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Based on the most current evidence, salmonids diverged from the rest of teleost fish no later than 88 million years ago, during the late Cretaceous. This divergence was marked by a whole-genome duplication event in the ancestral salmonid, where the diploid ancestor became tetraploid. This duplication is the fourth of i... | Salmonidae | Wikipedia | 458 | 48878 | https://en.wikipedia.org/wiki/Salmonidae | Biology and health sciences | Salmoniformes | null | vital_articles |
This more precise dating and examination of the salmonid whole-genome duplication event has allowed more speculation on the radiation of species within the group. Historically, the whole-genome duplication event was thought to be the reason for the variation within Salmonidae. Current evidence done with molecular clock... | Salmonidae | Wikipedia | 475 | 48878 | https://en.wikipedia.org/wiki/Salmonidae | Biology and health sciences | Salmoniformes | null | vital_articles |
The Scorpaeniformes are a diverse order of ray-finned fish, including the lionfishes and sculpins, but have also been called the Scleroparei. It is one of the five largest orders of bony fishes by number of species, with over 1,320.
They are known as "mail-cheeked" fishes due to their distinguishing characteristic, t... | Scorpaeniformes | Wikipedia | 503 | 48885 | https://en.wikipedia.org/wiki/Scorpaeniformes | Biology and health sciences | Fishes | null | vital_articles |
Order Scorpaeniformes
Suborder Scorpaenoidei
Superfamily Congiopodoidea
Family Aploactinidae Jordan & Starks, 1904 (Velvetfishes)
Family Congiopodidae Gill, 1889 (Racehorses, pigfishes or horsefishes)
Superfamily Pataecoidea
Family Pataecidae Gill, 1872 (Australian prowfishes)
Family Gnathanacanthidae Gill, 1892 ... | Scorpaeniformes | Wikipedia | 505 | 48885 | https://en.wikipedia.org/wiki/Scorpaeniformes | Biology and health sciences | Fishes | null | vital_articles |
Superfamily Anoplopomatoidea (Quast, 1965)
Family Anoplopomatidae Jordan & Gilbert, 1883 (Blackcod)
Superfamily Zaniolepidoidea Shinohara, 1994
Family Zaniolepididae Jordan & Gilbert, 1883 (Combfishes)
Superfamily Hexagrammoidea Gill, 1889
Family Hexagrammidae Jordan, 1888 (Greenlings)
Superfamily Trichodontoide... | Scorpaeniformes | Wikipedia | 408 | 48885 | https://en.wikipedia.org/wiki/Scorpaeniformes | Biology and health sciences | Fishes | null | vital_articles |
A lyrebird is either of two species of ground-dwelling Australian birds that compose the genus Menura, and the family Menuridae. They are most notable for their impressive ability to mimic natural and artificial sounds from their environment, and the striking beauty of the male bird's huge tail when it is fanned out in... | Lyrebird | Wikipedia | 489 | 48896 | https://en.wikipedia.org/wiki/Lyrebird | Biology and health sciences | Corvoidea | null | vital_articles |
Lyrebirds are ancient Australian animals: the Australian Museum has fossils of lyrebirds dating back to about 15 million years ago. The prehistoric Menura tyawanoides has been described from Early Miocene fossils found at the famous Riversleigh site.
Species
Two species of lyrebird are extant:
Description
The lyrebi... | Lyrebird | Wikipedia | 463 | 48896 | https://en.wikipedia.org/wiki/Lyrebird | Biology and health sciences | Corvoidea | null | vital_articles |
Lyrebirds are long-lived birds that can live as long as 30 years. They have long breeding cycles and start breeding later in life than other passerine birds. Female superb lyrebirds start breeding at the age of five or six, and males at the age of six to eight. Males defend territories from other males, and those terri... | Lyrebird | Wikipedia | 277 | 48896 | https://en.wikipedia.org/wiki/Lyrebird | Biology and health sciences | Corvoidea | null | vital_articles |
A lyrebird's song is one of the more distinctive aspects of its behavioural biology. Lyrebirds sing throughout the year, but the peak of the breeding season, from June to August, is when they sing with the most intensity. During this peak males may sing for four hours of the day, almost half the hours of daylight. The ... | Lyrebird | Wikipedia | 443 | 48896 | https://en.wikipedia.org/wiki/Lyrebird | Biology and health sciences | Corvoidea | null | vital_articles |
One researcher, Sydney Curtis, has recorded flute-like lyrebird calls in the vicinity of the New England National Park. Similarly, in 1969, a park ranger, Neville Fenton, recorded a lyrebird song which resembled flute sounds in the New England National Park, near Dorrigo in northern coastal New South Wales. After much ... | Lyrebird | Wikipedia | 507 | 48896 | https://en.wikipedia.org/wiki/Lyrebird | Biology and health sciences | Corvoidea | null | vital_articles |
The lyrebird is so called because the male bird has a spectacular tail, consisting of 16 highly modified feathers (two long slender lyrates at the centre of the plume, two broader medians on the outside edges and twelve filamentaries arrayed between them), which was originally thought to resemble a lyre. This happened ... | Lyrebird | Wikipedia | 342 | 48896 | https://en.wikipedia.org/wiki/Lyrebird | Biology and health sciences | Corvoidea | null | vital_articles |
A male superb lyrebird is featured on the reverse of the Australian 10-cent coin.
