text stringlengths 7 145k | page_title stringlengths 1 105 | source stringclasses 1
value | token_count int64 3 30.2k | id stringlengths 2 8 | url stringlengths 31 168 | topic stringclasses 198
values | section stringlengths 4 49 ⌀ | sublist stringlengths 0 628 ⌀ | method stringclasses 2
values |
|---|---|---|---|---|---|---|---|---|---|
For any , the ideal generated by is also generated by any associate of , that is, ; no other element generates the same ideal. As all the generators of an ideal have the same norm, the norm of an ideal is the norm of any of its generators.
In some circumstances, it is useful to choose, once for all, a generator for e... | Gaussian integer | Wikipedia | 484 | 48628 | https://en.wikipedia.org/wiki/Gaussian%20integer | Mathematics | Basics | null | vital_articles |
A Gaussian integer is a Gaussian prime if and only if either:
one of is zero and the absolute value of the other is a prime number of the form (with a nonnegative integer), or
both are nonzero and is a prime number (which will not be of the form ).
In other words, a Gaussian integer is a Gaussian prime if and on... | Gaussian integer | Wikipedia | 426 | 48628 | https://en.wikipedia.org/wiki/Gaussian%20integer | Mathematics | Basics | null | vital_articles |
where is a unit (that is, ), and are nonnegative integers, are positive integers, and are distinct Gaussian primes such that, depending on the choice of selected associates,
either with odd and positive, and even,
or the remainder of the Euclidean division of by equals 1 (this is Gauss's original choice).
An ... | Gaussian integer | Wikipedia | 505 | 48628 | https://en.wikipedia.org/wiki/Gaussian%20integer | Mathematics | Basics | null | vital_articles |
where the primes are pairwise non associated, and the exponents non-associated, a greatest common divisor is
with
Unfortunately, except in simple cases, the prime factorization is difficult to compute, and Euclidean algorithm leads to a much easier (and faster) computation. This algorithm consists of replacing of t... | Gaussian integer | Wikipedia | 458 | 48628 | https://en.wikipedia.org/wiki/Gaussian%20integer | Mathematics | Basics | null | vital_articles |
The congruence modulo is an equivalence relation (also called a congruence relation), which defines a partition of the Gaussian integers into equivalence classes, called here congruence classes or residue classes. The set of the residue classes is usually denoted , or , or simply .
The residue class of a Gaussian int... | Gaussian integer | Wikipedia | 508 | 48628 | https://en.wikipedia.org/wiki/Gaussian%20integer | Mathematics | Basics | null | vital_articles |
In the complex plane, one may consider a square grid, whose squares are delimited by the two lines
with and integers (blue lines in the figure). These divide the plane in semi-open squares (where and are integers)
The semi-open intervals that occur in the definition of have been chosen in order that every comple... | Gaussian integer | Wikipedia | 416 | 48628 | https://en.wikipedia.org/wiki/Gaussian%20integer | Mathematics | Basics | null | vital_articles |
Primitive residue class group and Euler's totient function
Many theorems (and their proofs) for moduli of integers can be directly transferred to moduli of Gaussian integers, if one replaces the absolute value of the modulus by the norm. This holds especially for the primitive residue class group (also called multiplic... | Gaussian integer | Wikipedia | 496 | 48628 | https://en.wikipedia.org/wiki/Gaussian%20integer | Mathematics | Basics | null | vital_articles |
Gauss's circle problem does not deal with the Gaussian integers per se, but instead asks for the number of lattice points inside a circle of a given radius centered at the origin. This is equivalent to determining the number of Gaussian integers with norm less than a given value.
