Have a deep view into what people are curious about.

🔗 Economics 🔗 Transport

The Downs–Thomson paradox (named after Anthony Downs and John Michael Thomson), also known as the Pigou–Knight–Downs paradox (after Arthur Cecil Pigou and Frank Knight), states that the equilibrium speed of car traffic on a road network is determined by the average door-to-door speed of equivalent journeys taken by public transport.

It is a paradox in that improvements in the road network will not reduce traffic congestion. Improvements in the road network can make congestion worse if the improvements make public transport more inconvenient or if it shifts investment, causing disinvestment in the public transport system.

🔗 Birds 🔗 Animal rights 🔗 Veterinary medicine

Abnormal behavior of birds in captivity has been found to occur among both domesticated and wild birds. Abnormal behavior can be defined in several ways. Statistically, 'abnormal' is when the occurrence, frequency or intensity of a behaviour varies statistically significantly, either more or less, from the normal value. This means that theoretically, almost any behaviour could become 'abnormal' in an individual. Less formally, 'abnormal' includes any activity judged to be outside the normal behaviour pattern for captive birds of that particular class or age. For example, running rather than flying may be a normal behaviour and regularly observed in one species, however, in another species it might be normal but becomes 'abnormal' if it reaches a high frequency, or in another species it is rarely observed and any incidence is considered 'abnormal'. This article does not include 'one-off' behaviours performed by individual birds that might be considered abnormal for that individual, unless these are performed repeatedly by other individuals in the species and are recognised as part of the ethogram of that species.

Most abnormal behaviours can be categorised collectively (e.g., eliminative, ingestive, stereotypies), however, many abnormal behaviours fall debatably into several of these categories and categorisation is therefore not attempted in this article. Abnormal behaviours here are considered to be related to captive housing but may also be due to medical conditions. The article does not include behaviours in birds that are genetically modified to express abnormal behaviour.

🔗 Apple Inc. 🔗 Computing 🔗 Computing/Software

Contiki is an operating system for networked, memory-constrained systems with a focus on low-power wireless Internet of Things (IoT) devices. Extant uses for Contiki include systems for street lighting, sound monitoring for smart cities, radiation monitoring, and alarms. It is open-source software released under the BSD-3-Clause license.

Contiki was created by Adam Dunkels in 2002 and has been further developed by a worldwide team of developers from Texas Instruments, Atmel, Cisco, ENEA, ETH Zurich, Redwire, RWTH Aachen University, Oxford University, SAP, Sensinode, Swedish Institute of Computer Science, ST Microelectronics, Zolertia, and many others. Contiki gained popularity because of its built in TCP/IP stack and lightweight preemptive scheduling over event-driven kernel which is a very motivating feature for IoT. The name Contiki comes from Thor Heyerdahl's famous Kon-Tiki raft.

Contiki provides multitasking and a built-in Internet Protocol Suite (TCP/IP stack), yet needs only about 10 kilobytes of random-access memory (RAM) and 30 kilobytes of read-only memory (ROM). A full system, including a graphical user interface, needs about 30 kilobytes of RAM.

A new branch has recently been created, known as Contiki-NG: The OS for Next Generation IoT Devices

🔗 Biography 🔗 Canada 🔗 Greece 🔗 Canada/British Columbia 🔗 Canada/History of Canada

Ioannis Phokas (Greek: Ἰωάννης Φωκᾶς), better known by the Spanish translation of his name, Juan de Fuca (born 1536 on the Ionian island of Cefalonia; died there 1602), was a Greek maritime pilot in the service of the King of Spain, Philip II. He is best known for his claim to have explored the Strait of Anián, now known as the Strait of Juan de Fuca, between Vancouver Island (now part of British Columbia, Canada) and the Olympic Peninsula (northwestern Washington state, United States).

🔗 Europe 🔗 Middle Ages 🔗 Middle Ages/History

An erdstall is a type of tunnel found across Europe. They are of unknown origin but are believed to date from the Middle Ages. A variety of purposes have been theorized, including that they were used as escape routes or hiding places, but the most prominent theory is that they served a religious or spiritual purpose.

🔗 Medicine 🔗 Psychology 🔗 Sociology 🔗 Science 🔗 Academic Journals

The replication crisis (or replicability crisis or reproducibility crisis) is, as of 2020, an ongoing methodological crisis in which it has been found that many scientific studies are difficult or impossible to replicate or reproduce. The replication crisis affects the social sciences and medicine most severely. The crisis has long-standing roots; the phrase was coined in the early 2010s as part of a growing awareness of the problem. The replication crisis represents an important body of research in the field of metascience.

Because the reproducibility of experimental results is an essential part of the scientific method, the inability to replicate the studies of others has potentially grave consequences for many fields of science in which significant theories are grounded on unreproducible experimental work. The replication crisis has been particularly widely discussed in the field of psychology and in medicine, where a number of efforts have been made to re-investigate classic results, to determine both the reliability of the results, and, if found to be unreliable, the reasons for the failure of replication.