A superb lyrebird featured on the Australian one shilling postage stamp first issued in 1932.
A stylised superb lyrebird appears in the transparent window of the Australian 100 dollar note.
A silhouette of a male superb lyrebird is the... | Lyrebird | Wikipedia | 361 | 48896 | https://en.wikipedia.org/wiki/Lyrebird | Biology and health sciences | Corvoidea | null | vital_articles |
The atomic radius of a chemical element is a measure of the size of its atom, usually the mean or typical distance from the center of the nucleus to the outermost isolated electron. Since the boundary is not a well-defined physical entity, there are various non-equivalent definitions of atomic radius. Four widely used... | Atomic radius | Wikipedia | 441 | 48900 | https://en.wikipedia.org/wiki/Atomic%20radius | Physical sciences | Periodic table | Chemistry | vital_articles |
The concept of atomic radius was preceded in the 19th century by the concept of atomic volume, a relative measure of how much space would on average an atom occupy in a given solid or liquid material. By the end of the century this term was also used in an absolute sense, as a molar volume divided by Avogadro constant.... | Atomic radius | Wikipedia | 440 | 48900 | https://en.wikipedia.org/wiki/Atomic%20radius | Physical sciences | Periodic table | Chemistry | vital_articles |
Ionic radius: the nominal radius of the ions of an element in a specific ionization state, deduced from the spacing of atomic nuclei in crystalline salts that include that ion. In principle, the spacing between two adjacent oppositely charged ions (the length of the ionic bond between them) should equal the sum of thei... | Atomic radius | Wikipedia | 512 | 48900 | https://en.wikipedia.org/wiki/Atomic%20radius | Physical sciences | Periodic table | Chemistry | vital_articles |
The increasing nuclear charge is partly counterbalanced by the increasing number of electrons—a phenomenon that is known as shielding—which explains why the size of atoms usually increases down each column despite an increase in attractive force from the nucleus. Electron shielding causes the attraction of an atom's nu... | Atomic radius | Wikipedia | 444 | 48900 | https://en.wikipedia.org/wiki/Atomic%20radius | Physical sciences | Periodic table | Chemistry | vital_articles |
The size of Ln3+ ions regularly decreases with atomic number. According to Fajans' rules, decrease in size of Ln3+ ions increases the covalent character and decreases the basic character between Ln3+ and OH− ions in Ln(OH)3, to the point that Yb(OH)3 and Lu(OH)3 can dissolve with difficulty in hot concentrated NaOH. H... | Atomic radius | Wikipedia | 301 | 48900 | https://en.wikipedia.org/wiki/Atomic%20radius | Physical sciences | Periodic table | Chemistry | vital_articles |
The kilogram per cubic metre (symbol: kg·m−3, or kg/m3) is the unit of density in the International System of Units (SI). It is defined by dividing the SI unit of mass, the kilogram, by the SI unit of volume, the cubic metre.
Conversions
1 kg/m3 = 1 g/L (exactly)
1 kg/m3 = 0.001 g/cm3 (exactly)
1 kg/m3 ≈ 0.06243 lb/ft... | Kilogram per cubic metre | Wikipedia | 254 | 48902 | https://en.wikipedia.org/wiki/Kilogram%20per%20cubic%20metre | Physical sciences | Density | Basics and measurement | vital_articles |
Nucleosynthesis is the process that creates new atomic nuclei from pre-existing nucleons (protons and neutrons) and nuclei. According to current theories, the first nuclei were formed a few minutes after the Big Bang, through nuclear reactions in a process called Big Bang nucleosynthesis. After about 20 minutes, the un... | Nucleosynthesis | Wikipedia | 497 | 48903 | https://en.wikipedia.org/wiki/Nucleosynthesis | Physical sciences | Nuclear physics | null | vital_articles |
On Earth new nuclei are also produced by radiogenesis, the decay of long-lived, primordial radionuclides such as uranium, thorium, and potassium-40.
History
Timeline
It is thought that the primordial nucleons themselves were formed from the quark–gluon plasma around 13.8 billion years ago during the Big Bang as it co... | Nucleosynthesis | Wikipedia | 416 | 48903 | https://en.wikipedia.org/wiki/Nucleosynthesis | Physical sciences | Nuclear physics | null | vital_articles |
The subsequent nucleosynthesis of heavier elements (Z ≥ 6, carbon and heavier elements) requires the extreme temperatures and pressures found within stars and supernovae. These processes began as hydrogen and helium from the Big Bang collapsed into the first stars after about 500 million years. Star formation has been ... | Nucleosynthesis | Wikipedia | 509 | 48903 | https://en.wikipedia.org/wiki/Nucleosynthesis | Physical sciences | Nuclear physics | null | vital_articles |
Fred Hoyle's original work on nucleosynthesis of heavier elements in stars, occurred just after World War II. His work explained the production of all heavier elements, starting from hydrogen. Hoyle proposed that hydrogen is continuously created in the universe from vacuum and energy, without need for universal beginni... | Nucleosynthesis | Wikipedia | 461 | 48903 | https://en.wikipedia.org/wiki/Nucleosynthesis | Physical sciences | Nuclear physics | null | vital_articles |
The goal of the theory of nucleosynthesis is to explain the vastly differing abundances of the chemical elements and their several isotopes from the perspective of natural processes. The primary stimulus to the development of this theory was the shape of a plot of the abundances versus the atomic number of the elements... | Nucleosynthesis | Wikipedia | 395 | 48903 | https://en.wikipedia.org/wiki/Nucleosynthesis | Physical sciences | Nuclear physics | null | vital_articles |
Big Bang nucleosynthesis occurred within the first three minutes of the beginning of the universe and is responsible for much of the abundance of (protium), (D, deuterium), (helium-3), and (helium-4). Although continues to be produced by stellar fusion and alpha decays and trace amounts of continue to be produced... | Nucleosynthesis | Wikipedia | 453 | 48903 | https://en.wikipedia.org/wiki/Nucleosynthesis | Physical sciences | Nuclear physics | null | vital_articles |
The first direct proof that nucleosynthesis occurs in stars was the astronomical observation that interstellar gas has become enriched with heavy elements as time passed. As a result, stars that were born from it late in the galaxy, formed with much higher initial heavy element abundances than those that had formed ear... | Nucleosynthesis | Wikipedia | 299 | 48903 | https://en.wikipedia.org/wiki/Nucleosynthesis | Physical sciences | Nuclear physics | null | vital_articles |
Supernova nucleosynthesis occurs in the energetic environment in supernovae, in which the elements between silicon and nickel are synthesized in quasiequilibrium established during fast fusion that attaches by reciprocating balanced nuclear reactions to 28Si. Quasiequilibrium can be thought of as almost equilibrium exc... | Nucleosynthesis | Wikipedia | 446 | 48903 | https://en.wikipedia.org/wiki/Nucleosynthesis | Physical sciences | Nuclear physics | null | vital_articles |
Explosive nucleosynthesis occurs too rapidly for radioactive decay to decrease the number of neutrons, so that many abundant isotopes with equal and even numbers of protons and neutrons are synthesized by the silicon quasi-equilibrium process. During this process, the burning of oxygen and silicon fuses nuclei that the... | Nucleosynthesis | Wikipedia | 500 | 48903 | https://en.wikipedia.org/wiki/Nucleosynthesis | Physical sciences | Nuclear physics | null | vital_articles |
Neutron star mergers
The merger of binary neutron stars (BNSs) is now believed to be the main source of r-process elements. Being neutron-rich by definition, mergers of this type had been suspected of being a source of such elements, but definitive evidence was difficult to obtain. In 2017 strong evidence emerged, when... | Nucleosynthesis | Wikipedia | 492 | 48903 | https://en.wikipedia.org/wiki/Nucleosynthesis | Physical sciences | Nuclear physics | null | vital_articles |
Tiny amounts of certain nuclides are produced on Earth by artificial means. Those are our primary source, for example, of technetium. However, some nuclides are also produced by a number of natural means that have continued after primordial elements were in place. These often act to create new elements in ways that can... | Nucleosynthesis | Wikipedia | 113 | 48903 | https://en.wikipedia.org/wiki/Nucleosynthesis | Physical sciences | Nuclear physics | null | vital_articles |
These mechanisms include:
Radioactive decay may lead to radiogenic daughter nuclides. The nuclear decay of many long-lived primordial isotopes, especially uranium-235, uranium-238, and thorium-232 produce many intermediate daughter nuclides before they too finally decay to isotopes of lead. The Earth's natural supply ... | Nucleosynthesis | Wikipedia | 499 | 48903 | https://en.wikipedia.org/wiki/Nucleosynthesis | Physical sciences | Nuclear physics | null | vital_articles |
The zenith (, ) is the imaginary point on the celestial sphere directly "above" a particular location. "Above" means in the vertical direction (plumb line) opposite to the gravity direction at that location (nadir). The zenith is the "highest" point on the celestial sphere.
Origin
The word zenith derives from an inacc... | Zenith | Wikipedia | 492 | 48909 | https://en.wikipedia.org/wiki/Zenith | Physical sciences | Celestial sphere: General | Astronomy | vital_articles |
A zenith telescope is a type of telescope designed to point straight up at or near the zenith, and used for precision measurement of star positions, to simplify telescope construction, or both. The NASA Orbital Debris Observatory and the Large Zenith Telescope are both zenith telescopes, since the use of liquid mirrors... | Zenith | Wikipedia | 284 | 48909 | https://en.wikipedia.org/wiki/Zenith | Physical sciences | Celestial sphere: General | Astronomy | vital_articles |
The horizon is the apparent curve that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This curve divides all viewing directions based on whether it intersects the relevant body's surface or not.
The true horizon is a t... | Horizon | Wikipedia | 457 | 48910 | https://en.wikipedia.org/wiki/Horizon | Physical sciences | Celestial sphere | null | vital_articles |
Historically, the distance to the visible horizon has long been vital to survival and successful navigation, especially at sea, because it determined an observer's maximum range of vision and thus of communication, with all the obvious consequences for safety and the transmission of information that this range implied.... | Horizon | Wikipedia | 400 | 48910 | https://en.wikipedia.org/wiki/Horizon | Physical sciences | Celestial sphere | null | vital_articles |
Examples
Assuming no atmospheric refraction and a spherical Earth with radius R=:
For an observer standing on the ground with h = , the horizon is at a distance of .
For an observer standing on the ground with h = , the horizon is at a distance of .
For an observer standing on a hill or tower above sea level, the h... | Horizon | Wikipedia | 509 | 48910 | https://en.wikipedia.org/wiki/Horizon | Physical sciences | Celestial sphere | null | vital_articles |
The exact formula above can be expanded as:
where R is the radius of the Earth (R and h must be in the same units). For example,
if a satellite is at a height of 2000 km, the distance to the horizon is ;
neglecting the second term in parentheses would give a distance of , a 7% error.
Approximation
If the observer i... | Horizon | Wikipedia | 501 | 48910 | https://en.wikipedia.org/wiki/Horizon | Physical sciences | Celestial sphere | null | vital_articles |
For a non-negative height , the angle is always ≥ 90°.
Objects above the horizon
To compute the greatest distance DBL at which an observer B can see the top of an object L above the horizon, simply add the distances to the horizon from each of the two points:
DBL = DB + DL
For example, for an observer B with a heig... | Horizon | Wikipedia | 506 | 48910 | https://en.wikipedia.org/wiki/Horizon | Physical sciences | Celestial sphere | null | vital_articles |
Due to atmospheric refraction the distance to the visible horizon is further than the distance based on a simple geometric calculation. If the ground (or water) surface is colder than the air above it, a cold, dense layer of air forms close to the surface, causing light to be refracted downward as it travels, and there... | Horizon | Wikipedia | 389 | 48910 | https://en.wikipedia.org/wiki/Horizon | Physical sciences | Celestial sphere | null | vital_articles |
This correction can be, and often is, applied as a fairly good approximation when atmospheric conditions are close to standard. When conditions are unusual, this approximation fails. Refraction is strongly affected by temperature gradients, which can vary considerably from day to day, especially over water. In extreme ... | Horizon | Wikipedia | 510 | 48910 | https://en.wikipedia.org/wiki/Horizon | Physical sciences | Celestial sphere | null | vital_articles |
Results from Young's method are quite close to those from Sweer's method, and are sufficiently accurate for many purposes.
Vanishing points
The horizon is a key feature of the picture plane in the science of graphical perspective. Assuming the picture plane stands vertical to ground, and P is the perpendicular projec... | Horizon | Wikipedia | 456 | 48910 | https://en.wikipedia.org/wiki/Horizon | Physical sciences | Celestial sphere | null | vital_articles |
Characiformes is an order of ray-finned fish, comprising the characins and their allies. Grouped in 18 recognized families, more than 2000 different species are described, including the well-known piranha and tetras.
Taxonomy
The Characiformes form part of a series called the Otophysi within the superorder Ostarioph... | Characiformes | Wikipedia | 494 | 48963 | https://en.wikipedia.org/wiki/Characiformes | Biology and health sciences | Characiformes | null | vital_articles |
Fossils
The earliest characiform fossils date back to the Late Cretaceous, around the Santonian. Other fossil teeth date back to the Cenomanian of Morocco, but it has been suggested that these teeth may be of early ginglymodians. Previously, the oldest characiform was assumed to be Santanichthys of the Early Cretaceou... | Characiformes | Wikipedia | 464 | 48963 | https://en.wikipedia.org/wiki/Characiformes | Biology and health sciences | Characiformes | null | vital_articles |
Description
Characins possess a Weberian apparatus, a series of bony parts connecting the swim bladder and inner ear. Superficially, the Characiformes somewhat resemble their relatives of the order Cypriniformes, but have a small, fleshy adipose fin between the dorsal fin and tail. Most species have teeth within the mo... | Characiformes | Wikipedia | 341 | 48963 | https://en.wikipedia.org/wiki/Characiformes | Biology and health sciences | Characiformes | null | vital_articles |
Characidae, the characids or characins, is a family of freshwater subtropical and tropical fish belonging to the order Characiformes. The name "characins" is a historical one, but scientists today tend to prefer "characids" to reflect their status as a, by and large, monophyletic group (at family rank). To arrive there... | Characidae | Wikipedia | 428 | 48971 | https://en.wikipedia.org/wiki/Characidae | Biology and health sciences | Characiformes | Animals | vital_articles |
Other fish families that were formerly classified as members of the Characidae, but which were moved into separate families of their own during recent taxonomic revisions (after 1994) include Acestrorhynchidae, Anostomidae, Chilodontidae, Citharinidae, Ctenoluciidae, Curimatidae, Distichodontidae, Gasteropelecidae, Hem... | Characidae | Wikipedia | 316 | 48971 | https://en.wikipedia.org/wiki/Characidae | Biology and health sciences | Characiformes | Animals | vital_articles |
Tribe Rhoadsiini [Astyanax clade]
Astyanacinus
Astyanax
Carlana
Ctenobrycon
Inpaichthys
Nematobrycon
Oligosarcus
Parastremma
Psellogrammus
Rhoadsia
Tribe Stygichthyini [Jupiaba clade]
Coptobrycon
Erythrocharax
Jupiaba
Macropsobrycon
Parecbasis
Stygichthys
Tribe Pristellini [Hemigrammus clade; Aphyodit... | Characidae | Wikipedia | 273 | 48971 | https://en.wikipedia.org/wiki/Characidae | Biology and health sciences | Characiformes | Animals | vital_articles |
Tribe Eretmobryconini
Eretmobrycon
Markiana
Tribe Xenurobryconini
Iotabrycon
Ptychocharax
Scopaeocharax
Tyttocharax
Xenurobrycon
Tribe Argopleura clade
Argopleura
Tribe Glandulocaudini
Glandulocauda
Lophiobrycon
Mimagoniates
Tribe Stevardiini
Chrysobrycon
Corynopoma
Gephyrocharax
Hysteronotus
Pseudo... | Characidae | Wikipedia | 474 | 48971 | https://en.wikipedia.org/wiki/Characidae | Biology and health sciences | Characiformes | Animals | vital_articles |
Bario
Deuterodon
Ectrepopterus
Hasemania
Hemigrammus
Hyphessobrycon
Moenkhausia
Myxiops
Paracheirodon
Parapristella
Petitella
Pristella
Probolodus
Thayeria
Former members
The Chalceidae, Iguanodectidae, Bryconidae and Heterocharacinae are the most recent clades to be removed in order to maintain a monophy... | Characidae | Wikipedia | 448 | 48971 | https://en.wikipedia.org/wiki/Characidae | Biology and health sciences | Characiformes | Animals | vital_articles |
Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basidiomycota includes these groups: agarics, puffballs, stinkhorns, bracket fu... | Basidiomycota | Wikipedia | 273 | 48980 | https://en.wikipedia.org/wiki/Basidiomycota | Biology and health sciences | Fungi | null | vital_articles |
A 2007 classification, adopted by a coalition of 67 mycologists recognized three subphyla (Pucciniomycotina, Ustilaginomycotina, Agaricomycotina) and two other class level taxa (Wallemiomycetes, Entorrhizomycetes) outside of these, among the Basidiomycota. As now classified, the subphyla join and also cut across variou... | Basidiomycota | Wikipedia | 417 | 48980 | https://en.wikipedia.org/wiki/Basidiomycota | Biology and health sciences | Fungi | null | vital_articles |
Agaricomycotina
The Agaricomycotina include what had previously been called the Hymenomycetes (an obsolete morphological based class of Basidiomycota that formed hymenial layers on their fruitbodies), the Gasteromycetes (another obsolete class that included species mostly lacking hymenia and mostly forming spores in en... | Basidiomycota | Wikipedia | 501 | 48980 | https://en.wikipedia.org/wiki/Basidiomycota | Biology and health sciences | Fungi | null | vital_articles |
Anastomyces W.P.Wu, B.Sutton & Gange (1997)
Anguillomyces Marvanová & Bärl. (2000)
Anthoseptobasidium Rick (1943)
Arcispora Marvanová & Bärl. (1998)
Arrasia Bernicchia, Gorjón & Nakasone (2011)
Brevicellopsis Hjortstam & Ryvarden (2008)
Celatogloea P.Roberts (2005)
Cleistocybe Ammirati, A.D.Parker & Matheny (200... | Basidiomycota | Wikipedia | 328 | 48980 | https://en.wikipedia.org/wiki/Basidiomycota | Biology and health sciences | Fungi | null | vital_articles |
Unlike animals and plants which have readily recognizable male and female counterparts, Basidiomycota (except for the Rust (Pucciniales)) tend to have mutually indistinguishable, compatible haploids which are usually mycelia being composed of filamentous hyphae. Typically haploid Basidiomycota mycelia fuse via plasmoga... | Basidiomycota | Wikipedia | 354 | 48980 | https://en.wikipedia.org/wiki/Basidiomycota | Biology and health sciences | Fungi | null | vital_articles |
The maintenance of the dikaryotic status in dikaryons in many Basidiomycota is facilitated by the formation of clamp connections that physically appear to help coordinate and re-establish pairs of compatible nuclei following synchronous mitotic nuclear divisions. Variations are frequent and multiple. In a typical Basid... | Basidiomycota | Wikipedia | 351 | 48980 | https://en.wikipedia.org/wiki/Basidiomycota | Biology and health sciences | Fungi | null | vital_articles |
In summary, meiosis takes place in a diploid basidium. Each one of the four haploid nuclei migrates into its own basidiospore. The basidiospores are ballistically discharged and start new haploid mycelia called monokaryons. There are no males or females, rather there are compatible thalli with multiple compatibility fa... | Basidiomycota | Wikipedia | 469 | 48980 | https://en.wikipedia.org/wiki/Basidiomycota | Biology and health sciences | Fungi | null | vital_articles |
Variations in lifecycles
Many variations occur: some variations are self-compatible and spontaneously form dikaryons without a separate compatible thallus being involved. These fungi are said to be homothallic, versus the normal heterothallic species with mating types. Others are secondarily homothallic, in that two co... | Basidiomycota | Wikipedia | 500 | 48980 | https://en.wikipedia.org/wiki/Basidiomycota | Biology and health sciences | Fungi | null | vital_articles |
Rusts (Pucciniales, previously known as Uredinales) at their greatest complexity, produce five different types of spores on two different host plants in two unrelated host families. Such rusts are heteroecious (requiring two hosts) and macrocyclic (producing all five spores types). Wheat stem rust is an example. By con... | Basidiomycota | Wikipedia | 507 | 48980 | https://en.wikipedia.org/wiki/Basidiomycota | Biology and health sciences | Fungi | null | vital_articles |
Autoecious rusts complete their life-cycles on one host instead of two, and microcyclic rusts cut out one or more stages | Basidiomycota | Wikipedia | 30 | 48980 | https://en.wikipedia.org/wiki/Basidiomycota | Biology and health sciences | Fungi | null | vital_articles |
Smuts
The characteristic part of the life-cycle of smuts is the thick-walled, often darkly pigmented, ornate, teliospore that serves to survive harsh conditions such as overwintering and also serves to help disperse the fungus as dry diaspores. The teliospores are initially dikaryotic but become diploid via karyogamy. ... | Basidiomycota | Wikipedia | 434 | 48980 | https://en.wikipedia.org/wiki/Basidiomycota | Biology and health sciences | Fungi | null | vital_articles |