There are also conjectures and unsolve... | Gaussian integer | Wikipedia | 196 | 48628 | https://en.wikipedia.org/wiki/Gaussian%20integer | Mathematics | Basics | null | vital_articles |
The English term lance is derived, via Middle English launce and Old French lance, from the Latin lancea, a generic term meaning a spear or javelin employed by both infantry and cavalry, with English initially keeping these generic meanings. It developed later into a term for spear-like weapons specially designed and m... | Lance | Wikipedia | 490 | 48774 | https://en.wikipedia.org/wiki/Lance | Technology | Polearms | null | vital_articles |
Middle Ages
The Byzantine cavalry used lances (kontos or kontarion) almost exclusively, often in mixed formations of mounted archers and lancers (cursores et defensores). The Byzantines used lances in both overarm and underarm grips, as well as being couched under the arm (held horizontally). The length of the standard... | Lance | Wikipedia | 385 | 48774 | https://en.wikipedia.org/wiki/Lance | Technology | Polearms | null | vital_articles |
In Europe, a jousting lance was a variation of the knight's lance which was modified from its original war design. In jousting, the lance tips would usually be blunt, often spread out like a cup or furniture foot, to provide a wider impact surface designed to unseat the opposing rider without spearing him through. The ... | Lance | Wikipedia | 504 | 48774 | https://en.wikipedia.org/wiki/Lance | Technology | Polearms | null | vital_articles |
Only the Polish–Lithuanian Commonwealth with its far greater emphasis on cavalry warfare, large population of Szlachta nobility and general lower military technology level among its foes retained the lance to a considerable degree, with the famously winged Polish hussars having their glory period during the 17th and 18... | Lance | Wikipedia | 465 | 48774 | https://en.wikipedia.org/wiki/Lance | Technology | Polearms | null | vital_articles |
The Franco-Prussian War of 1870 saw the extensive deployment of cavalry armed with lances on both sides. While the opportunities for decisive use of this weapon proved infrequent during the actual conflict, the entire cavalry corps (93 regiments of hussars, dragoons, cuirassiers, and uhlans) of the post-war Imperial Ge... | Lance | Wikipedia | 457 | 48774 | https://en.wikipedia.org/wiki/Lance | Technology | Polearms | null | vital_articles |
The relative value of the lance and the sword as a principal weapon for mounted troops was an issue of dispute in the years immediately preceding World War I. Opponents of the lance argued that the weapon was clumsy, conspicuous, easily deflected, and inefficient in a melee. Arguments favoring the retention of the lanc... | Lance | Wikipedia | 497 | 48774 | https://en.wikipedia.org/wiki/Lance | Technology | Polearms | null | vital_articles |
Mounted police use
When the Canadian North-West Mounted Police was established, it was modeled after certain British cavalry units that used lances. It made limited use of this weapon in small detachments during the 1870s, intended to impress indigenous peoples.
The modern Royal Canadian Mounted Police, the North-West... | Lance | Wikipedia | 239 | 48774 | https://en.wikipedia.org/wiki/Lance | Technology | Polearms | null | vital_articles |
A halberd (also called halbard, halbert or Swiss voulge) is a two-handed polearm that came to prominent use from the 13th to 16th centuries. The halberd consists of an axe blade topped with a spike mounted on a long shaft. It can have a hook or thorn on the back side of the axe blade for grappling mounted combatants an... | Halberd | Wikipedia | 460 | 48775 | https://en.wikipedia.org/wiki/Halberd | Technology | Polearms | null | vital_articles |
As long as pikemen fought other pikemen, the halberd remained a useful supplemental weapon for push of pike, but when their position became more defensive, to protect the slow-loading arquebusiers and matchlock musketeers from sudden attacks by cavalry, the percentage of halberdiers in the pike units steadily decreased... | Halberd | Wikipedia | 463 | 48775 | https://en.wikipedia.org/wiki/Halberd | Technology | Polearms | null | vital_articles |
The halberd has been used as a court bodyguard weapon for centuries, and is still the ceremonial weapon of the Swiss Guard in the Vatican and the Alabarderos (Halberdiers) Company of the Spanish Royal Guard. The halberd was one of the polearms sometimes carried by lower-ranking officers in European infantry units in th... | Halberd | Wikipedia | 353 | 48775 | https://en.wikipedia.org/wiki/Halberd | Technology | Polearms | null | vital_articles |
Bardiche, a type of two-handed battle axe known in the 16th and 17th centuries in Eastern Europe
Bill, similar to a halberd but with a hooked blade form
Ge or dagger-axe, a Chinese weapon in use from the Shang dynasty (est. 1500 BC) that had a dagger-shaped blade mounted perpendicular to a spearhead
Fauchard, a curved ... | Halberd | Wikipedia | 505 | 48775 | https://en.wikipedia.org/wiki/Halberd | Technology | Polearms | null | vital_articles |
Pathology is the study of disease. The word pathology also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in the context of modern medical treatment, the term is often used in a narrower fashion to refer to processes and tests t... | Pathology | Wikipedia | 450 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
The study of pathology, including the detailed examination of the body, including dissection and inquiry into specific maladies, dates back to antiquity. Rudimentary understanding of many conditions was present in most early societies and is attested to in the records of the earliest historical societies, including th... | Pathology | Wikipedia | 310 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
Modern pathology began to develop as a distinct field of inquiry during the 19th Century through natural philosophers and physicians that studied disease and the informal study of what they termed "pathological anatomy" or "morbid anatomy". However, pathology as a formal area of specialty was not fully developed until... | Pathology | Wikipedia | 504 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
Anatomical pathology (Commonwealth) or anatomic pathology (United States) is a medical specialty that is concerned with the diagnosis of disease based on the gross, microscopic, chemical, immunologic and molecular examination of organs, tissues, and whole bodies (as in a general examination or an autopsy). Anatomical ... | Pathology | Wikipedia | 326 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
