Have a deep view into what people are curious about.

🔗 Biology 🔗 Insects 🔗 Ecology

A hyperparasite, also known as a metaparasite is a parasite whose host, often an insect, is also a parasite, often specifically a parasitoid. Hyperparasites are found mainly among the wasp-waisted Apocrita within the Hymenoptera, and in two other insect orders, the Diptera (true flies) and Coleoptera (beetles). Seventeen families in Hymenoptera and a few species of Diptera and Coleoptera are hyperparasitic. Hyperparasitism developed from primary parasitism, which evolved in the Jurassic period in the Hymenoptera. Hyperparasitism intrigues entomologists because of its multidisciplinary relationship to evolution, ecology, behavior, biological control, taxonomy, and mathematical models.

🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/Military science, technology, and theory

MOLLE (pronounced , similar in pronunciation to the name Molly) is an acronym for Modular Lightweight Load-carrying Equipment. It is used to define the current generation of load-bearing equipment and backpacks used by a number of NATO armed forces, especially the British Army and the United States Army.

The system's modularity is derived from the use of Pouch Attachment Ladder System (PALS) webbing equipment as rows of heavy-duty nylon stitched onto the vest to allow for the attachment of various compatible pouches and accessories. This method of attachment has become a de facto standard for modular tactical gear, replacing the All-purpose Lightweight Individual Carrying Equipment (ALICE) system used in the earliest modular vest systems (which is still in use with many police forces).

🔗 Mathematics

The Banach–Tarski paradox is a theorem in set-theoretic geometry, which states the following: Given a solid ball in 3‑dimensional space, there exists a decomposition of the ball into a finite number of disjoint subsets, which can then be put back together in a different way to yield two identical copies of the original ball. Indeed, the reassembly process involves only moving the pieces around and rotating them without changing their shape. However, the pieces themselves are not "solids" in the usual sense, but infinite scatterings of points. The reconstruction can work with as few as five pieces.

A stronger form of the theorem implies that given any two "reasonable" solid objects (such as a small ball and a huge ball), the cut pieces of either one can be reassembled into the other. This is often stated informally as "a pea can be chopped up and reassembled into the Sun" and called the "pea and the Sun paradox".

The reason the Banach–Tarski theorem is called a paradox is that it contradicts basic geometric intuition. "Doubling the ball" by dividing it into parts and moving them around by rotations and translations, without any stretching, bending, or adding new points, seems to be impossible, since all these operations ought, intuitively speaking, to preserve the volume. The intuition that such operations preserve volumes is not mathematically absurd and it is even included in the formal definition of volumes. However, this is not applicable here because in this case it is impossible to define the volumes of the considered subsets. Reassembling them reproduces a volume, which happens to be different from the volume at the start.

Unlike most theorems in geometry, the proof of this result depends in a critical way on the choice of axioms for set theory. It can be proven using the axiom of choice, which allows for the construction of non-measurable sets, i.e., collections of points that do not have a volume in the ordinary sense, and whose construction requires an uncountable number of choices.

It was shown in 2005 that the pieces in the decomposition can be chosen in such a way that they can be moved continuously into place without running into one another.

🔗 Photography 🔗 Photography/History of photography

Kite aerial photography (KAP) is a type of photography. A camera is lifted using a kite and is triggered either remotely or automatically to take aerial photographs. The camera rigs can range from the extremely simple, consisting of a trigger mechanism with a disposable camera, to complex apparatus using radio control and digital cameras. On some occasions it can be a good alternative to other forms of aerial photography.

🔗 Computing 🔗 Computing/Software 🔗 Computing/Free and open-source software 🔗 Linux

The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems.

X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting with a mouse and keyboard. X does not mandate the user interface – this is handled by individual programs. As such, the visual styling of X-based environments varies greatly; different programs may present radically different interfaces.

X originated as part of Project Athena at Massachusetts Institute of Technology (MIT) in 1984. The X protocol has been at version 11 (hence "X11") since September 1987. The X.Org Foundation leads the X project, with the current reference implementation, X.Org Server, available as free and open-source software under the MIT License and similar permissive licenses.

