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In cryptography a blind signature, as introduced by David Chaum, is a form of digital signature in which the content of a message is disguised (blinded) before it is signed. The resulting blind signature can be publicly verified against the original, unblinded message in the manner of a regular digital signature. Blind signatures are typically employed in privacy-related protocols where the signer and message author are different parties. Examples include cryptographic election systems and digital cash schemes.

An often-used analogy to the cryptographic blind signature is the physical act of a voter enclosing a completed anonymous ballot in a special carbon paper lined envelope that has the voter's credentials pre-printed on the outside. An official verifies the credentials and signs the envelope, thereby transferring their signature to the ballot inside via the carbon paper. Once signed, the package is given back to the voter, who transfers the now signed ballot to a new unmarked normal envelope. Thus, the signer does not view the message content, but a third party can later verify the signature and know that the signature is valid within the limitations of the underlying signature scheme.

Blind signatures can also be used to provide unlinkability, which prevents the signer from linking the blinded message it signs to a later un-blinded version that it may be called upon to verify. In this case, the signer's response is first "un-blinded" prior to verification in such a way that the signature remains valid for the un-blinded message. This can be useful in schemes where anonymity is required.

Blind signature schemes can be implemented using a number of common public key signing schemes, for instance RSA and DSA. To perform such a signature, the message is first "blinded", typically by combining it in some way with a random "blinding factor". The blinded message is passed to a signer, who then signs it using a standard signing algorithm. The resulting message, along with the blinding factor, can be later verified against the signer's public key. In some blind signature schemes, such as RSA, it is even possible to remove the blinding factor from the signature before it is verified. In these schemes, the final output (message/signature) of the blind signature scheme is identical to that of the normal signing protocol.

Since the second half of the 20th century, inscriptions have been found on pottery in a variety of locations in China, such as Banpo near Xi'an, as well as on bone and bone marrows at Hualouzi, Chang'an County near Xi'an. These simple, often geometric, marks have been frequently compared to some of the earliest known Chinese characters appearing on the oracle bones, and some have taken them to mean that the history of Chinese writing extends back over six millennia. However, only isolated instances of these symbols have been found, and they show no indication of representing speech or of the non-pictorial processes that a writing system requires.

GNS theory is an informal field of study developed by Ron Edwards which attempts to create a unified theory of how role-playing games work. Focused on player behavior, in GNS theory participants in role-playing games organize their interactions around three categories of engagement: Gamism, Narrativism and Simulation.

The theory focuses on player interaction rather than statistics, encompassing game design beyond role-playing games. Analysis centers on how player behavior fits the above parameters of engagement and how these preferences shape the content and direction of a game. GNS theory is used by game designers to dissect the elements which attract players to certain types of games.

The haversine formula determines the great-circle distance between two points on a sphere given their longitudes and latitudes. Important in navigation, it is a special case of a more general formula in spherical trigonometry, the law of haversines, that relates the sides and angles of spherical triangles.

The first table of haversines in English was published by James Andrew in 1805, but Florian Cajori credits an earlier use by José de Mendoza y Ríos in 1801. The term haversine was coined in 1835 by James Inman.

These names follow from the fact that they are customarily written in terms of the haversine function, given by hav(θ) = sin²(θ/2). The formulas could equally be written in terms of any multiple of the haversine, such as the older versine function (twice the haversine). Prior to the advent of computers, the elimination of division and multiplication by factors of two proved convenient enough that tables of haversine values and logarithms were included in nineteenth and early twentieth century navigation and trigonometric texts. These days, the haversine form is also convenient in that it has no coefficient in front of the sin² function.

In professional wrestling, kayfabe (also called work or worked) is the portrayal of staged events within the industry as "real" or "true", specifically the portrayal of competition, rivalries, and relationships between participants as being genuine and not of a staged or predetermined nature of any kind. The term kayfabe has evolved to also become a code word of sorts for maintaining this "reality" within the direct or indirect presence of the general public.

Kayfabe is often seen as the suspension of disbelief that is used to create the non-wrestling aspects of promotions, such as feuds, angles, and gimmicks in a manner similar to other forms of fictional entertainment. In relative terms, a wrestler breaking kayfabe during a show would be likened to an actor breaking character on-camera. Also, since wrestling is performed in front of a live audience, whose interaction with the show is crucial to its success, kayfabe can be compared to the fourth wall in acting, since hardly any conventional fourth wall exists to begin with. In general, everything in a professional wrestling show is to some extent scripted, or "kayfabe", even though at times it is portrayed as real-life.

