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π Cashew of Pirangi
The Cashew of Pirangi (Cajueiro de Pirangi), also called the world's largest cashew tree (maior cajueiro do mundo), is a cashew tree in Pirangi do Norte, Rio Grande do Norte, Brazil. In 1994, the tree entered the Guinness Book of Records. It covers an area between 7,300 square metres (1.8 acres) and 8,400 square metres (2.1 acres). Having the size of 70 normally sized cashew trees, it has a circumference of 500Β m (1,600Β ft). The vicinity of the World's Largest Cashew Tree in North Pirangi is also a main place for the sale of lace and embroidery in Rio Grande do Norte state.
The spread over a hectare of land was, unlike other trees, created by the tree's outward growth. When bent towards the ground (because of their weight), the branches tend to take new roots where they touch the ground. This may be seen in the images of the interior. It is now difficult to distinguish the initial trunk from the rest of the tree.
The tree is said to have been planted in 1888. However, based on its growth nature, "the tree is estimated to be more than a thousand years old." The tree produces over 60,000 fruits each year.
FlΓ‘vio Nogueira, Jr., the state secretary of tourism for PiauΓ, has claimed that the Cashew of Pirangi in PiauΓ is, in fact, the largest tree, covering an area of 8,800 square metres (2.2 acres). That tree was studied by a laboratory from the State University of PiauΓ.
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- "Cashew of Pirangi" | 2020-12-04 | 177 Upvotes 38 Comments
π Kelvin's hydroelectric generator
The Kelvin water dropper, invented by Scottish scientist William Thomson (Lord Kelvin) in 1867, is a type of electrostatic generator. Kelvin referred to the device as his water-dropping condenser. The apparatus is variously called the Kelvin hydroelectric generator, the Kelvin electrostatic generator, or Lord Kelvin's thunderstorm. The device uses falling water to generate voltage differences by electrostatic induction occurring between interconnected, oppositely charged systems. This eventually leads to an electric arc discharging in the form of a spark. It is used in physics education to demonstrate the principles of electrostatics.
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- "Kelvin's hydroelectric generator" | 2009-04-09 | 17 Upvotes 7 Comments
π Oligodynamic Effect
The oligodynamic effect (from Greek oligos "few", and dynamis "force") is a biocidal effect of metals, especially heavy metals, that occurs even in low concentrations.
In modern times, the effect was observed by Karl Wilhelm von NΓ€geli, although he did not identify the cause. Scholarly texts from ancient India promoted the use of brass and silver in ritual cleansing practice as well as in consumption of food and drink. The ancient Indian medical text Sushruta Samhita promoted the use of specific metals in surgical procedures as a measure to prevent infection. Brass doorknobs and silverware both exhibit this effect to an extent.
Discussed on
- "Oligodynamic Effect" | 2020-03-14 | 62 Upvotes 10 Comments
π Maestro I β The First IDE?
Maestro I was an early integrated development environment for software. developed by Softlab Munich in the 1970s and 1980s.
The system was originally called "Programm-Entwicklungs-Terminal-System" ("program development terminal system") abbreviated as PET; it was renamed after Commodore International introduced a home computer called the Commodore PET in 1977.
At one time there were 22,000 installations worldwide. The first USA installations were at Boeing in 1979, with eight Maestro I systems and Bank of America with 24 system and 576 developer terminals. Until 1989, there were 6,000 installations in the Federal Republic of Germany [1].
One of the last Maestro I systems is at the Museum of Information Technology at Arlington.
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- "Maestro I β The First IDE?" | 2024-01-10 | 22 Upvotes 5 Comments
π Fractional calculus
Fractional calculus is a branch of mathematical analysis that studies the several different possibilities of defining real number powers or complex number powers of the differentiation operator D
and of the integration operator J
and developing a calculus for such operators generalizing the classical one.
In this context, the term powers refers to iterative application of a linear operator D to a function f, that is, repeatedly composing D with itself, as in .
For example, one may ask for a meaningful interpretation of:
as an analogue of the functional square root for the differentiation operator, that is, an expression for some linear operator that when applied twice to any function will have the same effect as differentiation. More generally, one can look at the question of defining a linear functional
for every real-number a in such a way that, when a takes an integer value n β β€, it coincides with the usual n-fold differentiation D if n > 0, and with the βnth power of J when n < 0.
One of the motivations behind the introduction and study of these sorts of extensions of the differentiation operator D is that the sets of operator powers { Da |a β β } defined in this way are continuous semigroups with parameter a, of which the original discrete semigroup of { Dn | n β β€ } for integer n is a denumerable subgroup: since continuous semigroups have a well developed mathematical theory, they can be applied to other branches of mathematics.
Fractional differential equations, also known as extraordinary differential equations, are a generalization of differential equations through the application of fractional calculus.
