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Effigia is an extinct genus of shuvosaurid known from the Late Triassic of New Mexico, south-western USA. With a bipedal stance, long neck, and a toothless beaked skull, Effigia and other shuvosaurids bore a resemblance to the ornithomimid dinosaurs of the Cretaceous Period. However, shuvosaurids were not dinosaurs, bu... | Effigia | Wikipedia | 361 | 3992446 | https://en.wikipedia.org/wiki/Effigia | Biology and health sciences | Other prehistoric archosaurs | Animals |
Effigia is noted for its remarkable similarity to ornithomimid dinosaurs. In 2007, Nesbitt's description demonstrated that Effigia was very similar to Shuvosaurus, and is definitely a member of the archosaur subgroup Pseudosuchia (the line leading towards modern crocodilians). Its similarity to ornithomimids represents... | Effigia | Wikipedia | 284 | 3992446 | https://en.wikipedia.org/wiki/Effigia | Biology and health sciences | Other prehistoric archosaurs | Animals |
Medulloblastoma is a common type of primary brain cancer in children. It originates in the part of the brain that is towards the back and the bottom, on the floor of the skull, in the cerebellum, or posterior fossa.
The brain is divided into two main parts, the larger cerebrum on top and the smaller cerebellum below t... | Medulloblastoma | Wikipedia | 490 | 3994623 | https://en.wikipedia.org/wiki/Medulloblastoma | Biology and health sciences | Cancer | Health |
Pathogenesis
Medulloblastomas are usually found in the vicinity of the fourth ventricle, between the brainstem and the cerebellum. Tumors with similar appearance and characteristics originate in other parts of the brain, but they are not identical to medulloblastoma.
Although medulloblastomas are thought to originate... | Medulloblastoma | Wikipedia | 495 | 3994623 | https://en.wikipedia.org/wiki/Medulloblastoma | Biology and health sciences | Cancer | Health |
Diagnosis
The tumor is distinctive on T1- and T2-weighted MRI with heterogeneous enhancement and a typical location adjacent to and extension into the fourth ventricle. Histologically, the tumor is solid, pink-gray in color, and is well circumscribed. The tumor is very cellular, with high mitotic activity, little cytop... | Medulloblastoma | Wikipedia | 396 | 3994623 | https://en.wikipedia.org/wiki/Medulloblastoma | Biology and health sciences | Cancer | Health |
Chemotherapy
Chemotherapy is often used as part of treatment. Evidence of benefit, however, is not clear as of 2013. A few different chemotherapeutic regimens for medulloblastoma are used; most involve a combination of lomustine, cisplatin, carboplatin, vincristine, or cyclophosphamide. In younger patients (less than 3... | Medulloblastoma | Wikipedia | 380 | 3994623 | https://en.wikipedia.org/wiki/Medulloblastoma | Biology and health sciences | Cancer | Health |
Survival
The historical cumulative relative survival rate for all age groups and histology follow-up was 60%, 52%, and 47% at 5 years, 10 years, and 20 years, respectively. Patients diagnosed with a medulloblastoma or PNET are 50 times more likely to die than a matched member of the general population.
A population-bas... | Medulloblastoma | Wikipedia | 511 | 3994623 | https://en.wikipedia.org/wiki/Medulloblastoma | Biology and health sciences | Cancer | Health |
Epidemiology
Medulloblastomas affect just under two people per million per year, and affect children 10 times more than adults. Medulloblastoma is the second-most frequent brain tumor in children after pilocytic astrocytoma and the most common malignant brain tumor in children, comprising 14.5% of newly diagnosed brain... | Medulloblastoma | Wikipedia | 435 | 3994623 | https://en.wikipedia.org/wiki/Medulloblastoma | Biology and health sciences | Cancer | Health |
The gray junglefowl (Gallus sonneratii), also known as Sonnerat's junglefowl, is one of the wild ancestors of the domestic chicken together with the red junglefowl and other junglefowls.
The species epithet commemorates the French explorer Pierre Sonnerat. Local names include Komri in Rajasthan, Geera kur or Parda kom... | Grey junglefowl | Wikipedia | 425 | 3998129 | https://en.wikipedia.org/wiki/Grey%20junglefowl | Biology and health sciences | Galliformes | Animals |
Behaviour
Their loud calls of Ku-kayak-kyuk-kyuk () are loud and distinctive, and can be heard in the early mornings and at dusk. Unlike the red junglefowl, the male does not flap its wings before uttering the call. They breed from February to May. They lay 4 to 7 eggs which are pale creamy in a scrape. Eggs hatch in a... | Grey junglefowl | Wikipedia | 471 | 3998129 | https://en.wikipedia.org/wiki/Grey%20junglefowl | Biology and health sciences | Galliformes | Animals |
An endogenous retroviral DNA sequence, of the EAV-HP group noted in domestic chickens is also found in the genome of this species pointing to the early integration of the virus DNA into the genome of Gallus. | Grey junglefowl | Wikipedia | 46 | 3998129 | https://en.wikipedia.org/wiki/Grey%20junglefowl | Biology and health sciences | Galliformes | Animals |
A photonic metamaterial (PM), also known as an optical metamaterial, is a type of electromagnetic metamaterial, that interacts with light, covering terahertz (THz), infrared (IR) or visible wavelengths. The materials employ a periodic, cellular structure.
