Chakras (UK: , US: CHUK-rəz, CHAH-krəz; Sanskrit: चक्र, romanized: cakra, lit. 'wheel, circle'; Pali: cakka) are various focal points used in a variety of ancient meditation practices, collectively denominated as Tantra, or the esoteric or inner traditions of Hinduism.The concept of the chakra arose in the early traditions of Hinduism. Beliefs differ between the Indian religions, with many Buddhist texts consistently mentioning five chakras, while Hindu sources reference six or seven. Early Sanskrit texts speak of them both as meditative visualizations combining flowers and mantras and as physical entities in the body. Within Kundalini yoga, the techniques of breathing exercises, visualizations, mudras, bandhas, kriyas, and mantras are focused on manipulating...

World Book Day is a charity event held annually in the United Kingdom and Ireland on the first Thursday in March. On World Book Day, every child in full-time education in the UK is given a voucher to be spent on books; the event was first celebrated in the United Kingdom in 1998. The event is the local manifestation of the original, global World Book Day organized by UNESCO to promote reading, publishing, and copyright, and widely observed on 23 April. Organizers in the UK moved the observance to avoid clashes with Easter school holidays and with Saint George's Day. Conversely, the World Book Night event organized by independent charity The Reading Agency is held on 23 April. History The United Kingdom's own version of World Book Day began in 1998, launched by Prime Minister Tony Blair at the Globe Theatre in London. Several million schoolchildren in the UK were given a special £1 World Book Day Book Token which could be redeemed against any book in any UK bookshop. A specially created WBD anthology priced at £1 was also published. All World Book Day point of sale and the £1 book carried the special World Book Day...

A cryostat (from cryo meaning cold and stat meaning stable) is a device used to maintain low cryogenic temperatures of samples or devices mounted within the cryostat. Low temperatures may be maintained within a cryostat by using various refrigeration methods, most commonly using cryogenic fluid bath such as liquid helium. Hence it is usually assembled into a vessel, similar in construction to a vacuum flask or Dewar. Cryostats have numerous applications within science, engineering, and medicine. Types Closed-cycle cryostats Closed-cycle cryostats consist of a chamber through which cold helium vapour is pumped. An external mechanical refrigerator extracts the warmer helium exhaust vapour, which is cooled and recycled. Closed-cycle cryostats consume a relatively large amount of electrical power, but need not be refilled with helium and can run continuously for an indefinite period. Objects may be cooled by attaching them to a metallic coldplate inside a vacuum chamber which is in thermal contact with the helium vapour chamber. ...

The lanner falcon (Falco biarmicus) is a medium-sized bird of prey that breeds in Africa, southeast Europe and just into Asia. It prefers open habitat and is mainly resident, but some birds disperse more widely after the breeding season. A large falcon, it preys on birds and bats. Taxonomy and etymology The lanner falcon was described by the Dutch zoologist Coenraad Jacob Temminck in 1825 under the current binomial name Falco biarmicus. The type locality is Caffraria and the Cape of Good Hope. Falco is Late Latin for a "falcon", from falx, falcis "sickle". The Swedish naturalist Carl Linnaeus had used the specific epithet biarmicus for the bearded reedling and Temminck clearly believed that the word meant "bearded" but it is likely that Linnaeus was using the Latinized form for Bjarmaland, a district in northern Russia. The English word "lanner" is believed to come from the Old French lanier meaning "cowardly". The first recorded use of the word in English is from around 1400.This is presumably the oldest living hierofalcon...

In its most general sense, the term "world" refers to the totality of entities, to the whole of reality or to everything that is. The nature of the world has been conceptualized differently in different fields. Some conceptions see the world as unique while others talk of a "plurality of worlds". Some treat the world as one simple object while others analyze the world as a complex made up of many parts. In scientific cosmology the world or universe is commonly defined as "[t]he totality of all space and time; all that is, has been, and will be". Theories of modality, on the other hand, talk of possible worlds as complete and consistent ways how things could have been. Phenomenology, starting from the horizon of co-given objects present in the periphery of every experience, defines the world as the biggest horizon or the "horizon of all horizons". In philosophy of mind, the world is commonly contrasted with the mind as that which is represented by the mind. Theology conceptualizes the world in relation to God, for example, as God's creation, as identical to God or as the two being interdependent. In religions...

Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz. This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies; these are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves. Different sources specify different upper and lower bounds for the frequency range. Electric current Electric currents that oscillate at radio frequencies (RF currents) have special properties not shared by direct current or lower audio frequency alternating current, such as the 50 or 60 Hz current used in electrical power distribution. Energy from RF currents in conductors can radiate into space as electromagnetic...

Rustication is a range of masonry techniques used in classical architecture giving visible surfaces a finish texture that contrasts with smooth, squared-block masonry called ashlar. The visible face of each individual block is cut back around the edges to make its size and placing very clear. In addition the central part of the face of each block may be given a deliberately rough or patterned surface.Rusticated masonry is usually "dressed", or squared off neatly, on all sides of the stones except the face that will be visible when the stone is put in place. This is given wide joints that emphasize the edges of each block, by angling the edges ("channel-jointed"), or dropping them back a little. The main part of the exposed face may be worked flat and smooth or left with, or worked, to give a more or less rough or patterned surface. Rustication is often used to give visual weight to the ground floor in contrast to smooth ashlar above. Though intended to convey a "rustic" simplicity, the finish is highly artificial, and the faces of the stones often carefully worked to achieve an appearance of a coarse finish.Rustication was used in ancient times, but became...

A comet tail—and coma—are features visible in comets when they are illuminated by the Sun and may become visible from Earth when a comet passes through the inner Solar System. As a comet approaches the inner Solar System, solar radiation causes the volatile materials within the comet to vaporize and stream out of the nucleus, carrying dust away with them. Separate tails are formed of dust and gases, becoming visible through different phenomena; the dust reflects sunlight directly and the gases glow from ionisation. Most comets are too faint to be visible without the aid of a telescope, but a few each decade become bright enough to be visible to the naked eye. Tail formation In the outer Solar System, comets remain frozen and are extremely difficult or impossible to detect from Earth due to their small size. Statistical detections of inactive comet nuclei in the Kuiper belt have been reported from the Hubble Space Telescope observations, but these detections have been questioned, and have not yet been independently confirmed. As a comet approaches the inner Solar System, solar radiation causes the volatile materials within...

Bacillus thuringiensis (or Bt) is a gram-positive, soil-dwelling bacterium, the most commonly used biological pesticide worldwide. B. thuringiensis also occurs naturally in the gut of caterpillars of various types of moths and butterflies, as well on leaf surfaces, aquatic environments, animal feces, insect-rich environments, and flour mills and grain-storage facilities. It has also been observed to parasitize other moths such as Cadra calidella—in laboratory experiments working with C. calidella, many of the moths were diseased due to this parasite.During sporulation, many Bt strains produce crystal proteins (proteinaceous inclusions), called delta endotoxins, that have insecticidal action. This has led to their use as insecticides, and more recently to genetically modified crops using Bt genes, such as Bt corn. Many crystal-producing Bt strains, though, do not have insecticidal properties. The subspecies israelensis is commonly used for control of mosquitoes and of fungus gnats.As a toxic mechanism, cry proteins bind to specific receptors on the membranes of mid-gut (epithelial...