Discussed on
- "What's your intuitive understanding of fractional derivatives?" | 2022-10-24 | 12 Upvotes 4 Comments
- "Fractional calculus" | 2010-05-30 | 45 Upvotes 7 Comments
π Battle of Vukovar: how 1,800 fighters held off a force of 36,000
The Battle of Vukovar was an 87-day siege of Vukovar in eastern Croatia by the Yugoslav People's Army (JNA), supported by various paramilitary forces from Serbia, between August and November 1991. Before the Croatian War of Independence the Baroque town was a prosperous, mixed community of Croats, Serbs and other ethnic groups. As Yugoslavia began to break up, Serbia's President Slobodan MiloΕ‘eviΔ and Croatia's President Franjo TuΔman began pursuing nationalist politics. In 1990, an armed insurrection was started by Croatian Serb militias, supported by the Serbian government and paramilitary groups, who seized control of Serb-populated areas of Croatia. The JNA began to intervene in favour of the rebellion, and conflict broke out in the eastern Croatian region of Slavonia in May 1991. In August, the JNA launched a full-scale attack against Croatian-held territory in eastern Slavonia, including Vukovar.
Vukovar was defended by around 1,800 lightly armed soldiers of the Croatian National Guard (ZNG) and civilian volunteers, against as many as 36,000 JNA soldiers and Serb paramilitaries equipped with heavy armour and artillery. During the battle, shells and rockets were fired into the town at a rate of up to 12,000 a day. At the time, it was the fiercest and most protracted battle seen in Europe since 1945, and Vukovar was the first major European town to be entirely destroyed since the Second World War. When Vukovar fell on 18 November 1991, several hundred soldiers and civilians were massacred by Serb forces and at least 20,000 inhabitants were expelled. Overall, around 3,000 people died during the battle. Most of Vukovar was ethnically cleansed of its non-Serb population and became part of the self-declared proto-state known as the Republic of Serbian Krajina. Several Serb military and political officials, including MiloΕ‘eviΔ, were later indicted and in some cases jailed for war crimes committed during and after the battle.
The battle exhausted the JNA and proved a turning point in the Croatian War of Independence. A cease-fire was declared a few weeks later. Vukovar remained in Serb hands until 1998, when it was peacefully reintegrated into Croatia with the signing of the Erdut Agreement. It has since been rebuilt but has less than half of its pre-war population and many buildings are still scarred by the battle. Its two principal ethnic communities remain deeply divided and it has not regained its former prosperity.
Discussed on
- "Battle of Vukovar: how 1,800 fighters held off a force of 36,000" | 2025-07-06 | 17 Upvotes 4 Comments
π SWEET16: Interpreted byte-code instruction set invented by Steve Wozniak
SWEET16 is an interpreted byte-code instruction set invented by Steve Wozniak and implemented as part of the Integer BASIC ROM in the Apple II series of computers. It was created because Wozniak needed to manipulate 16-bit pointer data, and the Apple II was an 8-bit computer.
SWEET16 was not used by the core BASIC code, but was later used to implement several utilities. Notable among these was the line renumbering routine, which was included in the Programmer's Aid #1 ROM, added to later Apple II models and available for user installation on earlier examples.
SWEET16 code is executed as if it were running on a 16-bit processor with sixteen internal 16-bit little-endian registers, named R0 through R15. Some registers have well-defined functions:
- R0Β β accumulator
- R12Β β subroutine stack pointer
- R13Β β stores the result of all comparison operations for branch testing
- R14Β β status register
- R15Β β program counter
The 16 virtual registers, 32 bytes in total, are located in the zero page of the Apple II's real, physical memory map (at $00β$1F), with values stored as low byte followed by high byte. The SWEET16 interpreter itself is located from $F689 to $F7FC in the Integer BASIC ROM.
According to Wozniak, the SWEET16 implementation is a model of frugal coding, taking up only about 300 bytes in memory. SWEET16 runs at about one-tenth the speed of the equivalent native 6502 code.
Discussed on
- "SWEET16: Interpreted byte-code instruction set invented by Steve Wozniak" | 2023-10-14 | 23 Upvotes 3 Comments
π Hostile Architecture
Hostile architecture is an intentional design strategy that uses elements of the built environment to guide or restrict behaviour in urban space as a form of crime prevention or order maintenance. It often targets people who use or rely on public space more than others, like people who are homeless and youth, by restricting the behaviours they engage in. Also known as defensive architecture, hostile design, unpleasant design, exclusionary design, or defensive urban design, hostile architecture is most typically associated with "anti-homeless spikes" β studs embedded in flat surfaces to make sleeping rough, uncomfortable, and impractical. Other measures include sloped window sills to stop people sitting, benches with armrests positioned to stop people lying on them, and water sprinklers that "intermittently come on but aren't really watering anything." Hostile architecture also seeks to deter skateboarding, littering, loitering, and public urination. Critics argue that such measures reinforce social divisions and create problems for all members of the public, especially seniors, people with disabilities, and children.
Discussed on
- "Hostile Architecture" | 2019-08-06 | 104 Upvotes 112 Comments
π Long Hundred
The long hundred, also known as the great hundred or twelfty, is the number that was referred to as "hundred" in Germanic languages prior to the 15th century, which is now known as 120, one hundred and twenty, or six score. The number was simply described as hundred and translated into Latin in Germanic-speaking countries as centum (Roman numeral C), but the qualifier "long" is now added because present English uses the word "hundred" exclusively to refer to the number of five score (100) instead.
The long hundred was 120 but the long thousand was reckoned decimally as 10 long hundreds (1200).
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- "Long Hundred" | 2021-02-08 | 97 Upvotes 106 Comments
π Paternoster
Pater Noster, or the Lord's Prayer, is a prayer in Christianity.
Pater Noster or Paternoster may also refer to:
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- "Paternoster" | 2015-03-29 | 127 Upvotes 72 Comments