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π Flexagon
In geometry, flexagons are flat models, usually constructed by folding strips of paper, that can be flexed or folded in certain ways to reveal faces besides the two that were originally on the back and front.
Flexagons are usually square or rectangular (tetraflexagons) or hexagonal (hexaflexagons). A prefix can be added to the name to indicate the number of faces that the model can display, including the two faces (back and front) that are visible before flexing. For example, a hexaflexagon with a total of six faces is called a hexahexaflexagon.
In hexaflexagon theory (that is, concerning flexagons with six sides), flexagons are usually defined in terms of pats.
Two flexagons are equivalent if one can be transformed to the other by a series of pinches and rotations. Flexagon equivalence is an equivalence relation.
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- "Flexagon" | 2024-03-04 | 166 Upvotes 39 Comments
π Human-powered helicopter
A human-powered helicopter (HPH) is a helicopter powered solely by one or more humans carried on board. As in other human-powered aircraft, the power is usually generated by pedalling. It remains a considerable engineering challenge to obtain both the power-to-weight ratio and rotor efficiency required to sustain a helicopter in flight.
On 13 June 2013, the AeroVelo Atlas was the first to complete a flight that lasted 64 seconds and reached an altitude of 3.3 metres, thus winning the American Helicopter Society (AHS) International's Igor I. Sikorsky Human Powered Helicopter Competition.
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- "Human-Powered Helicopter" | 2024-01-04 | 10 Upvotes 1 Comments
- "Human-powered helicopter" | 2018-05-23 | 28 Upvotes 6 Comments
π Can't Get You Out of My Head
Can't Get You Out of My Head: An Emotional History of the Modern World is a six-part BBC documentary television series created by Adam Curtis. It was released on BBC iPlayer on 11 February 2021.
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- "Can't Get You Out of My Head" | 2021-11-04 | 127 Upvotes 44 Comments
π Proxmox
Proxmox Virtual Environment (ProxmoxΒ VE or PVE) is an open-source software server for virtualization management. It is a hosted hypervisor that can run operating systems including Linux and Windows on x64 hardware. It is a Debian-based Linux distribution with a modified Ubuntu LTS kernel and allows deployment and management of virtual machines and containers. Proxmox VE includes a web console and command-line tools, and provides a REST API for third-party tools. Two types of virtualization are supported: container-based with LXC (starting from version 4.0 replacing OpenVZ used in version up to 3.4, included), and full virtualization with KVM. It includes a web-based management interface.
Proxmox VE is licensed under the GNU Affero General Public License, version 3.
Discussed on
- "Proxmox" | 2022-11-21 | 25 Upvotes 6 Comments
π Pirate Party
The Pirate Party (Swedish: Piratpartiet) is a political party in Sweden founded in 2006. Its sudden popularity has given rise to parties with the same name and similar goals in Europe and worldwide, forming the International Pirate Party movement.
The Pirate Party was initially formed to reform laws regarding copyright and patents. The party agenda includes support for strengthening the individual's right to privacy, both on the Internet and in everyday life, and the transparency of state administration. The Pirate Party has intentionally chosen to be bloc independent of the traditional left-right scale to pursue their political agenda with all mainstream parties. The party originally stayed neutral on other matters, but started broadening into other political areas in 2012.
The Pirate Party participated in the 2006 Riksdag elections and gained 0.63% of the votes, making them the third largest party outside parliament. In terms of membership, it passed the Green Party in December 2008, the Left Party in February 2009, the Liberal People's Party and the Christian Democrats in April 2009, and the Centre Party in May 2009, making it, for the time being, the third largest political party in Sweden by membership. The Pirate Party's associated youth organisation, Young Pirate (Swedish: Ung Pirat), was, for a part of 2009 and 2010, the largest political youth organisation in Sweden by membership count.
The Pirate Party came 5th in the 2009 European Parliament elections with 7.13% of the vote and 1 MEP (increasing to 2 after ratification of the Lisbon Treaty). Christian EngstrΓΆm became the first MEP for the party, and Amelia Andersdotter took the second seat on 1 December 2009.
Rick Falkvinge, founder of the party, stepped down on 1 January 2011 after five years as party leader, making vice leader Anna Troberg the party leader.
On 1 December 2014, Anna Troberg announced that she would not be available for re-election in 2015 after her term ended on 31 December 2014.
