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:
Most Viewed Latest Alphabetical (A-Z) Alphabetical (Z-A)
Filter:
All Topic Review Biography Peer Reviewed Entry Video Entry
Topic Review
Degua Tembien
Dogu'a Tembien (Template:Lang-ti, "Upper Tembien", sometimes transliterated as Degua Tembien) is one of the woredas in the Tigray Region of Ethiopia. It is named in part after the former province of Tembien. Nowadays, the mountainous district is part of the Southeastern Tigray Zone. The administrative centre of this woreda is Hagere Selam.
  • 1.6K
  • 01 Nov 2022
Topic Review
Prognathodon
Prognathodon is an extinct genus of marine lizard belonging to the mosasaur family. It is classified as part of the Mosasaurinae subfamily, alongside genera like Mosasaurus and Clidastes. Prognathodon has been recovered from deposits ranging in age from the Campanian to the Maastrichtian in the Middle East, Europe, New Zealand, and North America. Prognathodon means "forejaw tooth", which originates from the Latin pro- ("earlier" or "prior"), Greek gnathos ("jaw") and odṓn ("tooth"). Twelve nominal species of Prognathodon are recognised, from North America, northern and western Africa, the Middle East, western Europe and New Zealand. Due to the sometimes clear differences between them and the incomplete nature of many of the specimens, the systematics of the genus and which species should properly be considered Prognathodon is controversial. Some species have been assigned to other genera, such as Dollosaurus and Brachysaurana, but this has also been questioned. Prognathodon is known for its massively built jaws and teeth. Its distinct feeding adaptations have generated much interest in its ecology ever since its discovery, though direct evidence of its diet, such as gastric residues, is rare.
  • 1.6K
  • 19 Oct 2022
Topic Review
Lake Taupo
Lake Taupo, often spelled Taupō, is a lake in the North Island of New Zealand. It is in the caldera of the Taupo Volcano. The lake is the namesake of the town of Taupō, which sits on a bay in the lake's north-eastern shore. With a surface area of 616 square kilometres (238 sq mi), it is the largest lake by surface area in New Zealand, and the second largest freshwater lake by surface area in geopolitical Oceania after Lake Murray in Papua New Guinea. Motutaiko Island lies in the south east area of the lake. Lake Taupo has a perimeter of approximately 193 kilometres and a maximum depth of 186 metres. It is drained by the Waikato River (New Zealand's longest river), and its main tributaries are the Waitahanui River, the Tongariro River, and the Tauranga Taupo River. It is a noted trout fishery with stocks of introduced brown and rainbow trout. The level of the lake is controlled by Mercury Energy, the owner of the eight hydroelectric dams on the Waikato River downstream of Lake Taupo, using gates built in 1940–41. The gates are used to reduce flooding, conserve water and ensure a minimum flow of 50 m3/s (1,800 cu ft/s) in the Waikato River. The resource consent allows the level of the lake to be varied between 355.85 and 357.25 metres (1,167.5 and 1,172.1 ft) above sea level.
  • 1.5K
  • 08 Nov 2022
Topic Review
Map Projections Classification
Many books, textbooks and papers have been published in which the classification of map projections is based on auxiliary (developable) surfaces and projections are divided into conic, cylindrical and azimuthal projections.
  • 1.5K
  • 13 Jun 2022
Topic Review
Lignocellulosic Biofuels: A Renewable Bioenergy
Biofuel consists of non-fossil fuel derived from the organic biomass of renewable resources, including plants, animals, microorganisms, and waste. Energy derived from biofuel is known as bioenergy. The reserve of fossil fuels is now limited and continuing to decrease, while at the same time demand for energy is increasing. In order to overcome this scarcity, it is vital for human beings to transfer their dependency on fossil fuels to alternative types of fuel, including biofuels, which are effective methods of fulfilling present and future demands. The conversion of lignocellulosic feedstock is an important step during biofuel production. It is, however, important to note that, as a result of various technical restrictions, biofuel production is not presently cost efficient, thus leading to the need for improvement in the methods employed. 
