Subject:
All Disciplines Arts & Humanities Biology & Life Sciences Business & Economics Chemistry & Materials Science Computer Science & Mathematics Engineering Environmental & Earth Sciences Medicine & Pharmacology Physical Sciences Public Health & Healthcare Social Sciences
Sort:
Hottest Latest Alphabetical (A-Z) Alphabetical (Z-A)
Type:
All Topic Review Biography
Topic Review
Rank-Size Distribution
Rank-size distribution is the distribution of size by rank, in decreasing order of size. For example, if a data set consists of items of sizes 5, 100, 5, and 8, the rank-size distribution is 100, 8, 5, 5 (ranks 1 through 4). This is also known as the rank-frequency distribution, when the source data are from a frequency distribution. These are particularly of interest when the data vary significantly in scale, such as city size or word frequency. These distributions frequently follow a power law distribution, or less well-known ones such as a stretched exponential function or parabolic fractal distribution, at least approximately for certain ranges of ranks; see below. A rank-size distribution is not a probability distribution or cumulative distribution function. Rather, it is a discrete form of a quantile function (inverse cumulative distribution) in reverse order, giving the size of the element at a given rank.
  • 2.7K
  • 31 Oct 2022
Topic Review
Gaia Hypothesis
The Gaia hypothesis (/ˈɡaɪ.ə/), also known as the Gaia theory, Gaia paradigm, or the Gaia principle, proposes that living organisms interact with their inorganic surroundings on Earth to form a synergistic and self-regulating, complex system that helps to maintain and perpetuate the conditions for life on the planet. The hypothesis was formulated by the chemist James Lovelock and co-developed by the microbiologist Lynn Margulis in the 1970s. Lovelock named the idea after Gaia, the primordial goddess who personified the Earth in Greek mythology. The suggestion that the theory should be called "the Gaia hypothesis" came from Lovelock's neighbour, William Golding. In 2006, the Geological Society of London awarded Lovelock the Wollaston Medal in part for his work on the Gaia hypothesis. Topics related to the hypothesis include how the biosphere and the evolution of organisms affect the stability of global temperature, salinity of seawater, atmospheric oxygen levels, the maintenance of a hydrosphere of liquid water and other environmental variables that affect the habitability of Earth. The Gaia hypothesis was initially criticized for being teleological and against the principles of natural selection, but later refinements aligned the Gaia hypothesis with ideas from fields such as Earth system science, biogeochemistry and systems ecology. Even so, the Gaia hypothesis continues to attract criticism, and today many scientists consider it to be only weakly supported by, or at odds with, the available evidence.
  • 2.6K
  • 07 Nov 2022
Topic Review
Intermarium
Intermarium (Polish: Międzymorze, Polish pronunciation: [mʲɛnd͡zɨˈmɔʐɛ]) was a geopolitical project conceived by politicians in successor states of the former Polish–Lithuanian Commonwealth in several iterations, some of which anticipated the inclusion as well of other, neighboring states. The proposed multinational polity would have extended across territories lying between the Baltic, Black and Adriatic Seas, hence the name meaning "Between-Seas". Prospectively a federation of Central and Eastern European countries, the post-World War I Intermarium plan pursued by Polish leader and former political prisoner of the Russian Empire, Józef Piłsudski (1867–1935), sought to recruit to the proposed federation the Baltic states (Lithuania, Latvia, Estonia), Finland , Belarus, Ukraine, Hungary, Romania, Yugoslavia and Czechoslovakia. The Polish name Międzymorze (from między, "between"; and morze, "sea"), meaning "Between-Seas", was rendered into Latin as "Intermarium." The proposed federation was meant to emulate the Polish–Lithuanian Commonwealth, stretching from the Baltic Sea to the Black Sea, that, from the end of the 16th century to the end of the 18th, had united the Kingdom of Poland and the Grand Duchy of Lithuania. Intermarium complemented Piłsudski's other geopolitical vision, Prometheism, whose goal was the dismemberment of the Russian Empire and that Empire's divestment of its territorial acquisitions. Intermarium was, however, perceived by some Lithuanians as a threat to their newly established independence, and by some Ukrainians as a threat to their aspirations for independence, and while France backed the proposal, it was opposed by Russia and by most other Western powers. Within two decades of the failure of Piłsudski's grand scheme, all the countries that he had viewed as candidates for membership in the Intermarium federation had fallen to the Soviet Union or Nazi Germany, except for Finland (which suffered some territorial losses in the 1939–40 Winter War with the Soviet Union).
