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🔗 Internet 🔗 Computing 🔗 Telecommunications 🔗 Computing/Software 🔗 Computing/Networking

Project Xanadu ( ZAN-ə-doo) was the first hypertext project, founded in 1960 by Ted Nelson. Administrators of Project Xanadu have declared it an improvement over the World Wide Web, with the mission statement: "Today's popular software simulates paper. The World Wide Web (another imitation of paper) trivialises our original hypertext model with one-way ever-breaking links and no management of version or contents."

Wired magazine published an article called "The Curse of Xanadu", calling Project Xanadu "the longest-running vaporware story in the history of the computer industry". The first attempt at implementation began in 1960, but it was not until 1998 that an incomplete implementation was released. A version described as "a working deliverable", OpenXanadu, was made available in 2014.

🔗 Lists 🔗 Philosophy 🔗 Philosophy/Logic

This is a list of paradoxes, grouped thematically. The grouping is approximate, as paradoxes may fit into more than one category. This list collects only scenarios that have been called a paradox by at least one source and have their own article. Although considered paradoxes, some of these are simply based on fallacious reasoning (falsidical), or an unintuitive solution (veridical). Informally, the term paradox is often used to describe a counter-intuitive result.

However, some of these paradoxes qualify to fit into the mainstream perception of a paradox, which is a self-contradictory result gained even while properly applying accepted ways of reasoning. These paradoxes, often called antinomy, point out genuine problems in our understanding of the ideas of truth and description.

🔗 Philosophy 🔗 Philosophy/Philosophical literature 🔗 Philosophy/Contemporary philosophy 🔗 Philosophy/Philosophy of mind

"What Is It Like to Be a Bat?" is a paper by American philosopher Thomas Nagel, first published in The Philosophical Review in October 1974, and later in Nagel's Mortal Questions (1979). The paper presents several difficulties posed by phenomenal consciousness, including the potential insolubility of the mind–body problem owing to "facts beyond the reach of human concepts", the limits of objectivity and reductionism, the "phenomenological features" of subjective experience, the limits of human imagination, and what it means to be a particular, conscious thing.

Nagel asserts that "an organism has conscious mental states if and only if there is something that it is like to be that organism—something it is like for the organism." This assertion has achieved special status in consciousness studies as "the standard 'what it's like' locution". Daniel Dennett, while sharply disagreeing on some points, acknowledged Nagel's paper as "the most widely cited and influential thought experiment about consciousness".

🔗 Guild of Copy Editors 🔗 Automobiles

The Chrysler Turbine Car is an experimental two-door hardtop coupe powered by a turbine engine and manufactured by Chrysler from 1963–1964. The bodywork was constructed by Italian design studio Carrozzeria Ghia and Chrysler completed the final assembly in Detroit. A total of 55 cars were manufactured: five prototypes and a limited run of 50 cars for a public user program. All have a signature metallic paint named "turbine bronze", roughly the color of root beer. The car was styled by Elwood Engel and the Chrysler studios and featured power brakes, power steering, and a TorqueFlite transmission.

The Chrysler turbine engine program that produced the Turbine Car began during the late 1930s and created prototypes that completed long-distance trips in the 1950s and early 1960s. The A-831 engines that powered the Ghia-designed Turbine Car could operate on many fuels, required less maintenance, and lasted longer than conventional piston engines, although they were much more expensive to produce.

After testing, Chrysler conducted a user program from October 1963 to January 1966 that involved 203 drivers in 133 cities in the United States cumulatively driving more than one million miles (1.6 million km). The program helped the company determine problems with the cars, notably with their complicated starting procedure, relatively unimpressive acceleration, and sub-par fuel economy and noise. The experience also revealed advantages of the turbine engines, including their remarkable durability, smooth operation, and relatively modest maintenance requirements.

After the user program ended in 1966, Chrysler reclaimed the cars and destroyed all but nine; Chrysler kept two cars, six are displayed at museums in the United States, and one is in a private collection. Chrysler's turbine engine program ended in 1979, largely due to the failure of the engines to meet government emissions regulations, relatively poor fuel economy, and as a condition of receiving a government loan in 1979.

🔗 Food and drink 🔗 Glass

A teasmade is a machine for making tea automatically, which was once common in the United Kingdom and some British Commonwealth countries. Teasmades generally include an analogue alarm clock and are designed to be used at the bedside, to ensure tea is ready first thing in the morning. Although crude versions existed in Victorian times, they only became practical with the availability of electric versions in the 1930s. They reached their peak in popularity in the 1960s and 1970s, since when their use has declined, but they are now enjoying a revival, partly as a retro novelty item.

The name teasmade is an example of a genericised trademark, now commonly used to refer to any automatic tea-making appliance.

🔗 Mathematics 🔗 Physics

The triple product rule, known variously as the cyclic chain rule, cyclic relation, cyclical rule, Euler's chain rule, or the reciprocity theorem, is a formula which relates partial derivatives of three interdependent variables. The rule finds application in thermodynamics, where frequently three variables can be related by a function of the form f(x, y, z) = 0, so each variable is given as an implicit function of the other two variables. For example, an equation of state for a fluid relates temperature, pressure, and volume in this manner. The triple product rule for such interrelated variables x, y, and z comes from using a reciprocity relation on the result of the implicit function theorem, and is given by

${\displaystyle \left({\frac {\partial x}{\partial y}}\right)\left({\frac {\partial y}{\partial z}}\right)\left({\frac {\partial z}{\partial x}}\right)=-1,}$

where each factor is a partial derivative of the variable in the numerator, considered to be a function of the other two.

