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🔗 Amateur radio

A QSL card is a written confirmation of either a two-way radiocommunication between two amateur radio or citizens band stations; a one-way reception of a signal from an AM radio, FM radio, television or shortwave broadcasting station; or the reception of a two-way radiocommunication by a third party listener. A typical QSL card is the same size and made from the same material as a typical postcard, and most are sent through the mail as such.

QSL card derived its name from the Q code "QSL". A Q code message can stand for a statement or a question (when the code is followed by a question mark). In this case, 'QSL?' (note the question mark) means "Do you confirm receipt of my transmission?" while 'QSL' (without a question mark) means "I confirm receipt of your transmission."

🔗 United States 🔗 Comedy 🔗 Politics 🔗 Politics/American politics 🔗 Journalism 🔗 Politics/Gun politics

"'No Way to Prevent This', Says Only Nation Where This Regularly Happens" is the title of a series of articles perennially published by the American news satire organization The Onion satirizing the frequency of mass shootings in the United States and the lack of action taken in the wake of such incidents.

Each article is about 200 words long, detailing the location of the shooting and the number of victims, but otherwise remaining essentially the same. A fictitious resident—usually of a state in which the shooting did not take place—is quoted as saying that the shooting was "a terrible tragedy", but "there's nothing anyone can do to stop them." The article ends by pointing out that the United States is the "only economically advanced nation in the world where roughly two mass shootings have occurred every month for the past eight years," and that Americans view themselves and the situation as "helpless".

🔗 Australia 🔗 Languages 🔗 Australia/Indigenous peoples of Australia

Avoidance speech is a group of sociolinguistic phenomena in which a special restricted speech style must be used in the presence of or in reference to certain relatives. Avoidance speech is found in many Australian Aboriginal languages and Austronesian languages as well as some North American languages, Highland East Cushitic languages and Southern Bantu languages. Chinese naming taboo prohibits speaking and writing syllables or characters that appear in the names of esteemed people, such as emperors, parents, and ancestors.

Avoidance speech styles tend to have the same phonology and grammar as the standard language they are a part of. The lexicon, however, tends to be smaller than in normal speech since the styles are only used for limited communication.

🔗 Biography

Frank Rosenblatt (July 11, 1928 – July 11, 1971) was an American psychologist notable in the field of artificial intelligence. He is sometimes called the father of deep learning for his pioneering work on neural networks.

🔗 Philosophy 🔗 Systems 🔗 Philosophy/Philosophy of mind 🔗 Philosophy/Metaphysics

A holon (Greek: ὅλον, from ὅλος, holos, 'whole' and -ον, -on, 'part') is something that is simultaneously a whole in and of itself, as well as a part of a larger whole. In other words, holons can be understood as the constituent part–wholes of a hierarchy.

The holon represents a way to overcome the dichotomy between parts and wholes, as well as a way to account for both the self-assertive and the integrative tendencies of organisms. The term was coined by Arthur Koestler in The Ghost in the Machine (1967). In Koestler's formulations, a holon is something that has integrity and identity while simultaneously being a part of a larger system; it is a subsystem of a greater system.

Holons are sometimes discussed in the context of self-organizing holarchic open (SOHO) systems.

🔗 Musical Instruments 🔗 Percussion

Campanology () is the scientific and musical study of bells. It encompasses the technology of bells – how they are founded, tuned and rung – as well as the history, methods, and traditions of bellringing as an art.

It is common to collect together a set of tuned bells and treat the whole as one musical instrument. Such collections – such as a Flemish carillon, a Russian zvon, or an English "ring of bells" used for change ringing – have their own practices and challenges; and campanology is likewise the study of perfecting such instruments and composing and performing music for them.

In this sense, however, the word campanology is most often used in reference to relatively large bells, often hung in a tower. It is not usually applied to assemblages of smaller bells, such as a glockenspiel, a collection of tubular bells, or an Indonesian gamelan.

🔗 Medicine 🔗 Medicine/Ophthalmology

The Purkinje effect or Purkinje phenomenon (Czech: [ˈpurkɪɲɛ] (listen); sometimes called the Purkinje shift, often incorrectly pronounced ) is the tendency for the peak luminance sensitivity of the eye to shift toward the blue end of the color spectrum at low illumination levels as part of dark adaptation. In consequence, reds will appear darker relative to other colors as light levels decrease. The effect is named after the Czech anatomist Jan Evangelista Purkyně. While the effect is often described from the perspective of the human eye, it is well established in a number of animals under the same name to describe the general shifting of spectral sensitivity due to pooling of rod and cone output signals as a part of dark/light adaptation.

