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The photophone is a telecommunications device that allows transmission of speech on a beam of light. It was invented jointly by Alexander Graham Bell and his assistant Charles Sumner Tainter on February 19, 1880, at Bell's laboratory at 1325 L Street in Washington, D.C. Both were later to become full associates in the Volta Laboratory Association, created and financed by Bell.

On June 3, 1880, Bell's assistant transmitted a wireless voice telephone message from the roof of the Franklin School to the window of Bell's laboratory, some 213 meters (about 700 ft.) away.

Bell believed the photophone was his most important invention. Of the 18 patents granted in Bell's name alone, and the 12 he shared with his collaborators, four were for the photophone, which Bell referred to as his "greatest achievement", telling a reporter shortly before his death that the photophone was "the greatest invention [I have] ever made, greater than the telephone".

The photophone was a precursor to the fiber-optic communication systems that achieved worldwide popular usage starting in the 1980s. The master patent for the photophone (U.S. Patent 235,199 Apparatus for Signalling and Communicating, called Photophone) was issued in December 1880, many decades before its principles came to have practical applications.

🔗 United States 🔗 Computing 🔗 Computing/Computer hardware 🔗 Computing/Early computers 🔗 United States/Iowa

The Atanasoff–Berry computer (ABC) was the first automatic electronic digital computer. Limited by the technology of the day, and execution, the device has remained somewhat obscure. The ABC's priority is debated among historians of computer technology, because it was neither programmable, nor Turing-complete. Conventionally, the ABC would be considered the first electronic ALU (arithmetic logic unit) – which is integrated into every modern processor's design.

Its unique contribution was to make computing faster by being the first to use vacuum tubes to do the arithmetic calculations. Prior to this, slower electro-mechanical methods were used by Konrad Zuse's Z1, and the simultaneously developed Harvard Mark I. The first electronic, programmable, digital machine, the Colossus computer from 1943 to 1945, used similar tube-based technology as ABC.

🔗 London 🔗 Books 🔗 Sexology and sexuality 🔗 Sexology and sexuality/Sex work

Harris's List of Covent Garden Ladies, published from 1757 to 1795, was an annual directory of prostitutes then working in Georgian London. A small pocketbook, it was printed and published in Covent Garden, and sold for two shillings and sixpence. A contemporary report of 1791 estimates its circulation at about 8,000 copies annually.

Each edition contains entries describing the physical appearance and sexual specialities of about 120–190 prostitutes who worked in and around Covent Garden. Through their erotic prose, the list's entries review some of these women in lurid detail. While most compliment their subjects, some are critical of bad habits, and a few women are even treated as pariahs, perhaps having fallen out of favour with the list's authors, who are never revealed.

Samuel Derrick is the man normally credited for the design of Harris's List, possibly having been inspired by the activities of a Covent Garden pimp, Jack Harris. A Grub Street hack, Derrick may have written the lists from 1757 until his death in 1769; thereafter, the annual's authors are unknown. Throughout its print run it was published pseudonymously by H. Ranger, although from the late 1780s it was printed by three men: John and James Roach, and John Aitkin.

As the public's opinion began to turn against London's sex trade, and with reformers petitioning the authorities to take action, those involved in the release of Harris's List were in 1795 fined and imprisoned. That year's edition was the last to be published. By then, its content was cruder, lacking the originality of earlier editions. Modern writers tend to view Harris's List as erotica; in the words of one author, it was designed for "solitary sexual enjoyment".

🔗 Algae

Valonia ventricosa, also known as bubble algae or sailor's eyeballs is a species of alga found in oceans throughout the world in tropical and subtropical regions. It is one of the largest – if not the largest – unicellular organisms.

🔗 Economics 🔗 Sociology

Commons-based peer production (CBPP) is a term coined by Harvard Law School professor Yochai Benkler. It describes a model of socio-economic production in which large numbers of people work cooperatively; usually over the Internet. Commons-based projects generally have less rigid hierarchical structures than those under more traditional business models. Often—but not always—commons-based projects are designed without a need for financial compensation for contributors. For example, sharing of STL (file format) design files for objects freely on the internet enables anyone with a 3-D printer to digitally replicate the object saving the prosumer significant money.

The term is often used interchangeably with the term social production.

🔗 Biography 🔗 Internet culture 🔗 Comedy 🔗 Biography/arts and entertainment

@dril is a pseudonymous Twitter user best known for his idiosyncratic style of absurdist humor and non sequiturs. The account, its author, and the character associated with the tweets are all commonly referred to as dril (the handle without the at sign) or wint (the account's display name), both rendered lowercase but often capitalized by others. Since his first tweet in 2008, dril has become a popular and influential Twitter user with more than one million followers.

dril is one of the most notable accounts associated with "Weird Twitter", a subculture on the site that shares a surreal, ironic sense of humor. The character associated with dril is highly distinctive, often described as a bizarre reflection of a typical male American Internet user. Other social media users have repurposed dril's tweets for humorous or satiric effect in a variety of political and cultural contexts. Many of dril's tweets, phrases, and tropes have become familiar parts of Internet slang.

The author behind dril remained unknown for years, with the few available details about the author's life fueling speculation about his identity. In 2017, dril's author was "doxxed" (in other words, his identity was exposed) in a post that went viral and received media attention. After the doxxing, many Twitter users and journalists preferred to preserve dril's pseudonymity out of respect for the author's personal privacy and the character's mystique.

