To stay up to date you can also follow on Mastodon.

🔗 History 🔗 Mathematics 🔗 Books 🔗 Greece 🔗 History of Science

The Archimedes Palimpsest is a parchment codex palimpsest, originally a Byzantine Greek copy of a compilation of Archimedes and other authors. It contains two works of Archimedes that were thought to have been lost (the Ostomachion and the Method of Mechanical Theorems) and the only surviving original Greek edition of his work On Floating Bodies. The first version of the compilation is believed to have been produced by Isidorus of Miletus, the architect of the geometrically complex Hagia Sophia cathedral in Constantinople, sometime around AD 530. The copy found in the palimpsest was created from this original, also in Constantinople, during the Macedonian Renaissance (c. AD 950), a time when mathematics in the capital was being revived by the former Greek Orthodox bishop of Thessaloniki Leo the Geometer, a cousin of the Patriarch.

Following the sack of Constantinople by Western crusaders in 1204, the manuscript was taken to an isolated Greek monastery in Palestine, possibly to protect it from occupying crusaders, who often equated Greek script with heresy against their Latin church and either burned or looted many such texts (including at least two other copies of Archimedes). The complex manuscript was not appreciated at this remote monastery and was soon overwritten (1229) with a religious text. In 1899, nine hundred years after it was written, the manuscript was still in the possession of the Greek church, and back in Istanbul, where it was catalogued by the Greek scholar Papadopoulos-Kerameus, attracting the attention of Johan Heiberg. Heiberg visited the church library and was allowed to make detailed photographs in 1906. Most of the original text was still visible, and Heiberg published it in 1915. In 1922 the manuscript went missing in the midst of the evacuation of the Greek Orthodox library in Istanbul, during a tumultuous period following the World War I. Concealed for over 70 years by a Western businessman, forged pictures were painted on top of some text to increase resale value. Unable to sell the book privately, in 1998 the businessman's daughter risked a public auction in New York contested by the Greek church; the U.S. court ruled for the auction, and the manuscript was purchased by an anonymous buyer (rumored to be Jeff Bezos). The texts under the forged pictures, and previously unreadable texts, were revealed by analyzing images produced by ultraviolet, infrared, visible and raking light, and X-ray.

All images and transcriptions are now freely available on the web at the Archimedes Digital Palimpsest under the Creative Commons License CC BY.

🔗 Architecture 🔗 Classical Greece and Rome

The Roman architectural revolution, also known as the concrete revolution, is the name sometimes given to the widespread use in Roman architecture of the previously little-used architectural forms of the arch, vault, and dome. For the first time in history, their potential was fully exploited in the construction of a wide range of civil engineering structures, public buildings, and military facilities. These included amphitheatres, aqueducts, baths, bridges, circuses, dams, roads, and temples.

A crucial factor in this development that saw a trend to monumental architecture was the invention of Roman concrete (also called opus caementicium), which led to the liberation of the shape from the dictate of the traditional materials of stone and brick.

For the first time in recorded history we find evidence of an interest in the shapes of the space contained strong enough to outweigh the functional logic of the masonry masses that contained it. There was nothing new in the employment of curvilinear or polygonal forms, as such...But in so far as such buildings incorporated curvilinear or polygonal rooms and corridors, the shapes of these were determined by the form of the building as a whole, not by any aesthetic principle.

The development of Roman architecture, however, did not remain limited to these new forms and materials. An unrelated process of architectural innovation continued unabated, which, although less conspicuous, proved their usefulness for solving structural problems and found their way permanently into Western architecture, such as the lintel arch, the independent corbel, and the metal-tie.

During the Age of Augustus, almost the entire city of Rome was rebuilt causing an influx of craftsman and architects from all across Europe. Emperor Augustus aimed to develop new ideas in the construction of his buildings that would forever defy the limits that were ever thought possible. The Mausoleum in Campus Martius was one of the major monuments built by Augustus during his reign that was made almost entirely of concrete using updated construction techniques. The concrete is used in concentric rings that support the structure of the building like walls. The Theatre of Marcellus was another concrete triumph completed during the Age of Augustus, dedicated to the nephew of the emperor. The brick-faced concrete structure construction started under Julius Caesar but was completed under Augustus. It was this building that shows the integration of new concrete building techniques of Augustus's architects as opposed to those of Caesar. The Theatre of Marcellus uses a variety of materials that aid in the growth of the concrete revolution using readily available volcanic stones such as Tuscolo tuff and Tufo Lionato as aggregates in pozzolanic concretes.

These newly concocted recipes for concrete provided durability to walls and barrelled vaults as well as a unique aesthetic appeal. The integrated stone and masonry design illustrate a refinement that came with the concrete revolution as a result of the new techniques and styles developed under Augustus. The craftsmanship of the Theatre Marcellus demonstrated a skilled employment as well as rigorous technical supervision.

