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🔗 Computer science

The circle–ellipse problem in software development (sometimes called the square–rectangle problem) illustrates several pitfalls which can arise when using subtype polymorphism in object modelling. The issues are most commonly encountered when using object-oriented programming (OOP). By definition, this problem is a violation of the Liskov substitution principle, one of the SOLID principles.

The problem concerns which subtyping or inheritance relationship should exist between classes which represent circles and ellipses (or, similarly, squares and rectangles). More generally, the problem illustrates the difficulties which can occur when a base class contains methods which mutate an object in a manner which may invalidate a (stronger) invariant found in a derived class, causing the Liskov substitution principle to be violated.

The existence of the circle–ellipse problem is sometimes used to criticize object-oriented programming. It may also imply that hierarchical taxonomies are difficult to make universal, implying that situational classification systems may be more practical.

🔗 Aviation 🔗 Aviation/Aviation accident 🔗 Africa/Angola 🔗 Africa

On 25 May 2003, a Boeing 727, registered N844AA, was stolen at Quatro de Fevereiro Airport, Luanda, Angola. Its disappearance prompted a worldwide search by the United States' Federal Bureau of Investigation (FBI) and Central Intelligence Agency (CIA). No trace of the aircraft has since been found.

🔗 Telecommunications 🔗 Astronomy 🔗 Weather 🔗 Astronomy/Solar System 🔗 Weather/Weather 🔗 Weather/Space weather

The Carrington Event was the most intense geomagnetic storm in recorded history, peaking from 1–2 September 1859 during solar cycle 10. It created strong auroral displays that were reported globally and caused sparking and even fires in multiple telegraph stations. The geomagnetic storm was most likely the result of a coronal mass ejection (CME) from the Sun colliding with Earth's magnetosphere.

The geomagnetic storm was associated with a very bright solar flare on 1 September 1859. It was observed and recorded independently by British astronomers Richard Christopher Carrington and Richard Hodgson—the first records of a solar flare.

A geomagnetic storm of this magnitude occurring today would cause widespread electrical disruptions, blackouts, and damage due to extended outages of the electrical power grid.

🔗 Professional sound production 🔗 Stagecraft

The Schaffer–Vega diversity system (SVDS) was a wireless guitar system developed in 1975–76, engineered and prototyped by Ken Schaffer in New York City, and manufactured by the Vega Corporation, El Monte, California. A handheld microphone version was introduced in 1977.

The system was the first cordless system to be adopted by major rock acts because it solved technical problems common to earlier wireless systems. The reliable sound and freedom of movement it provided paved the way for bands to tour with large multi-level stages in arenas. Schaffer-Vegas were used in the late 1970s and early 1980s by many rock bands such as Pink Floyd (namely guitarist David Gilmour), the Rolling Stones, AC/DC and Kiss.

🔗 Aviation 🔗 Aviation/gliding

Dynamic soaring is a flying technique used to gain energy by repeatedly crossing the boundary between air masses of different velocity. Such zones of wind gradient are generally found close to obstacles and close to the surface, so the technique is mainly of use to birds and operators of radio-controlled gliders, but glider pilots are sometimes able to soar dynamically in meteorological wind shears at higher altitudes.

Dynamic soaring is sometimes confused with slope soaring which is a technique for achieving elevation.

🔗 Mathematics 🔗 Cryptography 🔗 Cryptography/Computer science

TWINKLE (The Weizmann Institute Key Locating Engine) is a hypothetical integer factorization device described in 1999 by Adi Shamir and purported to be capable of factoring 512-bit integers. It is also a pun on the twinkling LEDs used in the device. Shamir estimated that the cost of TWINKLE could be as low as $5000 per unit with bulk production. TWINKLE has a successor named TWIRL which is more efficient.

🔗 Physics

An exotic atom is an otherwise normal atom in which one or more sub-atomic particles have been replaced by other particles of the same charge. For example, electrons may be replaced by other negatively charged particles such as muons (muonic atoms) or pions (pionic atoms). Because these substitute particles are usually unstable, exotic atoms typically have very short lifetimes and all currently observed atoms cannot persist under normal conditions.