This effect introduces a difference in color contrast under different levels of illumination. For instance, in bright sunlight, geranium flowers appear bright red against the dull green of their leaves, or adjacent blue flowers, but in the same scene viewed at dusk, the contrast is reversed, with the red petals appearing a dark red or black, and the leaves and blue petals appearing relatively bright.

The sensitivity to light in scotopic vision varies with wavelength, though the perception is essentially black-and-white. The Purkinje shift is the relation between the absorption maximum of rhodopsin, reaching a maximum at about 500 nanometres (2.0×10⁻⁵ in), and that of the opsins in the longer-wavelength cones that dominate in photopic vision, about 555 nanometres (2.19×10⁻⁵ in) (green).

In visual astronomy, the Purkinje shift can affect visual estimates of variable stars when using comparison stars of different colors, especially if one of the stars is red.

🔗 Chemistry 🔗 Polymers

Retrobright refers to H₂O₂ (hydrogen peroxide) based processes used to remove yellowing from ABS plastics. The usage has also expanded to other retro restoration applications, such as classic and collectible sneaker restoration, where it is referred to by collectors as "sole sauce".

Yellowing in ABS plastic occurs when it is exposed to UV light or excessive heat, which causes photo-oxidation of polymers that breaks polymer chains and causes the plastic to yellow and become brittle.

One method of reversing the yellowed discoloration coined the term (stylized as retr0bright or Retrobrite) was first discovered in 2007 in a German retrocomputing forum, before spreading to an English blog where it was further detailed. The process has been continually refined since.

The long-term effectiveness of these techniques is questioned. Some have discovered the yellowing reappears, and there are concerns that the process weakens and only bleaches the already damaged plastic.

🔗 Greece 🔗 Middle Ages 🔗 Middle Ages/History 🔗 Sicily 🔗 Greece/Byzantine world 🔗 Normandy

The term Norman–Arab–Byzantine culture, Norman–Sicilian culture or, less inclusively, Norman–Arab culture, (sometimes referred to as the "Arab-Norman civilization") refers to the interaction of the Norman, Byzantine Greek, Latin, and Arab cultures following the Norman conquest of the former Emirate of Sicily and North Africa from 1061 to around 1250. The civilization resulted from numerous exchanges in the cultural and scientific fields, based on the tolerance shown by the Normans towards the Latin- and Greek-speaking Christian populations and the former Arab Muslim settlers. As a result, Sicily under the Normans became a crossroad for the interaction between the Norman and Latin Catholic, Byzantine–Orthodox, and Arab–Islamic cultures.

🔗 Organizations 🔗 Fashion

The Rational Dress Society was an organisation founded in 1881 in London, part of the movement for Victorian dress reform. It described its purpose thus:

The Rational Dress Society protests against the introduction of any fashion in dress that either deforms the figure, impedes the movements of the body, or in any way tends to injure the health. It protests against the wearing of tightly-fitting corsets; of high-heeled shoes; of heavily-weighted skirts, as rendering healthy exercise almost impossible; and of all tie down cloaks or other garments impeding on the movements of the arms. It protests against crinolines or crinolettes of any kind as ugly and deforming... [It] requires all to be dressed healthily, comfortably, and beautifully, to seek what conduces to birth, comfort and beauty in our dress as a duty to ourselves and each other.

In the catalogue of its inaugural exhibition, it listed the attributes of "perfect" dress as:

1. Freedom of Movement.
2. Absence of pressure over any part of the body.
3. Not more weight than is necessary for warmth, and both weight and warmth evenly distributed.
4. Grace and beauty combined with comfort and convenience.
5. Not departing too conspicuously from the ordinary dress of the time.

Leading members of the Society were Lady Harberton (who created the divided skirt), Mary Eliza Haweis and Constance Wilde (Irish author). Oscar Wilde helped spread the word by publishing the essay "The Philosophy of Dress" in which he stressed the important relationship between clothing and one’s soul. Woman cyclists, such as members of the Lady Cyclists' Association, were keen advocates of women's right to dress appropriately for the activity, as part of a belief that cycling offered women an opportunity to escape overly restrictive societal norms.

In 1889, a member of the Rational Dress Society, Charlotte Carmichael Stopes, staged a coup at a meeting of the British Association for the Advancement of Science in Newcastle upon Tyne, when she arranged an impromptu addition to the programme on the subject of rational dress. Her speech was reported by newspapers across Britain and the notion of rational dress was the biggest news from the meeting.