Kayfabe was fiercely maintained for decades, but with the advent of the Internet wrestling community, and the sports entertainment movement, the pro wrestling industry has become less concerned with protecting so-called backstage secrets and typically maintains kayfabe only during the shows. Kayfabe is, however, occasionally broken during shows, usually when dealing with genuine injuries during a match or paying tribute to wrestlers.

A Michigan left is an at-grade intersection design that replaces each left turn at an intersection between a (major) divided roadway and a secondary (minor) roadway with the combination of a right turn followed by a U-turn, or a U-turn followed by a right turn, depending on the situation.

The Cybiko is a Russian handheld computer introduced in the United States by David Yang's company Cybiko Inc. as a retail test market in New York on April 2000, and rolled out nationwide in May 2000. It is designed for teens, featuring its own two-way radio text messaging system. It had over 430 "official" freeware games and applications. Because of the text messaging system, it features a rubber QWERTY keyboard. An MP3 player add-on with a SmartMedia card slot was made for the unit as well. The company stopped manufacturing the units after two product versions and only a few years on the market. Cybikos can communicate with each other up to a maximum range of 100 metres (300 feet). Several Cybikos can chat with each other in a wireless chatroom. By the end of 2000, the Cybiko Classic sold over 500,000 units.

Bremermann's limit, named after Hans-Joachim Bremermann, is a limit on the maximum rate of computation that can be achieved in a self-contained system in the material universe. It is derived from Einstein's mass-energy equivalency and the Heisenberg uncertainty principle, and is c²/h ≈ 1.36 × 10⁵⁰ bits per second per kilogram. This value is important when designing cryptographic algorithms, as it can be used to determine the minimum size of encryption keys or hash values required to create an algorithm that could never be cracked by a brute-force search.

For example, a computer with the mass of the entire Earth operating at the Bremermann's limit could perform approximately 10⁷⁵ mathematical computations per second. If one assumes that a cryptographic key can be tested with only one operation, then a typical 128-bit key could be cracked in under 10⁻³⁶ seconds. However, a 256-bit key (which is already in use in some systems) would take about two minutes to crack. Using a 512-bit key would increase the cracking time to approaching 10⁷² years, without increasing the time for encryption by more than a constant factor (depending on the encryption algorithms used).

The limit has been further analysed in later literature as the maximum rate at which a system with energy spread ${\displaystyle \Delta E}$ can evolve into an orthogonal and hence distinguishable state to another, ${\displaystyle \Delta t={\frac {\pi \hbar }{2\Delta E}}.}$ In particular, Margolus and Levitin have shown that a quantum system with average energy E takes at least time ${\displaystyle \Delta t={\frac {\pi \hbar }{2E}}}$ to evolve into an orthogonal state. However, it has been shown that access to quantum memory in principle allows computational algorithms that require arbitrarily small amount of energy/time per one elementary computation step.

Yuan Longping (Chinese: 袁隆平; September 7, 1930 – May 22, 2021) was a Chinese agronomist, member of the Chinese Academy of Engineering, known for developing the first hybrid rice varieties in the 1970s.

Hybrid rice has since been grown in dozens of countries in Africa, America, and Asia—providing a robust food source in areas with a high risk of famine. For his contributions, Yuan is always called the "Father of Hybrid Rice" by the Chinese media. On May 22, 2021, Yuan Longping died of multiple organ failure at the age of 90.

The photophone is a telecommunications device that allows transmission of speech on a beam of light. It was invented jointly by Alexander Graham Bell and his assistant Charles Sumner Tainter on February 19, 1880, at Bell's laboratory at 1325 L Street in Washington, D.C. Both were later to become full associates in the Volta Laboratory Association, created and financed by Bell.

On June 3, 1880, Bell's assistant transmitted a wireless voice telephone message from the roof of the Franklin School to the window of Bell's laboratory, some 213 meters (about 700 ft.) away.

Bell believed the photophone was his most important invention. Of the 18 patents granted in Bell's name alone, and the 12 he shared with his collaborators, four were for the photophone, which Bell referred to as his "greatest achievement", telling a reporter shortly before his death that the photophone was "the greatest invention [I have] ever made, greater than the telephone".

The photophone was a precursor to the fiber-optic communication systems that achieved worldwide popular usage starting in the 1980s. The master patent for the photophone (U.S. Patent 235,199 Apparatus for Signalling and Communicating, called Photophone) was issued in December 1880, many decades before its principles came to have practical applications.