🔗 Electronics

In signal processing, the Nyquist frequency (or folding frequency), named after Harry Nyquist, is a characteristic of a sampler, which converts a continuous function or signal into a discrete sequence. For a given sampling rate (samples per second), the Nyquist frequency (cycles per second) is the frequency whose cycle-length (or period) is twice the interval between samples, thus 0.5 cycle/sample. For example, audio CDs have a sampling rate of 44100 samples/second. At 0.5 cycle/sample, the corresponding Nyquist frequency is 22050 cycles/second (Hz). Conversely, the Nyquist rate for sampling a 22050 Hz signal is 44100 samples/second.

When the highest frequency (bandwidth) of a signal is less than the Nyquist frequency of the sampler, the resulting discrete-time sequence is said to be free of the distortion known as aliasing, and the corresponding sample rate is said to be above the Nyquist rate for that particular signal.

In a typical application of sampling, one first chooses the highest frequency to be preserved and recreated, based on the expected content (voice, music, etc.) and desired fidelity. Then one inserts an anti-aliasing filter ahead of the sampler. Its job is to attenuate the frequencies above that limit. Finally, based on the characteristics of the filter, one chooses a sample rate (and corresponding Nyquist frequency) that will provide an acceptably small amount of aliasing. In applications where the sample rate is pre-determined (such as the CD rate), the filter is chosen based on the Nyquist frequency, rather than vice versa.

🔗 Agriculture 🔗 Indigenous peoples of North America

The Three Sisters are the three main agricultural crops of various Indigenous peoples of North America: squash, maize ("corn"), and climbing beans (typically tepary beans or common beans). In a technique known as companion planting, the maize and beans are often planted together in mounds formed by hilling soil around the base of the plants each year; squash is typically planted between the mounds. The cornstalk serves as a trellis for climbing beans, the beans fix nitrogen in their root nodules and stabilize the maize in high winds, and the wide leaves of the squash plant shade the ground, keeping the soil moist and helping prevent the establishment of weeds.

Indigenous peoples throughout North America cultivated different varieties of the Three Sisters, adapted to varying local environments. The individual crops and their use in polyculture originated in Mesoamerica; where squash was domesticated first, followed by maize and then beans, over a period of 5,000–6,500 years. European records from the sixteenth century describe highly productive Indigenous agriculture based on cultivation of the Three Sisters throughout what are now the Eastern United States and Canada, where the crops were used for both food and trade. Geographer Carl O. Sauer described the Three Sisters as "a symbiotic plant complex of North and Central America without an equal elsewhere".

🔗 Crime 🔗 Books

Hit Man: A Technical Manual for Independent Contractors is a book written under the pseudonym Rex Feral (real name Nancy Crampton-Brophy) and published by Paladin Press in 1983. Paladin Press owner Peder Lund claimed, in an interview with 60 Minutes, that the book started life as a detailed crime novel written by a Florida housewife, and that the format was later changed to appeal to Paladin's reader base accustomed to the publisher's non-fiction books on military, survivalist, weapons and similar topics. The book portrays itself as a how-to manual on starting a career as a hit man, fulfilling contracts. However, after a number of lawsuits claiming that the book was used as a handbook in several murders, the publication of the book was stopped. It marked "the first time in American publishing history that a publisher has been held liable for a crime committed by a reader."

🔗 Film 🔗 Film/American cinema 🔗 Film/Documentary films 🔗 Film/British cinema

The Up series of documentary films follows the lives of ten males and four females in England beginning in 1964, when they were seven years old. The first film was titled Seven Up!, with later films adjusting the number in the title to match the age of the subjects at the time of filming. The documentary has had nine episodes—one every seven years—thus spanning 56 years. The series has been produced by Granada Television for ITV, which has broadcast all of them except 42 Up (1998), which was broadcast on BBC One. Individual films and the series as a whole have received numerous accolades; in 1991, the then-latest instalment, 28 Up, was chosen for Roger Ebert's list of the ten greatest films of all time.

The children were selected for the original programme to represent the range of socio-economic backgrounds in Britain at that time, with the expectation that each child's social class would determine their future. The first instalment was made as a one-off edition of Granada Television's series, World in Action, directed by Canadian Paul Almond, with involvement by "a fresh-faced young researcher, a middle-class Cambridge graduate", Michael Apted, whose role in the initial programme included "trawling the nation's schools for 14 suitable subjects". About the first programme, Apted has said:

It was Paul's film ... but he was more interested in making a beautiful film about being seven, whereas I wanted to make a nasty piece of work about these kids who have it all, and these other kids who have nothing.