  • 2.6K
  • 19 Oct 2022
Topic Review
Climate Change Adaptation in Greenland
Climate change adaptation is a pressing issue in Greenland. The term climate change describes long-term changes to the climate system. Since the 1950s a stark rise in global temperatures has been observed. As climate change, whether natural or anthropogenic, impacts the livelihoods of people across the globe, responses i.e. ways to prepare and adjust under changing vulnerabilities become important. Such responses are commonly discussed under the term adaptation, "the process of adjustment to actual or expected climate and its effects", as defined by the IPCC. Geographically Greenland is situated between the Arctic and the Atlantic Ocean, with one third of the island being north of the Arctic Circle. Since the middle of the 20th century, the Arctic has been warming at about twice the global rate. Rising temperatures put increasing pressure on certain plant and tree species and contribute to Greenland's melting ice sheet. This affects and changes the livelihood of the Greenlandic population, particularly the Inuit people, which make up to 80 percent of the total population. Besides the decline of fish stocks, the country's landscape is changing: the melting ice reveals minerals, oil and gas. This has attracted interest from local and foreign investors for potential resource extraction. As new industries are accompanied by new job opportunities and potential wealth, lifestyles are changing. Greenland is in transition, in terms of biophysical as well as cultural and social conditions.
  • 2.6K
  • 20 Nov 2022
Topic Review
Restrictions on Geographic Data in China
Due to national security concerns, the use of geographic information in China is restricted to entities that obtain a special authorization from the administrative department for surveying and mapping under the State Council. Consequences of the restriction include fines for unauthorized surveys, lack of geotagging information on many cameras when the GPS chip detects a location within China, incorrect alignment of street maps with satellite maps in various applications, and seeming unlawfulness of crowdsourced mapping efforts such as OpenStreetMap.
  • 2.5K
  • 25 Nov 2022
Topic Review
Mercury's Magnetic Field
Mercury's magnetic field is approximately a magnetic dipole (meaning the field has only two magnetic poles) apparently global, on planet Mercury. Data from Mariner 10 led to its discovery in 1974; the spacecraft measured the field's strength as 1.1% that of Earth's magnetic field. The origin of the magnetic field can be explained by dynamo theory. The magnetic field is strong enough near the bow shock to slow the solar wind, which induces a magnetosphere.
  • 2.4K
  • 15 Nov 2022
Topic Review
List of Selected Stars for Navigation
Fifty-eight selected navigational stars are given a special status in the field of celestial navigation. Of the approximately 6,000 stars visible to the naked eye under optimal conditions, the selected stars are among the brightest and span 38 constellations of the celestial sphere from the declination of −70° to +89°. Many of the selected stars were named in antiquity by the Babylonians, Greeks, Romans, and Arabs. The star Polaris, often called the "North Star", is treated specially due to its proximity to the north celestial pole. When navigating in the Northern Hemisphere, special techniques can be used with Polaris to determine latitude or gyrocompass error. The other 57 selected stars have daily positions given in nautical almanacs, aiding the navigator in efficiently performing observations on them. A second group of 115 "tabulated stars" can also be used for celestial navigation, but are often less familiar to the navigator and require extra calculations. For purposes of identification, the positions of navigational stars — expressed as declination and sidereal hour angle — are often rounded to the nearest degree. In addition to tables, star charts provide an aid to the navigator in identifying the navigational stars, showing constellations, relative positions, and brightness.
  • 2.4K
  • 26 Oct 2022
Topic Review
Second Bulgarian Empire
The Second Bulgarian Empire (Bulgarian: Второ българско царство, Vtorо Bălgarskо Tsarstvo) was a medieval Bulgarian state that existed between 1185 and 1396. A successor to the First Bulgarian Empire, it reached the peak of its power under Tsars Kaloyan and Ivan Asen II before gradually being conquered by the Ottomans in the late 14th and early 15th centuries. It was succeeded by the Principality and later Kingdom of Bulgaria in 1878. Until 1256, the Second Bulgarian Empire was the dominant power in the Balkans, defeating the Byzantine Empire in several major battles. In 1205 Emperor Kaloyan defeated the newly established Latin Empire in the Battle of Adrianople. His nephew Ivan Asen II defeated the Despotate of Epiros and made Bulgaria a regional power again. During his reign, Bulgaria spread from the Adriatic to the Black Sea and the economy flourished. In the late 13th century, however, the Empire declined under constant invasions by Mongols, Byzantines, Hungarians, and Serbs, as well as internal unrest and revolts. The 14th century saw a temporary recovery and stability, but also the peak of Balkan feudalism as central authorities gradually lost power in many regions. Bulgaria was divided into three parts on the eve of the Ottoman invasion. Despite strong Byzantine influence, Bulgarian artists and architects created their own distinctive style. In the 14th century, during the period known as the Second Golden Age of Bulgarian culture, literature, art and architecture flourished. The capital city Tarnovo, which was considered a "New Constantinople", became the country's main cultural hub and the centre of the Eastern Orthodox world for contemporary Bulgarians. After the Ottoman conquest, many Bulgarian clerics and scholars emigrated to Serbia, Wallachia, Moldavia, and Russian principalities, where they introduced Bulgarian culture, books, and hesychastic ideas.
