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🔗 Companies

This page is an index for lists of some assets owned by large corporations.

🔗 Plants

A floral formula is a notation for representing the structure of particular types of flowers. Such notations use numbers, letters and various symbols to convey significant information in a compact form. They may represent the floral form of a particular species, or may be generalized to characterize higher taxa, usually giving ranges of numbers of organs. Floral formulae are one of the two ways of describing flower structure developed during the 19th century, the other being floral diagrams. The format of floral formulae differs according to the tastes of particular authors and periods, yet they tend to convey the same information.

A floral formula is often used along with a floral diagram.

🔗 Physics

A Halbach array (German: [ˈhalbax]) is a special arrangement of permanent magnets that augments the magnetic field on one side of the array while cancelling the field to near zero on the other side. This is achieved by having a spatially rotating pattern of magnetisation.

The rotating pattern of permanent magnets (on the front face; on the left, up, right, down) can be continued indefinitely and have the same effect. The effect of this arrangement is roughly similar to many horseshoe magnets placed adjacent to each other, with similar poles touching.

This magnetic orientation process replicates that applied by a magnetic recording tape head to the magnetic tape coating during the recording process. The principle was further described by James (Jim) M. Winey of Magnepan in 1970, for the ideal case of continuously rotating magnetization, induced by a one-sided stripe-shaped coil.

The effect was also discovered by John C. Mallinson in 1973, and these "one-sided flux" structures were initially described by him as a "curiosity", although at the time he recognized from this discovery the potential for significant improvements in magnetic tape technology.

Physicist Klaus Halbach, while at the Lawrence Berkeley National Laboratory during the 1980s, independently invented the Halbach array to focus particle accelerator beams.

🔗 Biography 🔗 Biography/science and academia

Gorō Shimura (志村 五郎, Shimura Gorō, 23 February 1930 – 3 May 2019) was a Japanese mathematician and Michael Henry Strater Professor Emeritus of Mathematics at Princeton University who worked in number theory, automorphic forms, and arithmetic geometry. He was known for developing the theory of complex multiplication of abelian varieties and Shimura varieties, as well as posing the Taniyama–Shimura conjecture which ultimately led to the proof of Fermat's Last Theorem.

🔗 Color 🔗 Amusement Parks 🔗 Disney

Go Away Green refers to a range of paint colors used in Disney Parks to divert attention away from infrastructure. It has been compared to military camouflage like Olive Drab.

Imagineer John Hench wrote about developing such colors, "We chose a neutral gray-brown for the railing, a 'go away' color that did not call attention to itself, even though it was entirely unrelated to the Colonial color scheme."

Large attraction buildings visible either inside or outside a park such as Soarin’ at California Adventure or Indiana Jones Adventure at Disneyland are often painted a muted green. Necessary in-park infrastructure like speakers, lamp posts, fences, trash cans, and the former entrance to Club 33 are also painted various shades of green.

This concept also extends to grays, browns, and blues for spaces with less greenery or buildings that extend above the tree line, such as Guardians of the Galaxy: Cosmic Rewind.

🔗 Meteorology 🔗 Chemicals 🔗 Soil 🔗 Weather 🔗 Weather/Weather

Petrichor () is the earthy scent produced when rain falls on dry soil. The word is constructed from Greek petra (πέτρα), meaning "stone", and īchōr (ἰχώρ), the fluid that flows in the veins of the gods in Greek mythology.

🔗 United States 🔗 New York City

This is a list of the longest-lasting incandescent light bulbs.

🔗 Computing 🔗 Computing/Software 🔗 Computer graphics

Xsnow is a software application that was originally created as a virtual greeting card for Macintosh systems in 1984. In 1993, the concept was ported to the X Window System as Xsnow, and was included on a number of Linux distributions in the late 1990s.

🔗 Physics

Certain systems can achieve negative thermodynamic temperature; that is, their temperature can be expressed as a negative quantity on the Kelvin or Rankine scales. This should be distinguished from temperatures expressed as negative numbers on non-thermodynamic Celsius or Fahrenheit scales, which are nevertheless higher than absolute zero.

The absolute temperature (Kelvin) scale can be understood loosely as a measure of average kinetic energy. Usually, system temperatures are positive. However, in particular isolated systems, the temperature defined in terms of Boltzmann's entropy can become negative.

The possibility of negative temperatures was first predicted by Lars Onsager in 1949, in his analysis of classical point vortices confined to a finite area. Confined point vortices are a system with bounded phase space as their canonical momenta are not independent degrees of freedom from their canonical position coordinates. Bounded phase space is the essential property that allows for negative temperatures, and such temperatures can occur in both classical and quantum systems. As shown by Onsager, a system with bounded phase space necessarily has a peak in the entropy as energy is increased. For energies exceeding the value where the peak occurs, the entropy decreases as energy increases, and high-energy states necessarily have negative Boltzmann temperature.

A system with a truly negative temperature on the Kelvin scale is hotter than any system with a positive temperature. If a negative-temperature system and a positive-temperature system come in contact, heat will flow from the negative- to the positive-temperature system. A standard example of such a system is population inversion in laser physics.

Temperature is loosely interpreted as the average kinetic energy of the system's particles. The existence of negative temperature, let alone negative temperature representing "hotter" systems than positive temperature, would seem paradoxical in this interpretation. The paradox is resolved by considering the more rigorous definition of thermodynamic temperature as the tradeoff between internal energy and entropy contained in the system, with "coldness", the reciprocal of temperature, being the more fundamental quantity. Systems with a positive temperature will increase in entropy as one adds energy to the system, while systems with a negative temperature will decrease in entropy as one adds energy to the system.

Thermodynamic systems with unbounded phase space cannot achieve negative temperatures: adding heat always increases their entropy. The possibility of a decrease in entropy as energy increases requires the system to "saturate" in entropy. This is only possible if the number of high energy states is limited. For a system of ordinary (quantum or classical) particles such as atoms or dust, the number of high energy states is unlimited (particle momenta can in principle be increased indefinitely). Some systems, however (see the examples below), have a maximum amount of energy that they can hold, and as they approach that maximum energy their entropy actually begins to decrease. The limited range of states accessible to a system with negative temperature means that negative temperature is associated with emergent ordering of the system at high energies. For example in Onsager's point-vortex analysis negative temperature is associated with the emergence of large-scale clusters of vortices. This spontaneous ordering in equilibrium statistical mechanics goes against common physical intuition that increased energy leads to increased disorder.

🔗 Technology 🔗 Physics 🔗 Radio 🔗 Astronomy 🔗 Engineering

In engineering, the terahertz gap is a frequency band in the terahertz region of the electromagnetic spectrum between radio waves and infrared light for which practical technologies for generating and detecting the radiation do not exist. It is defined as 0.1 to 10 THz (wavelengths of 3 mm to 30 µm). Currently, at frequencies within this range, useful power generation and receiver technologies are inefficient and unfeasible.

Mass production of devices in this range and operation at room temperature (at which energy k·T is equal to the energy of a photon with a frequency of 6.2 THz) are mostly impractical. This leaves a gap between mature microwave technologies in the highest frequencies of the radio spectrum and the well developed optical engineering of infrared detectors in their lowest frequencies. This radiation is mostly used in small-scale, specialized applications such as submillimetre astronomy. Research that attempts to resolve this issue has been conducted since the late 20th century.