Have a deep view into what people are curious about.

🔗 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.

🔗 Genetics 🔗 Molecular Biology/Molecular and Cell Biology

In genetic engineering, a gene gun or biolistic particle delivery system is a device used to deliver exogenous DNA (transgenes), RNA, or protein to cells. By coating particles of a heavy metal with a gene of interest and firing these micro-projectiles into cells using mechanical force, an integration of desired genetic information can be induced into cells. The technique involved with such micro-projectile delivery of DNA is often referred to as biolistics.

This device is able to transform almost any type of cell and is not limited to the transformation of the nucleus; it can also transform organelles, including plastids and mitochondria.

🔗 Internet 🔗 Computing 🔗 Computing/Computer hardware 🔗 Finance & Investment 🔗 Economics 🔗 Law 🔗 Computing/Software 🔗 Computing/Free and open-source software 🔗 Computing/Computer science 🔗 Cryptography 🔗 Cryptography/Computer science 🔗 Numismatics 🔗 Guild of Copy Editors 🔗 Numismatics/Cryptocurrency 🔗 Cryptocurrency 🔗 Open 🔗 Computing/Computer Security

Bitcoin (₿) is a cryptocurrency. It is a decentralized digital currency without a central bank or single administrator that can be sent from user to user on the peer-to-peer bitcoin network without the need for intermediaries.

Transactions are verified by network nodes through cryptography and recorded in a public distributed ledger called a blockchain. Bitcoin was invented in 2008 by an unknown person or group of people using the name Satoshi Nakamoto and started in 2009 when its source code was released as open-source software. Bitcoins are created as a reward for a process known as mining. They can be exchanged for other currencies, products, and services. Research produced by University of Cambridge estimates that in 2017, there were 2.9 to 5.8 million unique users using a cryptocurrency wallet, most of them using bitcoin.

Bitcoin has been criticized for its use in illegal transactions, its high electricity consumption, price volatility, and thefts from exchanges. Some economists, including several Nobel laureates, have characterized it as a speculative bubble. Bitcoin has also been used as an investment, although several regulatory agencies have issued investor alerts about bitcoin.

In 2011, Randall Munroe in his comic xkcd coined the term "citogenesis" to describe the creation of "reliable" sources through circular reporting. This is a list of some well-documented cases where Wikipedia has been the source.

🔗 United States 🔗 Books 🔗 Science Fiction

The Astronautilia (Czech: Hvězdoplavba; full title in Greek: Ποιητοῦ ἀδήλου ΑΣΤΡΟΝΑΥΤΙΛΙΑ ἢ ἡ Μικροοδύσσεια ἡ κοσμική; i.e. "An unknown poet's Starvoyage, or the Cosmic Micro-Odyssey") is the magnum opus, written in 1994 under the hellenised pseudonym Ἰωάννης Πυρεῖα, of Czech poet and writer Jan Křesadlo, one of the most unusual works of twentieth-century Czech literature. It was published shortly after his death, as a commemorative first edition.

While no full English translation exists as yet, there is a sample chapter translation online, and a German translation of the fully transcribed and annotated Greek text is in preparation.

🔗 Apple Inc. 🔗 Software 🔗 Software/Computing

A/UX is a Unix-based operating system from Apple Computer for Macintosh computers, integrated with System 7's graphical interface and application compatibility. It is Apple's first official Unix-based operating system, launched in 1988 and discontinued in 1995 with version 3.1.1. A/UX requires select 68k-based Macintosh models with an FPU and a paged memory management unit (PMMU), including the Macintosh II, SE/30, Quadra, and Centris series.

Described by InfoWorld as "an open systems solution with the Macintosh at its heart", A/UX is based on UNIX System V Release 2.2, with features from System V Releases 3 and 4 and BSD versions 4.2 and 4.3. It is POSIX- and System V Interface Definition (SVID)-compliant and includes TCP/IP networking since version 2. Having a Unix-compatible, POSIX-compliant operating system enabled Apple to bid for large contracts to supply computers to U.S. federal government institutes.

🔗 Mathematics

In symbolic computation (or computer algebra), at the intersection of mathematics and computer science, the Risch algorithm is an algorithm for indefinite integration. It is used in some computer algebra systems to find antiderivatives. It is named after the American mathematician Robert Henry Risch, a specialist in computer algebra who developed it in 1968.

The algorithm transforms the problem of integration into a problem in algebra. It is based on the form of the function being integrated and on methods for integrating rational functions, radicals, logarithms, and exponential functions. Risch called it a decision procedure, because it is a method for deciding whether a function has an elementary function as an indefinite integral, and if it does, for determining that indefinite integral.

The complete description of the Risch algorithm takes over 100 pages. The Risch–Norman algorithm is a simpler, faster, but less powerful variant that was developed in 1976 by Arthur Norman.

🔗 Robotics

Micromouse is an event where small robot mice solve a 16×16 maze. It began in the late 1970s. Events are held worldwide, and are most popular in the UK, U.S., Japan, Singapore, India, South Korea and becoming popular in subcontinent countries such as Sri Lanka.

The maze is made up of a 16×16 grid of cells, each 180 mm square with walls 50 mm high. The mice are completely autonomous robots that must find their way from a predetermined starting position to the central area of the maze unaided. The mouse needs to keep track of where it is, discover walls as it explores, map out the maze and detect when it has reached the goal. Having reached the goal, the mouse will typically perform additional searches of the maze until it has found an optimal route from the start to the finish. Once the optimal route has been found, the mouse will run that route in the shortest possible time.

Competitions and conferences are still run regularly.

🔗 Bridges and Tunnels 🔗 Civil engineering

Hobby tunneling (or tunnelling) is tunnel construction as a diversion. Usually, hobby tunnelers dig their tunnels by hand, using little equipment, and some can spend years or even decades to achieve any degree of completion. In some cases tunnels have been dug secretly, and only discovered by chance.

🔗 Death 🔗 England 🔗 Middle Ages 🔗 Middle Ages/History 🔗 Visual arts 🔗 Lincolnshire 🔗 Hertfordshire

The Eleanor crosses were a series of twelve tall and lavishly decorated stone monuments topped with crosses erected in a line down part of the east of England. King Edward I had them built between 1291 and about 1295 in memory of his beloved wife Eleanor of Castile. The King and Queen had been married for 36 years and she stayed by the King’s side through his many travels. While on a royal progress, she died in the East Midlands in November 1290, perhaps due to fever. The crosses, erected in her memory, marked the nightly resting-places along the route taken when her body was transported to Westminster Abbey near London.

The crosses stood at Lincoln, Grantham and Stamford, all in Lincolnshire; Geddington and Hardingstone in Northamptonshire; Stony Stratford in Buckinghamshire; Woburn and Dunstable in Bedfordshire; St Albans and Waltham (now Waltham Cross) in Hertfordshire; Cheapside in London; and Charing (now Charing Cross) in Westminster.

Three of the medieval monuments – those at Geddington, Hardingstone and Waltham Cross – survive more or less intact; but the other nine, other than a few fragments, are lost. The largest and most ornate of the twelve was the Charing Cross. Several memorials and elaborated reproductions of the crosses have been erected, including the Queen Eleanor Memorial Cross at Charing Cross Station (built 1865).