  • 2.4K
  • 10 Oct 2022
Topic Review
Pine Ridge Indian Reservation
The Pine Ridge Indian Reservation (Template:Lang-lkt), also called Pine Ridge Agency, is an Oglala Lakota Native American reservation located in the U.S. state of South Dakota. Originally included within the territory of the Great Sioux Reservation, Pine Ridge was created by the Act of March 2, 1889, 25 Stat. 888. in the southwest corner of South Dakota on the Nebraska border. Today it consists of 3,468.85 sq mi (8,984.3 km2) of land area and is the eighth-largest reservation in the United States, larger than Delaware and Rhode Island combined. The reservation encompasses the entirety of Oglala Lakota County and Bennett County, the southern half of Jackson County, and a small section of Sheridan County added by Executive Order No. 2980 of February 20, 1904. Of the 3,142 counties in the United States, these are among the poorest. Only 84,000 acres (340 km2) of land are suitable for agriculture. The 2000 census population of the reservation was 15,521; but a study conducted by Colorado State University and accepted by the United States Department of Housing and Urban Development has estimated the resident population to reach 28,787. Pine Ridge is the site of several events that mark milestones in the history between the Sioux of the area and the United States (U.S.) government. Stronghold Table—a mesa in what is today the Oglala-administered portion of Badlands National Park—was the location of the last of the Ghost Dances. The U.S. authorities' attempt to repress this movement eventually led to the Wounded Knee Massacre on December 29, 1890. A mixed band of Miniconjou Lakota and Hunkpapa Sioux, led by Chief Spotted Elk, sought sanctuary at Pine Ridge after fleeing the Standing Rock Agency, where Sitting Bull had been killed during efforts to arrest him. The families were intercepted by a heavily armed detachment of the Seventh Cavalry, which attacked them, killing many women and children as well as warriors. This was the last large engagement between U.S. forces and Native Americans and marked the end of the western frontier. Changes accumulated in the last quarter of the 20th century; in 1971 the Oglala Sioux Tribe (OST) started Oglala Lakota College, a tribal college, which offers 4-year degrees. In 1973 decades of discontent at the Pine Ridge Reservation resulted in a grassroots protest that escalated into the Wounded Knee Incident, gaining national attention. Members of the Oglala Lakota, the American Indian Movement and supporters occupied the town in defiance of federal and state law enforcement in a protest that turned into an armed standoff lasting 71 days. This event inspired American Indians across the country and gradually led to changes at the reservation, with a revival of some cultural traditions. In 1981 the Lakota Tim Giago started the Lakota Times at Pine Ridge, the first independent Native American newspaper in the nation; he published it until selling it in 1998. Located at the southern end of the Badlands, the reservation is part of the mixed grass prairie, an ecological transition zone between the short-grass and tall-grass prairies; all are part of the Great Plains. A great variety of plant and animal life flourishes on and adjacent to the reservation, including the endangered black-footed ferret. The area is also important in the field of paleontology; it contains deposits of Pierre Shale formed on the seafloor of the Western Interior Seaway, evidence of the marine Cretaceous–Paleogene boundary, and one of the largest deposits of fossils of extinct mammals from the Oligocene epoch.
  • 2.3K
  • 07 Oct 2022
Topic Review
Stone Mountain
Stone Mountain is a quartz monzonite dome monadnock and the site of Stone Mountain Park near Stone Mountain, Georgia. At its summit, the elevation is 1,686 feet (514 m) above sea level and 825 feet (251 m) above the surrounding area. Stone Mountain is well known for not only its geology, but also the enormous rock relief on its north face, the largest bas-relief in the world. The carving depicts three Confederate figures, Jefferson Davis, Robert E. Lee and Stonewall Jackson, and has been the subject of widespread controversy. Stone Mountain was once owned by the Venable Brothers. It was purchased by the State of Georgia in 1958 "as a memorial to the Confederacy." Stone Mountain Park officially opened on April 14, 1965 – 100 years to the day after Lincoln's assassination, although the park had been in use for a few years. It is the most visited destination in the state of Georgia. Stone Mountain is more than 5 miles (8 km) in circumference at its base. The summit of the mountain can be reached by a walk-up trail on the west side of the mountain or by the Skyride aerial tram.
  • 2.3K
  • 04 Nov 2022
  • Page
  • of
  • 31
Featured Entry Collections
>>

Featured Books

>>
Encyclopedia of Social Sciences
Encyclopedia of COVID-19
Encyclopedia of Fungi
Encyclopedia of Digital Society, Industry 5.0 and Smart City
Video Production Service
Feedback