After Almond's direction of the original programme, director Michael Apted continued the series with new instalments every seven years, filming material from those of the fourteen who chose to participate. The aim of the continuing series is stated at the beginning of 7 Up as: "Why did we bring these together? Because we wanted a glimpse of England in the year 2000. The union leader and the business executive of the year 2000 are now seven years old." The most recent instalment, the ninth, titled 63 Up, premiered in the UK on ITV in 2019. A special episode featuring celebrity fans of the series, 7 Up & Me, also aired on ITV in 2019. Apted is reported to have said, "I hope to do 84 Up when I'll be 99"; however, he died in 2021.

🔗 Religion 🔗 Philosophy 🔗 Philosophy/Philosophy of religion 🔗 Philosophy/Ethics 🔗 Christianity 🔗 Christianity/theology 🔗 Christianity/Calvinism

The Protestant work ethic, also known as the Calvinist work ethic or the Puritan work ethic, is a work ethic concept in scholarly sociology, economics and historiography. It emphasizes that diligence, discipline, and frugality are a result of a person's subscription to the values espoused by the Protestant faith, particularly Calvinism.

The phrase was initially coined in 1905 by Max Weber in his book The Protestant Ethic and the Spirit of Capitalism. Weber asserted that Protestant ethics and values, along with the Calvinist doctrines of asceticism and predestination, enabled the rise and spread of capitalism. It is one of the most influential and cited books in sociology, although the thesis presented has been controversial since its release. In opposition to Weber, historians such as Fernand Braudel and Hugh Trevor-Roper assert that the Protestant work ethic did not create capitalism and that capitalism developed in pre-Reformation Catholic communities. Just as priests and caring professionals are deemed to have a vocation (or "calling" from God) for their work, according to the Protestant work ethic the "lowly" workman also has a noble vocation which he can fulfill through dedication to his work.

The concept is often credited with helping to define the societies of Northern, Central and Northwestern Europe as well as the United States of America.

🔗 History 🔗 France 🔗 Medicine 🔗 Dance

The Dancing Plague of 1518, or Dance Epidemic of 1518, was a case of dancing mania that occurred in Strasbourg, Alsace (modern-day France), in the Holy Roman Empire from July 1518 to September 1518. Somewhere between 50 and 400 people took to dancing for weeks.

🔗 Mathematics 🔗 Statistics

In statistics, the 68–95–99.7 rule, also known as the empirical rule, is a shorthand used to remember the percentage of values that lie within an interval estimate in a normal distribution: 68%, 95%, and 99.7% of the values lie within one, two, and three standard deviations of the mean, respectively.

In mathematical notation, these facts can be expressed as follows, where Pr() is the probability function, Χ is an observation from a normally distributed random variable, μ (mu) is the mean of the distribution, and σ (sigma) is its standard deviation:

${\displaystyle {\begin{aligned}\Pr(\mu -1\sigma \leq X\leq \mu +1\sigma )&\approx 68.27\%\\\Pr(\mu -2\sigma \leq X\leq \mu +2\sigma )&\approx 95.45\%\\\Pr(\mu -3\sigma \leq X\leq \mu +3\sigma )&\approx 99.73\%\end{aligned}}}$

The usefulness of this heuristic especially depends on the question under consideration.

In the empirical sciences, the so-called three-sigma rule of thumb (or 3σ rule) expresses a conventional heuristic that nearly all values are taken to lie within three standard deviations of the mean, and thus it is empirically useful to treat 99.7% probability as near certainty.

In the social sciences, a result may be considered "significant" if its confidence level is of the order of a two-sigma effect (95%), while in particle physics, there is a convention of a five-sigma effect (99.99994% confidence) being required to qualify as a discovery.

A weaker three-sigma rule can be derived from Chebyshev's inequality, stating that even for non-normally distributed variables, at least 88.8% of cases should fall within properly calculated three-sigma intervals. For unimodal distributions, the probability of being within the interval is at least 95% by the Vysochanskij–Petunin inequality. There may be certain assumptions for a distribution that force this probability to be at least 98%.

🔗 Film 🔗 Television 🔗 Novels 🔗 Screenwriters

In fiction, a MacGuffin (sometimes McGuffin) is an object, device, or event that is necessary to the plot and the motivation of the characters, but insignificant, unimportant, or irrelevant in itself. The term was originated by Angus MacPhail for film, adopted by Alfred Hitchcock, and later extended to a similar device in other fiction.

The MacGuffin technique is common in films, especially thrillers. Usually, the MacGuffin is revealed in the first act, and thereafter declines in importance. It can reappear at the climax of the story but may actually be forgotten by the end of the story. Multiple MacGuffins are sometimes derisively identified as plot coupons.