Beyond tweeting, dril has created animated short films and contributed illustrations and writing to other artists' collaborative projects. His first book, Dril Official "Mr. Ten Years" Anniversary Collection (2018), is a compilation of the account's "greatest hits" alongside new illustrations. In 2019 he announced the launch of a streaming web series called Truthpoint: Darkweb Rising, an InfoWars parody co-created with comedian Derek Estevez-Olsen for Adult Swim. Writers have praised dril for the originality and humor of his tweets; for example, the poet Patricia Lockwood called dril "a master of tone [and] character," and The A.V. Club dubbed him "arguably the most iconic Twitter account in the history of social media."

🔗 Measurement 🔗 Malaysia 🔗 Myanmar

The traditional Burmese units of measurement as of 2010 were still in everyday use in Myanmar (also known as Burma). According to the 2010 CIA Factbook, Myanmar is one of three countries that have not adopted the International System of Units (SI) metric system as their official system of weights and measures. However, in June 2011, the Burmese government's Ministry of Commerce began discussing proposals to reform the measurement system in Burma and adopt the metric system used by most of its trading partners, and in October 2013, Dr. Pwint San, Deputy Minister for Commerce, announced that the country was preparing to adopt the metric system.

Most of the nation uses Burmese units only, although Burmese government web pages in English use imperial and metric units inconsistently. For instance, the Ministry of Construction uses miles to describe the length of roads and square feet for the size of houses, but square kilometres for the total land area of new town developments in Yangon City. The Ministry of Agriculture uses acres for land areas. The Ministry of Foreign Affairs uses kilometres (with mile equivalents in parentheses) to describe the dimensions of the country.

🔗 Mathematics

Gabriel's horn (also called Torricelli's trumpet) is a geometric figure which has infinite surface area but finite volume. The name refers to the Abrahamic tradition identifying the archangel Gabriel as the angel who blows the horn to announce Judgment Day, associating the divine, or infinite, with the finite. The properties of this figure were first studied by Italian physicist and mathematician Evangelista Torricelli in the 17th century.

🔗 Physics

Certain systems can achieve negative thermodynamic temperature; that is, their temperature can be expressed as a negative quantity on the Kelvin or Rankine scales. This should be distinguished from temperatures expressed as negative numbers on non-thermodynamic Celsius or Fahrenheit scales, which are nevertheless higher than absolute zero.

The absolute temperature (Kelvin) scale can be understood loosely as a measure of average kinetic energy. Usually, system temperatures are positive. However, in particular isolated systems, the temperature defined in terms of Boltzmann's entropy can become negative.

The possibility of negative temperatures was first predicted by Lars Onsager in 1949, in his analysis of classical point vortices confined to a finite area. Confined point vortices are a system with bounded phase space as their canonical momenta are not independent degrees of freedom from their canonical position coordinates. Bounded phase space is the essential property that allows for negative temperatures, and such temperatures can occur in both classical and quantum systems. As shown by Onsager, a system with bounded phase space necessarily has a peak in the entropy as energy is increased. For energies exceeding the value where the peak occurs, the entropy decreases as energy increases, and high-energy states necessarily have negative Boltzmann temperature.

A system with a truly negative temperature on the Kelvin scale is hotter than any system with a positive temperature. If a negative-temperature system and a positive-temperature system come in contact, heat will flow from the negative- to the positive-temperature system. A standard example of such a system is population inversion in laser physics.

Temperature is loosely interpreted as the average kinetic energy of the system's particles. The existence of negative temperature, let alone negative temperature representing "hotter" systems than positive temperature, would seem paradoxical in this interpretation. The paradox is resolved by considering the more rigorous definition of thermodynamic temperature as the tradeoff between internal energy and entropy contained in the system, with "coldness", the reciprocal of temperature, being the more fundamental quantity. Systems with a positive temperature will increase in entropy as one adds energy to the system, while systems with a negative temperature will decrease in entropy as one adds energy to the system.

Thermodynamic systems with unbounded phase space cannot achieve negative temperatures: adding heat always increases their entropy. The possibility of a decrease in entropy as energy increases requires the system to "saturate" in entropy. This is only possible if the number of high energy states is limited. For a system of ordinary (quantum or classical) particles such as atoms or dust, the number of high energy states is unlimited (particle momenta can in principle be increased indefinitely). Some systems, however (see the examples below), have a maximum amount of energy that they can hold, and as they approach that maximum energy their entropy actually begins to decrease. The limited range of states accessible to a system with negative temperature means that negative temperature is associated with emergent ordering of the system at high energies. For example in Onsager's point-vortex analysis negative temperature is associated with the emergence of large-scale clusters of vortices. This spontaneous ordering in equilibrium statistical mechanics goes against common physical intuition that increased energy leads to increased disorder.

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

Klára Dán von Neumann (born Klára Dán; 18 August 1911 – 10 November 1963) was a Hungarian-American mathematician, self-taught engineer and computer scientist, noted as one of the first computer programmers. She was the first woman to execute modern-style code on a computer. Klára made significant contributions to the world of programming, including work on the Monte Carlo method, ENIAC, and MANIAC I.