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🔗 Economics 🔗 Statistics

The Herfindahl index (also known as Herfindahl–Hirschman Index, HHI, or sometimes HHI-score) is a measure of the size of firms in relation to the industry and an indicator of the amount of competition among them. Named after economists Orris C. Herfindahl and Albert O. Hirschman, it is an economic concept widely applied in competition law, antitrust and also technology management. It is defined as the sum of the squares of the market shares of the firms within the industry (sometimes limited to the 50 largest firms), where the market shares are expressed as fractions. The result is proportional to the average market share, weighted by market share. As such, it can range from 0 to 1.0, moving from a huge number of very small firms to a single monopolistic producer. Increases in the Herfindahl index generally indicate a decrease in competition and an increase of market power, whereas decreases indicate the opposite. Alternatively, if whole percentages are used, the index ranges from 0 to 10,000 "points". For example, an index of .25 is the same as 2,500 points.

The major benefit of the Herfindahl index in relationship to such measures as the concentration ratio is that it gives more weight to larger firms.

The measure is essentially equivalent to the Simpson diversity index, which is a diversity index used in ecology; the inverse participation ratio (IPR) in physics; and the effective number of parties index in politics.

🔗 Software 🔗 Software/Computing

Worse is better, also called New Jersey style, was conceived by Richard P. Gabriel in an essay "Worse is better" to describe the dynamics of software acceptance, but it has broader application. It is the subjective idea that quality does not necessarily increase with functionality—that there is a point where less functionality ("worse") is a preferable option ("better") in terms of practicality and usability. Software that is limited, but simple to use, may be more appealing to the user and market than the reverse.

As to the oxymoronic title, Gabriel calls it a caricature, declaring the style bad in comparison with "The Right Thing". However he also states that "it has better survival characteristics than the-right-thing" development style and is superior to the "MIT Approach" with which he contrasted it in the original essay.

🔗 Biography 🔗 Mathematics 🔗 Physics 🔗 Biography/science and academia 🔗 Robotics 🔗 United Kingdom 🔗 Physics/Biographies 🔗 Christianity

Freeman John Dyson (15 December 1923 – 28 February 2020) was an English-born American theoretical physicist and mathematician known for his work in quantum electrodynamics, solid-state physics, astronomy and nuclear engineering. He was professor emeritus in the Institute for Advanced Study in Princeton, a member of the Board of Visitors of Ralston College and a member of the Board of Sponsors of the Bulletin of the Atomic Scientists.

Dyson originated several concepts that bear his name, such as Dyson's transform, a fundamental technique in additive number theory, which he developed as part of his proof of Mann's theorem; the Dyson tree, a hypothetical genetically-engineered plant capable of growing in a comet; the Dyson series, a perturbative series where each term is represented by Feynman diagrams; the Dyson sphere, a thought experiment that attempts to explain how a space-faring civilization would meet its energy requirements with a hypothetical megastructure that completely encompasses a star and captures a large percentage of its power output; and Dyson's eternal intelligence, a means by which an immortal society of intelligent beings in an open universe could escape the prospect of the heat death of the universe by extending subjective time to infinity while expending only a finite amount of energy.

Dyson believed global warming is caused merely by increased carbon dioxide but that some of the effects of this are favourable and not taken into account by climate scientists, such as increased agricultural yield. He was skeptical about the simulation models used to predict climate change, arguing that political efforts to reduce causes of climate change distract from other global problems that should take priority. He also signed the World Climate Declaration that there "is no Climate Emergency".

🔗 Biography 🔗 Computing 🔗 England 🔗 Women 🔗 Women scientists 🔗 Biography/science and academia 🔗 Biography/Royalty and Nobility 🔗 Women's History

Augusta Ada King, Countess of Lovelace (née Byron; 10 December 1815 – 27 November 1852) was an English mathematician and writer, chiefly known for her work on Charles Babbage's proposed mechanical general-purpose computer, the Analytical Engine. She was the first to recognise that the machine had applications beyond pure calculation, and published the first algorithm intended to be carried out by such a machine. As a result, she is sometimes regarded as the first to recognise the full potential of a "computing machine" and one of the first computer programmers.

Augusta Byron was the only legitimate child of poet Lord Byron and his wife Lady Byron. All of Byron's other children were born out of wedlock to other women. Byron separated from his wife a month after Ada was born and left England forever four months later. He commemorated the parting in a poem that begins, "Is thy face like thy mother's my fair child! ADA! sole daughter of my house and heart?". He died of disease in the Greek War of Independence when Ada was eight years old. Her mother remained bitter and promoted Ada's interest in mathematics and logic in an effort to prevent her from developing her father's perceived insanity. Despite this, Ada remained interested in Byron, naming her two sons Byron and Gordon. Upon her eventual death, she was buried next to him at her request. Although often ill in her childhood, Ada pursued her studies assiduously. She married William King in 1835. King was made Earl of Lovelace in 1838, Ada thereby becoming Countess of Lovelace.

Her educational and social exploits brought her into contact with scientists such as Andrew Crosse, Charles Babbage, Sir David Brewster, Charles Wheatstone, Michael Faraday and the author Charles Dickens, contacts which she used to further her education. Ada described her approach as "poetical science" and herself as an "Analyst (& Metaphysician)".

When she was a teenager, her mathematical talents led her to a long working relationship and friendship with fellow British mathematician Charles Babbage, who is known as "the father of computers". She was in particular interested in Babbage's work on the Analytical Engine. Lovelace first met him in June 1833, through their mutual friend, and her private tutor, Mary Somerville.