The subwavelength periodicity distinguishes photonic metamateri... | Photonic metamaterial | Wikipedia | 276 | 24706093 | https://en.wikipedia.org/wiki/Photonic%20metamaterial | Physical sciences | Basics_3 | Physics |
History
While researching whether or not matter interacts with the magnetic component of light, Victor Veselago (1967) envisioned the possibility of refraction with a negative sign, according to Maxwell's equations. A refractive index with a negative sign is the result of permittivity, ε < 0 (less than zero) and magnet... | Photonic metamaterial | Wikipedia | 490 | 24706093 | https://en.wikipedia.org/wiki/Photonic%20metamaterial | Physical sciences | Basics_3 | Physics |
Only fabricated NIMs exhibit this capability. Photonic crystals, like many other known systems, can exhibit unusual propagation behavior such as reversal of phase and group velocities. However, negative refraction does not occur in these systems.
Naturally occurring ferromagnetic and antiferromagnetic materials can ac... | Photonic metamaterial | Wikipedia | 472 | 24706093 | https://en.wikipedia.org/wiki/Photonic%20metamaterial | Physical sciences | Basics_3 | Physics |
Coupling magnetism
Negative magnetic permeability was originally achieved in a left-handed medium at microwave frequencies by using arrays of split-ring resonators. In most natural materials, the magnetically coupled response starts to taper off at frequencies in the gigahertz range, which implies that significant magn... | Photonic metamaterial | Wikipedia | 411 | 24706093 | https://en.wikipedia.org/wiki/Photonic%20metamaterial | Physical sciences | Basics_3 | Physics |
The metamaterial is made of four layers on a silicon substrate. The first layer is palladium, covered by polyimide (plastic) and a palladium screen on top. The screen has sub-wavelength cutouts that block the various wavelengths. A polyimide layer caps the whole absorber. It can absorb 90 percent of infrared radiation ... | Photonic metamaterial | Wikipedia | 464 | 24706093 | https://en.wikipedia.org/wiki/Photonic%20metamaterial | Physical sciences | Basics_3 | Physics |
Lumped circuit elements
By employing a combination of plasmonic and non-plasmonic nanoparticles, lumped circuit element nanocircuits at infrared and optical frequencies appear to be possible. Conventional lumped circuit elements are not available in a conventional way.
Subwavelength lumped circuit elements proved wor... | Photonic metamaterial | Wikipedia | 427 | 24706093 | https://en.wikipedia.org/wiki/Photonic%20metamaterial | Physical sciences | Basics_3 | Physics |
Layering
Stacking layers produces NIMs at optical frequencies. However, the surface configuration (non-planar, bulk) of the SRR normally prevents stacking. Although a single-layer SRR structure can be constructed on a dielectric surface, it is relatively difficult to stack these bulk structures due to alignment toleran... | Photonic metamaterial | Wikipedia | 420 | 24706093 | https://en.wikipedia.org/wiki/Photonic%20metamaterial | Physical sciences | Basics_3 | Physics |
A separation process is a method that converts a mixture or a solution of chemical substances into two or more distinct product mixtures, a scientific process of separating two or more substances in order to obtain purity. At least one product mixture from the separation is enriched in one or more of the source mixture... | Separation process | Wikipedia | 467 | 34880278 | https://en.wikipedia.org/wiki/Separation%20process | Physical sciences | Separation processes | Chemistry |
List of separation techniques
Centrifugation and cyclonic separation, separates based on density differences
Chelation
Chromatography separates dissolved substances by different interaction with (i.e., travel through) a material.
High-performance liquid chromatography (HPLC)
Thin-layer chromatography (TLC)
Counte... | Separation process | Wikipedia | 500 | 34880278 | https://en.wikipedia.org/wiki/Separation%20process | Physical sciences | Separation processes | Chemistry |
Vapor–liquid separation, separates by gravity, based on the Souders–Brown equation
Winnowing
Zone refining | Separation process | Wikipedia | 23 | 34880278 | https://en.wikipedia.org/wiki/Separation%20process | Physical sciences | Separation processes | Chemistry |
Endospore staining is a technique used in bacteriology to identify the presence of endospores in a bacterial sample. Within bacteria, endospores are protective structures used to survive extreme conditions, including high temperatures making them highly resistant to chemicals. Endospores contain little or no ATP which ... | Endospore staining | Wikipedia | 487 | 34888669 | https://en.wikipedia.org/wiki/Endospore%20staining | Biology and health sciences | Basics_3 | Biology |
Bacillus anthraces, which causes anthrax
Bacillus cereus- Can cause two types of food poisoning: emetic and diarrheal
Bacillus subtilis- Found in soil
Clostridium tetani,- Spore that causes lockjaw (tetanus) and rigid paralysis.