Dermatopathology is a subspecialty of anatomic pathology that focuses on the skin and the rest of the integumentary system as an organ. It is unique, in that there are two paths a physician can take to obtain the specialization. All general pathologists and general dermatologists train in the pathology of the skin, s... | Pathology | Wikipedia | 333 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
Forensic pathology focuses on determining the cause of death by post-mortem examination of a corpse or partial remains. An autopsy is typically performed by a coroner or medical examiner, often during criminal investigations; in this role, coroners and medical examiners are also frequently asked to confirm the identit... | Pathology | Wikipedia | 436 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
Neuropathology is the study of disease of nervous system tissue, usually in the form of either surgical biopsies or sometimes whole brains in the case of autopsy. Neuropathology is a subspecialty of anatomic pathology, neurology, and neurosurgery. In many English-speaking countries, neuropathology is considered a subf... | Pathology | Wikipedia | 411 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
Renal pathology is a subspecialty of anatomic pathology that deals with the diagnosis and characterization of disease of the kidneys. In a medical setting, renal pathologists work closely with nephrologists and transplant surgeons, who typically obtain diagnostic specimens via percutaneous renal biopsy. The renal patho... | Pathology | Wikipedia | 277 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
There are two major types of specimens submitted for surgical pathology analysis: biopsies and surgical resections. A biopsy is a small piece of tissue removed primarily for surgical pathology analysis, most often in order to render a definitive diagnosis. Types of biopsies include core biopsies, which are obtained th... | Pathology | Wikipedia | 446 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
Hematopathology is the study of diseases of blood cells (including constituents such as white blood cells, red blood cells, and platelets) and the tissues, and organs comprising
the hematopoietic system. The term hematopoietic system refers to tissues and organs that produce and/or primarily host hematopoietic cells an... | Pathology | Wikipedia | 508 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
Oral and maxillofacial pathology
Oral and Maxillofacial Pathology is one of nine dental specialties recognized by the American Dental Association, and is sometimes considered a specialty of both dentistry and pathology. Oral Pathologists must complete three years of post doctoral training in an accredited program an... | Pathology | Wikipedia | 451 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
In the United Kingdom, pathologists are physicians licensed by the UK General Medical Council. The training to become a pathologist is under the oversight of the Royal College of Pathologists. After four to six years of undergraduate medical study, trainees proceed to a two-year foundation program. Full-time training i... | Pathology | Wikipedia | 473 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
Medical imaging is the generating of visual representations of the interior of a body for clinical analysis and medical intervention. Medical imaging reveals details of internal physiology that help medical professionals plan appropriate treatments for tissue infection and trauma. Medical imaging is also central in su... | Pathology | Wikipedia | 393 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
Psychopathology is the study of mental illness, particularly of severe disorders. Informed heavily by both psychology and neurology, its purpose is to classify mental illness, elucidate its underlying causes, and guide clinical psychiatric treatment accordingly. Although diagnosis and classification of mental norms a... | Pathology | Wikipedia | 494 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
Although the pathogens and their mechanics differ greatly from those of animals, plants are subject to a wide variety of diseases, including those caused by fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes and parasitic plants. Damage caused by insects, mites, verte... | Pathology | Wikipedia | 129 | 48791 | https://en.wikipedia.org/wiki/Pathology | Biology and health sciences | Fields of medicine | Health | vital_articles |
In gamma-ray astronomy, gamma-ray bursts (GRBs) are immensely energetic events occurring in distant galaxies which represent the brightest and "most powerful class of explosion in the universe." These extreme electromagnetic events are second only to the Big Bang as the most energetic and luminous phenomenon ever known... | Gamma-ray burst | Wikipedia | 509 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
Gamma-ray bursts were first observed in the late 1960s by the U.S. Vela satellites, which were built to detect gamma radiation pulses emitted by nuclear weapons tested in space. The United States suspected that the Soviet Union might attempt to conduct secret nuclear tests after signing the Nuclear Test Ban Treaty in 1... | Gamma-ray burst | Wikipedia | 391 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
Counterpart objects as candidate sources
For decades after the discovery of GRBs, astronomers searched for a counterpart at other wavelengths: i.e., any astronomical object in positional coincidence with a recently observed burst. Astronomers considered many distinct classes of objects, including white dwarfs, pulsars... | Gamma-ray burst | Wikipedia | 375 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
Because of the very faint luminosity of this galaxy, its exact distance was not measured for several years. Well after then, another major breakthrough occurred with the next event registered by BeppoSAX, GRB 970508. This event was localized within four hours of its discovery, allowing research teams to begin making ob... | Gamma-ray burst | Wikipedia | 244 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
BeppoSAX functioned until 2002 and CGRO (with BATSE) was deorbited in 2000. However, the revolution in the study of gamma-ray bursts motivated the development of a number of additional instruments designed specifically to explore the nature of GRBs, especially in the earliest moments following the explosion. The first ... | Gamma-ray burst | Wikipedia | 502 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
In October 2018, astronomers reported that (detected in 2015) and GW170817, a gravitational wave event detected in 2017 (which has been associated with , a burst detected 1.7 seconds later), may have been produced by the same mechanism—the merger of two neutron stars. The similarities between the two events, in terms ... | Gamma-ray burst | Wikipedia | 360 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
Although some light curves can be roughly reproduced using certain simplified models, little progress has been made in understanding the full diversity observed. Many classification schemes have been proposed, but these are often based solely on differences in the appearance of light curves and may not always reflect a... | Gamma-ray burst | Wikipedia | 309 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
The true nature of these objects was thus initially unknown, but the leading hypothesis was that they originated from the mergers of binary neutron stars or a neutron star with a black hole. Such mergers were hypothesized to produce kilonovae, and evidence for a kilonova associated with short GRB 130603B was reported i... | Gamma-ray burst | Wikipedia | 459 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
In December 2022, astronomers reported the observation of GRB 211211A for 51 seconds, the first evidence of a long GRB likely associated with mergers of "compact binary objects" such as neutron stars or white dwarfs. Following this, GRB 191019A (2019, 64s) and GRB 230307A (2023, 35s) have been argued to signify an emer... | Gamma-ray burst | Wikipedia | 497 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
Gamma-ray bursts are thought to be highly focused explosions, with most of the explosion energy collimated into a narrow jet. The jets of gamma-ray bursts are ultrarelativistic, and are the most relativistic jets in the universe. The matter in gamma-ray burst jets may also become superluminal, or faster than the speed ... | Gamma-ray burst | Wikipedia | 443 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
With the discovery of GRB 190114C, astronomers may have been missing half of the total energy that gamma-ray bursts produce, with Konstancja Satalecka, an astrophysicist at the German Electron Synchrotron, stating that "Our measurements show that the energy released in very-high-energy gamma-rays is comparable to the a... | Gamma-ray burst | Wikipedia | 403 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
However, a new model which has gained support and was developed by the Italian astrophysicist Remo Ruffini and other scientists at ICRANet is that of the binary-driven hypernova (BdHN) model. The model succeeds and improves upon both the fireshell model and the induced gravitational collapse (IGC) paradigm suggested be... | Gamma-ray burst | Wikipedia | 484 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
An alternative explanation proposed by Friedwardt Winterberg is that in the course of a gravitational collapse and in reaching the event horizon of a black hole, all matter disintegrates into a burst of gamma radiation.
Tidal disruption events
This class of GRB-like events was first discovered through the detection ... | Gamma-ray burst | Wikipedia | 479 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
The nature of the longer-wavelength afterglow emission (ranging from X-ray through radio) that follows gamma-ray bursts is better understood. Any energy released by the explosion not radiated away in the burst itself takes the form of matter or energy moving outward at nearly the speed of light. As this matter collides... | Gamma-ray burst | Wikipedia | 454 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
Estimating the exact rate at which GRBs occur is difficult; for a galaxy of approximately the same size as the Milky Way, estimates of the expected rate (for long-duration GRBs) can range from one burst every 10,000 years, to one burst every 1,000,000 years. Only a small percentage of these would be beamed towards Eart... | Gamma-ray burst | Wikipedia | 319 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
The long-term effects from a nearby burst are more dangerous. Gamma rays cause chemical reactions in the atmosphere involving oxygen and nitrogen molecules, creating first nitrogen oxide then nitrogen dioxide gas. The nitrogen oxides cause dangerous effects on three levels. First, they deplete ozone, with models showin... | Gamma-ray burst | Wikipedia | 445 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
The major Ordovician–Silurian extinction event 450 million years ago may have been caused by a GRB. Estimates suggest that approximately 20–60% of the total phytoplankton biomass in the Ordovician oceans would have perished in a GRB, because the oceans were mostly oligotrophic and clear. The late Ordovician species of ... | Gamma-ray burst | Wikipedia | 428 | 48803 | https://en.wikipedia.org/wiki/Gamma-ray%20burst | Physical sciences | Stellar astronomy | null | vital_articles |
A gravitational lens is matter, such as a cluster of galaxies or a point particle, that bends light from a distant source as it travels toward an observer. The amount of gravitational lensing is described by Albert Einstein's general theory of relativity. If light is treated as corpuscles travelling at the speed of lig... | Gravitational lens | Wikipedia | 505 | 48824 | https://en.wikipedia.org/wiki/Gravitational%20lens | Physical sciences | Basics_2 | Astronomy | vital_articles |
Strong lensing Where there are easily visible distortions such as the formation of Einstein rings, arcs, and multiple images. Despite being considered "strong", the effect is in general relatively small, such that even a galaxy with a mass more than 100 billion times that of the Sun will produce multiple images separat... | Gravitational lens | Wikipedia | 510 | 48824 | https://en.wikipedia.org/wiki/Gravitational%20lens | Physical sciences | Basics_2 | Astronomy | vital_articles |
Gravitational lenses act equally on all kinds of electromagnetic radiation, not just visible light, and also in non-electromagnetic radiation, like gravitational waves. Weak lensing effects are being studied for the cosmic microwave background as well as galaxy surveys. Strong lenses have been observed in radio and x-r... | Gravitational lens | Wikipedia | 359 | 48824 | https://en.wikipedia.org/wiki/Gravitational%20lens | Physical sciences | Basics_2 | Astronomy | vital_articles |
The result was considered spectacular news and made the front page of most major newspapers. It made Einstein and his theory of general relativity world-famous. When asked by his assistant what his reaction would have been if general relativity had not been confirmed by Eddington and Dyson in 1919, Einstein said "Then ... | Gravitational lens | Wikipedia | 479 | 48824 | https://en.wikipedia.org/wiki/Gravitational%20lens | Physical sciences | Basics_2 | Astronomy | vital_articles |
In the 1980s, astronomers realized that the combination of CCD imagers and computers would allow the brightness of millions of stars to be measured each night. In a dense field, such as the galactic center or the Magellanic clouds, many microlensing events per year could potentially be found. This led to efforts such a... | Gravitational lens | Wikipedia | 473 | 48824 | https://en.wikipedia.org/wiki/Gravitational%20lens | Physical sciences | Basics_2 | Astronomy | vital_articles |
In general relativity, light follows the curvature of spacetime, hence when light passes around a massive object, it is bent. This means that the light from an object on the other side will be bent towards an observer's eye, just like an ordinary lens. In general relativity the path of light depends on the shape of spa... | Gravitational lens | Wikipedia | 276 | 48824 | https://en.wikipedia.org/wiki/Gravitational%20lens | Physical sciences | Basics_2 | Astronomy | vital_articles |
A similar search in the southern hemisphere would be a very good step towards complementing the northern hemisphere search as well as obtaining other objectives for study. If such a search is done using well-calibrated and well-parameterized instruments and data, a result similar to the northern survey can be expected.... | Gravitational lens | Wikipedia | 443 | 48824 | https://en.wikipedia.org/wiki/Gravitational%20lens | Physical sciences | Basics_2 | Astronomy | vital_articles |
Research published Sep 30, 2013 in the online edition of Physical Review Letters, led by McGill University in Montreal, Québec, Canada, has discovered the B-modes, that are formed due to gravitational lensing effect, using National Science Foundation's South Pole Telescope and with help from the Herschel space observat... | Gravitational lens | Wikipedia | 471 | 48824 | https://en.wikipedia.org/wiki/Gravitational%20lens | Physical sciences | Basics_2 | Astronomy | vital_articles |
Kaiser, Squires and Broadhurst (1995), Luppino & Kaiser (1997) and Hoekstra et al. (1998) prescribed a method to invert the effects of the point spread function (PSF) smearing and shearing, recovering a shear estimator uncontaminated by the systematic distortion of the PSF. This method (KSB+) is the most widely used me... | Gravitational lens | Wikipedia | 315 | 48824 | https://en.wikipedia.org/wiki/Gravitational%20lens | Physical sciences | Basics_2 | Astronomy | vital_articles |
Kava or kava kava (Piper methysticum: Latin 'pepper' and Latinized Greek 'intoxicating') is a plant in the pepper family, native to the Pacific Islands. The name kava is from Tongan and Marquesan, meaning 'bitter.’ Other names for kava include ʻawa (Hawaiʻi), ʻava (Samoa), yaqona or yagona (Fiji), sakau (Pohnpei), seka... | Kava | Wikipedia | 456 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
It was spread by the Austronesian Lapita culture after contact eastward into the rest of Polynesia. It is endemic to Oceania and is not found in other Austronesian groups. Kava reached Hawaii, but it is absent in New Zealand, where it cannot grow. Consumption of kava is also believed to be the reason why betel nut chew... | Kava | Wikipedia | 285 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
In the Cook Islands, the reduplicated forms of kawakawa or kavakava are also applied to the unrelated members of the genus Pittosporum. In other languages, such as Futunan, compound terms like kavakava atua refer to other species belonging to the genus Piper. The reduplication of the base form is indicative of falsehoo... | Kava | Wikipedia | 462 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
Noble and non-noble kava
Scholars make a distinction between the so-called noble and non-noble kava. The latter category comprises the so-called tudei (or "two-day") kavas, medicinal kavas, and wild kava (Piper wichmanii, the ancestor of domesticated Piper methysticum). Traditionally, only noble kavas have been used f... | Kava | Wikipedia | 498 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
Growing regions
In Vanuatu, exportation of kava is strictly regulated. Only cultivars classified as noble are allowed to be exported. Only the most desirable cultivars for everyday drinking are classified as noble to maintain quality control. In addition, their laws mandate that exported kava must be at least five yea... | Kava | Wikipedia | 496 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
The Kawakawa (Piper excelsum) plant, known also as "Māori kava", may be confused with kava. While the two plants look similar and have similar names, they are different, but related, species. Kawakawa is a small tree endemic to New Zealand, having importance to traditional medicine and Māori culture. As noted by the Ka... | Kava | Wikipedia | 481 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
The mature roots of the kava plant are harvested after a minimum of four years (at least five years, ideally) for peak kavalactone content. Most kava plants produce around of root when they are harvested. Kava root is classified into two categories: crown root (or chips) and lateral root. Crown roots are the large-dia... | Kava | Wikipedia | 505 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
Receptor binding assays with botanical extracts have revealed direct interactions of leaf extracts of kava (which appear to be more active than root extracts) with the GABA (i.e., main) binding site of the GABAA receptor, the D2 receptor, the μ- and δ-opioid receptors, and the H1 and H2 receptors. Weak interaction with... | Kava | Wikipedia | 502 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
Kava prepared as described above is much more potent than processed kava. Chewing produces the strongest effect because it produces the finest particles. Fresh, undried kava produces a stronger beverage than dry kava. The strength also depends on the species and techniques of cultivation.