  • 1.5K
  • 26 Apr 2022
Topic Review
Celestial Coordinate System
In astronomy, a celestial coordinate system (or celestial reference system) is a system for specifying positions of satellites, planets, stars, galaxies, and other celestial objects relative to physical reference points available to a situated observer (e.g. the true horizon and north cardinal direction to an observer situated on the Earth's surface). Coordinate systems can specify an object's position in three-dimensional space or plot merely its direction on a celestial sphere, if the object's distance is unknown or trivial. The coordinate systems are implemented in either spherical or rectangular coordinates. Spherical coordinates, projected on the celestial sphere, are analogous to the geographic coordinate system used on the surface of Earth. These differ in their choice of fundamental plane, which divides the celestial sphere into two equal hemispheres along a great circle. Rectangular coordinates, in appropriate units, are simply the Cartesian equivalent of the spherical coordinates, with the same fundamental (x, y) plane and primary (x-axis) direction. Each coordinate system is named after its choice of fundamental plane.
  • 1.5K
  • 02 Dec 2022
Topic Review
Mekong
The Mekong, or Mekong River, is a trans-boundary river in East Asia and Southeast Asia. It is the world's twelfth longest river and the sixth longest in Asia. Its estimated length is 4,909 km (3,050 mi), and it drains an area of 795,000 km2 (307,000 sq mi), discharging 475 km3 (114 cu mi) of water annually. From the Tibetan Plateau the river runs through China , Myanmar, Laos, Thailand, Cambodia, and Vietnam. The extreme seasonal variations in flow and the presence of rapids and waterfalls in the Mekong make navigation difficult. Even so, the river is a major trade route between western China and Southeast Asia.
  • 1.5K
  • 25 Nov 2022
Topic Review
Alcohol Belts of Europe
The alcohol belts of Europe divide Europe by their traditional alcoholic beverages: beer, wine, or spirits. They do not necessarily correspond with current drinking habits, as beer has become the most popular alcoholic drink world-wide. The definitions of these belts are not completely objective.
  • 1.5K
  • 25 Oct 2022
Topic Review
Río Negro Province
Río Negro (Spanish pronunciation: [ˈri.o ˈneɣɾo], Black River) is a province of Argentina , located at the northern edge of Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean. Its capital is Viedma, and its largest city is Bariloche. Other important cities include General Roca and Cipolletti.
  • 1.4K
  • 14 Oct 2022
Topic Review
List of Minerals I (Complete)
This list includes those recognised minerals beginning with the letter I. The International Mineralogical Association is the international group that recognises new minerals and new mineral names, however minerals discovered before 1959 did not go through the official naming procedure, although some minerals published previously have been either confirmed or discredited since that date. This list contains a mixture of mineral names that have been approved since 1959 and those mineral names believed to still refer to valid mineral species (these are called "grandfathered" species). The list is divided into groups: The data was exported from mindat.org on 29 April 2005; updated up to 'IMA2018'. The minerals are sorted by name, followed by the structural group (rruff.info/ima and ima-cnmnc by mineralienatlas.de, mainly) or chemical class (mindat.org and basics), the year of publication (if it's before of an IMA approval procedure), the IMA approval and the Nickel–Strunz code. The first link is to mindat.org, the second link is to webmineral.com, and the third is to the Handbook of Mineralogy (Mineralogical Society of America).
  • 1.4K
  • 20 Oct 2022
Topic Review
Karratha, Western Australia
Karratha is a city in the Pilbara region of Western Australia, adjoining the port of Dampier. It was established in 1968 to accommodate the processing and exportation workforce of the Hamersley Iron mining company and, in the 1980s, the petroleum and liquefied natural gas operations of the North West Shelf Venture. At June 2018, Karratha had an urban population of 16,708. The city's name comes from the cattle station of the same name, which derives from a word in a local Aboriginal language meaning "good country" or "soft earth". The city is the seat of government of the City of Karratha, a local government area covering the surrounding region.
  • 1.4K
  • 30 Sep 2022
Topic Review
Global Storm Activity of 2009
Global storm activity of 2009 profiles the major worldwide storms, including blizzards, ice storms, and other winter events, from January 1, 2009 to December 31, 2009. Wintery storms are events in which the dominant varieties of precipitation are forms that only occur at cold temperatures, such as snow or sleet, or a rainstorm where ground temperatures are cold enough to allow ice to form (i.e. freezing rain). It may be marked by strong wind, thunder and lightning (a thunderstorm), heavy precipitation, such as ice (ice storm), or wind transporting some substance through the atmosphere (as in a dust storm, snowstorm, hailstorm, etc.). Summer storms including flooding, severe thunderstorms and extratropical cyclones (which can occur in summer or winter) are also included in this list to a certain extent. As this occurred a heat wave and/or unforeseen monsoon weather also hit parts of Australia in 2009 and 2010. Victoria, the scene of horrific bushfires the year before, had a far colder summer, with hot weather arriving more than a month later than usual in 2009. August 17 saw a dust storm at Laguna Mar Chiquita as a major drought hit Argentina , and flooding and hailstorms hit southeastern Australia and Queensland in March 2010. The lack of winter precipitation in parts of China, however, contributed to a severe drought in the southwest. Bolivia, Venezuela, Mali, Mauritania, Morocco and Spain have also seen periods of drought in 2009 and 2010. On between May 12 and 26, both Mauritania, the Sénégal River Area and neighbouring parts of both Senegal and Mali faced both a drought and famine in 2010. A storm (from Proto-Germanic *sturmaz "noise, tumult") is any disturbed state of an astronomical body's atmosphere, especially affecting its surface, and strongly implying severe weather. Storms are created when a centre of low pressure develops, with a system of high pressure surrounding it. This combination of opposing forces can create winds and result in the formation of storm clouds, such as the cumulonimbus. Small, localized areas of low pressure can form from hot air rising off hot ground, resulting in smaller meteorological disturbances such as dust devils and whirlwinds.
  • 1.4K
  • 09 Nov 2022
Topic Review
List of Minerals U–V (Complete)
This list includes those recognised minerals beginning with the letters U and V. The International Mineralogical Association is the international group that recognises new minerals and new mineral names, however minerals discovered before 1959 did not go through the official naming procedure, although some minerals published previously have been either confirmed or discredited since that date. This list contains a mixture of mineral names that have been approved since 1959 and those mineral names believed to still refer to valid mineral species (these are called "grandfathered" species). The list is divided into groups: The data was exported from mindat.org on 29 April 2005; updated up to 'IMA2018'. The minerals are sorted by name, followed by the structural group (rruff.info/ima and ima-cnmnc by mineralienatlas.de, mainly) or chemical class (mindat.org and basics), the year of publication (if it's before of an IMA approval procedure), the IMA approval and the Nickel–Strunz code. The first link is to mindat.org, the second link is to webmineral.com, and the third is to the Handbook of Mineralogy (Mineralogical Society of America).
  • 1.4K
  • 07 Oct 2022
Topic Review
Reinforcement (Speciation)
Reinforcement is a process of speciation where natural selection increases the reproductive isolation (further divided to pre-zygotic isolation and post-zygotic isolation) between two populations of species. This occurs as a result of selection acting against the production of hybrid individuals of low fitness. The idea was originally developed by Alfred Russel Wallace and is sometimes referred to as the Wallace effect. The modern concept of reinforcement originates from Theodosius Dobzhansky. He envisioned a species separated allopatrically, where during secondary contact the two populations mate, producing hybrids with lower fitness. Natural selection results from the hybrid's inability to produce viable offspring; thus members of one species who do not mate with members of the other have greater reproductive success. This favors the evolution of greater prezygotic isolation (differences in behavior or biology that inhibit formation of hybrid zygotes). Reinforcement is one of the few cases in which selection can favor an increase in prezygotic isolation, influencing the process of speciation directly. This aspect has been particularly appealing among evolutionary biologists. The support for reinforcement has fluctuated since its inception, and terminological confusion and differences in usage over history have led to multiple meanings and complications. Various objections have been raised by evolutionary biologists as to the plausibility of its occurrence. Since the 1990s, data from theory, experiments, and nature have overcome many of the past objections, rendering reinforcement widely accepted,:354 though its prevalence in nature remains unknown. Numerous models have been developed to understand its operation in nature, most relying on several facets: genetics, population structures, influences of selection, and mating behaviors. Empirical support for reinforcement exists, both in the laboratory and in nature. Documented examples are found in a wide range of organisms: both vertebrates and invertebrates, fungi, and plants. The secondary contact of originally separated incipient species (the initial stage of speciation) is increasing due to human activities such as the introduction of invasive species or the modification of natural habitats. This has implications for measures of biodiversity and may become more relevant in the future.
  • 1.4K
  • 28 Apr 2023
Topic Review
Map Symbolization
Map symbolization is the characters, letters, or similar graphic representations used on a map to indicate an object or characteristic in the real world.
  • 1.4K
  • 02 Dec 2022
Topic Review
HANPP
Human appropriation of net primary production (HANPP) is a substantial improvement upon 20th century attempts at developing an ecological footprint indicator because of its measurability in relation to net primary production, its close relationship to other key footprint measures, such as carbon and water, and its spatial specificity. HANPP informs different sustainability narratives at different scales. At the planetary scale, HANPP is a critical planetary limit that improves upon areal land use indicators. At the country macroscale, HANPP indicates the degree to which meeting the needs of the domestic population for provisioning ecosystem services (food, feed, biofiber, biofuel) presses against the domestic ecological endowment of net primary production. At the county mesoscale, HANPP reveals the dependency of metropolitan areas upon regional specialized rural forestry and agroecosystems to which they are teleconnected through trade and transport infrastructures. At the pixel microscale, HANPP provides the basis for deriving spatial patterns of remaining net primary production upon which biodiversity and regulatory and cultural ecosystem services are dependent. HANPP is thus a sustainability indicator that can fulfill similar needs as carbon, water and other footprints.
  • 1.3K
  • 23 Aug 2021
Topic Review
Ciolo (Apulia)
Ciolo is a narrow coastal inlet and a site of historical and environmental interest, which is located in Apulia, Italy. The location is also known as a geological site and for the presence of numerous sea caves, the largest one being the Grotta del Ciolo. Since October 2006 the Ciolo's area has become part of the Regional Park "Costa Otranto - Santa Maria di Leuca e Bosco di Tricase", created by the Apulia region to protect the eastern coast of Salento, specifically the architectural assets as well as important animal and plant species. The name Ciolo comes from the noun in salentino dialect "ciole", which refers to crows or magpies, which are widespread in this region.
  • 1.3K
  • 14 Nov 2022
Topic Review
Sulfate-Reducing Microorganisms
Sulfate-reducing microorganisms (SRM) or sulfate-reducing prokaryotes (SRP) are a group composed of sulfate-reducing bacteria (SRB) and sulfate-reducing archaea (SRA), both of which can perform anaerobic respiration utilizing sulfate (SO42–) as terminal electron acceptor, reducing it to hydrogen sulfide (H2S). Therefore, these sulfidogenic microorganisms "breathe" sulfate rather than molecular oxygen (O2), which is the terminal electron acceptor reduced to water (H2O) in aerobic respiration. Most sulfate-reducing microorganisms can also reduce some other oxidized inorganic sulfur compounds, such as sulfite (SO32–), dithionite (S2O42–), thiosulfate (S2O32–), trithionate (S3O62–), tetrathionate (S4O62−), elemental sulfur (S8), and polysulfides (Sn2−). Depending on the context, "sulfate-reducing microorganisms" can be used in a broader sense (including all species that can reduce any of these sulfur compounds) or in a narrower sense (including only species that reduce sulfate, and excluding strict thiosulfate and sulfur reducers, for example). Sulfate-reducing microorganisms can be traced back to 3.5 billion years ago and are considered to be among the oldest forms of microbes, having contributed to the sulfur cycle soon after life emerged on Earth. Many organisms reduce small amounts of sulfates in order to synthesize sulfur-containing cell components; this is known as assimilatory sulfate reduction. By contrast, the sulfate-reducing microorganisms considered here reduce sulfate in large amounts to obtain energy and expel the resulting sulfide as waste; this is known as dissimilatory sulfate reduction. They use sulfate as the terminal electron acceptor of their electron transport chain. Most of them are anaerobes; however, there are examples of sulfate-reducing microorganisms that are tolerant of oxygen, and some of them can even perform aerobic respiration. No growth is observed when oxygen is used as the electron acceptor. In addition, there are sulfate-reducing microorganisms that can also reduce other electron acceptors, such as fumarate, nitrate (NO3−), nitrite (NO2−), ferric iron [Fe(III)], and dimethyl sulfoxide. In terms of electron donor, this group contains both organotrophs and lithotrophs. The organotrophs oxidize organic compounds, such as carbohydrates, organic acids (e.g., formate, lactate, acetate, propionate, and butyrate), alcohols (methanol and ethanol), aliphatic hydrocarbons (including methane), and aromatic hydrocarbons (benzene, toluene, ethylbenzene, and xylene). The lithotrophs oxidize molecular hydrogen (H2), for which they compete with methanogens and acetogens in anaerobic conditions. Some sulfate-reducing microorganisms can directly utilize metallic iron [Fe(0)] as electron donor, oxidizing it to ferrous iron [Fe(II)].
  • 1.3K
  • 04 Nov 2022
Topic Review
Application of Environmental Enrichment Strategies in Sea Turtles
Environmental enrichment (EE) is a series of techniques and methods aimed to improve the welfare of animals in captivity and/or under rehabilitation. It uses external stimuli to enhance their psychological and physiological wellbeing to promote natural abilities and behaviors.
  • 1.3K
  • 09 Feb 2022
Topic Review
Cairn
A cairn is a man-made pile (or stack) of stones. The word cairn comes from the Scottish Gaelic: càrn [ˈkʰaːrˠn̪ˠ] (plural càirn [ˈkʰaːrˠɲ]). Cairns have been and are used for a broad variety of purposes, from prehistoric times to the present. In modern times, cairns are often erected as landmarks, a use they have had since ancient times. However, since prehistory, they have also been built and used as burial monuments; for defense and hunting; for ceremonial purposes, sometimes relating to astronomy; to locate buried items, such as caches of food or objects; and to mark trails, among other purposes. Cairns are used as trail markers in many parts of the world, in uplands, on moorland, on mountaintops, near waterways and on sea cliffs, as well as in barren deserts and tundras. They vary in size from small stone markers to entire artificial hills, and in complexity from loose conical rock piles to delicately balanced sculptures and elaborate feats of megalithic engineering. Cairns may be painted or otherwise decorated, whether for increased visibility or for religious reasons. An ancient example is the inuksuk (plural inuksuit), used by the Inuit, Inupiat, Kalaallit, Yupik, and other peoples of the Arctic region of North America. Inuksuit are found from Alaska to Greenland. This region, above the Arctic Circle, is dominated by the tundra biome and has areas with few natural landmarks.
  • 1.3K
  • 30 Nov 2022
  • Page
  • of
  • 16
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
ScholarVision Creations
Feedback