Have a deep view into what people are curious about.

🔗 Germany 🔗 Germany/Hamburg 🔗 Germany/German transportation

Old Elbe Tunnel or St. Pauli Elbe Tunnel (German: Alter Elbtunnel colloquially or St. Pauli Elbtunnel officially) which opened in 1911, is a pedestrian and vehicle tunnel in Hamburg. The 426 m (1,398 ft) long tunnel was a technical sensation; 24 m (80 ft) beneath the surface, two 6 m (20 ft) diameter tubes connect central Hamburg with the docks and shipyards on the south side of the river Elbe. This was a big improvement for tens of thousands of workers in one of the busiest harbors in the world.

Six large lifts on either side of the tunnel carry pedestrians and vehicles to the bottom. The two tunnels are both still in operation, though due to their limited capacity by today's standards, other bridges and tunnels have been built and taken over most of the traffic.

In 2008 approximately 300,000 cars, 63,000 bicycles, and 700,000 pedestrians used the tunnel. The tunnel is opened 24 hours for pedestrians and bicycles. For motorized vehicles, opening times are currently Monday to Friday from 5:20 a.m. to 8:00 p.m. and on Saturdays from 5:20 a.m. to 4:00 p.m.

🔗 Mathematics

In mathematics, tetration (or hyper-4) is an operation based on iterated, or repeated, exponentiation. It is the next hyperoperation after exponentiation, but before pentation. The word was coined by Reuben Louis Goodstein from tetra- (four) and iteration.

Under the definition as repeated exponentiation, the notation ${\displaystyle {^{n}a}}$ means ${\displaystyle {a^{a^{\cdot ^{\cdot ^{a}}}}}}$, where n copies of a are iterated via exponentiation, right-to-left, I.e. the application of exponentiation ${\displaystyle n-1}$ times. n is called the "height" of the function, while a is called the "base," analogous to exponentiation. It would be read as "the nth tetration of a".

Tetration is also defined recursively as

${\displaystyle {^{n}a}:={\begin{cases}1&{\text{if }}n=0\\a^{\left(^{(n-1)}a\right)}&{\text{if }}n>0\end{cases}}}$,

allowing for attempts to extend tetration to non-natural numbers such as real and complex numbers.

The two inverses of tetration are called the super-root and the super-logarithm, analogous to the nth root and the logarithmic functions. None of the three functions are elementary.

Tetration is used for the notation of very large numbers.

🔗 Aviation 🔗 Military history 🔗 Military history/Military aviation 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Skepticism 🔗 Nevada 🔗 Paranormal 🔗 Aviation/airport

Area 51 is the common name of a highly classified United States Air Force (USAF) facility within the Nevada Test and Training Range. A remote detachment administered by Edwards Air Force Base, the facility is officially called Homey Airport (ICAO: KXTA, FAA LID: XTA) or Groom Lake (after the salt flat next to its airfield). Details of its operations are not made public, but the USAF says that it is an open training range, and it is commonly thought to support the development and testing of experimental aircraft and weapons systems. The USAF and CIA acquired the site in 1955, primarily for flight testing the Lockheed U-2 aircraft.

The intense secrecy surrounding the base has made it the frequent subject of conspiracy theories and a central component of unidentified flying object (UFO) folklore. It has never been declared a secret base, but all research and occurrences in Area 51 are Top Secret/Sensitive Compartmented Information (TS/SCI). The CIA publicly acknowledged the base's existence on 25 June 2013, following a Freedom of Information Act (FOIA) request filed in 2005 and declassified documents detailing its history and purpose.

Area 51 is located in the southern portion of Nevada, 83 miles (134 km) north-northwest of Las Vegas. The surrounding area is a popular tourist destination, including the small town of Rachel on the "Extraterrestrial Highway".

🔗 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.

🔗 Novels 🔗 Children's literature 🔗 Novels/Science fiction 🔗 Novels/Short story

"The Toynbee Convector" is a science fiction short story by American writer Ray Bradbury. First published in Playboy magazine in 1984, the story was subsequently featured in a 1988 short story collection also titled The Toynbee Convector.

🔗 Computing 🔗 Computer science 🔗 C/C++ 🔗 C/C++/C

In the C programming language, Duff's device is a way of manually implementing loop unrolling by interleaving two syntactic constructs of C: the do-while loop and a switch statement. Its discovery is credited to Tom Duff in November 1983, when Duff was working for Lucasfilm and used it to speed up a real-time animation program.

Loop unrolling attempts to reduce the overhead of conditional branching needed to check whether a loop is done, by executing a batch of loop bodies per iteration. To handle cases where the number of iterations is not divisible by the unrolled-loop increments, a common technique among assembly language programmers is to jump directly into the middle of the unrolled loop body to handle the remainder. Duff implemented this technique in C by using C's case label fall-through feature to jump into the unrolled body.

