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🔗 Classical Greece and Rome 🔗 Greece 🔗 Trains 🔗 Archaeology

The Diolkos (Δίολκος, from the Greek διά, dia "across" and ὁλκός, holkos "portage machine") was a paved trackway near Corinth in Ancient Greece which enabled boats to be moved overland across the Isthmus of Corinth. The shortcut allowed ancient vessels to avoid the long and dangerous circumnavigation of the Peloponnese peninsula. The phrase "as fast as a Corinthian", penned by the comic playwright Aristophanes, indicates that the trackway was common knowledge and had acquired a reputation for swiftness.

The main function of the Diolkos was the transfer of goods, although in times of war it also became a preferred means of speeding up naval campaigns. The 6 km (3.7 mi) to 8.5 km (5.3 mi) long roadway was a rudimentary form of railway, and operated from c. 600 BC until the middle of the 1st century AD. The scale on which the Diolkos combined the two principles of the railway and the overland transport of ships remained unique in antiquity.

🔗 Computer science

In computer science, the shunting-yard algorithm is a method for parsing mathematical expressions specified in infix notation. It can produce either a postfix notation string, also known as Reverse Polish notation (RPN), or an abstract syntax tree (AST). The algorithm was invented by Edsger Dijkstra and named the "shunting yard" algorithm because its operation resembles that of a railroad shunting yard. Dijkstra first described the Shunting Yard Algorithm in the Mathematisch Centrum report MR 34/61.

Like the evaluation of RPN, the shunting yard algorithm is stack-based. Infix expressions are the form of mathematical notation most people are used to, for instance "3 + 4" or "3 + 4 × (2 − 1)". For the conversion there are two text variables (strings), the input and the output. There is also a stack that holds operators not yet added to the output queue. To convert, the program reads each symbol in order and does something based on that symbol. The result for the above examples would be (in Reverse Polish notation) "3 4 +" and "3 4 2 1 − × +", respectively.

The shunting-yard algorithm was later generalized into operator-precedence parsing.

🔗 Medicine 🔗 Viruses

Original antigenic sin, also known as antigenic imprinting or the Hoskins effect, refers to the propensity of the body's immune system to preferentially utilize immunological memory based on a previous infection when a second slightly different version of that foreign pathogen (e.g. a virus or bacterium) is encountered. This leaves the immune system "trapped" by the first response it has made to each antigen, and unable to mount potentially more effective responses during subsequent infections. Antibodies or T-cells induced during infections with the first variant of the pathogen are subject to a form of original antigenic sin, termed repertoire freeze.

The phenomenon of original antigenic sin has been described in relation to influenza virus, dengue fever, human immunodeficiency virus (HIV) and to several other viruses.

This phenomenon was first described in 1960 by Thomas Francis Jr. in the article "On the Doctrine of Original Antigenic Sin". It is named by analogy to the theological concept of original sin. According to Francis as cited by Richard Krause:

"The antibody of childhood is largely a response to dominant antigen of the virus causing the first type A influenza infection of the lifetime. [...] The imprint established by the original virus infection governs the antibody response thereafter. This we have called the Doctrine of the Original Antigenic Sin."

🔗 Internet culture 🔗 Climate change 🔗 Environment 🔗 United Kingdom 🔗 Antarctica 🔗 Arctic 🔗 Oceans 🔗 Antarctica/British Antarctic Territory

Boaty McBoatface (also known as Boaty) is the British lead boat in a fleet of three robotic lithium battery–powered autonomous underwater vehicles (AUVs) of the Autosub Long Range (ALR) class. Launched in 2017 and carried on board the polar scientific research vessel RRS Sir David Attenborough, she is a focal point of the Polar Explorer Programme of the UK Government.

Boaty and her two fleet-mates are part of the UK National Marine Equipment Pool and owned by the National Oceanography Centre in Southampton. She is classified as an "autosub long range (ALR) autonomous underwater vehicle", and will use her onboard sensors to map the movement of deep waters that play a vital role in regulating the Earth's climate.

🔗 Death 🔗 Visual arts 🔗 Latin

Memento mori (Latin for 'remember that you [have to] die') is an artistic or symbolic trope acting as a reminder of the inevitability of death. The concept has its roots in the philosophers of classical antiquity and Christianity, and appeared in funerary art and architecture from the medieval period onwards.

The most common motif is a skull, often accompanied by one or more bones. Often this alone is enough to evoke the trope, but other motifs such as a coffin, hourglass and wilting flowers signified the impermanence of human life. Often these function within a work whose main subject is something else, such as a portrait, but the vanitas is an artistic genre where the theme of death is the main subject. The Danse Macabre and Death personified with a scythe as the Grim Reaper are even more direct evocations of the trope.

🔗 Automobiles

A cyclecar was a type of small, lightweight and inexpensive car manufactured in Europe and the United States between 1910 and the early 1920s. The purpose of cyclecars was to fill a gap in the market between the motorcycle and the car.

The demise of cyclecars was due to larger cars – such as the Citroën Type C, Austin 7 and Morris Cowley – becoming more affordable. Small, inexpensive vehicles reappeared after World War II, and were known as microcars.

🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry

Improvised firearms (sometimes called zip guns or pipe guns) are firearms manufactured other than by a firearms manufacturer or a gunsmith, and are typically constructed by adapting existing materials to the purpose. They range in quality from crude weapons that are as much a danger to the user as the target to high-quality arms produced by cottage industries using salvaged and repurposed materials.

Improvised firearms are commonly used as tools by criminals and insurgents and are often associated with such groups; other uses include self-defense in lawless areas and hunting game in poor rural areas.

🔗 Computing 🔗 Perl

The WikiWikiWeb is the first-ever wiki, or user-editable website. It was launched on 25 March 1995 by its inventor, programmer Ward Cunningham, to accompany the Portland Pattern Repository website discussing software design patterns. The name WikiWikiWeb originally also applied to the wiki software that operated the website, written in the Perl programming language and later renamed to "WikiBase". The site is frequently referred to by its users as simply "Wiki", and a convention established among users of the early network of wiki sites that followed was that using the word with a capitalized W referred exclusively to the original site.