The advantage of the triple product rule is that by rearranging terms, one can derive a number of substitution identities which allow one to replace partial derivatives which are difficult to analytically evaluate, experimentally measure, or integrate with quotients of partial derivatives which are easier to work with. For example,

${\displaystyle \left({\frac {\partial x}{\partial y}}\right)=-{\frac {\left({\frac {\partial z}{\partial y}}\right)}{\left({\frac {\partial z}{\partial x}}\right)}}}$

Various other forms of the rule are present in the literature; these can be derived by permuting the variables {x, y, z}.

🔗 Education 🔗 Organizations

The University of the Third Age is an international movement whose aims are the education and stimulation of mainly retired members of the community—those in their third 'age' of life. It is commonly referred to as U3A.

There is no universally accepted model for the U3A. Its original conception in France as an extramural university activity was significantly modified in the United Kingdom where it was recognized that most people of retirement age have something to contribute and the emphasis has been on sharing, without formal links to traditional universities.

Many English-speaking countries have followed this geragogic model, whereas continental European countries have mostly followed the French model. For historical reasons, Lifelong learning institutes is the term used in the United States for organizations that are similar to U3A groups.

A British U3A website reports this about "The Third Age" membership eligibility: "U3A membership is not related to a specific age but to a period in one’s life (the third age) after the second age of full-time employment and parental responsibility. Anybody in their third age can join U3A and this includes people who are working part-time. There is no lower age for membership."

🔗 Philosophy 🔗 Philosophy/Logic

The raven paradox, also known as Hempel's paradox, Hempel's ravens, or rarely the paradox of indoor ornithology, is a paradox arising from the question of what constitutes evidence for a statement. Observing objects that are neither black nor ravens may formally increase the likelihood that all ravens are black even though, intuitively, these observations are unrelated.

This problem was proposed by the logician Carl Gustav Hempel in the 1940s to illustrate a contradiction between inductive logic and intuition.

🔗 California 🔗 Companies 🔗 California/San Francisco Bay Area 🔗 Computing 🔗 Lists 🔗 Google

Google is a computer software and a web search engine company that acquired, on average, more than one company per week in 2010 and 2011. The table below is an incomplete list of acquisitions, with each acquisition listed being for the respective company in its entirety, unless otherwise specified. The acquisition date listed is the date of the agreement between Google and the acquisition subject. As Google is headquartered in the United States, acquisition is listed in US dollars. If the price of an acquisition is unlisted, then it is undisclosed. If the Google service that is derived from the acquired company is known, then it is also listed here. Google itself was re-organized into a subsidiary of a larger holding company known as Alphabet Inc. in 2015.

As of December 2016, Alphabet has acquired over 200 companies, with its largest acquisition being the purchase of Motorola Mobility, a mobile device manufacturing company, for $12.5 billion. Most of the firms acquired by Google are based in the United States, and, in turn, most of these are based in or around the San Francisco Bay Area. To date, Alphabet has divested itself of four business units: Frommers, which was sold back to Arthur Frommer in April 2012; SketchUp, which was sold to Trimble in April 2012, Boston Dynamics in early 2016 and Google Radio Automation, which was sold to WideOrbit in 2009.

Many Google products originated as services provided by companies that Google has since acquired. For example, Google's first acquisition was the Usenet company Deja News, and its services became Google Groups. Similarly, Google acquired Dodgeball, a social networking service company, and eventually replaced it with Google Latitude. Other acquisitions include web application company JotSpot, which became Google Sites; Voice over IP company GrandCentral, which became Google Voice; and video hosting service company Next New Networks, which became YouTube Next Lab and Audience Development Group. CEO Larry Page has explained that potential acquisition candidates must pass a sort of "toothbrush test": Are their products potentially useful once or twice a day, and do they improve your life?

Following the acquisition of Israel-based startup Waze in June 2013, Google submitted a 10-Q filing with the Securities Exchange Commission (SEC) that revealed that the corporation spent $1.3 billion on acquisitions during the first half of 2013, with $966 million of that total going to Waze.

🔗 Time 🔗 Christianity

The computus (Latin for 'computation') is a calculation that determines the calendar date of Easter. Easter is traditionally celebrated on the first Sunday after the Paschal full moon, which is the first full moon on or after 21 March (an approximation of the March equinox). Determining this date in advance requires a correlation between the lunar months and the solar year, while also accounting for the month, date, and weekday of the calendar. The calculations produce different results depending on whether the Julian calendar or the Gregorian calendar is used.

In late antiquity, it was feasible for the entire Christian church to receive the date of Easter each year through an annual announcement from the Pope. By the early third century, however, communications had deteriorated to the point that the church put great value in a system that would allow the clergy to independently and consistently determine the date for themselves. Additionally, the church wished to eliminate dependencies on the Hebrew calendar, by deriving Easter directly from the vernal equinox.

In The Reckoning of Time (725), Bede uses computus as a general term for any sort of calculation, although he refers to the Easter cycles of Theophilus as a "Paschal computus." By the end of the 8th century, computus came to refer specifically to the calculation of time.