🔗 Law 🔗 Thailand

In Thailand, lèse-majesté is a crime according to Section 112 of the Thai Criminal Code. It is illegal to defame, insult, or threaten the monarch of Thailand (king, queen, heir-apparent, heir-presumptive, or regent). Modern Thai lèse-majesté law has been on the statute books since 1908. Thailand is the only constitutional monarchy to have strengthened its lèse-majesté law since World War II. With penalties ranging from three to fifteen years imprisonment for each count, it has been described as the "world's harshest lèse majesté law" and "possibly the strictest criminal-defamation law anywhere". Its enforcement has been described as being "in the interest of the palace".^: 134

The law has criminalised acts of insult since 1957. There is substantial room for interpretation, which causes controversy. Broad interpretation of the law reflects the inviolable status of the king, resembling feudal or absolute monarchs. Thailand's Supreme Court decided the law also applies to prior monarchs. Criticism of any privy council member has raised the question whether lèse-majesté applies by association. Even attempting to commit lèse-majesté, making sarcastic comments about the King's pet, and failure to rebuke an offense have been prosecuted as lèse-majesté.

Anyone can file a lèse-majesté complaint, and the police formally investigate all of them. Details of the charges are rarely made public. A Section 112 defendant meets with official obstruction throughout the case. There are months-long pretrial detentions, and courts routinely deny bail to those charged. The United Nations Working Group on Arbitrary Detention determined that the pretrial detention of an alleged lèse-majesté offender violated international human rights law. The courts seem not to recognise the principle of granting defendants the benefit of the doubt. Judges have said accusers did not have to prove the factuality of the alleged lèse-majesté material but only claim it is defamatory. Pleading guilty, then asking for a royal pardon, is seen as the quickest route to freedom for any accused.

Since the 1976 coup, coup makers have regularly cited a surge of alleged lèse-majesté charges as a reason for overthrowing elected governments. This was cited as one of the major reasons for the 2006 coup and that of 2014. In 2006 and 2007, there were notable changes in the trend. Those targeted by lèse-majesté complaints included more average citizens who were given longer jail sentences. Human rights groups condemned its use as a political weapon and a means to restrict freedom. The 2014 junta government granted authority to army courts to prosecute lèse-majesté, which has usually resulted in secret trials and harsh sentences. Prior to the law's revival in 2020, for three years the Thai government often invoked other laws, such as the Computer Crimes Act and sedition laws, to deal with perceived damages and insults to the monarchy. The longest recorded sentence was in 2021: 87 years imprisonment, reduced to 43 years because the defendant pleaded guilty. In 2023, the Supreme Court ordered a female politician from the Move Forward Party to be banned from politics for life due to her alleged lèse-majesté posts on social media.

🔗 Medicine 🔗 Dance

Dancing mania (also known as dancing plague, choreomania, St. John's Dance and St. Vitus's Dance) was a social phenomenon that occurred primarily in mainland Europe between the 14th and 17th centuries. It involved groups of people dancing erratically, sometimes thousands at a time. The mania affected men, women, and children who danced until they collapsed from exhaustion. One of the first major outbreaks was in Aachen, in the Holy Roman Empire, in 1374, and it quickly spread throughout Europe; one particularly notable outbreak occurred in Strasbourg in 1518, also in the Holy Roman Empire.

Affecting thousands of people across several centuries, dancing mania was not an isolated event, and was well documented in contemporary reports. It was nevertheless poorly understood, and remedies were based on guesswork. Often musicians accompanied dancers, due to a belief that music would treat the mania, but this tactic sometimes backfired by encouraging more to join in. There is no consensus among modern-day scholars as to the cause of dancing mania.

The several theories proposed range from religious cults being behind the processions to people dancing to relieve themselves of stress and put the poverty of the period out of their minds. It is speculated to have been a mass psychogenic illness, in which physical symptoms with no known physical cause are observed to affect a group of people, as a form of social influence.

🔗 Mathematics 🔗 Systems 🔗 Systems/Chaos theory

In mathematics, the Cantor function is an example of a function that is continuous, but not absolutely continuous. It is a notorious counterexample in analysis, because it challenges naive intuitions about continuity, derivative, and measure. Though it is continuous everywhere and has zero derivative almost everywhere, its value still goes from 0 to 1 as its argument reaches from 0 to 1. Thus, in one sense the function seems very much like a constant one which cannot grow, and in another, it does indeed monotonically grow, by construction.

It is also referred to as the Cantor ternary function, the Lebesgue function, Lebesgue's singular function, the Cantor–Vitali function, the Devil's staircase, the Cantor staircase function, and the Cantor–Lebesgue function. Georg Cantor (1884) introduced the Cantor function and mentioned that Scheeffer pointed out that it was a counterexample to an extension of the fundamental theorem of calculus claimed by Harnack. The Cantor function was discussed and popularized by Scheeffer (1884), Lebesgue (1904) and Vitali (1905).