Clostridium botulinum- Spore found in foods that have not been canned properly. Clostridi... | Endospore staining | Wikipedia | 494 | 34888669 | https://en.wikipedia.org/wiki/Endospore%20staining | Biology and health sciences | Basics_3 | Biology |
Using aseptic technique, prepare and air dried heat fixed slide with the desired organism.
Prepare a boiling water bath.
Cover the slide with a piece of paper towel and place on staining rack over the water bath.
Flood the paper towel on the slide with Malachite Green ( primary stain).
Steam the slide for 5 to 7 mi... | Endospore staining | Wikipedia | 204 | 34888669 | https://en.wikipedia.org/wiki/Endospore%20staining | Biology and health sciences | Basics_3 | Biology |
In probability theory, statistics and related fields, a Poisson point process (also known as: Poisson random measure, Poisson random point field and Poisson point field) is a type of mathematical object that consists of points randomly located on a mathematical space with the essential feature that the points occur ind... | Poisson point process | Wikipedia | 311 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
The point process depends on a single mathematical object, which, depending on the context, may be a constant, a locally integrable function or, in more general settings, a Radon measure. In the first case, the constant, known as the rate or intensity, is the average density of the points in the Poisson process located... | Poisson point process | Wikipedia | 492 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
where denotes factorial and the parameter determines the shape of the distribution. (In fact, equals the expected value of .)
By definition, a Poisson point process has the property that the number of points in a bounded region of the process's underlying space is a Poisson-distributed random variable.
Complete in... | Poisson point process | Wikipedia | 510 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
Interpreted as a point process on the real line
Interpreted as a point process, a Poisson point process can be defined on the real line by considering the number of points of the process in the interval . For the homogeneous Poisson point process on the real line with parameter , the probability of this random number o... | Poisson point process | Wikipedia | 506 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
Orderliness and simplicity
A point process with stationary increments is sometimes said to be orderly or regular if:
where little-o notation is being used. A point process is called a simple point process when the probability of any of its two points coinciding in the same position, on the underlying space, is zero. ... | Poisson point process | Wikipedia | 474 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
A spatial Poisson process is a Poisson point process defined in the plane . For its mathematical definition, one first considers a bounded, open or closed (or more precisely, Borel measurable) region of the plane. The number of points of a point process existing in this region is a random variable, denoted by . If ... | Poisson point process | Wikipedia | 471 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
If the homogeneous point process is defined on the real line as a mathematical model for occurrences of some phenomenon, then it has the characteristic that the positions of these occurrences or events on the real line (often interpreted as time) will be uniformly distributed. More specifically, if an event occurs (acc... | Poisson point process | Wikipedia | 442 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
Counting process interpretation
The inhomogeneous Poisson point process, when considered on the positive half-line, is also sometimes defined as a counting process. With this interpretation, the process, which is sometimes written as , represents the total number of occurrences or events that have happened up to and in... | Poisson point process | Wikipedia | 490 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
For example, given a homogeneous Poisson point process on the real line, the probability of finding a single point of the process in a small interval of width is approximately . In fact, such intuition is how the Poisson point process is sometimes introduced and its distribution derived.
Simple point process
If a Po... | Poisson point process | Wikipedia | 436 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
Inhomogeneous case
For the inhomogeneous case, a couple of different methods can be used depending on the nature of the intensity function . If the intensity function is sufficiently simple, then independent and random non-uniform (Cartesian or other) coordinates of the points can be generated. For example, simulating ... | Poisson point process | Wikipedia | 508 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
where the density is known, among other terms, as the intensity function.
History
Poisson distribution
Despite its name, the Poisson point process was neither discovered nor studied by its namesake. It is cited as an example of Stigler's law of eponymy. The name arises from the process's inherent relation to the Po... | Poisson point process | Wikipedia | 462 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
In Denmark A.K. Erlang derived the Poisson distribution in 1909 when developing a mathematical model for the number of incoming phone calls in a finite time interval. Erlang unaware of Poisson's earlier work and assumed that the number phone calls arriving in each interval of time were independent of each other. He the... | Poisson point process | Wikipedia | 453 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
It is believed that William Feller was the first in print to refer to it as the Poisson process in a 1940 paper. Although the Swede Ove Lundberg used the term Poisson process in his 1940 PhD dissertation, in which Feller was acknowledged as an influence, it has been claimed that Feller coined the term before 1940. It h... | Poisson point process | Wikipedia | 452 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
The measure is called the intensity measure, mean measure, or parameter measure, as there are no standard terms. If has a derivative or density, denoted by , is called the intensity function of the Poisson point process. For the homogeneous Poisson point process, the derivative of the intensity measure is simply a ... | Poisson point process | Wikipedia | 481 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
demonstrates two different ways to write a summation over a point process (see also Campbell's theorem (probability)). More specifically, the integral notation on the left-hand side is interpreting the point process as a random counting measure while the sum on the right-hand side suggests a random set interpretation.