🔗 Shopping Centers 🔗 Zimbabwe

The Eastgate Centre is a shopping centre and office block in central Harare, Zimbabwe whose architect is Mick Pearce. Designed to be ventilated and cooled by entirely natural means, it was probably the first building in the world to use natural cooling to this level of sophistication. It opened in 1996 on Robert Mugabe Avenue and Second Street, and provides 5,600 m² of retail space, 26,000 m² of office space and parking for 450 cars.

🔗 History 🔗 Politics 🔗 Sociology 🔗 Politics/Oligarchy 🔗 Project-independent assessment

The iron law of oligarchy is a political theory, first developed by the German sociologist Robert Michels in his 1911 book, Political Parties. It asserts that rule by an elite, or oligarchy, is inevitable as an "iron law" within any democratic organization as part of the "tactical and technical necessities" of organization.

Michels's theory states that all complex organizations, regardless of how democratic they are when started, eventually develop into oligarchies. Michels observed that since no sufficiently large and complex organization can function purely as a direct democracy, power within an organization will always get delegated to individuals within that group, elected or otherwise.

Using anecdotes from political parties and trade unions struggling to operate democratically to build his argument in 1911, Michels addressed the application of this law to representative democracy, and stated: "Who says organization, says oligarchy." He went on to state that "Historical evolution mocks all the prophylactic measures that have been adopted for the prevention of oligarchy."

According to Michels all organizations eventually come to be run by a "leadership class", who often function as paid administrators, executives, spokespersons or political strategists for the organization. Far from being "servants of the masses", Michels argues this "leadership class," rather than the organization's membership, will inevitably grow to dominate the organization's power structures. By controlling who has access to information, those in power can centralize their power successfully, often with little accountability, due to the apathy, indifference and non-participation most rank and file members have in relation to their organization's decision-making processes. Michels argues that democratic attempts to hold leadership positions accountable are prone to fail, since with power comes the ability to reward loyalty, the ability to control information about the organization, and the ability to control what procedures the organization follows when making decisions. All of these mechanisms can be used to strongly influence the outcome of any decisions made 'democratically' by members.

Michels stated that the official goal of representative democracy of eliminating elite rule was impossible, that representative democracy is a façade legitimizing the rule of a particular elite, and that elite rule, which he refers to as oligarchy, is inevitable. Later Michels migrated to Italy and joined Benito Mussolini's Fascist Party, as he believed this was the next legitimate step of modern societies. The thesis became popular once more in post-war America with the publication of Union Democracy: The Internal Politics of the International Typographical Union (1956) and during the red scare brought about by McCarthyism.

🔗 Environment 🔗 Economics 🔗 Philosophy 🔗 Politics 🔗 Philosophy/Ethics 🔗 Game theory 🔗 Fisheries and Fishing

In economic science, the tragedy of the commons is a situation in which individual users, who have open access to a resource unhampered by shared social structures or formal rules that govern access and use, act independently according to their own self-interest and, contrary to the common good of all users, cause depletion of the resource through their uncoordinated action. The concept originated in an essay written in 1833 by the British economist William Forster Lloyd, who used a hypothetical example of the effects of unregulated grazing on common land (also known as a "common") in Great Britain and Ireland. The concept became widely known as the "tragedy of the commons" over a century later after an article written by Garrett Hardin in 1968. Faced with evidence of historical and existing commons, Hardin later retracted his original thesis, stating that the title should have been "The Tragedy of the Unmanaged Commons".

Although taken as a hypothetical example by Lloyd, the historical demise of the commons of Britain and Europe resulted not from misuse of long-held rights of usage by the commoners, but from the commons' owners enclosing and appropriating the land, abrogating the commoners' rights.

Although open-access resource systems may collapse due to overuse (such as in overfishing), many examples have existed and still do exist where members of a community with regulated access to a common resource co-operate to exploit those resources prudently without collapse, or even creating "perfect order". Elinor Ostrom was awarded the 2009 Nobel Memorial Prize in Economic Sciences for demonstrating this concept in her book Governing the Commons, which included examples of how local communities were able to do this without top-down regulations or privatization. On the other hand, Dieter Helm argues that these examples are context-specific and the tragedy of the commons "is not generally solved this way. If it were, the destruction of nature would not have occurred."

In a modern economic context, "commons" is taken to mean any open-access and unregulated resource such as the atmosphere, oceans, rivers, ocean fish stocks, or even an office refrigerator. In a legal context, it is a type of property that is neither private nor public, but rather held jointly by the members of a community, who govern access and use through social structures, traditions, or formal rules.

In environmental science, the "tragedy of the commons" is often cited in connection with sustainable development, meshing economic growth and environmental protection, as well as in the debate over global warming. It has also been used in analyzing behavior in the fields of economics, evolutionary psychology, anthropology, game theory, politics, taxation, and sociology.