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- "Pirate Party" | 2023-06-10 | 31 Upvotes 4 Comments
π Cantor function, a.k.a. devil's staircase: increasing function with 0 derivative
In mathematics, the Cantor function is an example of a function that is continuous, but not absolutely continuous. It is a notorious counterexample in analysis, because it challenges naive intuitions about continuity, derivative, and measure. Though it is continuous everywhere and has zero derivative almost everywhere, its value still goes from 0 to 1 as its argument reaches from 0 to 1. Thus, in one sense the function seems very much like a constant one which cannot grow, and in another, it does indeed monotonically grow, by construction.
It is also referred to as the Cantor ternary function, the Lebesgue function, Lebesgue's singular function, the CantorβVitali function, the Devil's staircase, the Cantor staircase function, and the CantorβLebesgue function. Georg CantorΒ (1884) introduced the Cantor function and mentioned that Scheeffer pointed out that it was a counterexample to an extension of the fundamental theorem of calculus claimed by Harnack. The Cantor function was discussed and popularized by Scheeffer (1884), Lebesgue (1904) and Vitali (1905).
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- "Cantor function, a.k.a. devil's staircase: increasing function with 0 derivative" | 2020-06-11 | 96 Upvotes 52 Comments
π Elizabeth Fleischman
Elizabeth Fleischman-Aschheim (nΓ©e Fleischman 5 March 1867 β 3 August 1905) was an American radiographer who is considered an X-ray pioneer. Fleischman was the first woman to die as a result of X-ray radiation exposure.
π The Population Bomb (1968)
The Population Bomb is a 1968 book co-authored by former Stanford University professor Paul R. Ehrlich and former Stanford senior researcher in conservation biology Anne H. Ehrlich. From the opening page, it predicted worldwide famines due to overpopulation, as well as other major societal upheavals, and advocated immediate action to limit population growth. Fears of a "population explosion" existed in the mid-20th century baby boom years, but the book and its authors brought the idea to an even wider audience.
The book has been criticized since its publication for an alarmist tone, and over the subsequent decades, for inaccurate assertions and failed predictions. For instance, regional famines have occurred since the publication of the book, but not world famines. The Ehrlichs themselves still stand by the book despite the flaws identified by its critics, with Paul stating in 2009 that "perhaps the most serious flaw in The Bomb was that it was much too optimistic about the future," despite having predicted catastrophic global famines that never came to pass. They believe that it achieved their goals because "it alerted people to the importance of environmental issues and brought human numbers into the debate on the human future."
π Kugelmugel
Kugelmugel, officially the Republic of Kugelmugel (German: Republik Kugelmugel), is a spherical art object located in Vienna, Austria.
It came about as the result of the artist Edwin Lipburger constructing the 8 meter diameter spherical object without permissions from the authorities in Austria. After the dispute between the artist and authorities, the artist declared it a micronation, and it was eventually granted asylum by the then-mayor Helmut Zilk in Vienna where it is housed in the Prater park.
The 'Republic' is currently administered by Linda Treiber as president.
π Late Bronze Age Collapse
The Late Bronze Age collapse was a dark age transition in a large area covering much of Southeast Europe, West Asia and North Africa (comprising the overlapping regions of the Near East, the Eastern Mediterranean and North Africa, with the Balkans, the Aegean, Anatolia, and the Caucasus), which took place from the Late Bronze Age to the emerging Early Iron Age. It was a transition which historians believe was violent, sudden, and culturally disruptive, and involved societal collapse for some civilizations during the 12th century BCE. The palace economy of Mycenaean Greece, the Aegean region and Anatolia that characterized the Late Bronze Age disintegrated, transforming into the small isolated village cultures of the Greek Dark Ages. The Hittite Empire of Anatolia and the Levant collapsed, while states such as the Middle Assyrian Empire in Mesopotamia and the New Kingdom of Egypt survived but were considerably weakened.
Competing and even mutually compatible theories for the ultimate cause of the Late Bronze Age collapse have been made since the 19th century. These include volcanic eruptions, droughts, invasions by the Sea Peoples or migrations of Dorians, economic disruptions due to the rising use of ironworking, and changes in military technology and methods of war that saw the decline of chariot warfare.
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- "Late Bronze Age Collapse" | 2021-07-02 | 13 Upvotes 1 Comments