Between 1842 and 1843, Ada translated an article by Italian military engineer Luigi Menabrea on the calculating engine, supplementing it with an elaborate set of notes, simply called Notes. These notes contain what many consider to be the first computer program—that is, an algorithm designed to be carried out by a machine. Other historians reject this perspective and point out that Babbage's personal notes from the years 1836/1837 contain the first programs for the engine. Lovelace's notes are important in the early history of computers. She also developed a vision of the capability of computers to go beyond mere calculating or number-crunching, while many others, including Babbage himself, focused only on those capabilities. Her mindset of "poetical science" led her to ask questions about the Analytical Engine (as shown in her notes) examining how individuals and society relate to technology as a collaborative tool.

She died of uterine cancer in 1852 at the age of 36.

🔗 Zoo 🔗 Primates

Ken Allen (February 13, 1971 – December 1, 2000) was a Bornean orangutan at the San Diego Zoo. He became one of the most popular animals in the history of the zoo because of his many successful escapes from his enclosures. He was nicknamed "the hairy Houdini".

Ken Allen was born in captivity at the San Diego Zoo in 1971. During the 1980s, Ken Allen gained worldwide attention for a series of three escapes from his enclosure, which had been thought to be escape-proof. During some of his escapes, his female companions would join him. Ken Allen's ability to outwit his keepers, as well as his docile demeanor during his escapes, resulted in fame. He had his own fan club, and was the subject of T-shirts and bumper stickers (most reading "Free Ken Allen"). A song, The Ballad of Ken Allen, was written about him.

Ken Allen developed prostate cancer and was euthanized on December 1, 2000. He was 29 years old.

🔗 Numbers

142857, the six repeating digits of 1/7, 0.142857, is the best-known cyclic number in base 10. If it is multiplied by 2, 3, 4, 5, or 6, the answer will be a cyclic permutation of itself, and will correspond to the repeating digits of 2/7, 3/7, 4/7, 5/7, or 6/7 respectively.

142,857 is a Kaprekar number and a Harshad number (in base 10).

🔗 Computing 🔗 Libraries

"As We May Think" is a 1945 essay by Vannevar Bush which has been described as visionary and influential, anticipating many aspects of information society. It was first published in The Atlantic in July 1945 and republished in an abridged version in September 1945—before and after the atomic bombings of Hiroshima and Nagasaki. Bush expresses his concern for the direction of scientific efforts toward destruction, rather than understanding, and explicates a desire for a sort of collective memory machine with his concept of the memex that would make knowledge more accessible, believing that it would help fix these problems. Through this machine, Bush hoped to transform an information explosion into a knowledge explosion.

🔗 Computing

A quine is a computer program which takes no input and produces a copy of its own source code as its only output. The standard terms for these programs in the computability theory and computer science literature are "self-replicating programs", "self-reproducing programs", and "self-copying programs".

A quine is a fixed point of an execution environment, when the execution environment is viewed as a function transforming programs into their outputs. Quines are possible in any Turing complete programming language, as a direct consequence of Kleene's recursion theorem. For amusement, programmers sometimes attempt to develop the shortest possible quine in any given programming language.

The name "quine" was coined by Douglas Hofstadter, in his popular science book Gödel, Escher, Bach, in honor of philosopher Willard Van Orman Quine (1908–2000), who made an extensive study of indirect self-reference, and in particular for the following paradox-producing expression, known as Quine's paradox:

"Yields falsehood when preceded by its quotation" yields falsehood when preceded by its quotation.

Monocular rivalry is a phenomenon of human visual perception that occurs when two different images are optically superimposed. During prolonged viewing, one image becomes clearer than the other for a few moments, then the other image becomes clearer than the first for a few moments. These alternations in clarity continue at random for as long as one looks. Occasionally one image will become exclusively visible and the other image invisible.

In the demonstration, one image is a green grating and the other is a red grating. During prolonged inspection, the viewer can see the green grating as clearer than the red grating for a few moments, then the reverse. Occasionally the green grating will be all that is visible and occasionally the red grating will be all that is visible. Occasionally, at transitions, one will briefly see irregular composites of the two gratings (such as the red and green gratings superimposed but with one or two bars of the green grating invisible).

Monocular rivalry is easier to see when the component stimuli are of opposite colors, but it also occurs when the component stimuli have the same colors. As long as the two component stimuli differ spatiotemporally in some way, such as orientation (as shown), spatial frequency, or direction of movement, monocular rivalry can be seen.

🔗 Books 🔗 Psychology 🔗 Japan

The Mariko Aoki phenomenon (青木まりこ現象, Aoki Mariko genshō) is a Japanese expression referring to an urge to defecate that is suddenly felt after entering bookstores. The phenomenon's name derives from the name of the woman who mentioned the phenomenon in a magazine article in 1985. According to Japanese social psychologist Shozo Shibuya, the specific causes that trigger a defecation urge in bookstores are not yet clearly understood (as of 2014). There are also some who are skeptical about whether such a peculiar phenomenon really exists at all, and it is sometimes discussed as one type of urban myth.

The series of processes through which being in a bookstore leads to an awareness of a defecation urge is something that cannot be explained from a medical perspective as a single pathological concept, at least at present. According to a number of discussions on the topic, even if it can be sufficiently found that this phenomenon actually exists, it is a concept that would be difficult to be deemed a specific pathological entity (such as a "Mariko Aoki disease", for example). On the other hand, it is also a fact that a considerable number of the intellectuals (particularly clinicians) who discuss this phenomenon have adopted existing medical terminology such as from diagnostics and pathology. Borrowing from this approach, this article also uses expressions from existing medical terminology for convenience.