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🔗 Geographical coordinates 🔗 Microformats

Geohash is a public domain geocode system invented in 2008 by Gustavo Niemeyer and (similar work in 1966) G.M. Morton, which encodes a geographic location into a short string of letters and digits. It is a hierarchical spatial data structure which subdivides space into buckets of grid shape, which is one of the many applications of what is known as a Z-order curve, and generally space-filling curves.

Geohashes offer properties like arbitrary precision and the possibility of gradually removing characters from the end of the code to reduce its size (and gradually lose precision). As a consequence of the gradual precision degradation, nearby places will often (but not always) present similar prefixes. While in rare cases nearby places may have very short shared prefixes, the longer their shared prefix is, the closer two places are guaranteed to be.

🔗 Chemistry

Aqua regia (; from Latin, lit. "regal water" or "king's water") is a mixture of nitric acid and hydrochloric acid, optimally in a molar ratio of 1:3. Aqua regia is a yellow-orange (sometimes red) fuming liquid, so named by alchemists because it can dissolve the noble metals, gold and platinum, though not all metals.

🔗 Computing

The IBM 5100 Portable Computer is a portable computer (one of the first) introduced in September 1975, six years before the IBM Personal Computer. It was the evolution of a prototype called the SCAMP (Special Computer APL Machine Portable) that was developed at the IBM Palo Alto Scientific Center in 1973. In January 1978, IBM announced the IBM 5110, its larger cousin, and in February 1980 IBM announced the IBM 5120. The 5100 was withdrawn in March 1982.

When the IBM PC was introduced in 1981, it was originally designated as the IBM 5150, putting it in the "5100" series, though its architecture was unrelated to the IBM 5100's.

🔗 Computer science 🔗 Economics 🔗 Engineering 🔗 Gender Studies

Pareto efficiency or Pareto optimality is a situation where no action or allocation is available that makes one individual better off without making another worse off. The concept is named after Vilfredo Pareto (1848–1923), Italian civil engineer and economist, who used the concept in his studies of economic efficiency and income distribution. The following three concepts are closely related:

• Given an initial situation, a Pareto improvement is a new situation where some agents will gain, and no agents will lose.
• A situation is called Pareto-dominated or Pareto-inefficient if there is some possible Pareto improvement that has not been made.
• A situation is called Pareto-optimal or Pareto-efficient if no change could lead to improved satisfaction for some agent without some other agent losing or, equivalently, if there is no scope for further Pareto improvement (in other words, the situation is not Pareto-dominated).

The Pareto front (also called Pareto frontier or Pareto set) is the set of all Pareto-efficient situations.

Pareto originally used the word "optimal" for the concept, but as it describes a situation where a limited number of people will be made better off under finite resources, and it does not take equality or social well-being into account, it is in effect a definition of and better captured by "efficiency".

In addition to the context of efficiency in allocation, the concept of Pareto efficiency also arises in the context of efficiency in production vs. x-inefficiency: a set of outputs of goods is Pareto-efficient if there is no feasible re-allocation of productive inputs such that output of one product increases while the outputs of all other goods either increase or remain the same.

Pareto efficiency is measured along the production possibility frontier (PPF), which is a graphical representation of all the possible options of output for two products that can be produced using all factors of production.

Besides economics, the notion of Pareto efficiency has been applied to the selection of alternatives in engineering and biology. Each option is first assessed, under multiple criteria, and then a subset of options is ostensibly identified with the property that no other option can categorically outperform the specified option. It is a statement of impossibility of improving one variable without harming other variables in the subject of multi-objective optimization (also termed Pareto optimization).

🔗 Science

Literature-based discovery is a form of knowledge extraction and automated hypothesis generation that uses papers and other academic publications (the "literature") to find new relationships between existing knowledge (the "discovery"). The technique was pioneered by Don R. Swanson in the 1980s and has since seen widespread use.

Literature-based discovery does not generate new knowledge through laboratory experiments, as is customary for empirical sciences. Instead it seeks to connect existing knowledge from empirical results by bringing to light relationships that are implicated and "neglected". It is marked by empiricism and rationalism in concert or consilience.

