point was his essay on Vauban in which he praises the engineer on his works while at the same time developing his own career as a writer/engineer. Vauban's work had a profound effect on his work as a general and engineer. In that same year, he also received a promotion to the rank of captain.

Political career.

At the outbreak of the French Revolution in 1789, Carnot entered political life. He became a delegate to the Legislature in 1791. While a member of the Legislative Assembly, Carnot was elected to the Committee of Public Instruction. He believed that all citizens should be educated. As a member of that committee, he wrote a series of reforms for the teaching and educational systems, but they were not implemented due to the violent social and economic climate of the Revolution.  After the Legislative Assembly was dissolved, Carnot was elected to the National Convention in 1792. He spent the last few months of 1792 on a mission to Bayonne, organizing the military defense effort in an attempt to ward off any possible attacks from Enlightenment-era Spain. Upon returning to Paris, Carnot voted for the death of King Louis XVI, although he had been absent for the debates surrounding the Trial of Louis XVI.  On 14 August 1793 Carnot was elected to the Committee of Public Safety, where he took charge of the military situation as one of the Ministers of War.  With the establishment of the Directory in 1795, Carnot became one of the five initial directors. For the first year, the Directors did well working harmoniously together as well as with the Councils. However, difference of political views led to a schism between Carnot and Étienne-François Letourneur, followed by François de Barthélemy, on the one side, and the triumvirate of Paul François Jean Nicolas, vicomte de Barras, Jean-François Rewbell, and Louis Marie de La Révellière-Lépeaux on the other side. Carnot and Barthélemy supported concessions to end the war, and hoped to oust the triumvirate and replace them with more conservative men. After Letourneur had been replaced by another close collaborator of Carnot, François de Barthélemy, both of them, alongside many deputies in the Council of Five Hundred, were ousted in the Coup of 18 Fructidor (4 September 1797), engineered by Generals Napoleon Bonaparte (originally, Carnot's "protégé") and Pierre François Charles Augereau. Carnot took refuge in Geneva, and there in 1797 issued his "La métaphysique du calcul infinitésimal".

Military accomplishments.

The creation of the French Revolutionary Army was largely due to his powers of organization and enforcing discipline. In order to raise more troops for the war, Carnot introduced conscription: the "levée en masse" approved by the National Convention was able to raise France’s army from 645,000 troops in mid-1793 to 1,500,000 in September 1794. He was the first to execute the modern waging of war with mass armies and strategic planning realized by the Revolution. As a military engineer, Carnot favored fortresses and defensive strategies. He developed innovative defensive designs for forts, including the Carnot wall, called after him. However, with the constant invasions he decided to take his strategic planning to an offensive strike. From his intellect sprang the maneuvers and organization that turned the tides of war from 1793 to 1794. The basic idea was to have a massive army separated into several units that could move more quickly than the enemy and attack from the flanks rather than head on, which had led to resounding defeats before Carnot was elected to the Committee of Public Safety. This tactic was extremely successful against the more traditional tactics of existing European armies. It was his initiative to train the conscripts in the art of war and to place new recruits with experienced soldiers rather than having a massive volunteer army without any real idea of how to wage battle.  Once the problem of troop numbers had been solved, Carnot turned his administrative skills to the supplies that this massive army would need. Many of the munitions and supplies were in short supply: copper was lacking for guns so he ordered church bells seized in order to melt them down; saltpeter was lacking and he called chemistry to his aid; leather for boots was scarce so he demanded and secured new methods for tanning. He quickly organized the army and helped to turn the tide of the war. It added significantly to discontent with the course of the Revolution in still Bourbon-loyalist areas – such as the Vendée, which had broken out in open revolt 5 months earlier – but the government of the time considered it a success, and Carnot became known as the "Organizer of Victory". In autumn 1793, he took charge of French columns on the Northern Front, and contributed to Jean-Baptiste Jourdan's victory in the Battle of Wattignies.

Relationship with Maximilien Robespierre and the Jacobin Club.

Carnot met Robespierre for the first time in Arras where he was assigned for military duty and shortly after Robespierre finished his legal studies. Both of them were members of the literary and singing "Societe des Rosati." The group was founded in 1778 and was inspired by the works of Chapelle, La Fontaine, and Chaulieu. It was here where they became acquaintances and eventually friends. Robespierre preceded Carnot into the Academy of Arras entering in April 1784 while he entered three years later in 1787.  While being an active member of the Committee of Public Safety in 1794, tensions between Carnot and Robespierre began to rise massively. During his time on the committee, which was heavily radical, Carnot signed a total of 43 decrees and drafted 18 of them. Most of them regarding military tactics and education. Despite leaning on Jacobin beliefs, Carnot was considered the "conservative" of his half. He was not an official member of the radical group and therefore took on his own independent beliefs in regards to many issues. One of these issues included Robespierre's proposal on an egalitarian social system with which he feverishly disagreed.  Although he had taken no steps to oppose the Reign of Terror, he and some other technocrats on the committee, including Robert Lindet and Louis-Bernard Guyton de Morveau, turned on Maximilien Robespierre and his allies during the Thermidorian Reaction by having him arrested. Robespierre was later killed along with 21 of his followers. Shortly after Robespierre's fall, Carnot was charged for his role during the time but the charges were quickly dismissed when he became a member of the Directory.

Relationship with Napoleon Bonaparte.

In 1795, Lazare appointed Napoleon Bonaparte as general in chief of the Army of Italy. He is known to be the only member of the Directory to have supported Napoleon during this time.  In 1800 Bonaparte appointed Carnot as Minister of War, and he served in that office at the time of the Battle of Marengo. In 1802 he voted against the establishment of Napoleon's Consular powers for life and the passing of the title to his children, for as Carnot said when speaking of the power necessary to govern a state "If this power is the appendage of a hereditary family it becomes despotic."  After Napoleon crowned himself emperor on 2 December 1804, Carnot's republican convictions precluded his acceptance of high office under the First French Empire, and he resigned from public life. Probably in response to the fall of the fortress of Vlissingen to the British during the Walcheren Campaign in 1809, Napoleon employed Carnot to write a treatise describing how fortifications could be improved, for the use of the École militaire de Metz. Building on the theories of the controversial engineer Montalembert, Carnot advanced ideas on how the long established bastioned system of fortification could be modified for close defense and to allow for counter attack by the besieged garrison.  In 1812, Carnot returned to office in defense of Napoleon during the disastrous invasion of Russia; he was assigned the defense of Antwerp against the Sixth Coalition – he only surrendered on the demand of the Count of Artois, who was the younger brother of Louis XVIII and later Charles X. He was later made a Count of the Empire by Napoleon as Lazare Nicolas Marguerite, Comte Carnot. During the Hundred Days, Carnot served as Minister of the Interior for Napoleon, and was exiled as a "regicide" during the White Terror after the Second Restoration during the reign of Louis XVIII.

Retirement and legacy.

In 1803 Carnot produced his "Géométrie de position". This work deals with projective rather than descriptive geometry. Carnot is responsible for initiating the use of cross-ratios: "He was the first to introduce the cross (anharmonic) ratio of four points of a line taking account of its sign, thereby sharpening Pappus' concept. He then proved that this ratio is invariant for the four points obtained by cutting four lines of a pencil of lines with different secants. In this way, he established the harmonic properties of the complete quadrilateral." This approach to geometry was used by Karl von Staudt four decades later to set a new foundation to mathematics.  The Borda–Carnot equation in fluid dynamics and several theorems in geometry are named after him: one that describes a property of the incircle and the circumcircle of triangle, one that describes a relation between triangles and conic sections and one that describes a property of certain perpendiculars on triangle sides.  Published in 1810 under the title ""Traité de la Défense des Places Fortes"", his ideas on fortification were further developed in the third edition which was published in 1812. An English translation, "A Treatise on the Defence of Fortified Places" was published in 1814. Although few of his proposals were accepted by mainstream engineers, the Carnot wall, a detached wall at the foot of the, became a common feature in fortifications built in the mid-19th century.  He lived in Warsaw, Congress Poland, and then moved to the Kingdom of Prussia, where he died in the city of Magdeburg. Carnot's remains were interred at the Panthéon in 1889, at the same time as those of Marie Victor de La Tour-Maubourg, Jean-Baptiste Baudin, and François Séverin Marceau-Desgraviers.  Carnot survived all the phases of the French Revolution, from its beginnings in 1789 until the fall of Napoleon in 1815. On the social and political front, Carnot was the author of many reforms sought to improve the country. One of these was the proposal for compulsory public education for all citizens. He also penned a proposal for the new Constitution which included the "Declaration of the Duties of the Citizens" that held that there should be not only education but military service for all citizens of France between the ages of twenty and twenty-five. These proposals were in accordance with the Revolutionaries' thinking at the time, which held that men and women should be honored through ability and intelligence rather than through birthright, even though Carnot himself was nobly born.

Work in mathematics and theoretical engineering.

He also published essays about engineering theory. "Essai sur les machines en général" won honorable mention from the Academie sur Science of Paris in 1780. It was revised and published in 1783. In this he outlined a mathematical theory of power transmission in mechanical systems. His essay "Principes fondamentaux de l'équilibre et du mouvement" 1803 was a further revision and expansion of the earlier work. This was "the first theoretical analysis of engineering mechanics". In this "he went on to analyze the movement of energy from one part of the system to another; he found that power is transmitted most efficiently, and the largest amount of useful work done, when friction, turbulence, and other energy wasting factors are kept to a minimum. This was an early and incomplete approach to the general law of conservation of energy." Carnot's son Nicolas Léonard Sadi Carnot was influenced by his father's work when he undertook his research into the thermal efficiency of steam engines.  Lazare Carnot's name is one of the 72 names inscribed on the Eiffel Tower.

Lazare Nicolas Marguerite, Count Carnot (13 May 1753 – 2 August 1823) was a French mathematician, physicist and politician. He was known as the "Organizer of Victory" in the French Revolutionary Wars and Napoleonic Wars.

Lazare Carnot est un mathématicien, physicien, général et homme politique français, né à Nolay le et mort en exil à Magdebourg en Prusse le. Membre de la Convention nationale et du Comité de salut public, il est surnommé « L'Organisateur de la Victoire » ou « Le Grand Carnot ». Directeur, il est ensuite comte de l'Empire.