... | Poisson point process | Wikipedia | 493 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
where is the length, area, or volume (or more generally, the Lebesgue measure) of . Furthermore, the -th factorial moment density is:
Avoidance function
The avoidance function or void probability of a point process is defined in relation to some set , which is a subset of the underlying space , as the probability... | Poisson point process | Wikipedia | 467 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
The two separate Poisson point processes formed respectively from the removed and kept points are stochastically independent of each other. In other words, if a region is known to contain kept points (from the original Poisson point process), then this will have no influence on the random number of removed points in t... | Poisson point process | Wikipedia | 497 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
In other words, after each random and independent displacement of points, the original Poisson point process still exists.
The displacement theorem can be extended such that the Poisson points are randomly displaced from one Euclidean space to another Euclidean space , where is not necessarily equal to .
Mapping
A... | Poisson point process | Wikipedia | 415 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
One method for approximating random events or phenomena with Poisson processes is called the clumping heuristic. The general heuristic or principle involves using the Poisson point process (or Poisson distribution) to approximate events, which are considered rare or unlikely, of some stochastic process. In some cases... | Poisson point process | Wikipedia | 475 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
Similar convergence results have been developed for thinning and superposition operations that show that such repeated operations on point processes can, under certain conditions, result in the process converging to a Poisson point processes, provided a suitable rescaling of the intensity measure (otherwise values of t... | Poisson point process | Wikipedia | 424 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
In general, the concept of distance is of practical interest for applications, while topological structure is needed for Palm distributions, meaning that point processes are usually defined on mathematical spaces with metrics. Furthermore, a realization of a point process can be considered as a counting measure, so poi... | Poisson point process | Wikipedia | 459 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
Marking theorem
If a general point process is defined on some mathematical space and the random marks are defined on another mathematical space, then the marked point process is defined on the Cartesian product of these two spaces. For a marked Poisson point process with independent and identically distributed marks, t... | Poisson point process | Wikipedia | 476 | 41597450 | https://en.wikipedia.org/wiki/Poisson%20point%20process | Mathematics | Probability | null |
The Paleo-Tethys or Palaeo-Tethys Ocean was an ocean located along the northern margin of the paleocontinent Gondwana that started to open during the Middle Cambrian, grew throughout the Paleozoic, and finally closed during the Late Triassic; existing for about 400 million years.
Paleo-Tethys was a precursor to the Te... | Paleo-Tethys Ocean | Wikipedia | 462 | 5369676 | https://en.wikipedia.org/wiki/Paleo-Tethys%20Ocean | Physical sciences | Paleogeography | Earth science |
The Paleo-Tethys Ocean began to form when back-arc spreading separated the European Hunic terranes from Gondwana in the late Ordovician, to begin moving toward Euramerica (also known as the Old Red Sandstone Continent) in the north. In the process, the plate under the Rheic Ocean between Euramerica and the European Hu... | Paleo-Tethys Ocean | Wikipedia | 485 | 5369676 | https://en.wikipedia.org/wiki/Paleo-Tethys%20Ocean | Physical sciences | Paleogeography | Earth science |
The Paleo-Tethys Ocean sat where the Indian Ocean and Southern Asia are now located. The Equator ran the length of the sea, giving it a tropical climate. The shores and islands probably supported dense coal forests. | Paleo-Tethys Ocean | Wikipedia | 45 | 5369676 | https://en.wikipedia.org/wiki/Paleo-Tethys%20Ocean | Physical sciences | Paleogeography | Earth science |
Anurognathidae is a family of small, short-tailed pterosaurs that lived in Europe, Asia, and possibly North America during the Jurassic and Cretaceous periods. Five genera are known: Anurognathus, from the Late Jurassic of Germany; Jeholopterus, from the Middle to Late Jurassic of China; Dendrorhynchoides, from the Mid... | Anurognathidae | Wikipedia | 265 | 5377010 | https://en.wikipedia.org/wiki/Anurognathidae | Biology and health sciences | Pterosaurs | Animals |
The phylogeny of Anurognathidae is disputed. Both Alexander Kellner and David Unwin in 2003 defined the group as a node clade: the last common ancestor of Anurognathus and Batrachognathus and all its descendants. Some analyses, such as that of Kellner (2003), place them as the most basal group in the pterosaur tree. Un... | Anurognathidae | Wikipedia | 508 | 5377010 | https://en.wikipedia.org/wiki/Anurognathidae | Biology and health sciences | Pterosaurs | Animals |
Feathers
A 2018 study of the remains of two small Jurassic-age pterosaurs from Inner Mongolia, China, named as the genus Cascocauda in 2022, found that pterosaurs had a wide array of pycnofiber shapes and structures, as opposed to the homogeneous structures that had generally been assumed to cover them. Some of these h... | Anurognathidae | Wikipedia | 388 | 5377010 | https://en.wikipedia.org/wiki/Anurognathidae | Biology and health sciences | Pterosaurs | Animals |
The wild Bactrian camel (Camelus ferus) is an endangered species of camel endemic to Northwest China and southwestern Mongolia. It is closely related but not ancestral to the domestic Bactrian camel (Camelus bactrianus). Genetic studies have established it as a separate species which diverged from the Bactrian camel ab... | Wild Bactrian camel | Wikipedia | 440 | 37405934 | https://en.wikipedia.org/wiki/Wild%20Bactrian%20camel | Biology and health sciences | Camelidae | Animals |
Like its close relative, the domesticated Bactrian camel, it is one of the few mammals able to eat snow to provide itself with liquids in the winter. While the legend that camels store water in their humps is a misconception, they are adapted to conserve water. However, long periods without water will result in a deter... | Wild Bactrian camel | Wikipedia | 483 | 37405934 | https://en.wikipedia.org/wiki/Wild%20Bactrian%20camel | Biology and health sciences | Camelidae | Animals |
Distribution and habitat
Their habitat is in arid plains and hills where water sources are scarce and very little vegetation exists with shrubs as their main food source. These habitats have widely varying temperatures: the summer temperature ranges from and winter temperature a low of .