🔗 Biography 🔗 Canada 🔗 Physics 🔗 Women 🔗 Women scientists 🔗 Biography/science and academia 🔗 Physics/Biographies 🔗 Canada/Ontario

Donna Theo Strickland, (born 27 May 1959) is a Canadian optical physicist and pioneer in the field of pulsed lasers. She was awarded the Nobel Prize in Physics in 2018, together with Gérard Mourou, for the invention of chirped pulse amplification. She is a professor at the University of Waterloo.

She served as fellow, vice president, and president of The Optical Society, and is currently chair of their Presidential Advisory Committee. In 2018, she was listed as one of BBC's 100 Women.

🔗 Lists 🔗 Buddhism 🔗 Project-independent assessment

The Buddhist games list is a list of games that Gautama Buddha is reputed to have said that he would not play and that his disciples should likewise not play, because he believed them to be a 'cause for negligence'. This list dates from the 6th or 5th century BCE and is the earliest known list of games.

There is some debate about the translation of some of the games mentioned, and the list given here is based on the translation by T. W. Rhys Davids of the Brahmajāla Sutta and is in the same order given in the original. The list is duplicated in a number of other early Buddhist texts, including the Vinaya Pitaka.

1. Games on boards with 8 or 10 rows. This is thought to refer to ashtapada and dasapada respectively, but later Sinhala commentaries refer to these boards also being used with games involving dice.
2. The same games played on imaginary boards. Akasam astapadam was an ashtapada variant played with no board, literally "astapadam played in the sky". A correspondent in the American Chess Bulletin identifies this as likely the earliest literary mention of a blindfold chess variant.
3. Games of marking diagrams on the floor such that the player can only walk on certain places. This is described in the Vinaya Pitaka as "having drawn a circle with various lines on the ground, there they play avoiding the line to be avoided". Rhys Davids suggests that it may refer to parihāra-patham, a form of hop-scotch.
4. Games where players either remove pieces from a pile or add pieces to it, with the loser being the one who causes the heap to shake (similar to the modern game pick-up sticks).
5. Games of throwing dice.
6. "Dipping the hand with the fingers stretched out in lac, or red dye, or flour-water, and striking the wet hand on the ground or on a wall, calling out 'What shall it be?' and showing the form required—elephants, horses, &c."
7. Ball games.
8. Blowing through a pat-kulal, a toy pipe made of leaves.
9. Ploughing with a toy plough.
10. Playing with toy windmills made from palm leaves.
11. Playing with toy measures made from palm leaves.
12. Playing with toy carts.
13. Playing with toy bows.
14. Guessing at letters traced with the finger in the air or on a friend's back.
15. Guessing a friend's thoughts.
16. Imitating deformities.

Although the modern game of chess had not been invented at the time the list was made, earlier chess-like games such as chaturaji may have existed. H.J.R. Murray refers to Rhys Davids' 1899 translation, noting that the 8×8 board game is most likely ashtapada while the 10×10 game is dasapada. He states that both are race games.

🔗 Computing 🔗 Computing/Software

The syntax of the Python programming language is the set of rules that defines how a Python program will be written and interpreted (by both the runtime system and by human readers). The Python language has many similarities to Perl, C, and Java. However, there are some definite differences between the languages.

🔗 Business 🔗 Psychology

Theory X and Theory Y are theories of human work motivation and management. They were created by Douglas McGregor while he was working at the MIT Sloan School of Management in the 1950s, and developed further in the 1960s. McGregor's work was rooted in motivation theory alongside the works of Abraham Maslow, who created the hierarchy of needs. The two theories proposed by McGregor describe contrasting models of workforce motivation applied by managers in human resource management, organizational behavior, organizational communication and organizational development. Theory X explains the importance of heightened supervision, external rewards, and penalties, while Theory Y highlights the motivating role of job satisfaction and encourages workers to approach tasks without direct supervision. Management use of Theory X and Theory Y can affect employee motivation and productivity in different ways, and managers may choose to implement strategies from both theories into their practices.

🔗 Disambiguation

A rat king is a rare phenomenon where a group of rats' tails become entangled.

Rat King or Ratking may also refer to: