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Robinson's estimation of P. robustus size was soon challenged in 1974 by American palaeontologist Stephen Jay Gould and English palaeoanthropologist David Pilbeam, who guessed from the available skeletal elements a weight of about . Similarly, in 1988, American anthropologist Henry McHenry reported much lighter weights... | Paranthropus robustus | Wikipedia | 378 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
In 2001, palaeoanthropologist Randall L. Susman and colleagues, using two recently discovered proximal femoral fragments from Swartkrans, estimated an average of for males and for females. If these four proximal femur specimens—SK 82, SK 97, SKW 19, and SK 3121—are representative of the entire species, they said that... | Paranthropus robustus | Wikipedia | 222 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
In 1954, Robinson suggested that the heavily built skull of P. robustus and resultantly exorbitant bite force was indicative of a specialist diet adapted for frequently cracking hard foods such as nuts. Because of this, the predominant model of Paranthropus extinction for the latter half of the 20th century was that th... | Paranthropus robustus | Wikipedia | 294 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
In 2004, in their review of Paranthropus dietary literature, anthropologists Bernard Wood and David Strait concluded that Paranthropus were most definitely generalist feeders, and that P. robustus was an omnivore. They found that the microwear patterns in P. robustus suggest hard food was infrequently consumed, and the... | Paranthropus robustus | Wikipedia | 271 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
A 2006 carbon isotope analysis suggested that P. robustus subsisted on mainly C4 savanna plants or C3 forest plants depending on the season, which could indicate either seasonal shifts in diet or seasonal migration from forest to savanna. H. ergaster/H. erectus appears to have consumed about the same proportion of C3 t... | Paranthropus robustus | Wikipedia | 511 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
However, in 2011, palaeoanthropologist Sandi Copeland and colleagues studied the strontium isotope ratio of P. robustus teeth from the dolomite Sterkfontein Valley, and found that like other hominins, but unlike other great apes, P. robustus females were more likely to leave their place of birth (patrilocal). This disc... | Paranthropus robustus | Wikipedia | 496 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
Technology
Cave sites in the Cradle of Humankind often have stone and bone tools, with the former attributed to early Homo and the latter generally to P. robustus, as bone tools are most abundant when P. robustus remains far outnumber Homo remains. Australopithecine bone technology was first proposed by Dart in the 195... | Paranthropus robustus | Wikipedia | 501 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
In 1988, Brain and South African archaeologist A. Sillent analysed the 59,488 bone fragments from Swartkrans Member 3, and found that 270 had been burnt, mainly belonging to medium-sized antelope, but also zebra, warthog, baboon, and P. robustus. They were found across the entire depth of Member 3, so fire was a regula... | Paranthropus robustus | Wikipedia | 345 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
Australopithecines are generally considered to have had a faster, apelike growth rate than modern humans largely due to dental development trends. Broadly speaking, the emergence of the first permanent molar in early hominins has been variously estimated anywhere from 2.5 to 4.5 years, which all contrast markedly with ... | Paranthropus robustus | Wikipedia | 238 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
While growing, the front part of the jaw in P. robustus is depository (so it grows) whereas the sides are resorptive (so they recede). For comparison, chimp jaws are generally depository reflecting prognathism, and modern humans resorptive reflecting a flat face. In Paranthropus, this may have functioned to thicken the... | Paranthropus robustus | Wikipedia | 496 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
Females may have reached skeletal maturity by the time the third molar erupted, but males appear to have continued growing after reaching dental maturity, during which time they become markedly more robust than females (sexual bimaturism). Similarly, male gorillas complete dental development about the same time as fema... | Paranthropus robustus | Wikipedia | 457 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
In 1985, British biologists Paul H. Harvey and Tim Clutton-Brock came up with equations relating body size to life history events for primates, which McHenry applied to australopithecines in 1994. For P. robustus, he reported newborn brain size of 175 cc and weight of , gestation 7.6 months, weaning after 30.1 months o... | Paranthropus robustus | Wikipedia | 468 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
As many as four P. robustus individuals have been identified as having had dental cavities, indicating a rate similar to non-agricultural modern humans (1–5%). This is odd as P. robustus is thought to have had a diet high in gritty foods, and gritty foods should decrease cavity incidence rate, so P. robustus may have o... | Paranthropus robustus | Wikipedia | 444 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
While removing the matrix encapsulating TM 1517, Schepers noted a large rock, which would have weighed , which had driven itself into the braincase through the parietal bone. He considered this evidence that another individual had killed TM 1517 by launching the rock as a projectile in either defense or attack, but the... | Paranthropus robustus | Wikipedia | 344 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
P. robustus also cohabited the Cradle of Humankind with H. ergaster/H. erectus. In addition, these two species resided alongside Australopithecus sediba which is known from about 2 million years ago at Malapa. The most recent A. africanus specimen, Sts 5, dates to about 2.07 million years ago, around the arrival of P. ... | Paranthropus robustus | Wikipedia | 507 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
Cosmogenic nuclide geochronology has reported much more constrained dates of 2.2–1.8 million years ago for Member 1, and 0.96 million years ago for Member 3. No suitable section of Member 2 could be identified to date.
Sterkfontein
At Sterkfontein, only the specimens StW 566 and StW 569 are firmly assigned to P. robu... | Paranthropus robustus | Wikipedia | 501 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
The animal remains of Kromdraai A suggest deposition occurred anywhere between 1.89 and 1.63 million years ago, and the presence of Oldowan or Achulean tools indicates early Homo activity. The biostratigraphic dating of Kromdraai B is less clear as there are no animal species which are known to have existed in a narrow... | Paranthropus robustus | Wikipedia | 474 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
Cooper's Cave
Cooper's Cave was first reported to yield P. robustus remains in 2000 by South African palaeoanthropologists Christine Steininger and Lee Rogers Berger. Specimens include a crushed partial right face (COB 101), three isolated teeth, a juvenile jawbone, and several skull fragments.
The animal remains in t... | Paranthropus robustus | Wikipedia | 341 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
Australopithecine bones may have accumulated in caves due to large carnivores dragging in carcasses, which was first explored in detail by Brain in his 1981 book The Hunters or the Hunted?: An Introduction to African Cave Taphonomy. The juvenile P. robustus skullcap SK 54 has two puncture marks consistent with the lowe... | Paranthropus robustus | Wikipedia | 321 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
Extinction
Though P. robustus was a rather hardy species with a tolerance for environmental variability, it seems to have preferred wooded environments, and similarly most P. robustus remains date to a wet period in South Africa 2–1.75 million years ago conducive to such biomes. The extinction of P. robustus coincided ... | Paranthropus robustus | Wikipedia | 324 | 2165269 | https://en.wikipedia.org/wiki/Paranthropus%20robustus | Biology and health sciences | Australopithecines | Biology |
Paranthropus boisei is a species of australopithecine from the Early Pleistocene of East Africa about 2.5 to 1.15 million years ago. The holotype specimen, OH 5, was discovered by palaeoanthropologist Mary Leakey in 1959 at Olduvai Gorge, Tanzania and described by her husband Louis a month later. It was originally plac... | Paranthropus boisei | Wikipedia | 332 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
P. boisei was originally believed to have been a specialist species of hard foods, such as nuts, due to its heavily built skull, but it was more likely a generalist feeder of predominantly abrasive C4 plants, such as grasses or underground storage organs. Like gorillas, the apparently specialised adaptations of the sku... | Paranthropus boisei | Wikipedia | 420 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
Louis determined OH 5 to be a subadult or adolescent based on dental development, and he and Mary nicknamed it "Dear Boy". After they reconstructed the skull and jaws, newspapers began referring to it as "Nutcracker Man" due to the large back teeth and jaws which gave it a resemblance to vintage nutcrackers. South Afri... | Paranthropus boisei | Wikipedia | 220 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
The first identified jawbone, Peninj 1, was discovered Lake Natron just north of Olduvai Gorge in 1964. Especially from 1966 to 1975, several more specimens revealing facial elements were reported from the Shungura Formation, Ethiopia; Koobi Fora and Chesowanja, Kenya; and Omo and Konso, Ethiopia. Among the notable spe... | Paranthropus boisei | Wikipedia | 507 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
Soon after, Louis presented "Z." boisei to the 4th Pan-African Congress on Prehistory in Léopoldville, Belgian Congo (now Kinshasa, Democratic Republic of the Congo). Dart made his now famous joke, "... what would have happened if [the A. africanus specimen] Mrs. Ples had met Dear Boy one dark night." At the time of di... | Paranthropus boisei | Wikipedia | 333 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
The genus Paranthropus (otherwise known as "robust australopithecines") typically includes P. boisei, P. aethiopicus and P. robustus. It is debated if Paranthropus is a valid natural grouping (monophyletic) or an invalid grouping of similar-looking hominins (paraphyletic). Because skeletal elements are so limited in th... | Paranthropus boisei | Wikipedia | 216 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
Before P. boisei was described (and P. robustus was the only member of Paranthropus), Broom and Robinson continued arguing that P. robustus and A. africanus (the then only known australopithecines) were two distinct lineages. However, remains were not firmly dated, and it was debated if there were indeed multiple homin... | Paranthropus boisei | Wikipedia | 476 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
Because P. boisei and P. aethiopicus are both known from East Africa and P. aethiopicus is only confidently identified from the skull KNM WT 17000 and a few jaws and isolated teeth, it is debated if P. aethiopicus should be subsumed under P. boisei or if the differences stemming from archaicness justifies species disti... | Paranthropus boisei | Wikipedia | 313 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
P. boisei is the most robust of the robust australopithecines, whereas the South African P. robustus is smaller with comparatively more gracile features. The P. boisei skull is heavily built, and features a defined brow ridge, receding forehead, rounded bottom margins of the eye sockets, inflated and concave cheek bone... | Paranthropus boisei | Wikipedia | 472 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
Regarding the dural venous sinuses, in 1983, American neuroanthropologist Dean Falk and anthropologist Glenn Conroy suggested that, unlike A. africanus or modern humans, all Paranthropus (and A. afarensis) had expanded occipital and marginal (around the foramen magnum) sinuses, completely supplanting the transverse and... | Paranthropus boisei | Wikipedia | 478 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
Instead, the OH 80 femur, more like H. erectus femora, is quite thick, features a laterally flattened shaft, and indicates similarly arranged gluteal, pectineal and intertrochanteric lines around the hip joint. Nonetheless, the intertrochanteric line is much more defined in OH 80, the gluteal tuberosity is more towards... | Paranthropus boisei | Wikipedia | 442 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
However, in 1981, English anthropologist Alan Walker found that the microwearing patterns on the molars were inconsistent with a diet high in hard foods, and were effectively indistinguishable from the pattern seen in the molars of fruit-eating (frugivorous) mandrills, chimpanzees and orangutans. The microwearing on P.... | Paranthropus boisei | Wikipedia | 470 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
Technology
By the time OH 5 was discovered, the Leakeys had spent 24 years excavating the area for early hominin remains, but had instead recovered mainly other animal remains as well as the Oldowan stone tool industry. Because OH 5 was associated with the tools and processed animal bones, they presumed it was the tool... | Paranthropus boisei | Wikipedia | 310 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
Social structure
In 1979, American biological anthropologist Noel T. Boaz noticed that the relative proportions between large mammal families at the Shungura Formation are quite similar to the proportion in modern-day across sub-Saharan Africa. Boaz believed that hominins would have had about the same population densit... | Paranthropus boisei | Wikipedia | 462 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
Development
Australopithecines are generally considered to have had a faster, apelike growth rate than modern humans largely due to dental development trends. Broadly speaking, the emergence of the first permanent molar in early hominins has been variously estimated anywhere from 2.5 to 4.5 years of age, which all cont... | Paranthropus boisei | Wikipedia | 333 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
Palaeoecology
P. boisei remains have been found predominantly in what were wet, wooded environments, such as wetlands along lakes and rivers, wooded or arid shrublands, and semi-arid woodlands, with the exception of the savanna-dominated Malawian Chiwondo Beds. Its abundance likely increased during precession-driven p... | Paranthropus boisei | Wikipedia | 463 | 2165275 | https://en.wikipedia.org/wiki/Paranthropus%20boisei | Biology and health sciences | Australopithecines | Biology |
Traditional Japanese units of measurement or the shakkanhō () is the traditional system of measurement used by the people of the Japanese archipelago. It is largely based on the Chinese system, which spread to Japan and the rest of the Sinosphere in antiquity. It has remained mostly unaltered since the adoption of the ... | Japanese units of measurement | Wikipedia | 422 | 2985420 | https://en.wikipedia.org/wiki/Japanese%20units%20of%20measurement | Physical sciences | Measurement systems | Basics and measurement |
In 1909, English units were also made legal within the Empire of Japan. Following World War I, the Ministry of Agriculture and Commerce established a Committee for Weights and Measures and Industrial Standards, part of whose remit was to investigate which of Japan's three legal systems should be adopted. Upon its advic... | Japanese units of measurement | Wikipedia | 480 | 2985420 | https://en.wikipedia.org/wiki/Japanese%20units%20of%20measurement | Physical sciences | Measurement systems | Basics and measurement |
With the majority of the public now exposed to it since childhood, the metric system became the sole legal measurement system in most fields of Japanese life on 1 January 1959. Redrafting of laws to use metric equivalents had already been accomplished, but conversion of the land registries required until 31 March 1966 ... | Japanese units of measurement | Wikipedia | 478 | 2985420 | https://en.wikipedia.org/wiki/Japanese%20units%20of%20measurement | Physical sciences | Measurement systems | Basics and measurement |
The Japanese ri is now much longer than the Chinese or Korean li, comprising 36 chō, 2160 ken, or 12,960shaku. A still longer unit was formerly standard in Ise on Honshu and throughout the 9 provinces of Kyushu, which comprised 50 chō, 3000 ken, or 18,000shaku. The imperial nautical mile of 6080feet (1853.19m) was also... | Japanese units of measurement | Wikipedia | 438 | 2985420 | https://en.wikipedia.org/wiki/Japanese%20units%20of%20measurement | Physical sciences | Measurement systems | Basics and measurement |
The koku is historically important: since it was reckoned as the amount of rice necessary to feed a person for a single year, it was used to compute agricultural output and official salaries. The koku of rice was sometimes reckoned as 3000"sacks". By the 1940s the shipping koku was of the shipping ton of 40 or 42cuft ... | Japanese units of measurement | Wikipedia | 393 | 2985420 | https://en.wikipedia.org/wiki/Japanese%20units%20of%20measurement | Physical sciences | Measurement systems | Basics and measurement |