The dimorphic Basidiomycota with yeast stages and the pleiomorphic rusts are examples of fungi with anamorphs, which are the asexual stages. Some Basidiomycota are only known as anamorphs. Many are called basidiomycetous yeasts, which differentiates them from ascomycetous yeasts in the Ascomycota. Aside from yeast anam... | Basidiomycota | Wikipedia | 235 | 48980 | https://en.wikipedia.org/wiki/Basidiomycota | Biology and health sciences | Fungi | null | vital_articles |
Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The defining feature of this fungal group is the "ascus" (), a microscopic sexual ... | Ascomycota | Wikipedia | 479 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Several species of ascomycetes are biological model organisms in laboratory research. Most famously, Neurospora crassa, several species of yeasts, and Aspergillus species are used in many genetics and cell biology studies.
Sexual reproduction in ascomycetes
Ascomycetes are 'spore shooters'. They are fungi which prod... | Ascomycota | Wikipedia | 507 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
The diverse conidia and conidiophores sometimes develop in asexual sporocarps with different characteristics (e.g. acervulus, pycnidium, sporodochium). Some species of ascomycetes form their structures within plant tissue, either as parasite or saprophytes. These fungi have evolved more complex asexual sporing structur... | Ascomycota | Wikipedia | 386 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Ascomycota are morphologically diverse. The group includes organisms from unicellular yeasts to complex cup fungi.
98% of lichens have an Ascomycota as the fungal part of the lichen.
There are 2000 identified genera and 30,000 species of Ascomycota.
The unifying characteristic among these diverse groups is the prese... | Ascomycota | Wikipedia | 476 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
A unique character of the Ascomycota (but not present in all ascomycetes) is the presence of Woronin bodies on each side of the septa separating the hyphal segments which control the septal pores. If an adjoining hypha is ruptured, the Woronin bodies block the pores to prevent loss of cytoplasm into the ruptured compa... | Ascomycota | Wikipedia | 108 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Modern classification
There are three subphyla that are described and accepted:
The Pezizomycotina are the largest subphylum and contains all ascomycetes that produce ascocarps (fruiting bodies), except for one genus, Neolecta, in the Taphrinomycotina. It is roughly equivalent to the previous taxon, Euascomycetes. Th... | Ascomycota | Wikipedia | 332 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Outdated taxon names
Several outdated taxon names—based on morphological features—are still occasionally used for species of the Ascomycota. These include the following sexual (teleomorphic) groups, defined by the structures of their sexual fruiting bodies: the Discomycetes, which included all species forming apotheci... | Ascomycota | Wikipedia | 512 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Morphology
Most species grow as filamentous, microscopic structures called hyphae or as budding single cells (yeasts). Many interconnected hyphae form a thallus usually referred to as the mycelium, which—when visible to the naked eye (macroscopic)—is commonly called mold. During sexual reproduction, many Ascomycota t... | Ascomycota | Wikipedia | 423 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Except for lichens, the non-reproductive (vegetative) mycelium of most ascomycetes is usually inconspicuous because it is commonly embedded in the substrate, such as soil, or grows on or inside a living host, and only the ascoma may be seen when fruiting. Pigmentation, such as melanin in hyphal walls, along with prolif... | Ascomycota | Wikipedia | 500 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Metabolism
In common with other fungal phyla, the Ascomycota are heterotrophic organisms that require organic compounds as energy sources. These are obtained by feeding on a variety of organic substrates including dead matter, foodstuffs, or as symbionts in or on other living organisms. To obtain these nutrients from ... | Ascomycota | Wikipedia | 321 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
The Ascomycota is characterized by a high degree of specialization; for instance, certain species of Laboulbeniales attack only one particular leg of one particular insect species. Many Ascomycota engage in symbiotic relationships such as in lichens—symbiotic associations with green algae or cyanobacteria—in which the ... | Ascomycota | Wikipedia | 458 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Asexual spores
Different types of asexual spores can be identified by colour, shape, and how they are released as individual spores. Spore types can be used as taxonomic characters in the classification within the Ascomycota. The most frequent types are the single-celled spores, which are designated amerospores. If th... | Ascomycota | Wikipedia | 369 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
These two basic types can be further classified as follows:
blastic-acropetal (repeated budding at the tip of the conidiogenic hypha, so that a chain of spores is formed with the youngest spores at the tip),
blastic-synchronous (simultaneous spore formation from a central cell, sometimes with secondary acropetal chai... | Ascomycota | Wikipedia | 486 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Heterokaryosis and parasexuality
Several Ascomycota species are not known to have a sexual cycle. Such asexual species may be able to undergo genetic recombination between individuals by processes involving heterokaryosis and parasexual events.
