| Brownleeinae | |
|---|---|
 | |
| Brownleea parviflora | |
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Order: | Asparagales |
| Family: | Orchidaceae |
| Subfamily: | Orchidoideae |
| Tribe: | Orchideae |
| Subtribe: | Brownleeinae H.P.Linder & Kurzweil |
| Genera [1] | |
Brownleeinae is an orchid subtribe in the tribe Orchideae.
In physics, angular momentum is the rotational analog of linear momentum. It is an important physical quantity because it is a conserved quantity – the total angular momentum of a closed system remains constant. Angular momentum has both a direction and a magnitude, and both are conserved. Bicycles and motorcycles, flying discs, rifled bullets, and gyroscopes owe their useful properties to conservation of angular momentum. Conservation of angular momentum is also why hurricanes form spirals and neutron stars have high rotational rates. In general, conservation limits the possible motion of a system, but it does not uniquely determine it.
Density is the substance's mass per unit of volume. The symbol most often used for density is ρ, although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume:
In physics, the kinetic energy of an object is the form of energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes. The same amount of work is done by the body when decelerating from its current speed to a state of rest. Formally, a kinetic energy is any term in a system's Lagrangian which includes a derivative with respect to time and the second term in a Taylor expansion of a particle's relativistic energy.
In statistics and probability theory, the median is the value separating the higher half from the lower half of a data sample, a population, or a probability distribution. For a data set, it may be thought of as "the middle" value. The basic feature of the median in describing data compared to the mean is that it is not skewed by a small proportion of extremely large or small values, and therefore provides a better representation of the center. Median income, for example, may be a better way to describe center of the income distribution because increases in the largest incomes alone have no effect on median. For this reason, the median is of central importance in robust statistics.
In Newtonian mechanics, momentum is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. If m is an object's mass and v is its velocity, then the object's momentum p is :
A supernova is a powerful and luminous explosion of a star. A supernova occurs during the last evolutionary stages of a massive star or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the progenitor, either collapses to a neutron star or black hole, or is completely destroyed to form a diffuse nebula. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months.
In physics, spacetime is a mathematical model that combines the three dimensions of space and one dimension of time into a single four-dimensional manifold. Spacetime diagrams can be used to visualize relativistic effects, such as why different observers perceive differently where and when events occur.
The M1 Abrams is a third-generation American main battle tank designed by Chrysler Defense and named for General Creighton Abrams. Conceived for modern armored ground warfare and now one of the heaviest tanks in service at nearly 68 short tons, it introduced several modern technologies to US armored forces, including a multifuel turbine engine, sophisticated Chobham composite armor, a computer fire control system, separate ammunition storage in a blow-out compartment, and NBC protection for crew safety. Initial models of the M1 were armed with a 105 mm M68 gun, while later variants feature a license-produced Rheinmetall 120 mm L/44.
Newton's laws of motion are three basic laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows:
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. At 20 °C (68 °F), the speed of sound in air is about 343 metres per second, or one kilometre in 2.91 s or one mile in 4.69 s. It depends strongly on temperature as well as the medium through which a sound wave is propagating. At 0 °C (32 °F), the speed of sound in air is about 331 m/s. More simply, the speed of sound is how fast vibrations travel.
In physics, work is the energy transferred to or from an object via the application of force along a displacement. In its simplest form, for a constant force aligned with the direction of motion, the work equals the product of the force strength and the distance traveled. A force is said to do positive work if when applied it has a component in the direction of the displacement of the point of application. A force does negative work if it has a component opposite to the direction of the displacement at the point of application of the force.
The following are examples of orders of magnitude for different lengths.
In biochemistry, Michaelis–Menten kinetics, named after Leonor Michaelis and Maud Menten, is the simplest case of enzyme kinetics, applied to enzyme-catalysed reactions of one substrate and one product. It takes the form of an equation describing the rate reaction rate to , the concentration of the substrate A. Its formula is given by the Michaelis–Menten equation:
In physics, mass–energy equivalence is the relationship between mass and energy in a system's rest frame, where the two quantities differ only by a multiplicative constant and the units of measurement. The principle is described by the physicist Albert Einstein's famous formula: . In a reference frame where the system is moving, its relativistic energy and relativistic mass obey the same formula.
Disperis is a genus of plants in the orchid family, Orchidaceae. It has about 78 species. Most of the species are from tropical and southern Africa, as well as Indian Ocean islands. A few are native to the tropical or the warmer subtropical regions of Asia and Malesia.
An assault rifle is a selective fire rifle that uses an intermediate cartridge and a detachable magazine. Assault rifles were first put into mass production and accepted into widespread service during World War II. The first assault rifle to see major usage was the German StG 44, a development of the earlier Mkb 42. While immediately after World War II, NATO countries were equipped with battle rifles, the development of the M16 rifle during the Vietnam War prompted the adoption of assault rifles by the rest of NATO. By the end of the 20th century, assault rifles had become the standard weapon in most of the world's armies, replacing full-powered rifles and sub-machine guns in most roles. The two most successful modern assault rifles are the AK-47 and the M16 designs and their derivatives.
Orchideae is a tribe of orchids in the subfamily Orchidoideae. Historically, it was divided into 2 subtribes, Orchidinae and Habenariinae. The subtribe Orchidinae alone contains about 1,800 species. However, although some phylogenetic studies have established the monophyly of the subtribes, the generic boundaries are unclear, with many genera as traditionally circumscribed being paraphyletic or even polyphyletic. Species of genera such as Habenaria and Platanthera have been placed into both subtribes. A 2017 molecular phylogenetic study found that both subtribes did form clades, but did not formally recognize Habenariinae, because of missing genera and uncertainty over generic boundaries. The Asian species of Orchideae, in particular, have been subject to repeated changes of generic placement from 2012 onwards.
Coryciinae is a subtribe of orchids that has been differently defined and placed in the two classification systems that are currently in use for orchids. Genera Orchidacearum, which is currently the definitive work on orchid taxonomy, delimits Coryciinae as consisting of five genera: Disperis, Evotella, Ceratandra, Pterygodium, and Corycium, and it places Coryciinae in the mostly African tribe Diseae, along with four other subtribes: Brownleeinae, Huttonaeinae, Disinae, and Satyriinae. The genera of Coryciinae are small to medium in size and the number of species in each genus is as follows: Disperis (78), Pterygodium (19), Corycium (15), Ceratandra (6), and Evotella (1).
Disinae is a subtribe of orchids that has been differently defined and placed in the two classification systems that are currently in use for orchids. Genera Orchidacearum, which is currently the definitive work on orchid taxonomy, delimits Disinae as consisting of two closely related genera, Disa and Schizodium, and it places Disinae in the mostly African tribe Diseae, along with four other subtribes: Brownleeinae, Huttonaeinae, Coryciinae, and Satyriinae. In the classification for orchids that was published by Chase et alii in 2015, Schizodium was placed in synonymy under Disa, while Pachites and Huttonaea were transferred to Disinae. In Genera Orchidacearum, Pachites and Satyrium form the subtribe Satyriinae, and Huttonaea is the sole genus in the subtribe Huttonaeinae. The transfer of Pachites and Huttonaea to Disinae by Chase et alii (2015) was done with considerable doubt, and was based upon uncertainty about the relationships of these two genera. In 2009, a molecular phylogenetic study found only weak statistical support for a sister relationship between Huttonaea and Disa.
Coronavirus disease 2019 (COVID-19) is a contagious disease caused by a virus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The first known case was identified in Wuhan, China, in December 2019. The disease quickly spread worldwide, resulting in the COVID-19 pandemic.
Data related to Brownleeinae at Wikispecies
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