🔗 Military history 🔗 Poland 🔗 Hungary 🔗 Military history/World War II 🔗 Jewish history 🔗 European history 🔗 Military history/Polish military history 🔗 Military history/European military history

Witold's Report, also known as Pilecki's Report, is a report about the Auschwitz concentration camp written in 1943 by Witold Pilecki, a Polish military officer and agent of the Polish resistance. Pilecki volunteered in 1940 to be imprisoned in Auschwitz to organize a resistance movement and send out information about it. His was the first comprehensive record of a Holocaust death camp to be obtained by the Allies. He escaped from the camp in April 1943.

The report includes details about the gas chambers, "Selektion" and the sterilization experiments. It states that there were three crematoria in Auschwitz II able to cremate 8000 people daily.

Pilecki's Report preceded and complemented the Auschwitz Protocols, compiled from late 1943, which warned about the mass murder and other atrocities taking place inside the camp. The latter consists of the Polish Major's Report by Jerzy Tabeau, who escaped with Roman Cieliczko on 19 November 1943 and compiled a report between December 1943 and January 1944; the Vrba-Wetzler report; and the Rosin-Mordowicz report.

🔗 Mathematics 🔗 Economics 🔗 Game theory

A Vickrey auction or sealed-bid second-price auction (SBSPA) is a type of sealed-bid auction. Bidders submit written bids without knowing the bid of the other people in the auction. The highest bidder wins but the price paid is the second-highest bid. This type of auction is strategically similar to an English auction and gives bidders an incentive to bid their true value. The auction was first described academically by Columbia University professor William Vickrey in 1961 though it had been used by stamp collectors since 1893. In 1797 Johann Wolfgang von Goethe sold a manuscript using a sealed-bid, second-price auction.

Vickrey's original paper mainly considered auctions where only a single, indivisible good is being sold. The terms Vickrey auction and second-price sealed-bid auction are, in this case only, equivalent and used interchangeably. In the case of multiple identical goods, the bidders submit inverse demand curves and pay the opportunity cost.

Vickrey auctions are much studied in economic literature but uncommon in practice. Generalized variants of the Vickrey auction for multiunit auctions exist, such as the generalized second-price auction used in Google's and Yahoo!'s online advertisement programmes (not incentive compatible) and the Vickrey–Clarke–Groves auction (incentive compatible).

🔗 Architecture 🔗 London 🔗 England 🔗 United Kingdom 🔗 Citizendium Porting 🔗 Glass 🔗 Kent 🔗 Scouting/Girl Guiding and Girl Scouting 🔗 Scouting

The Crystal Palace was a cast-iron and plate-glass structure originally built in Hyde Park, London, to house the Great Exhibition of 1851. The exhibition took place from 1 May until 15 October 1851, and more than 14,000 exhibitors from around the world gathered in its 990,000 square feet (92,000 m²) exhibition space to display examples of technology developed in the Industrial Revolution. Designed by Joseph Paxton, the Great Exhibition building was 1,851 feet (564 m) long, with an interior height of 128 feet (39 m). It was three times the size of St Paul's Cathedral.

The introduction of the sheet glass method into Britain by Chance Brothers in 1832 made possible the production of large sheets of cheap but strong glass, and its use in the Crystal Palace created a structure with the greatest area of glass ever seen in a building. It astonished visitors with its clear walls and ceilings that did not require interior lights.

It has been suggested that the name of the building resulted from a piece penned by the playwright Douglas Jerrold, who in July 1850 wrote in the satirical magazine Punch about the forthcoming Great Exhibition, referring to a "palace of very crystal".

After the exhibition, the Palace was relocated to an area of South London known as Penge Common. It was rebuilt at the top of Penge Peak next to Sydenham Hill, an affluent suburb of large villas. It stood there from June 1854 until its destruction by fire in November 1936. The nearby residential area was renamed Crystal Palace after the landmark. This included the Crystal Palace Park that surrounds the site, home of the Crystal Palace National Sports Centre, which had previously been a football stadium that hosted the FA Cup Final between 1895 and 1914. Crystal Palace F.C. were founded at the site in 1905 and played at the Cup Final venue in their early years. The park still contains Benjamin Waterhouse Hawkins's Crystal Palace Dinosaurs which date back to 1854.

🔗 Insects 🔗 Insects/Ant

An ant mill is an observed phenomenon in which a group of army ants are separated from the main foraging party, lose the pheromone track and begin to follow one another, forming a continuously rotating circle, commonly known as a "death spiral" because the ants might eventually die of exhaustion. It has been reproduced in laboratories and has been produced in ant colony simulations. The phenomenon is a side effect of the self-organizing structure of ant colonies. Each ant follows the ant in front of it, which works until a slight deviation begins to occur, typically by an environmental trigger, and an ant mill forms. An ant mill was first described in 1921 by William Beebe, who observed a mill 1200 ft (~370 m) in circumference. It took each ant 2.5 hours to make one revolution. Similar phenomena have been noted in processionary caterpillars and fish.