Parasexuality refers to the process of heterokaryosis, caused by merging ... | Ascomycota | Wikipedia | 498 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Formation of sexual spores
The sexual part of the life cycle commences when two hyphal structures mate. In the case of homothallic species, mating is enabled between hyphae of the same fungal clone, whereas in heterothallic species, the two hyphae must originate from fungal clones that differ genetically, i.e., those ... | Ascomycota | Wikipedia | 418 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
From the fertilized ascogonium, dinucleate hyphae emerge in which each cell contains two nuclei. These hyphae are called ascogenous or fertile hyphae. They are supported by the vegetative mycelium containing uni– (or mono–) nucleate hyphae, which are sterile. The mycelium containing both sterile and fertile hyphae may ... | Ascomycota | Wikipedia | 472 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Fusion of the nuclei (karyogamy) takes place in the U-shaped cells in the hymenium, and results in the formation of a diploid zygote. The zygote grows into the ascus, an elongated tube-shaped or cylinder-shaped capsule. Meiosis then gives rise to four haploid nuclei, usually followed by a further mitotic division that ... | Ascomycota | Wikipedia | 432 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Probably since early in their evolutionary history, the Ascomycota have formed symbiotic associations with green algae (Chlorophyta), and other types of algae and cyanobacteria. These mutualistic associations are commonly known as lichens, and can grow and persist in terrestrial regions of the earth that are inhospitab... | Ascomycota | Wikipedia | 423 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Symbiotic relationships with animals
Several ascomycetes of the genus Xylaria colonize the nests of leafcutter ants and other fungus-growing ants of the tribe Attini, and the fungal gardens of termites (Isoptera). Since they do not generate fruiting bodies until the insects have left the nests, it is suspected that, a... | Ascomycota | Wikipedia | 268 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Dutch elm disease, caused by the closely related species Ophiostoma ulmi and Ophiostoma novo-ulmi, has led to the death of many elms in Europe and North America.
The originally Asian Cryphonectria parasitica is responsible for attacking Sweet Chestnuts (Castanea sativa), and virtually eliminated the once-widespread Am... | Ascomycota | Wikipedia | 303 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Aspergillus fumigatus, the most common cause of fungal infection in the lungs of immune-compromised patients often resulting in death. Also the most frequent cause of Allergic bronchopulmonary aspergillosis, which often occurs in patients with Cystic fibrosis as well as Asthma.
Candida albicans, a yeast that attacks ... | Ascomycota | Wikipedia | 420 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Beneficial effects for humans
On the other hand, ascus fungi have brought some significant benefits to humanity.
The most famous case may be that of the mold Penicillium chrysogenum (formerly Penicillium notatum), which, probably to attack competing bacteria, produces an antibiotic that, under the name of penicillin,... | Ascomycota | Wikipedia | 169 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Some ascomycete fungi can be easily altered through genetic engineering procedures. They can then produce useful proteins such as insulin, human growth hormone, or TPa, which is employed to dissolve blood clots.
Several species are common model organisms in biology, including Saccharomyces cerevisiae, Schizosaccharomy... | Ascomycota | Wikipedia | 501 | 48981 | https://en.wikipedia.org/wiki/Ascomycota | Biology and health sciences | Fungi | null | vital_articles |
Road transport or road transportation is a type of transport using roads. Transport on roads can be roughly grouped into the transportation of goods and transportation of people. In many countries licensing requirements and safety regulations ensure a separation of the two industries. Movement along roads may be by bik... | Road transport | Wikipedia | 510 | 49020 | https://en.wikipedia.org/wiki/Road%20transport | Technology | Road transport | null | vital_articles |
New road networks
As states developed and became richer, especially with the Renaissance, new roads and bridges began to be built, often based on Roman designs. Although there were attempts to rediscover Roman methods, there was little useful innovation in road building before the 18th century.