Copper(II) acetate, also referred to as cupric acetate, is the chemical compound with the formula Cu(OAc)2 where AcO− is acetate (). The hydrated derivative, Cu2(OAc)4(H2O)2, which contains one molecule of water for each copper atom, is available commercially. Anhydrous copper(II) acetate is a dark green crystalline so... | Copper(II) acetate | Wikipedia | 418 | 2987828 | https://en.wikipedia.org/wiki/Copper%28II%29%20acetate | Physical sciences | Acetates | Chemistry |
Uses in chemical synthesis
Copper(II) acetate has found some use as an oxidizing agent in organic syntheses. In the Eglinton reaction Cu2(OAc)4 is used to couple terminal alkynes to give a 1,3-diyne:
Cu2(OAc)4 + 2 RC≡CH → 2 CuOAc + RC≡C−C≡CR + 2 HOAc
The reaction proceeds via the intermediacy of copper(I) acetylides, w... | Copper(II) acetate | Wikipedia | 399 | 2987828 | https://en.wikipedia.org/wiki/Copper%28II%29%20acetate | Physical sciences | Acetates | Chemistry |
Calcium acetate is a chemical compound which is a calcium salt of acetic acid. It has the formula Ca(C2H3O2)2. Its standard name is calcium acetate, while calcium ethanoate is the systematic name. An older name is acetate of lime. The anhydrous form is very hygroscopic; therefore the monohydrate (Ca(CH3COO)2•H2O) is t... | Calcium acetate | Wikipedia | 479 | 2988583 | https://en.wikipedia.org/wiki/Calcium%20acetate | Physical sciences | Acetates | Chemistry |
Natural occurrence
Pure calcium acetate is yet unknown among minerals. calcium acetate chloride is listed as a known mineral, but its genesis is anthropogenic (human-generated, as opposed to naturally occurring). | Calcium acetate | Wikipedia | 43 | 2988583 | https://en.wikipedia.org/wiki/Calcium%20acetate | Physical sciences | Acetates | Chemistry |
Chromium(II) acetate hydrate, also known as chromous acetate, is the coordination compound with the formula Cr2(CH3CO2)4(H2O)2. This formula is commonly abbreviated Cr2(OAc)4(H2O)2. This red-coloured compound features a quadruple bond. The preparation of chromous acetate once was a standard test of the synthetic skills... | Chromium(II) acetate | Wikipedia | 379 | 2988743 | https://en.wikipedia.org/wiki/Chromium%28II%29%20acetate | Physical sciences | Acetates | Chemistry |
The quadruple bond between the two chromium atoms arises from the overlap of four d-orbitals on each metal with the same orbitals on the other metal: the dz2 orbitals overlap to give a sigma bonding component, the dxz and dyz orbitals overlap to give two pi bonding components, and the dxy orbitals give a delta bond. Th... | Chromium(II) acetate | Wikipedia | 457 | 2988743 | https://en.wikipedia.org/wiki/Chromium%28II%29%20acetate | Physical sciences | Acetates | Chemistry |
Because it is so easily prepared, Cr2(OAc)4(H2O)2 is a starting material for other chromium(II) compounds. Also, many analogues have been prepared using other carboxylic acids in place of acetate and using different bases in place of the water.
Applications
Chromium(II) acetate has few practical applications. It has ... | Chromium(II) acetate | Wikipedia | 153 | 2988743 | https://en.wikipedia.org/wiki/Chromium%28II%29%20acetate | Physical sciences | Acetates | Chemistry |
Ferret-badgers are the six species of the genus Melogale, which is the only genus of the monotypic mustelid subfamily Helictidinae.
Bornean ferret-badger (Melogale everetti)
Chinese ferret-badger (Melogale moschata)
Formosan ferret-badger (Melogale subaurantiaca)
Javan ferret-badger (Melogale orientalis)
Burmese f... | Ferret-badger | Wikipedia | 165 | 6974397 | https://en.wikipedia.org/wiki/Ferret-badger | Biology and health sciences | Mustelidae | Animals |
In continuum mechanics, shearing refers to the occurrence of a shear strain, which is a deformation of a material substance in which parallel internal surfaces slide past one another. It is induced by a shear stress in the material. Shear strain is distinguished from volumetric strain. The change in a material's volu... | Shearing (physics) | Wikipedia | 433 | 7139621 | https://en.wikipedia.org/wiki/Shearing%20%28physics%29 | Physical sciences | Solid mechanics | Physics |
The dwarf crocodile (Osteolaemus tetraspis), also known as the African dwarf crocodile, broad-snouted crocodile (a name more often used for the Asian mugger crocodile) or bony crocodile, is an African crocodile that is also the smallest extant (living) species of crocodile.
Description
Dwarf crocodiles attain a mediu... | Dwarf crocodile | Wikipedia | 504 | 7139731 | https://en.wikipedia.org/wiki/Dwarf%20crocodile | Biology and health sciences | Crocodilia | Animals |
Dwarf crocodiles live from lowlands to mid-altitude in streams, small rivers, swamps, pools and mangrove, but generally avoid main sections of large rivers. Most of their range is within forested regions, but it may extend into more open regions where the streams or river are well-shaded. They are also found in seasona... | Dwarf crocodile | Wikipedia | 434 | 7139731 | https://en.wikipedia.org/wiki/Dwarf%20crocodile | Biology and health sciences | Crocodilia | Animals |
Reproduction
Interacting closely only in breeding season, female dwarf crocodiles build their nest mounds at the beginning of the wet season, which spans May and June. The nest, situated near the water, is a mound of wet, decaying vegetation that incubates the eggs due to the heat generated by the decomposition of the ... | Dwarf crocodile | Wikipedia | 487 | 7139731 | https://en.wikipedia.org/wiki/Dwarf%20crocodile | Biology and health sciences | Crocodilia | Animals |
The specific epithet, tetraspis, means "four shields", and derives from the Ancient Greek (four) and (shield), as the back of the neck has four large, shield-like scales.
Phylogeny
A 2018 tip dating study by Lee & Yates simultaneously using morphological, molecular (DNA sequencing), and stratigraphic (fossil age) da... | Dwarf crocodile | Wikipedia | 445 | 7139731 | https://en.wikipedia.org/wiki/Dwarf%20crocodile | Biology and health sciences | Crocodilia | Animals |
Soil steam sterilization (soil steaming) is a farming technique that sterilizes soil with steam in open fields or greenhouses. Pests of plant cultures such as weeds, bacteria, fungi and viruses are killed through induced hot steam which causes vital cellular proteins to unfold. Biologically, the method is considered a... | Soil steam sterilization | Wikipedia | 474 | 15946878 | https://en.wikipedia.org/wiki/Soil%20steam%20sterilization | Technology | Pest and disease control | null |
Surface steaming
Several methods for surface steaming are in use amongst which are: area sheet steaming, the steaming hood, the steaming harrow, the steaming plough and vacuum steaming with drainage pipes or mobile pipe systems.
In order to pick the most suitable steaming method, certain factors have to be considered ... | Soil steam sterilization | Wikipedia | 507 | 15946878 | https://en.wikipedia.org/wiki/Soil%20steam%20sterilization | Technology | Pest and disease control | null |
In practice, working with at least two sheets simultaneously has proven to be highly effective. While one sheet is used for steaming the other one is prepared for steam injection, therefore unnecessary steaming recesses are avoided.
Depth steaming with vacuum
Steaming with vacuum which is induced through a mobile or f... | Soil steam sterilization | Wikipedia | 418 | 15946878 | https://en.wikipedia.org/wiki/Soil%20steam%20sterilization | Technology | Pest and disease control | null |
Negative pressure technique
Negative pressure technique generates appropriate soil temperature at a 60 cm depth and complete control of nematodes, fungi and weeds is achieved. In this technique, the steam is introduced under the steaming sheath and forced to enter the soil profile by a negative pressure. The negative p... | Soil steam sterilization | Wikipedia | 438 | 15946878 | https://en.wikipedia.org/wiki/Soil%20steam%20sterilization | Technology | Pest and disease control | null |
Sandwich steaming offers several advantages. On the one hand, application of energy can be increased to up to 120 kg steam per m2/h. In comparison to other steaming methods up to 30% energy savings can be achieved and the usage of fuel (e.g. heating oil) accordingly decreases. The increased application of energy leads ... | Soil steam sterilization | Wikipedia | 383 | 15946878 | https://en.wikipedia.org/wiki/Soil%20steam%20sterilization | Technology | Pest and disease control | null |
History
Modern soil steam sterilization was first discovered in 1888 (by Frank in Germany) and was first commercially used in the United States (by Rudd) in 1893 (Baker 1962). Since then, a wide variety of steam machines have been built to disinfest both commercial greenhouse and nursery field soils (Grossman and Liebm... | Soil steam sterilization | Wikipedia | 236 | 15946878 | https://en.wikipedia.org/wiki/Soil%20steam%20sterilization | Technology | Pest and disease control | null |
Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means development of an embryo from an unfertilized egg cell. In plants, parthenogenesis is a component process of apomixis. In a... | Parthenogenesis | Wikipedia | 452 | 9276466 | https://en.wikipedia.org/wiki/Parthenogenesis | Biology and health sciences | Biological reproduction | Biology |
Parthenogenesis is a form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. It occurs naturally in some plants, algae, invertebrate animal species (including nematodes, some tardigrades, water fleas, some scorpions, aphids, some mites, some bees, some Phasmatodea,... | Parthenogenesis | Wikipedia | 457 | 9276466 | https://en.wikipedia.org/wiki/Parthenogenesis | Biology and health sciences | Biological reproduction | Biology |
Many taxa with heterogony have within them species that have lost the sexual phase and are now completely asexual. Many other cases of obligate parthenogenesis (or gynogenesis) are found among polyploids and hybrids where the chromosomes cannot pair for meiosis.
The production of female offspring by parthenogenesis i... | Parthenogenesis | Wikipedia | 462 | 9276466 | https://en.wikipedia.org/wiki/Parthenogenesis | Biology and health sciences | Biological reproduction | Biology |
Some authors consider all forms of automixis sexual as they involve recombination. Many others classify the endomitotic variants as asexual and consider the resulting embryos parthenogenetic. Among these authors, the threshold for classifying automixis as a sexual process depends on when the products of anaphase I or o... | Parthenogenesis | Wikipedia | 501 | 9276466 | https://en.wikipedia.org/wiki/Parthenogenesis | Biology and health sciences | Biological reproduction | Biology |
When meiosis is involved, the sex of the offspring depends on the type of sex determination system and the type of apomixis. In species that use the XY sex-determination system, parthenogenetic offspring have two X chromosomes and are female. In species that use the ZW sex-determination system the offspring genotype ma... | Parthenogenesis | Wikipedia | 472 | 9276466 | https://en.wikipedia.org/wiki/Parthenogenesis | Biology and health sciences | Biological reproduction | Biology |
In aphids, a generation sexually conceived by a male and a female produces only females. The reason for this is the non-random segregation of the sex chromosomes 'X' and 'O' during spermatogenesis.
Facultative parthenogenesis is often used to describe cases of spontaneous parthenogenesis in normally sexual animals. Fo... | Parthenogenesis | Wikipedia | 387 | 9276466 | https://en.wikipedia.org/wiki/Parthenogenesis | Biology and health sciences | Biological reproduction | Biology |
Some invertebrate species that feature (partial) sexual reproduction in their native range are found to reproduce solely by parthenogenesis in areas to which they have been introduced. Relying solely on parthenogenetic reproduction has several advantages for an invasive species: it obviates the need for individuals in ... | Parthenogenesis | Wikipedia | 431 | 9276466 | https://en.wikipedia.org/wiki/Parthenogenesis | Biology and health sciences | Biological reproduction | Biology |
To initiate unfertilised development of swine oocytes, various methods exist to induce an artificial activation that mimics sperm entry, such as calcium ionophore treatment, microinjection of calcium ions, or electrical stimulation. Treatment with cycloheximide, a non-specific protein synthesis inhibitor, enhances the ... | Parthenogenesis | Wikipedia | 389 | 9276466 | https://en.wikipedia.org/wiki/Parthenogenesis | Biology and health sciences | Biological reproduction | Biology |
In 1955, Helen Spurway, a geneticist specializing in the reproductive biology of the guppy (Lebistes reticulatus), claimed that parthenogenesis may occur (though very rarely) in humans, leading to so-called "virgin births". This created some sensation among her colleagues and the lay public alike. Sometimes an embryo m... | Parthenogenesis | Wikipedia | 429 | 9276466 | https://en.wikipedia.org/wiki/Parthenogenesis | Biology and health sciences | Biological reproduction | Biology |
In 2007, the International Stem Cell Corporation of California announced that Elena Revazova had intentionally created human stem cells from unfertilized human eggs using parthenogenesis. The process may offer a way for creating stem cells genetically matched to a particular female to treat degenerative diseases. The s... | Parthenogenesis | Wikipedia | 331 | 9276466 | https://en.wikipedia.org/wiki/Parthenogenesis | Biology and health sciences | Biological reproduction | Biology |
A form of asexual reproduction related to parthenogenesis is gynogenesis. Here, offspring are produced by the same mechanism as in parthenogenesis, but with the requirement that the egg merely be stimulated by the presence of sperm in order to develop. However, the sperm cell does not contribute any genetic material to... | Parthenogenesis | Wikipedia | 510 | 9276466 | https://en.wikipedia.org/wiki/Parthenogenesis | Biology and health sciences | Biological reproduction | Biology |
Other examples where hybridogenesis is at least one of modes of reproduction include i.e.
Iberian minnow Tropidophoxinellus alburnoides (Squalius pyrenaicus × hypothetical ancestor related with Anaecypris hispanica)
spined loaches Cobitis hankugensis × C. longicorpus
Bacillus stick insects B. rossius × Bacillus gran... | Parthenogenesis | Wikipedia | 183 | 9276466 | https://en.wikipedia.org/wiki/Parthenogenesis | Biology and health sciences | Biological reproduction | Biology |
Fault blocks are very large blocks of rock, sometimes hundreds of kilometres in extent, created by tectonic and localized stresses in Earth's crust. Large areas of bedrock are broken up into blocks by faults. Blocks are characterized by relatively uniform lithology. The largest of these fault blocks are called crusta... | Fault block | Wikipedia | 493 | 5470669 | https://en.wikipedia.org/wiki/Fault%20block | Physical sciences | Montane landforms | Earth science |
An example of a graben is the basin of the Narmada River in India, between the Vindhya and Satpura horsts. | Fault block | Wikipedia | 29 | 5470669 | https://en.wikipedia.org/wiki/Fault%20block | Physical sciences | Montane landforms | Earth science |
The near side of the Moon is the lunar hemisphere that always faces towards Earth, opposite to the far side. Only one side of the Moon is visible from Earth because the Moon rotates on its axis at the same rate that the Moon orbits the Earth—a situation known as tidal locking.
The Moon is directly illuminated by the S... | Near side of the Moon | Wikipedia | 318 | 5473867 | https://en.wikipedia.org/wiki/Near%20side%20of%20the%20Moon | Physical sciences | Solar System | Astronomy |
On the north pole, if the Moon is visible, it stands low above the horizon with its north pole up.