In Vanuatu, a strong kava dri... | Kava | Wikipedia | 436 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
Also, "chemical solvents used do not extract the same compounds as the natural water extracts in traditional use. The extraction process may exclude important modifying constituents soluble only in water". In particular, it has been noted that, unlike traditional water-based preparations, products obtained with the use... | Kava | Wikipedia | 473 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
While some bars have been committed to only serving the traditional forms and types of kava, other establishments have been accused of serving non-traditionally consumed non-noble kava varieties, which are cheaper but far more likely to cause unpleasant effects and adverse reactions, or of serving kava with other subst... | Kava | Wikipedia | 475 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
Effects on the liver
There is published evidence of the hepatotoxicity of kava extracts, and concerns about this led to kava being omitted from the US Pharmacopeia.
Other adverse reactions
Adverse reactions may result from the poor quality of kava raw material used in the manufacturing of various kava products. In a... | Kava | Wikipedia | 259 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
A few notable potential drug interactions are, but are not limited to:
Alcohol: It has been reported that combined use of alcohol and kava extract can have additive sedative effects. Regarding cognitive function, kava has been shown to have additive cognitive impairments while taken with alcohol when compared to takin... | Kava | Wikipedia | 481 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
Research
Kava is under preliminary research for its potential psychoactive — primarily anxiolytic — sleep-inducing, and sleep-enhancing properties. Preliminary analysis of kava effects in people with short-term anxiety disorders indicated a small level of improvement.
Traditional medicine
Over centuries, kava has bee... | Kava | Wikipedia | 431 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
Europe
Following discussions on the safety of certain pharmaceutical products derived from kava and sold in Germany, the EU imposed a temporary ban on imports of kava-based pharmaceutical products in 2002. The sale of kava plant became regulated in Switzerland, France, and in prepared form in the Netherlands. Some Paci... | Kava | Wikipedia | 459 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
New Zealand
When used traditionally, kava is regulated as a food under the Food Standards Code. Kava may also be used as an herbal remedy, where it is currently regulated by the Dietary Supplements Regulations. Only traditionally consumed forms and parts of the kava plant (i.e., pure roots of the kava plant, water extr... | Kava | Wikipedia | 333 | 48836 | https://en.wikipedia.org/wiki/Kava | Biology and health sciences | Piperales | Plants | vital_articles |
Sidereal time ("sidereal" pronounced ) is a system of timekeeping used especially by astronomers. Using sidereal time and the celestial coordinate system, it is easy to locate the positions of celestial objects in the night sky. Sidereal time is a "time scale that is based on Earth's rate of rotation measured relative... | Sidereal time | Wikipedia | 427 | 48837 | https://en.wikipedia.org/wiki/Sidereal%20time | Physical sciences | Celestial mechanics | Astronomy | vital_articles |
The March equinox itself precesses slowly westward relative to the fixed stars, completing one revolution in about 25,800 years, so the misnamed "sidereal" day ("sidereal" is derived from the Latin sidus meaning "star") is 0.0084 seconds shorter than the stellar day, Earth's actual period of rotation relative to the fi... | Sidereal time | Wikipedia | 456 | 48837 | https://en.wikipedia.org/wiki/Sidereal%20time | Physical sciences | Celestial mechanics | Astronomy | vital_articles |
Another way to understand this difference is to notice that, relative to the stars, as viewed from Earth, the position of the Sun at the same time each day appears to move around Earth once per year. A year has about 365.24 solar days but 366.24 sidereal days. Therefore, there is one fewer solar day per year than ther... | Sidereal time | Wikipedia | 433 | 48837 | https://en.wikipedia.org/wiki/Sidereal%20time | Physical sciences | Celestial mechanics | Astronomy | vital_articles |
Modern definitions
During the past, time was measured by observing stars with instruments such as photographic zenith tubes and Danjon astrolabes, and the passage of stars across defined lines would be timed with the observatory clock. Then, using the right ascension of the stars from a star catalog, the time when the ... | Sidereal time | Wikipedia | 493 | 48837 | https://en.wikipedia.org/wiki/Sidereal%20time | Physical sciences | Celestial mechanics | Astronomy | vital_articles |
Although ERA is intended to replace sidereal time, there is a need to maintain definitions for sidereal time during the transition, and when working with older data and documents.