Starting in the early ... | Road transport | Wikipedia | 491 | 49020 | https://en.wikipedia.org/wiki/Road%20transport | Technology | Road transport | null | vital_articles |
The first professional road builder to emerge during the Industrial Revolution was John Metcalf, who constructed about of turnpike road, mainly in the north of England, from 1765. He believed a good road should have good foundations, be well drained and have a smooth convex surface to allow rainwater to drain quickly ... | Road transport | Wikipedia | 495 | 49020 | https://en.wikipedia.org/wiki/Road%20transport | Technology | Road transport | null | vital_articles |
Also unlike Telford and other road builders, McAdam laid his roads as level as possible. His road required only a rise of three inches from the edges to the center. Cambering and elevation of the road above the water table enabled rainwater to run off into ditches on either side. Size of stones was central to the McAd... | Road transport | Wikipedia | 251 | 49020 | https://en.wikipedia.org/wiki/Road%20transport | Technology | Road transport | null | vital_articles |
Outside cities, roads were dirt or gravel; mud in the winter and dust in the summer. Early organizers cited Europe where road construction and maintenance was supported by national and local governments. In its early years, the main goal of the movement was education for road building in rural areas between cities and ... | Road transport | Wikipedia | 480 | 49020 | https://en.wikipedia.org/wiki/Road%20transport | Technology | Road transport | null | vital_articles |
Modern controlled-access highways originated in the early 1920s in response to the rapidly increasing use of the automobile, the demand for faster movement between cities and as a consequence of improvements in paving processes, techniques and materials. These original high-speed roads were referred to as "dual highway... | Road transport | Wikipedia | 385 | 49020 | https://en.wikipedia.org/wiki/Road%20transport | Technology | Road transport | null | vital_articles |
The word freeway was first used in February 1930 by Edward M. Bassett. Bassett argued that roads should be classified into three basic types: highways, parkways, and freeways. In Bassett's zoning and property law-based system, abutting property owners have the rights of light, air and access to highways but to not park... | Road transport | Wikipedia | 398 | 49020 | https://en.wikipedia.org/wiki/Road%20transport | Technology | Road transport | null | vital_articles |
Hours of service
To avoid accidents caused by fatigue, truckers have to adhere to strict rules for drive time and required rest periods. In the United States and Canada, these regulations are known as hours of service, and in the European Union as drivers working hours. One such regulation is the Hours of Work and Rest... | Road transport | Wikipedia | 465 | 49020 | https://en.wikipedia.org/wiki/Road%20transport | Technology | Road transport | null | vital_articles |
The European Union uses the International Recommendation, OIML R 134-2 (2009). The process may involve a scale house and low-speed scales or higher-speed WIM road or bridge scales with the goal of public safety, as well as road and bridge safety, according to the Bridges Act.
Modern roads
Today, roadways are primaril... | Road transport | Wikipedia | 441 | 49020 | https://en.wikipedia.org/wiki/Road%20transport | Technology | Road transport | null | vital_articles |
Nearly all roadways are built with devices meant to control traffic. Most notable to the motorist are those meant to communicate directly with the driver. Broadly, these fall into three categories: signs, signals or pavement markings. They help the driver navigate; they assign the right-of-way at intersections; they in... | Road transport | Wikipedia | 469 | 49020 | https://en.wikipedia.org/wiki/Road%20transport | Technology | Road transport | null | vital_articles |
Early toll roads were usually built by private companies under a government franchise. They typically paralleled or replaced routes already with some volume of commerce, hoping the improved road would divert enough traffic to make the enterprise profitable. Plank roads were particularly attractive as they greatly reduc... | Road transport | Wikipedia | 478 | 49020 | https://en.wikipedia.org/wiki/Road%20transport | Technology | Road transport | null | vital_articles |
With the development, mass production, and popular embrace of the automobile, faster and higher capacity roads were needed. In the 1920s limited access highways appeared. Their main characteristics were dual roadways with access points limited to (but not always) grade-separated interchanges. Their dual roadways allowe... | Road transport | Wikipedia | 399 | 49020 | https://en.wikipedia.org/wiki/Road%20transport | Technology | Road transport | null | vital_articles |
By 1956, most limited access highways in the eastern United States were toll roads. In that year, the Federal Aid Highway Act of 1956 was passed, funding non-toll roads with 90% federal dollars and 10% state match, giving little incentive for states to expand their turnpike system. Funding rules initially restricted co... | Road transport | Wikipedia | 359 | 49020 | https://en.wikipedia.org/wiki/Road%20transport | Technology | Road transport | null | vital_articles |
In biology, epigenetics is the study of heritable traits, or a stable change of cell function, that happen without changes to the DNA sequence. The Greek prefix epi- ( "over, outside of, around") in epigenetics implies features that are "on top of" or "in addition to" the traditional (DNA sequence based) genetic mechan... | Epigenetics | Wikipedia | 500 | 49033 | https://en.wikipedia.org/wiki/Epigenetics | Biology and health sciences | Genetics and taxonomy | null | vital_articles |
A definition of the concept of epigenetic trait as a "stably heritable phenotype resulting from changes in a chromosome without alterations in the DNA sequence" was formulated at a Cold Spring Harbor meeting in 2008, although alternate definitions that include non-heritable traits are still being used widely.
Waddingt... | Epigenetics | Wikipedia | 482 | 49033 | https://en.wikipedia.org/wiki/Epigenetics | Biology and health sciences | Genetics and taxonomy | null | vital_articles |
The term has also been used, however, to describe processes which have not been demonstrated to be heritable, such as some forms of histone modification. Consequently, there are attempts to redefine "epigenetics" in broader terms that would avoid the constraints of requiring heritability. For example, Adrian Bird defin... | Epigenetics | Wikipedia | 498 | 49033 | https://en.wikipedia.org/wiki/Epigenetics | Biology and health sciences | Genetics and taxonomy | null | vital_articles |
Covalent modification of either DNA (e.g. cytosine methylation and hydroxymethylation) or of histone proteins (e.g. lysine acetylation, lysine and arginine methylation, serine and threonine phosphorylation, and lysine ubiquitination and sumoylation) play central roles in many types of epigenetic inheritance. Therefore,... | Epigenetics | Wikipedia | 175 | 49033 | https://en.wikipedia.org/wiki/Epigenetics | Biology and health sciences | Genetics and taxonomy | null | vital_articles |
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