Wild Bactrian camels travel o... | Wild Bactrian camel | Wikipedia | 330 | 37405934 | https://en.wikipedia.org/wiki/Wild%20Bactrian%20camel | Biology and health sciences | Camelidae | Animals |
In 1964, China began testing nuclear weapons at Lop Nur, home to many of the wild Bactrian camels. The camels experienced no apparent ill effects from the radiation and continued to breed naturally. Instead, their habitat became a restricted military zone where human activity was kept to a minimum. After China signed t... | Wild Bactrian camel | Wikipedia | 345 | 37405934 | https://en.wikipedia.org/wiki/Wild%20Bactrian%20camel | Biology and health sciences | Camelidae | Animals |
Status
The wild Bactrian camel has been classified as "critically endangered", according to the International Union for Conservation of Nature and Natural Resources (IUCN), since 2002; its status was deemed "critical" in the 1960s, gradually being elevated to "critically endangered". The UK-based Wild Camel Protection... | Wild Bactrian camel | Wikipedia | 481 | 37405934 | https://en.wikipedia.org/wiki/Wild%20Bactrian%20camel | Biology and health sciences | Camelidae | Animals |
Several actions have been initiated by the governments of China and Mongolia to conserve this species, including ecosystem-based management. Two programmes instituted in this respect are the Great Gobi Reserve A in Mongolia, set up in 1982; and the Lop Nur Wild Camel National Nature Reservein China, established in 2000... | Wild Bactrian camel | Wikipedia | 285 | 37405934 | https://en.wikipedia.org/wiki/Wild%20Bactrian%20camel | Biology and health sciences | Camelidae | Animals |
Igneous rock ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava.
The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust. Typically, the mel... | Igneous rock | Wikipedia | 426 | 24712184 | https://en.wikipedia.org/wiki/Igneous%20rock | Physical sciences | Petrology | null |
Intrusive igneous rocks make up the majority of igneous rocks and are formed from magma that cools and solidifies within the crust of a planet. Bodies of intrusive rock are known as intrusions and are surrounded by pre-existing rock (called country rock). The country rock is an excellent thermal insulator, so the magma... | Igneous rock | Wikipedia | 455 | 24712184 | https://en.wikipedia.org/wiki/Igneous%20rock | Physical sciences | Petrology | null |
The molten rock, which typically contains suspended crystals and dissolved gases, is called magma. It rises because it is less dense than the rock from which it was extracted. When magma reaches the surface, it is called lava. Eruptions of volcanoes into air are termed subaerial, whereas those occurring underneath the ... | Igneous rock | Wikipedia | 404 | 24712184 | https://en.wikipedia.org/wiki/Igneous%20rock | Physical sciences | Petrology | null |
Because volcanic rocks are mostly fine-grained or glassy, it is much more difficult to distinguish between the different types of extrusive igneous rocks than between different types of intrusive igneous rocks. Generally, the mineral constituents of fine-grained extrusive igneous rocks can only be determined by examina... | Igneous rock | Wikipedia | 486 | 24712184 | https://en.wikipedia.org/wiki/Igneous%20rock | Physical sciences | Petrology | null |
An igneous rock with larger, clearly discernible crystals embedded in a finer-grained matrix is termed porphyry. Porphyritic texture develops when the larger crystals, called phenocrysts, grow to considerable size before the main mass of the magma crystallizes as finer-grained, uniform material called groundmass. Grai... | Igneous rock | Wikipedia | 489 | 24712184 | https://en.wikipedia.org/wiki/Igneous%20rock | Physical sciences | Petrology | null |
Mineralogical classification of an intrusive rock begins by determining if the rock is ultramafic, a carbonatite, or a lamprophyre. An ultramafic rock contains more than 90% of iron- and magnesium-rich minerals such as hornblende, pyroxene, or olivine, and such rocks have their own classification scheme. Likewise, rock... | Igneous rock | Wikipedia | 315 | 24712184 | https://en.wikipedia.org/wiki/Igneous%20rock | Physical sciences | Petrology | null |
There are relatively few minerals that are important in the formation of common igneous rocks, because the magma from which the minerals crystallize is rich in only certain elements: silicon, oxygen, aluminium, sodium, potassium, calcium, iron, and magnesium. These are the elements that combine to form the silicate min... | Igneous rock | Wikipedia | 511 | 24712184 | https://en.wikipedia.org/wiki/Igneous%20rock | Physical sciences | Petrology | null |
The percentage of alkali metal oxides (Na2O plus K2O) is second only to silica in its importance for chemically classifying volcanic rock. The silica and alkali metal oxide percentages are used to place volcanic rock on the TAS diagram, which is sufficient to immediately classify most volcanic rocks. Rocks in some fiel... | Igneous rock | Wikipedia | 480 | 24712184 | https://en.wikipedia.org/wiki/Igneous%20rock | Physical sciences | Petrology | null |
These three magma series occur in a range of plate tectonic settings. Tholeiitic magma series rocks are found, for example, at mid-ocean ridges, back-arc basins, oceanic islands formed by hotspots, island arcs and continental large igneous provinces.