🔗 Cryptography 🔗 Cryptography/Computer science 🔗 Poland

The method of Zygalski sheets was a cryptologic technique used by the Polish Cipher Bureau before and during World War II, and during the war also by British cryptologists at Bletchley Park, to decrypt messages enciphered on German Enigma machines.

The Zygalski-sheet apparatus takes its name from Polish Cipher Bureau mathematician–cryptologist Henryk Zygalski, who invented it about October 1938.

🔗 Mathematics

Legendre's constant is a mathematical constant occurring in a formula conjectured by Adrien-Marie Legendre to capture the asymptotic behavior of the prime-counting function ${\displaystyle \pi (x)}$. Its value is now known to be exactly 1.

Examination of available numerical evidence for known primes led Legendre to suspect that ${\displaystyle \pi (x)}$ satisfies an approximate formula.

Legendre conjectured in 1808 that

${\displaystyle \pi (x)={\frac {x}{\ln(x)-B(x)}}}$

where ${\displaystyle \lim _{x\to \infty }B(x)=1.08366}$....OEIS: A228211

Or similarly,

${\displaystyle \lim _{n\to \infty }\left(\ln(n)-{n \over \pi (n)}\right)=B}$

where B is Legendre's constant. He guessed B to be about 1.08366, but regardless of its exact value, the existence of B implies the prime number theorem.

Pafnuty Chebyshev proved in 1849 that if the limit B exists, it must be equal to 1. An easier proof was given by Pintz in 1980.

It is an immediate consequence of the prime number theorem, under the precise form with an explicit estimate of the error term

${\displaystyle \pi (x)={\rm {Li}}(x)+O\left(xe^{-a{\sqrt {\ln x}}}\right)\quad {\text{as }}x\to \infty }$

(for some positive constant a, where O(…) is the big O notation), as proved in 1899 by Charles de La Vallée Poussin, that B indeed is equal to 1. (The prime number theorem had been proved in 1896, independently by Jacques Hadamard and La Vallée Poussin, but without any estimate of the involved error term).

Being evaluated to such a simple number has made the term Legendre's constant mostly only of historical value, with it often (technically incorrectly) being used to refer to Legendre's first guess 1.08366... instead.

Pierre Dusart proved in 2010

${\displaystyle {\frac {x}{\ln x-1}}<\pi (x)}$ for ${\displaystyle x\geq 5393}$, and

${\displaystyle \pi (x)<{\frac {x}{\ln x-1.1}}}$ for ${\displaystyle x\geq 60184}$. This is of the same form as

${\displaystyle \pi (x)={\frac {x}{\ln(x)-B(x)}}}$ with ${\displaystyle 1<B(x)<1.1}$.

🔗 Germany 🔗 Denmark 🔗 Automobiles

The CityEl is a 3-wheel lightweight electric car originally designed and manufactured in Denmark, but currently made in Germany by Citycom GmbH.

🔗 Companies

Geneva Freeport (French: Ports Francs et Entrepôts de Genève SA) is a warehouse complex in Geneva, Switzerland, for the storage of art and other valuables and collectibles. The free port has been described as the "premier place" to store valuable works of art, and users "come for the security and stay for the tax treatment."

It is the oldest and largest freeport facility, and the one with the most artworks, with an estimated art collection value of US$100 billion. According to Jean-René Saillard of the British Fine Art Fund, "It would be probably the best museum in the world if it was a museum."

🔗 Human rights 🔗 Philosophy 🔗 Freedom of speech 🔗 Philosophy/Logic 🔗 Politics 🔗 Psychology 🔗 Sociology 🔗 Education 🔗 Popular Culture 🔗 Debating

A lie-to-children is a simplified, and often technically incorrect, explanation of technical or complex subjects employed as a teaching method. Educators who employ lies-to-children do not intend to deceive, but instead seek to 'meet the child/pupil/student where they are', in order to facilitate initial comprehension, which they build upon over time as the learner's intellectual capacity expands. The technique has been incorporated by academics within the fields of biology, evolution, bioinformatics and the social sciences.