Similarly to mean solar time, every location on Earth has its own local sidereal time (LST), depending on the longitude of the point. Since... | Sidereal time | Wikipedia | 445 | 48837 | https://en.wikipedia.org/wiki/Sidereal%20time | Physical sciences | Celestial mechanics | Astronomy | vital_articles |
Sidereal days compared to solar days on other planets
Six of the eight solar planets have prograde rotation—that is, they rotate more than once per year in the same direction as they orbit the Sun, so the Sun rises in the east. Venus and Uranus, however, have retrograde rotation. For prograde rotation, the formula rela... | Sidereal time | Wikipedia | 449 | 48837 | https://en.wikipedia.org/wiki/Sidereal%20time | Physical sciences | Celestial mechanics | Astronomy | vital_articles |
In astronomy and celestial navigation, the hour angle is the dihedral angle between the meridian plane (containing Earth's axis and the zenith) and the hour circle (containing Earth's axis and a given point of interest).
It may be given in degrees, time, or rotations depending on the application.
The angle may be exp... | Hour angle | Wikipedia | 425 | 48838 | https://en.wikipedia.org/wiki/Hour%20angle | Physical sciences | Celestial sphere: General | Astronomy | vital_articles |
Observing the Sun from Earth, the solar hour angle is an expression of time, expressed in angular measurement, usually degrees, from solar noon. At solar noon the hour angle is zero degrees, with the time before solar noon expressed as negative degrees, and the local time after solar noon expressed as positive degrees.... | Hour angle | Wikipedia | 274 | 48838 | https://en.wikipedia.org/wiki/Hour%20angle | Physical sciences | Celestial sphere: General | Astronomy | vital_articles |
Gadiformes , also called the Anacanthini, are an order of ray-finned fish that include the cod, hakes, pollock, haddock, burbot, rocklings and moras, many of which are food fish of major commercial value. They are mostly marine fish found throughout the world and the vast majority are found in temperate or colder regio... | Gadiformes | Wikipedia | 321 | 48866 | https://en.wikipedia.org/wiki/Gadiformes | Biology and health sciences | Acanthomorpha | Animals | vital_articles |
Sparidae is a family of ray-finned fishes belonging to the order Spariformes, the seabreams and porgies, although they were traditionally classified in the order Perciformes. They are found in shallow temperate and tropical waters around the world and are demersal carnivores.
Taxonomy
Sparidae was first proposed as a ... | Sparidae | Wikipedia | 421 | 48868 | https://en.wikipedia.org/wiki/Sparidae | Biology and health sciences | Acanthomorpha | Animals | vital_articles |
†Abromasta Day, 2003
†Burtinia van Beneden, 1873
†Crommyodus Cope, 1875
†Ctenodentex Storms, 1896
†Ellaserrata Day, 2003
†Kreyenhagenius David, 1946
†Paracalamus Arambourg, 1927
†Plectrites Jordan & Gilbert, 1920
†Pseudosparnodus Day, 2003
†Pshekharus Bannikov & Kotylar, 2015
†Rhythmias Jordan & Gilbert, 1... | Sparidae | Wikipedia | 117 | 48868 | https://en.wikipedia.org/wiki/Sparidae | Biology and health sciences | Acanthomorpha | Animals | vital_articles |
Characteristics
Sparidae breams have oblong, moderately deep and compressed bodies. The head is large, with a characteristic steep dorsal slant. There are no scales on the snout but there are scales on the cheeks. The preoperculum may or may not have scales and has no spines or serrations on its margin. The operculum ... | Sparidae | Wikipedia | 491 | 48868 | https://en.wikipedia.org/wiki/Sparidae | Biology and health sciences | Acanthomorpha | Animals | vital_articles |
Biology
Sparidae breams are predatory with most feeding on benthic invertebrates. Smaller species in the family usually gather in schools, as do the juveniles of the larger species. The larger adult fishes are normally solitary or, at least, are less sociable and prefer deeper waters. The juveniles and subadults are of... | Sparidae | Wikipedia | 219 | 48868 | https://en.wikipedia.org/wiki/Sparidae | Biology and health sciences | Acanthomorpha | Animals | vital_articles |
Clupeiformes is the order of ray-finned fish that includes the herring family, Clupeidae, and the anchovy family, Engraulidae and sardines. The group includes many of the most important forage and food fish.