All three series are found in relatively close proximity to each oth... | Igneous rock | Wikipedia | 459 | 24712184 | https://en.wikipedia.org/wiki/Igneous%20rock | Physical sciences | Petrology | null |
Geological occurrence, structure, mineralogical constitution—the hitherto accepted criteria for the discrimination of rock species—were relegated to the background. The completed rock analysis is first to be interpreted in terms of the rock-forming minerals which might be expected to be formed when the magma crystalliz... | Igneous rock | Wikipedia | 504 | 24712184 | https://en.wikipedia.org/wiki/Igneous%20rock | Physical sciences | Petrology | null |
Other mechanisms, such as melting from a meteorite impact, are less important today, but impacts during the accretion of the Earth led to extensive melting, and the outer several hundred kilometres of our early Earth was probably an ocean of magma. Impacts of large meteorites in the last few hundred million years have ... | Igneous rock | Wikipedia | 512 | 24712184 | https://en.wikipedia.org/wiki/Igneous%20rock | Physical sciences | Petrology | null |
The addition of carbon dioxide is relatively a much less important cause of magma formation than the addition of water, but genesis of some silica-undersaturated magmas has been attributed to the dominance of carbon dioxide over water in their mantle source regions. In the presence of carbon dioxide, experiments docume... | Igneous rock | Wikipedia | 437 | 24712184 | https://en.wikipedia.org/wiki/Igneous%20rock | Physical sciences | Petrology | null |
As magma cools, minerals typically crystallize from the melt at different temperatures (fractional crystallization). As minerals crystallize, the composition of the residual melt typically changes. If crystals separate from the melt, then the residual melt will differ in composition from the parent magma. For instance,... | Igneous rock | Wikipedia | 408 | 24712184 | https://en.wikipedia.org/wiki/Igneous%20rock | Physical sciences | Petrology | null |
The coconut crab (Birgus latro) is a terrestrial species of giant hermit crab, and is also known as the robber crab or palm thief. It is the largest terrestrial arthropod known, with a weight of up to . The distance from the tip of one leg to the tip of another can be as wide as . It is found on islands across the Indi... | Coconut crab | Wikipedia | 467 | 23229753 | https://en.wikipedia.org/wiki/Coconut%20crab | Biology and health sciences | Crabs and hermit crabs | Animals |
Mating occurs on dry land, but the females return to the edge of the sea to release their fertilized eggs, and then retreat up the beach. The larvae that hatch are planktonic for 3–4 weeks, before settling to the sea floor, entering a gastropod shell and returning to dry land. Sexual maturity is reached after about 5 y... | Coconut crab | Wikipedia | 438 | 23229753 | https://en.wikipedia.org/wiki/Coconut%20crab | Biology and health sciences | Crabs and hermit crabs | Animals |
The body of the coconut crab is, like those of all decapods, divided into a front section (cephalothorax) with 10 legs, and an abdomen. The front-most pair of legs has large chelae (claws) with the left being larger than the right. The next two pairs of legs, as with other hermit crabs, are large, powerful walking legs... | Coconut crab | Wikipedia | 451 | 23229753 | https://en.wikipedia.org/wiki/Coconut%20crab | Biology and health sciences | Crabs and hermit crabs | Animals |
Except as larvae, coconut crabs cannot swim, and they drown if left in water for more than an hour. They use a special organ called a branchiostegal lung to breathe. This organ can be interpreted as a developmental stage between gills and lungs, and is one of the most significant adaptations of the coconut crab to its ... | Coconut crab | Wikipedia | 500 | 23229753 | https://en.wikipedia.org/wiki/Coconut%20crab | Biology and health sciences | Crabs and hermit crabs | Animals |
Life cycle
Coconut crabs mate frequently and quickly on dry land in the period from May to September, especially between early June and late August. Males have spermatophores and deposit a mass of spermatophores on the abdomens of females; the oviducts opens at the base of the third pereiopods, and fertilisation is tho... | Coconut crab | Wikipedia | 508 | 23229753 | https://en.wikipedia.org/wiki/Coconut%20crab | Biology and health sciences | Crabs and hermit crabs | Animals |
Distribution
Coconut crabs live in the Indian Ocean and the central Pacific Ocean, with a distribution that closely matches that of the coconut palm. The western limit of the range of B. latro is Zanzibar, off the coast of Tanzania, while the tropics of Cancer and Capricorn mark the northern and southern limits, respec... | Coconut crab | Wikipedia | 417 | 23229753 | https://en.wikipedia.org/wiki/Coconut%20crab | Biology and health sciences | Crabs and hermit crabs | Animals |
The diet of coconut crabs consists primarily of fleshy fruits (particularly Ochrosia ackeringae, Arenga listeri, Pandanus elatus, P. christmatensis); nuts (Aleurites moluccanus), drupes (Cocos nucifera) and seeds (Annona reticulata); and the pith of fallen trees. However, as they are omnivores, they will consume other ... | Coconut crab | Wikipedia | 317 | 23229753 | https://en.wikipedia.org/wiki/Coconut%20crab | Biology and health sciences | Crabs and hermit crabs | Animals |
Thomas Hale Streets discussed the behaviour in 1877, doubting that the animal would climb trees to get at the coconuts. As late as the 1970s there were doubts about the crab's ability to open coconuts. In the 1980s, Holger Rumpf was able to confirm Streets' report, observing and studying how they open coconuts in the w... | Coconut crab | Wikipedia | 441 | 23229753 | https://en.wikipedia.org/wiki/Coconut%20crab | Biology and health sciences | Crabs and hermit crabs | Animals |
Relationship with humans
Adult coconut crabs have no known predators apart from other coconut crabs and humans. Its large size and the quality of its meat means that the coconut crab is extensively hunted and is very rare on islands with a human population. The coconut crab is eaten as a delicacy – and regarded as an a... | Coconut crab | Wikipedia | 487 | 23229753 | https://en.wikipedia.org/wiki/Coconut%20crab | Biology and health sciences | Crabs and hermit crabs | Animals |
Conservation
Coconut crab populations in several areas have declined or become locally extinct due to both habitat loss and human predation. In 1981, it was listed on the IUCN Red List as a vulnerable species, but a lack of biological data caused its assessment to be amended to "data deficient" in 1996. In 2018, IUCN u... | Coconut crab | Wikipedia | 229 | 23229753 | https://en.wikipedia.org/wiki/Coconut%20crab | Biology and health sciences | Crabs and hermit crabs | Animals |
A kilonova (also called a macronova) is a transient astronomical event that occurs in a compact binary system when two neutron stars or a neutron star and a black hole merge. These mergers are thought to produce gamma-ray bursts and emit bright electromagnetic radiation, called "kilonovae", due to the radioactive decay... | Kilonova | Wikipedia | 281 | 40167806 | https://en.wikipedia.org/wiki/Kilonova | Physical sciences | Stellar astronomy | Astronomy |
On October 16, 2017, the LIGO and Virgo collaborations announced the first detection of a gravitational wave (GW170817) which would correspond with electromagnetic observations, and demonstrated that the source was a binary neutron star merger. This merger was followed by a short GRB (GRB 170817A) and a longer lasting ... | Kilonova | Wikipedia | 492 | 40167806 | https://en.wikipedia.org/wiki/Kilonova | Physical sciences | Stellar astronomy | Astronomy |
In October 2018, astronomers reported that GRB 150101B, a gamma-ray burst event detected in 2015, may be analogous to the historic GW170817. The similarities between the two events, in terms of gamma ray, optical and x-ray emissions, as well as to the nature of the associated host galaxies, are considered "striking", a... | Kilonova | Wikipedia | 353 | 40167806 | https://en.wikipedia.org/wiki/Kilonova | Physical sciences | Stellar astronomy | Astronomy |
The family Fulgoridae is a large group of hemipteran insects, especially abundant and diverse in the tropics, containing over 125 genera worldwide. They are mostly of moderate to large size, many with a superficial resemblance to Lepidoptera due to their brilliant and varied coloration. Various genera and species (espe... | Fulgoridae | Wikipedia | 403 | 3999979 | https://en.wikipedia.org/wiki/Fulgoridae | Biology and health sciences | Hemiptera (true bugs) | Animals |
Palaeotherium is an extinct genus of equoid that lived in Europe and possibly the Middle East from the Middle Eocene to the Early Oligocene. It is the type genus of the Palaeotheriidae, a group exclusive to the Palaeogene that was closest in relation to the Equidae, which contains horses plus their closest relatives an... | Palaeotherium | Wikipedia | 347 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
Palaeotherium is an evolutionarily derived member of its family with tridactyl (or three-toed) forelimbs and hindlimbs, small post-canine diastemata (gaps between teeth), and premolars that are usually developed into molar-like forms. It shares many similar anatomical traits with other perissodactyls and has a large di... | Palaeotherium | Wikipedia | 454 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
By the early Oligocene, most of its species went extinct along with many genera of western European mammals as part of the Grande Coupure extinction and faunal turnover event, the causes of the extinctions being attributed mainly to environmental changes from increased glaciation and seasonality, negative interactions ... | Palaeotherium | Wikipedia | 465 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