In mid northern latitudes (North America, Europe, Asia) the Moon rises in the east with its northeastern limb up (Mare Crisium), it reaches its highest point in the south with its north on top, and sets in the west with i... | Near side of the Moon | Wikipedia | 272 | 5473867 | https://en.wikipedia.org/wiki/Near%20side%20of%20the%20Moon | Physical sciences | Solar System | Astronomy |
The two hemispheres have distinctly different appearances, with the near side covered in multiple, large maria (Latin for 'seas'). These lowlands were believed to be seas of lunar water by the astronomers who first mapped them, in the 17th century (notably, Giovanni Battista Riccioli and Francesco Maria Grimaldi). Alth... | Near side of the Moon | Wikipedia | 257 | 5473867 | https://en.wikipedia.org/wiki/Near%20side%20of%20the%20Moon | Physical sciences | Solar System | Astronomy |
In quantum physics, a measurement is the testing or manipulation of a physical system to yield a numerical result. A fundamental feature of quantum theory is that the predictions it makes are probabilistic. The procedure for finding a probability involves combining a quantum state, which mathematically describes a quan... | Measurement in quantum mechanics | Wikipedia | 442 | 573875 | https://en.wikipedia.org/wiki/Measurement%20in%20quantum%20mechanics | Physical sciences | Quantum mechanics | Physics |
In quantum mechanics, each physical system is associated with a Hilbert space, each element of which represents a possible state of the physical system. The approach codified by John von Neumann represents a measurement upon a physical system by a self-adjoint operator on that Hilbert space termed an "observable". Thes... | Measurement in quantum mechanics | Wikipedia | 456 | 573875 | https://en.wikipedia.org/wiki/Measurement%20in%20quantum%20mechanics | Physical sciences | Quantum mechanics | Physics |
A density operator that is a rank-1 projection is known as a pure quantum state, and all quantum states that are not pure are designated mixed. Pure states are also known as wavefunctions. Assigning a pure state to a quantum system implies certainty about the outcome of some measurement on that system (i.e., for some ... | Measurement in quantum mechanics | Wikipedia | 498 | 573875 | https://en.wikipedia.org/wiki/Measurement%20in%20quantum%20mechanics | Physical sciences | Quantum mechanics | Physics |
In quantum mechanics, the POVM element is associated with the measurement outcome , such that the probability of obtaining it when making a measurement on the quantum state is given by
,
where is the trace operator. When the quantum state being measured is a pure state this formula reduces to
.
State change due... | Measurement in quantum mechanics | Wikipedia | 459 | 573875 | https://en.wikipedia.org/wiki/Measurement%20in%20quantum%20mechanics | Physical sciences | Quantum mechanics | Physics |
The prototypical example of a finite-dimensional Hilbert space is a qubit, a quantum system whose Hilbert space is 2-dimensional. A pure state for a qubit can be written as a linear combination of two orthogonal basis states and with complex coefficients:
A measurement in the basis will yield outcome with probabi... | Measurement in quantum mechanics | Wikipedia | 491 | 573875 | https://en.wikipedia.org/wiki/Measurement%20in%20quantum%20mechanics | Physical sciences | Quantum mechanics | Physics |
The old quantum theory is a collection of results from the years 1900–1925 which predate modern quantum mechanics. The theory was never complete or self-consistent, but was rather a set of heuristic corrections to classical mechanics. The theory is now understood as a semi-classical approximation to modern quantum mech... | Measurement in quantum mechanics | Wikipedia | 508 | 573875 | https://en.wikipedia.org/wiki/Measurement%20in%20quantum%20mechanics | Physical sciences | Quantum mechanics | Physics |
Writing and for the self-adjoint operators representing position and momentum respectively, a standard deviation of position can be defined as
and likewise for the momentum:
The Kennard–Pauli–Weyl uncertainty relation is
This inequality means that no preparation of a quantum particle can imply simultaneously preci... | Measurement in quantum mechanics | Wikipedia | 473 | 573875 | https://en.wikipedia.org/wiki/Measurement%20in%20quantum%20mechanics | Physical sciences | Quantum mechanics | Physics |
Quantum systems as measuring devices
The Robertson–Schrödinger uncertainty principle establishes that when two observables do not commute, there is a tradeoff in predictability between them. The Wigner–Araki–Yanase theorem demonstrates another consequence of non-commutativity: the presence of a conservation law limits ... | Measurement in quantum mechanics | Wikipedia | 467 | 573875 | https://en.wikipedia.org/wiki/Measurement%20in%20quantum%20mechanics | Physical sciences | Quantum mechanics | Physics |
To illustrate, let denote the initial state of the system, the initial state of the environment and the Hamiltonian specifying the system-environment interaction. The density operator can be diagonalized and written as a linear combination of the projectors onto its eigenvectors:
Expressing time evolution for a du... | Measurement in quantum mechanics | Wikipedia | 455 | 573875 | https://en.wikipedia.org/wiki/Measurement%20in%20quantum%20mechanics | Physical sciences | Quantum mechanics | Physics |
Quantum circuits are a model for quantum computation in which a computation is a sequence of quantum gates followed by measurements. The gates are reversible transformations on a quantum mechanical analog of an n-bit register. This analogous structure is referred to as an n-qubit register. Measurements, drawn on a circ... | Measurement in quantum mechanics | Wikipedia | 426 | 573875 | https://en.wikipedia.org/wiki/Measurement%20in%20quantum%20mechanics | Physical sciences | Quantum mechanics | Physics |
The double-slit experiment is a prototypical illustration of quantum interference, typically described using electrons or photons. The first interference experiment to be carried out in a regime where both wave-like and particle-like aspects of photon behavior are significant was G. I. Taylor's test in 1909. Taylor use... | Measurement in quantum mechanics | Wikipedia | 481 | 573875 | https://en.wikipedia.org/wiki/Measurement%20in%20quantum%20mechanics | Physical sciences | Quantum mechanics | Physics |
A central concern within quantum foundations is the "quantum measurement problem," though how this problem is delimited, and whether it should be counted as one question or multiple separate issues, are contested topics. Of primary interest is the seeming disparity between apparently distinct types of time evolution. V... | Measurement in quantum mechanics | Wikipedia | 338 | 573875 | https://en.wikipedia.org/wiki/Measurement%20in%20quantum%20mechanics | Physical sciences | Quantum mechanics | Physics |
In physics, circular motion is movement of an object along the circumference of a circle or rotation along a circular arc. It can be uniform, with a constant rate of rotation and constant tangential speed, or non-uniform with a changing rate of rotation. The rotation around a fixed axis of a three-dimensional body invo... | Circular motion | Wikipedia | 512 | 574544 | https://en.wikipedia.org/wiki/Circular%20motion | Physical sciences | Classical mechanics | Physics |
The speed of the object traveling the circle is:
The angle swept out in a time is:
The angular acceleration, , of the particle is:
In the case of uniform circular motion, will be zero.
The acceleration due to change in the direction is:
The centripetal and centrifugal force can also be found using acceleration:... | Circular motion | Wikipedia | 466 | 574544 | https://en.wikipedia.org/wiki/Circular%20motion | Physical sciences | Classical mechanics | Physics |
Because the radius of the circle is constant, the radial component of the velocity is zero. The unit vector has a time-invariant magnitude of unity, so as time varies its tip always lies on a circle of unit radius, with an angle the same as the angle of . If the particle displacement rotates through an angle in time... | Circular motion | Wikipedia | 423 | 574544 | https://en.wikipedia.org/wiki/Circular%20motion | Physical sciences | Classical mechanics | Physics |
Velocity
Figure 1 illustrates velocity and acceleration vectors for uniform motion at four different points in the orbit. Because the velocity is tangent to the circular path, no two velocities point in the same direction. Although the object has a constant speed, its direction is always changing. This change in velo... | Circular motion | Wikipedia | 478 | 574544 | https://en.wikipedia.org/wiki/Circular%20motion | Physical sciences | Classical mechanics | Physics |
The normal force is actually the sum of the radial and tangential forces. The component of weight force is responsible for the tangential force (when we neglect friction). The centripetal force is due to the change in the direction of velocity.
The normal force and weight may also point in the same direction. Both for... | Circular motion | Wikipedia | 440 | 574544 | https://en.wikipedia.org/wiki/Circular%20motion | Physical sciences | Classical mechanics | Physics |
Applications
Solving applications dealing with non-uniform circular motion involves force analysis. With a uniform circular motion, the only force acting upon an object traveling in a circle is the centripetal force. In a non-uniform circular motion, there are additional forces acting on the object due to a non-zero t... | Circular motion | Wikipedia | 403 | 574544 | https://en.wikipedia.org/wiki/Circular%20motion | Physical sciences | Classical mechanics | Physics |
Callinectes sapidus (from the Ancient Greek ,"beautiful" + , "swimmer", and Latin , "savory"), the blue crab, Atlantic blue crab, or, regionally, the Maryland blue crab, is a species of crab native to the waters of the western Atlantic Ocean and the Gulf of Mexico, and introduced internationally.
C. sapidus is of cons... | Callinectes sapidus | Wikipedia | 458 | 574796 | https://en.wikipedia.org/wiki/Callinectes%20sapidus | Biology and health sciences | Crabs and hermit crabs | Animals |
Other species of Callinectes may be easily confused with C. sapidus because of overlapping ranges and similar morphology. One species is the lesser blue crab (C. similis). It is found further offshore than the common blue crab, and has a smoother granulated carapace. Males of the lesser blue crab also have mottled whit... | Callinectes sapidus | Wikipedia | 474 | 574796 | https://en.wikipedia.org/wiki/Callinectes%20sapidus | Biology and health sciences | Crabs and hermit crabs | Animals |
Ecology
The natural predators of C. sapidus include eels, drum, striped bass, spot, trout, some sharks, humans, cownose rays, and whiptail stingrays. C. sapidus is an omnivore, eating both plants and animals. It typically consumes thin-shelled bivalves (such as clams, mussels, and oysters), crustaceans, annelids, small... | Callinectes sapidus | Wikipedia | 507 | 574796 | https://en.wikipedia.org/wiki/Callinectes%20sapidus | Biology and health sciences | Crabs and hermit crabs | Animals |
Growth
Eggs of C. sapidus hatch in high-salinity waters of inlets, coastal waters, and mouths of rivers, and are carried to the ocean by ebb tides. During seven planktonic (zoeal) stages, blue crab larvae float near the surface and feed on microorganisms they encounter. After the eighth zoeal stage, larvae molt into me... | Callinectes sapidus | Wikipedia | 168 | 574796 | https://en.wikipedia.org/wiki/Callinectes%20sapidus | Biology and health sciences | Crabs and hermit crabs | Animals |
A blue crab grows by shedding its exoskeleton, or molting, to expose a new, larger exoskeleton. After it hardens, the new shell fills with body tissue. Shell hardening occurs most quickly in low-salinity water where high osmotic pressure allows the shell to become rigid soon after molting. Molting reflects only increme... | Callinectes sapidus | Wikipedia | 402 | 574796 | https://en.wikipedia.org/wiki/Callinectes%20sapidus | Biology and health sciences | Crabs and hermit crabs | Animals |
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