Clupeiformes are physostomes, which means that their gas bladder has a pneumatic duct connecting it to the gut... | Clupeiformes | Wikipedia | 347 | 48869 | https://en.wikipedia.org/wiki/Clupeiformes | Biology and health sciences | Clupeiformes | Animals | vital_articles |
Families
The order includes about 405 species in ten families:
Order Clupeiformes
Genus †Histiothrissa Woodward, 1901
Genus ?†Jhingrania Misra & Saxena, 1959 (possibly a clupavid)
Genus †Santanaclupea Maisey, 1993
Genus †Spratticeps Patterson, 1970
Suborder Denticipitoidei Grande, 1982
Family Denticipitidae C... | Clupeiformes | Wikipedia | 333 | 48869 | https://en.wikipedia.org/wiki/Clupeiformes | Biology and health sciences | Clupeiformes | Animals | vital_articles |
Clupeidae is a family of clupeiform ray-finned fishes, comprising, for instance, the herrings and sprats. Many members of the family have a body protected with shiny cycloid (very smooth and uniform) scales, a single dorsal fin, and a fusiform body for quick, evasive swimming and pursuit of prey composed of small plank... | Clupeidae | Wikipedia | 387 | 48870 | https://en.wikipedia.org/wiki/Clupeidae | Biology and health sciences | Clupeiformes | Animals | vital_articles |
Feeding physiology
The Clupeidae family primarily feed on small planktonic organisms. The teeth of members of this family are either reduced or absent, reduced teeth are miniature teeth that would be barely visible and line the interior of the fish's mouth. The structure of these teeth indicate that these organisms do... | Clupeidae | Wikipedia | 505 | 48870 | https://en.wikipedia.org/wiki/Clupeidae | Biology and health sciences | Clupeiformes | Animals | vital_articles |
Clupea Linnaeus, 1758
Ethmidium W. F. Thompson, 1916
Hyperlophus Ogilby, 1892
Potamalosa Ogilby, 1897
Ramnogaster Whitehead, 1965
Sprattus Girgensohn 1846
Strangomera Whitehead,genera from ECoF 1965
The family arguably also contains the "Sundasalangidae", a paedomorphic taxon first thought to be a distinct salmo... | Clupeidae | Wikipedia | 414 | 48870 | https://en.wikipedia.org/wiki/Clupeidae | Biology and health sciences | Clupeiformes | Animals | vital_articles |
The mackerel, tuna, and bonito family, Scombridae, includes many of the most important and familiar food fishes. The family consists of 51 species in 15 genera and two subfamilies. All species are in the subfamily Scombrinae, except the butterfly kingfish, which is the sole member of subfamily Gasterochismatinae.
Scom... | Scombridae | Wikipedia | 448 | 48872 | https://en.wikipedia.org/wiki/Scombridae | Biology and health sciences | Acanthomorpha | Animals | vital_articles |
Family Scombridae
Subfamily Gasterochismatinae
Genus Gasterochisma
Subfamily Scombrinae
Tribe Scombrini – mackerels
Genus Rastrelliger
Genus Scomber
Tribe Scomberomorini – Spanish mackerels
Genus Acanthocybium
Genus Grammatorcynus
Genus Orcynopsis
Genus Scomberomorus
Tribe Sardini – bonitos
Genus Sarda
Ge... | Scombridae | Wikipedia | 404 | 48872 | https://en.wikipedia.org/wiki/Scombridae | Biology and health sciences | Acanthomorpha | Animals | vital_articles |
Serranidae is a large family of fishes belonging to the order Perciformes. The family contains about 450 species in 65 genera, including the sea basses and the groupers (subfamily Epinephelinae). Although many species are small, in some cases less than , the giant grouper (Epinephelus lanceolatus) is one of the largest... | Serranidae | Wikipedia | 503 | 48873 | https://en.wikipedia.org/wiki/Serranidae | Biology and health sciences | Acanthomorpha | null | vital_articles |
The subfamilies and genera are as follows: | Serranidae | Wikipedia | 11 | 48873 | https://en.wikipedia.org/wiki/Serranidae | Biology and health sciences | Acanthomorpha | null | vital_articles |
Salmonidae (, ) is a family of ray-finned fish that constitutes the only currently extant family in the order Salmoniformes (, lit. "salmon-shaped"), consisting of 11 extant genera and over 200 species collectively known as "salmonids" or "salmonoids". The family includes salmon (both Atlantic and Pacific species), tro... | Salmonidae | Wikipedia | 453 | 48878 | https://en.wikipedia.org/wiki/Salmonidae | Biology and health sciences | Salmoniformes | null | vital_articles |
Current salmonids comprise three main clades taxonomically treated as subfamilies: Coregoninae (freshwater whitefishes), Thymallinae (graylings), and Salmoninae (trout, salmon, char, taimens and lenoks). Generally, all three lineages are accepted to allocate a suite of derived traits indicating a monophyletic group.
... | Salmonidae | Wikipedia | 469 | 48878 | https://en.wikipedia.org/wiki/Salmonidae | Biology and health sciences | Salmoniformes | null | vital_articles |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.