In 1804, Cuvier confirmed that the skull previously reported by de Lamanon belonged to a mammal. The skull preserves a complete set of 44 teeth that are similar to those of rhinoceroses and hyraxes. Cuvier recognized that the skull differs from other mammals and therefore established a new genus and species, Palaeother... | Palaeotherium | Wikipedia | 458 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
In 1812, Cuvier defined Palaeotherium as containing only tridactyl (or three-toed) species. He also speculated on life appearance and behaviour of several Palaeotherium species, but cautioned that such interpretations are limited by the fragmentary fossil material. He suggested that P. magnum would have resembled a hor... | Palaeotherium | Wikipedia | 423 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
Of the three sculptures, P. medium most closely resembles a tapir, and it has remained mostly intact. P. medium was depicted as having thick skin and a slender face and trunk, representing outdated perceptions that it was a slow animal. The original P. magnum sculpture was last known from a 1958 photograph before it wa... | Palaeotherium | Wikipedia | 445 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
The 19th century also saw the erection of several new Palaeotherium species. In 1853, French palaeontologist Auguste Pomel erected the species P. duvali based on limb bones that he thought were less stocky than those of P. curtum. In his 1839–1864 osteography, Blainville erected P. girondicum, pointing out that its fos... | Palaeotherium | Wikipedia | 464 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
During the 20th century, a second complete skeleton of P. magnum was excavated from the plasters in the French commune of Mormoiron. It was sent to the geological department of the University of Lyon and described after preparation by the Austrian geologist Frédéric Roman in 1922. Roman published a reconstruction of th... | Palaeotherium | Wikipedia | 377 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
In 1968, upcoming German palaeontologist Jens Lorenz Franzen, then a graduate student, made major revisions of Palaeotherium in his dissertation. He invalidated several species as dubious names (P. giganteum (considered to have been a rhinocerotid instead), P. gracile, P. parvulum, P. commune, P. primaevum, and P. gerv... | Palaeotherium | Wikipedia | 442 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
In 1991, Casanovas-Cladellas and Santafé Llopis erected P. llamaquiquense from partial jaw material from the Spanish locality of Llamaquique in the city of Oviedo, where the name derived from. The next year in 1992, Remy proposed the creation of two subgenera of Palaeotherium based on cranial characteristics: Palaeothe... | Palaeotherium | Wikipedia | 209 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
Palaeotherium is the type genus of the Palaeotheriidae, largely considered to be one of two major hippomorph families in the superfamily Equoidea, the other being the Equidae. Alternatively, some authors have proposed that equids are more closely related to the Tapiromorpha than to the Palaeotheriidae. It is also usual... | Palaeotherium | Wikipedia | 344 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
The Perissodactyla makes its earliest known appearance in the European landmass in the MP7 faunal unit of the Mammal Palaeogene zones. During the temporal unit, many genera of basal equoids such as Hyracotherium, Pliolophus, Cymbalophus, and Hallensia made their first appearances there. A majority of the genera persist... | Palaeotherium | Wikipedia | 340 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
As shown in the above phylogeny, the Palaeotheriidae is recovered as a monophyletic clade, meaning that it did not leave any derived descendant groups in its evolutionary history. Hyracotherium sensu stricto (in a strict sense) is defined as amongst the first offshoots of the family and a member of the Pachynolophinae.... | Palaeotherium | Wikipedia | 224 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
Inner systematics
Since 1968, many species of Palaeotherium have multiple defined subspecies that are justified by various intraspecific variations. Later since 1992, two subgenera are officially recognized for Palaeotherium. The first of these subgenera is Palaeotherium, which includes the type species P. magnum alon... | Palaeotherium | Wikipedia | 463 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
The height and weight proportions of the skull of Palaeotherium are roughly equivalent with those of other taxa within the Equoidea; members of the superfamily have relatively shortened front facial areas. The skull's top peaks at the far back area, although this is not observed in P. lautricense. The sagittal crest ca... | Palaeotherium | Wikipedia | 469 | 4004214 | https://en.wikipedia.org/wiki/Palaeotherium | Biology and health sciences | Perissodactyla | Animals |
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