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🔗 Mathematics

The gömböc (Hungarian: [ˈɡømbøt͡s]) is a convex three-dimensional homogeneous body that when resting on a flat surface has just one stable and one unstable point of equilibrium. Its existence was conjectured by the Russian mathematician Vladimir Arnold in 1995 and proven in 2006 by the Hungarian scientists Gábor Domokos and Péter Várkonyi. The gömböc shape is not unique; it has countless varieties, most of which are very close to a sphere and all with a very strict shape tolerance (about 0.1 mm per 100 mm).

The most famous solution, capitalized as Gömböc to distinguish it from the generic gömböc, has a sharpened top, as shown in the photo. Its shape helped to explain the body structure of some tortoises in relation to their ability to return to equilibrium position after being placed upside down. Copies of the gömböc have been donated to institutions and museums, and the largest one was presented at the World Expo 2010 in Shanghai in China. In December 2017, a 4.5 m gömböc statue was installed in the Corvin Quarter in Budapest.

🔗 Technology 🔗 Military history 🔗 Military history/Military aviation 🔗 Military history/North American military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Canada 🔗 Architecture 🔗 United Kingdom 🔗 Military history/Maritime warfare 🔗 Military history/World War II 🔗 Engineering 🔗 Ships 🔗 Military history/Canadian military history 🔗 Military history/European military history 🔗 Military history/British military history

Project Habakkuk or Habbakuk (spelling varies) was a plan by the British during the Second World War to construct an aircraft carrier out of pykrete (a mixture of wood pulp and ice) for use against German U-boats in the mid-Atlantic, which were beyond the flight range of land-based planes at that time. The idea came from Geoffrey Pyke, who worked for Combined Operations Headquarters. After promising scale tests and the creation of a prototype on a lake (Patricia Lake, Jasper National Park) in Alberta, Canada, the project was shelved due to rising costs, added requirements, and the availability of longer-range aircraft and escort carriers which closed the Mid-Atlantic gap the project was intended to address.

🔗 Economics

"The Market for Lemons: Quality Uncertainty and the Market Mechanism" is a well-known 1970 paper by economist George Akerlof which examines how the quality of goods traded in a market can degrade in the presence of information asymmetry between buyers and sellers, leaving only "lemons" behind. In American slang, a lemon is a car that is found to be defective after it has been bought.

Suppose buyers cannot distinguish between a high-quality car (a "peach") and a "lemon". Then they are only willing to pay a fixed price for a car that averages the value of a "peach" and "lemon" together (p_avg). But sellers know whether they hold a peach or a lemon. Given the fixed price at which buyers will buy, sellers will sell only when they hold "lemons" (since p_lemon < p_avg) and they will leave the market when they hold "peaches" (since p_peach > p_avg). Eventually, as enough sellers of "peaches" leave the market, the average willingness-to-pay of buyers will decrease (since the average quality of cars on the market decreased), leading to even more sellers of high-quality cars to leave the market through a positive feedback loop.

Thus the uninformed buyer's price creates an adverse selection problem that drives the high-quality cars from the market. Adverse selection is a market mechanism that can lead to a market collapse.

Akerlof's paper shows how prices can determine the quality of goods traded on the market. Low prices drive away sellers of high-quality goods, leaving only lemons behind. In 2001, Akerlof, along with Michael Spence, and Joseph Stiglitz, jointly received the Nobel Memorial Prize in Economic Sciences, for their research on issues related to asymmetric information.

🔗 Trains 🔗 Ships

A train ferry is a ship (ferry) designed to carry railway vehicles. Typically, one level of the ship is fitted with railway tracks, and the vessel has a door at the front and/or rear to give access to the wharves. In the United States, train ferries are sometimes referred to as "car ferries", as distinguished from "auto ferries" used to transport automobiles. The wharf (sometimes called a "slip") has a ramp, and a linkspan or "apron", balanced by weights, that connects the railway proper to the ship, allowing for the water level to rise and fall with the tides.

While railway vehicles can be and are shipped on the decks or in the holds of ordinary ships, purpose-built train ferries can be quickly loaded and unloaded by roll-on/roll-off, especially as several vehicles can be loaded or unloaded at once. A train ferry that is a barge is called a car float or rail barge.

🔗 Computing

When writing firmware for an embedded system, immunity-aware programming refers to programming techniques which improve the tolerance of transient errors in the program counter or other modules of a program that would otherwise lead to failure. Transient errors are typically caused by single event upsets, insufficient power, or by strong electromagnetic signals transmitted by some other "source" device.

Immunity-aware programming is an example of defensive programming and EMC-aware programming. Although most of these techniques apply to the software in the "victim" device to make it more reliable, a few of these techniques apply to software in the "source" device to make it emit less unwanted noise.

🔗 Computing 🔗 Economics 🔗 Computing/Early computers

The MONIAC (Monetary National Income Analogue Computer) also known as the Phillips Hydraulic Computer and the Financephalograph, was created in 1949 by the New Zealand economist Bill Phillips (William Phillips) to model the national economic processes of the United Kingdom, while Phillips was a student at the London School of Economics (LSE). The MONIAC was an analogue computer which used fluidic logic to model the workings of an economy. The MONIAC name may have been suggested by an association of money and ENIAC, an early electronic digital computer.

🔗 Computer Security 🔗 Computer Security/Computing

In computer security, a billion laughs attack is a type of denial-of-service (DoS) attack which is aimed at parsers of XML documents.

It is also referred to as an XML bomb or as an exponential entity expansion attack.

🔗 Spaceflight 🔗 Spaceflight/Timeline of spaceflight working group

This article documents notable spaceflight events during the year 2019.

🔗 Transhumanism 🔗 Alternative Views 🔗 Futures studies

American author, inventor and futurist Raymond Kurzweil has become well known for his predictions about artificial intelligence and the human species, mainly concerning the technological singularity. He predicts that Artificial Intelligence would outsmart the human brain in computational capabilities by mid-21st century. His first book, The Age of Intelligent Machines, published in 1990, put forth his theories on the results of the increasing use of technology and predicted the explosive growth in the internet, among other predictions. Later works, 1999's The Age of Spiritual Machines and 2005's The Singularity is Near outlined other theories including the rise of clouds of nano-robots (nanobots) called foglets and the development of Human Body 2.0 and 3.0, whereby nanotechnology is incorporated into many internal organs.

🔗 Russia 🔗 Russia/technology and engineering in Russia 🔗 Film 🔗 Film/Filmmaking 🔗 Russia/science and education in Russia 🔗 Russia/performing arts in Russia 🔗 Film/Soviet and post-Soviet cinema

The Kuleshov effect is a film editing (montage) effect demonstrated by Soviet filmmaker Lev Kuleshov in the 1910s and 1920s. It is a mental phenomenon by which viewers derive more meaning from the interaction of two sequential shots than from a single shot in isolation.